More Important Topics of Cylinder

The discovery of the specimen OH 5 ("Zinj") in 1959, by Mary Leakey, was a watershed in the history of paleoanthropology.

The find vindicated Louis and Mary Leakey's work at Olduvai (which had been relatively fruitless over the previous 30 years), which led to renewed research interest in the area, added an important stage in a relatively sparse hominid lineage at the time, and also was important in focusing attention on multidisciplinary research. The fairly complete cranium (sans mandible) was given the species name

Zinjanthropus boisei by Louis Leakey, which eventually became known as Australopithecus boisei. However,

Zinjanthropus lives on in the well known nickname of OH 5, "Zinj". Specimens attributed to A. boisei have been found mostly in Ethiopia, Tanzania, and Kenya in East Africa. The oldest has been found at Omo, Ethiopia, dating to approximately 2.3 myr (L. 74a-21), and the youngest has been found at Olduvai Gorge, dating to approximately 1.2 myr (OH 3 and OH 38).A. boisei seems to be the end point of a lineage that that was adapted to high masticatory stress needed to deal with hard low-quality foods.

This species is sometimes called "hyper-robust" due to the relative and absolute size of their postcanines. This lineage may have died out due to overspecialization to a specific environment, and when the environment changed, evolution could not keep up. This seems to be the generally accepted idea regarding boisei, and there seems little hard evidence to contradict it. The most striking feature of the A. boisei specimens is

the degree of megadontia. These species has the absolute largest teeth found in any hominid group, with teeth similar in size to gorillas (who weigh as much as 10 times as much). They are often referred to as hyper-robust due to the massive postcanine megadontia.

The features of boisei are best described in relation to the other "robusts" (including aethiopicus), since this best shows some of the features that exclude aethiopicus from the "robust" lineage in favor of africanus. Features that line up boisei as a descendent of africanus rather than aethiopicus include:

The face is more vertically set, more orthognathic (variability in this trait).

There is anterior teeth reduction. There is a continued increase in postcanine teeth size. There is a larger cranial capacity (500-550 cc). The sagittal crest is on the mid-brain case, not the posterior.

Since aethiopicus and africanus are contemporary, only one can be the ancestor to boisei, and africanus seems a more likely scenario. Perhaps more importantly, boisei shares unique traits with later species that undoubtedly link it with africanus (who is likely the ancestor of these later species). Features that link boisei with A. robustus (and possibly early Homo) include:

Some structural brain differences reflected in endocasts, such as: A) greater frontal lobe breadth B) expanded parietal cortex C) increased cerebral height (high cerebral to cerebellar height) D) cerebellar lobes "tucked in" and not projecting laterally or posteriorly.

Increased flexion of the cranial base. Shortening of the base and decrease in the angle of the petrous pyramids. More anterior foramen magnum position. Deeper mandibular fossa with well-delineated, projecting, articular eminence. Nearly horizontal orientation of nuchal plane. Expanded height of occipital plane of the occiput, with a concomitant low inion position. Decreased facial prognathism, especially subnasal.

Shortened distance between the tooth row and the mandibular fossa. Reduced posterior component of temporalis muscle. Weakly developed or absence of pneumatized bone in the temporal squama. The hyper-robusticity of boisei did not extend to their body size, as they are approximately only 10% larger than africanus (and a whopping 60% smaller than aethiopicus). A. boisei also shows a progression toward a more modern form relative to its ancestors, as sexual dimorphism is reduced (with males 1.3 time larger than females).

A. boisei was very important in clearing up a controversy that raged in the 1960s over the idea of the "Single Species Hypothesis" (championed by University of Michigan professor Milford Wolpoff). The single species hypothesis states that every environmental niche can only support one species, and that in hominids, "monkey-see monkey-do" holds true.

Thus, if contemporary hominid groups came into contact, they would have the same behaviors, would attempt to fill the same niche, and conflict would ensue with one species the evolutionary victor, and one the loser (or would create an atmosphere where multiple hominid groups could not arise, due to the competition).

It was argued that the known remains belonged to a single sexually dimorphic species, with the males attributed to robustus, and the females attributed to africanus.

The discovery of boisei of both sexes in the same site, dated to the same time, showed that even if the South African material was a single sexually dimorphic species, boisei was a different species contemporary with it, bringing into doubt the validity of the single species hypothesis.

It is now generally accepted that (in the instance of the South African australopithecines) there is two separate species, and not a single sexually dimorphic one. While some claim that this was the "death" of the single species hypothesis, it really only showed that two different species could be contemporary, and modified single species concept (one highly variable population concept) is alive and well, and difficult to prove or disprove, which guarantees it will be around and debated for a long time to come.

Australopithecus boisei is an important species both in the history of paleoanthropological research and in constructing the phylogeny of the hominid lines. The features it shares or lacks with contemporary and earlier species makes relatively clear the relative phylogeny of the "robust" australopithecines.

It also is present at a time when stone tools become much more common, and may have even made and used some. In the end, however, it seems that boisei became too specialized, and died with climatic and/or environmental shifts.

The shape and the size of the molar convinced Broom that this was a different species than A. africanus (Broom's transvaalensis), and upon further investigation, found that the specimen had been found by a young boy who worked in the cave as a guide on Sundays.

Broom searched for the boy (Gert Terblanche) and found him at school. Broom lectured the boy's class on the cave sites of the area, and was then led to the place of the

specimen's discovery, Kromdraai. Broom found several

Broom spent some time working on a monograph of the australopithecines, which was published in 1946. This monograph included the description of TM 1517, and was a turning point for the South African australopithecines in the eyes of the world. The monograph received the U.S. National Academy of Sciences award for the most important book of the year in biology, and along

with L Gros Clark's published approval of the South African australopithecines as hominids, was very important in altering the view that the South African specimens were human ancestors and not simply an ape.

Another important find was SK 6, a portion of mandible and several teeth. Another discovery of Broom's, he originally named a new species on it (Paranthropus crassidens). However, the specimen is generally accepted as robustus, though it is also considered a type specimen because of this separate species designation. One of the more complete robustus specimens is SK 48, a fairly complete crania of what is probably a female.

This specimen - due to its completeness - added much information on the cranial characteristics of the robust australopithecines. One specimen may or may not be robustus, since it was found at Sterkfontein, and the presence of robustus and africanus in the same place at basically the same time would cause some phylogentic attribution of the robust australopithecines major problems.

STW 252 is considered by those who see more than one species at Sterkfontein as robustus, and as africanus by those that see one species. The dentition seems to indicate inclusion in robustus, but the uncertainty of the date causes some to view it cautiously. The A. robustus remains generally are from three sites: Swartkrans, Dreimulen, and Kromdraai (with the aforementioned Sterkfontein specimen possibly included).

By far the largest of these sites is Swartkrans. One of the major problems with these South African sites is dating, but generally, robustus remains can be safely placed from 2.0-1.0 myr, and possibly even earlier. The dating of these sites is crucial to understanding the phylogeny of the robust australopithecines, but for now, the dates are somewhat in question.

An understanding of the characteristics of robustus can best be seen by comparing them to an earlier specie (africanus) and a penecontemporary one (boisei).

The robustus crania are many, but fragmentary, with a known cranial capacity for just one individual specimen, SK 1585, an endocast with a 530 cc capacity. There is evidence of significant expansion over africanus, with an estimated 15% average increase in brain size over africanus.

The sexual dimorphism level of about 20% seems to be basically unchanged. In his analysis of SK 1585, R. Holloway concluded that robustus shows a general trend towards a more modern brain - similar to that of boisei - over that of africanus. These modern trends include:

Some structural brain differences reflected in endocasts, such as: A) greater frontal lobe breadth B) expanded parietal cortex C) increased cerebral height (high cerebral to cerebellar height) D) cerebellar lobes "tucked in" and not projecting laterally or posteriorly. Increased flexion of the cranial base.

Shortening of the base and decrease in the angle of the petrous pyramids. More anterior foramen magnum position. Deeper mandibular fossa with well-delineated, projecting, articular eminence. Nearly horizontal orientation of nuchal plane. Expanded height of occipital plane of the occiput, with a concomitant low inion position. Decreased facial prognathism, especially subnasal.

Shortened distance between the tooth row and the mandibular fossa. Reduced posterior component of temporalis muscle. Weakly developed or absence of pneumatized bone in the temporal squama. The increase in body size over africanus is minimal, which means that there is significantly increased encephalization, rather than simply an allometric increase with increased body size.

The remains from Swartkrans are very variable, but seem (compared to africanus) to have more robust crania, with better developed muscle markings, more prominent tori, and thicker buttressing structures. Like the earlier specimens, these features are on a fairly thin cranial vault.

The cranial bases seem to differ, but the preservation makes comparisons difficult, with only one unambiguously preserved specimen (SK 47). What evidence there is seems to indicate that the Swartkrans hominids have a broader and shorter (more Homo-like) cranial bases with a more anterior foramen magnum position, and a petrous bone that is more transversely oriented than in earlier australopithecines.

The amount of basicranial flexion seems moderate (more than africanus, less than boisei). However, these observations are made unclear due to the specimen being a juvenile, but the 495 cc cranial capacity is close to the female mean, and there likely would have been little change.

A. robustus continues the trends seen in africanus with regards to facial changes, but remains very similar (and distinct from boisei). These features include:

The two species are equally prognathic.

Both have nasal bones that are the same size and shape.

Both have anterior pillars that border the nasal aperture, extending upward from the buttresses for the canine roots.

Both have a lower border of the cheek that is virtually a straight line from its origin on the side of the palate, extending to the base of the zygomatic arch, which is the widest portion of the face.

There is substantial increases in postcanine tooth size (though not at the level of boisei), with increases in both absolute and relative size over africanus. The canines seem to have changed little, while the incisors decreased in size significantly, possibly due to overcrowding, as there is overlap of anterior teeth in 43% of the Swartkrans remains.

The increase in postcanine tooth size includes an increase in enamel thickness, and while this has been interpreted in various ways, the idea that robustus was an herbivore/frugivore that subsisted on hard gritty nuts and plants (J.T. Robinson's dietary hypothesis) seems to be in serious doubt, with an eclectic omnivorous diet seems to be more likely due to recent work determining low strontium/calcium ratios, and C4 contribution (likely from eating grazing animals).

Postcranial evidence shows little difference between robustus, africanus, or boisei. They were all small-bodied obligate bipeds, that used an efficient walking gait.

The main question regarding A. robustus seems to be the question of whether or not it is a separate species from A. boisei, or if they are geographic species of a wide-ranging variable population.

Most researchers seem to agree that they are separate lineages, with several important evolutionary trends that distinguish them. However, they share even more of the same evolutionary trends. It seems safe to call these separate lineages, but a vocal protest exists among those who see a monophyletic lineage (re: Paranthropus).

For its antiquity, A. afarensis is one of the better known species of early human, with specimens collected from over 300 individuals.

It is a species that exhibits many cranial features which are reminiscent of our ape ancestry, such as a forward protruding (prognathic) face, a "U-shaped" palate (with the cheek teeth parallel in rows to each other similar to an ape) and not the parabolic shape of a modern human, and a small neurocranium (brain case) that averages only 430cc in size (not significantly larger than a modern chimpanzee).

The specimens recovered have given representative examples of almost all of the bones of the A. afarensis skeleton. From this, it is clear that there are many

significant difference between A. afarensis and its ape predecessors, one of which is crucial to later human evolution, bipedality.

The position of A. afarensis in the phylogeny of early humans is under debate. Many feel that it is ancestral to the east African "robust" early humans, and possibly to all robust forms.

Additionally, A. afarensis is proposed as the ancestor to later Homo.

The species of Australopithecus africanus was named in a February, 1925, issue of Nature by Raymond Dart. R. Dart was one of the pioneers of paleoanthropology, and created quite a furor over the naming of the fossil specimen (the Taung Child skull and endocast) as a hominid.

The standard line at the time by some of the powerful figures in the field (e.g., A. Keith and O. Abel) was that the ancestors of humans should be found in Europe, and should have an enlarged brain and an apelike jaw (as was the case in the Piltdown Man hoax).

The claim that the specimen was a hominid was rejected by those who saw the material as that of a young chimpanzee or gorilla.

This view was not helped by the difficulty in acquiring casts, the material was distant from many in the field (few of which ever travelled to actually view the material), and most importantly, was that of a juvenile.

Juveniles are often misrepresentative of adult states, and most researchers claimed that the Taung Child would have developed into a chimpanzee or gorilla ancestor.

Due to the hostile or indifferent response of his peers, Dart never followed up the find with further excavations, and no other specimens of the species have been found at Taung. Dart dedicated himself to developing the anatomy department at the University of Witwatersrand, and it would be twenty years later when sites like Sterkfontein were found that corroborated Darts ideas.

Though the genus designation mixed both Latin ("australo") and Greek ("pithecus"), the genus name has become accepted as the label by which the group of pre-Homo hominids in Africa have come to be known. Dart claimed that A. africanus was bipedal due to the position of the foramen magnum, and was vindicated by later finds, such as STS 14, which showed unequivocally that africanus was an obligate biped.

The earliest africanus material comes from sites such as Sterkfontein, Makapansgat, Gladysvale, and Taung. This material dates to the end of the Early Pliocene, mostly between 2.9-2.4 myr, with the Sterkfontein Member 2 material (possibly afarensis or other species) being the earliest known possible africanus, dating to about 3.5 myr.

The Sterkfontein material are problematic, as there may be intrusions from later strata, and there is a heterogenous mixture of earlier and more modern faunal species, and thus, this material may be as young as 1.0 myr.

Most postcrania material attributed to africanus is well within the range of variation of the afarensis material, however, the limb proportions may be different. STS 14 is a 2.5 myr old specimen from Sterkfontein.

This specimen is particularly important as it includes both os coxa, as well as many of the vertebrae. This find showed unequivocally that these hominids were bipedal, and were not simply apes, vindicating Raymond Dart. Features of STS 14 that align it with a more humanlike locomotor capacity include: The iliac blade is short and wide. There is a well-

developed sciatic notch. There is a strong anterior inferior iliac spine.

STS 14 has six lumbar vertebrae (whereas modern humans have five, and chimps usually have three). With an increased number of lumbar vertebrae (the ancestral condition, as in cercopithecoids), bipedalism may have been the ancestral condition (from a very small-bodied primate?). While it is ver similar in morphology (relative to its size), there are also differences.

This specimen differs from modern human in that: There is a forward projecting anterior superior iliac spine. A very small articular surface for the sacrum. A marked outward flare of the iliac blades. There is a fairly large sample of africanus teeth known (though not as large a smaple as the afarensis material).

The material shows several important differences when compared to afarensis that include: Postcanine teeth are larger, more bulbously cusped, and relatively broader (the size difference is greater in the later erupting teeth of each type), and may have somewhat thicker enamel, especially on the tooth walls. Dm1 is larger and more squared, with more equal sized cusps.

The anterior lower premolars are always bicuspid, usually with equal or close to equal sized cusps, and wear more similarly to the other premolars. The anterior lower premolars have greater enamel thickness. Compared intrasex, the africanus central incisors show no reduction but the other anterior teeth are usually smaller.

The ranges almost completely overlap, however, and there are very large canines and incisors in both samples. No canines wear to have cutting edges (canine-premolar diatemata are rare), even though a few are large enough to project beyond the level of the other teeth (this is much more common in the afarensis sample).

Although the canines are reduced compared with the earlier Plocene samples, their roots - especially those of the maxilla teeth - are still long and robust. The canines also wear more rapidly than the afarensis material, with the wear almost always on the tips. There is significant sexual dimorphism in the canines, although not as much as any of the apes, while there is sexual dimorphism on the level of gorillas in the postcanine material.

This pattern of big teeth seems to have been influenced by the africanus diet and chewing pattern. A. Walker and M. Wolpoff claim that the africanus chewing pattern is similar to modern hunter-gatherer groups, with the molars and premolars designed to last a lifetime of wear and tear (the oldest individuals dying at about the time they have no crowns left in their mouth - max age about 35). The diet of these South African hominids seems to have been seasonal, with emphasis on a frugivory diet, with much seeds and other hard objects being masticated.

There is a good sized sample of africanus crania, allowing reasonably strong comments to be made on the materials affinities to other material. Some of the better-known specimens include STS 5 (Mrs. Ples), a 2.5 myr cranium of an adult male with a brain about 485 cc, STS 71, a 2.5 myr male partial cranium with an estimated 428 cc brain, STW 505, an indovidual with a brain esimated to have been 625 cc, and the type specimen of africanus, the Taung Child. The facial features of the africanus material are a mixture of more modern and archaic ones, with similarity to (and important differences between) the afarensis material.

Some of these features (relative to afarensis include: Retraction of the palate from a position in front of the face to under it. Forward shift of the zygomatic processes of the maxilla, the zygomatic bone, and the front of the masseter muscle, creating the zygomatic prominence.

Expansion of the anterior part of the temporalis muscle. A broader nasal aperture.

Anterior pillars extending above the canine roots, of variable expression creating thickened lateral nasal margins. Structural changes in the jaw related to expanding premolars and molars, as well as incisor and (especially) canine reduction and decreased emphasis on anterior loading.

The africanus material is seen as different things by different people. Some see this as a regional variation or subspecies of afarensis, some see it as two completely different species, and some consider the africanus material to be the descendants of afarensis.

Another important question that has been, is, and will probably always be debated is the question of whether the africanus material represents two or more species, a sexually dimorphic species, or a very variable species (especially with regards to inter-era speculation).

The accepted view seems to be that they deserve separate species status due to both their differences from the afarensis material and their geographic separation from them. However, a very important question in debate is whether or not this species contributed to the modern human lineage.

The species designation of Homo rudolfensis is a much debated topic, over both whether it is a separate species, and if it is an australopithecine rather than a member of the genus Homo.

The type specimen of the species is KNM-ER 1470. This specimen was discovered by Richard Leakey's team in 1972, east of Lake Turkana at Koobi Fora in northern Kenya. This discovery was of a fairly complete cranium without any remaining teeth.

Due to uncertainties created by its large brain size and its early initial dates, Leakey did not attribute the specimen to a species, but simply as a member of the genus Homo.

In 1986, Russian anthropologist Valerii Alexeev applied the species name of Pithecanthropus rudolfensis to ER 1470. Despite the incompleteness of the description, and Alexeev's unfamiliarity with the original specimen, the name stuck.

The genus name of Pithecanthropus has been dropped by those who see rudolfensis as a valid species and replaced with the genus Homo. Recently, there have been attributions of the rudolfensis specimens as belonging to Australopithecus, and thus another genus change may be in the future of this species if it retains validity as a separate species.

One of the main problems with the rudolfensis species is that there are no postcranial remains that are associated with cranial remains.

The rudolfensis specimens have large brains in conjunction with megadont postcanines, and without postcranial evidence it is unknown whether these features are due to a larger body size than contemporary habilis specimens. Due to this problem, many competing ideas abound regarding

the validity of rudolfensis and its proper place in hominid phylogeny. Some researchers see the larger brain and tooth size as indicative of allometric changes due to increased body size, with rudolfensis and habilis constituting the same species, with the former the males and the later the females. Some see rudolfensis as the ancestor of habilis with a decrease in brain size occurring, and others see the two on completely different evolutionary lines.

This debate is long from over, and all the scenarios have one problem or another. Perhaps with future discoveries that are attributed to the rudolfensis, a clearer picture will appear as to the relationship of these early Homo.

Diagnostic Features

The type specimen of Homo rudolfensis is KNM-ER 1470, discovered by Bernard Ngeneo at Koobi Fora, Kenya, in 1972. The research team involved (led by Richard Leakey) attributed the toothless cranium to the genus Homo with the species indeterminate due to the large brain size and questionable morphological association with known hominids. The cranium was reconstructed by Meave Leakey into two main pieces that give an estimated brain size of 775cc.

The specimen was originally thought to be around 2.9 myr old, due to an inaccurate dating of 2.6 myr for the KBS volcanic tuff located above it. This inaccuracy was caused by contamination of older material, and the tuff is now know to be much younger. The specimen is now thought to date to approximately 1.8 myr (Leakey et al. may have been more willing to attribute the specimen to habilis had they known the real antiquity of the specimen from the beginning).

Though this date is now generally accepted for the specimen, the geologists who orignally dated the KBS tuff continue to argue for a later date for the specimen. While the admit the dating of the volcanic tuff was inaccurate, F. Fitch and colleagues claim that the depth of the specimen beneath the tuff shows a much earlier age, daing to around 2.4 myr.

Compared to a smaller Koobi Fora cranium, KNM-ER 1813, ER 1470 shows many differences that distinguish the specimen from habilis. These features include:

A slight supraorbital torus across the forehead with no sulcus or depression behind it.

A much longer face, with the upper part narrower than the middle.

The maxilla is squared off rather than rounded, with a very short, shallow palate.

Evidence of much more megadont postcanines.

Other features that comprise ER 1470 (but which are not necessarily distinct to the species) include:

A lack of crests and heavy muscle markings that characterize australopithecine crania.

A marked constriction of the braincase behind the orbitals (but less that occurs in robust australopithecines. A bulging frontal bone that rises steeply to meet the square parietal bone that form the thin-walled sides of the brain case. An occipital bone that is smoothly rounded rather than flexed as in Homo erectus.

Other cranial remains that have been attributed to rudolfensis include KNM-ER 1590, KNM-ER 3732, KNM-ER 1801, and KNM-ER 1802. Alexeev originally attributed ER 1470 as a male rudolfensis and ER 1813 as a female, but ER 1813 is generally considered to be habilis. There is no directly associated postcrania for rudolfensis (which makes the species problematic), though some specimens have been attributed to the species.

Limbs such as the ER 1472 and ER 1481 femora have been attributed to rudolfensis, suggesting a dramatic allometric difference, but there is much questionable about associating postcrania and cranial material together, when there is no objective sample to compare them to (an associated cranium and postcranial material).

Another specimen that may be attributable to rudolfensis is OMO 75-14, a mandible and cranial fragments that have been dated to around 2.0 myr. In spite of very large postcanine size (the M2 size exceeds all other non-robust specimens and its shape resembles the boisei condition), its premolar morphology is not like any robust australopithecine, according to G. Suwa et al.

The teeth are larger than any habilis specimen, and seem to show definite Homo-like patterns> However, isolated mandibles and fragments are hard enough to attribute, and even worse when trying to attribute them to a species many researchers do not even consider a valid taxon. B. Wood has given a diagnosis of mandibles that should be placed within rudolfensis which include:

Broader postcanine tooth crowns; they are narrower in habilis.

A large P4 talonid (an extra area on the back of the tooth that acts to make it squarer in profile). Double-rooted P4s and sometimes P3s (these are single-rooted in habilis).

The dating of this species is significant, in that a date earlier than habilis makes this species the first habiline, and with its very large brain, a candidate for being a direct human ancestor.

The initial date of 2.9 myr for ER 1470 has been modified, but as mentioned above, there is some support for a date of approximately 2.4 myr for the specimen. However, habilis itself has had its origins pushed back to approximately 2.3 myr (A.L. 666-1), making the designation of the "first" habiline difficult even if ER 1470 is older than is now generally accepted. Also important when considering the habilines (and rudolfensis in particular) is the idea that they are not Homo at all, but rather Australopithecus.

Analyses by D. Lieberman and B. Wood seem to indicate that the habilines share more features with the australopithecines than with Homo. Evidence for this position include: A. Walker's initial impression of ER 1470 was of an expanded but very similar specimen to STS 5, an africanus specimen. D. Lieberman et al. analysis which showed that rudolfensis shows more affinities to the australopithecines rather than with the other species of Homo.

It would help account for the robust australopithecine features found in rudolfensis, because africanus closely resembles the robusts in many ways.

The large degree of variation in africanus shows that the degree of difference between rudolfensis and earlier africanus is such that attribution to differing species is not required.

Conclusions

As stated, the attribution of the species rudolfensis to any specimen is somewheat controversial, since many paleoanthropologists do not see rudolfensis as a valid species. Its dating (whether the early dates proposed by some or the contemporaneous dates to habilis) makes its brain size an issue, and raises questions about current standard phylogeny of the human line.

Homo rudolphensis may be the first member of the genus Homo on a path to modern humans, or it may be a more Homo-like australopithecine with no direct bearing on the evolution of H. sapiens. Nothing can be stated for sure at this point, except that there will be much more future debate on the issue.

Homo habilis is a well-known, but poorly defined species. The specimen that led to the naming of this species (OH 7) was discovered in 1960, by the Leakey team in Olduvai Gorge, Tanzania.

This specimen and its designation was the subject of much controversies up through the 1970s. The material was found in the same region where A. boisei had previously been found, and many researchers of the time did not fully accept that the material was sufficiently different from that material (or maybe A. africanus) to denote a new species.

Louis Leakey was convinced that this was the Olduvai toolmaker he had spent his life looking for, and placed this as a direct human ancestor, with H. erectus a dead-end side-branch. The specimen was subjected to intense study by the multidisciplinary team of Louis Leakey, John Napier, and Phillip Tobias.

They placed the material as different from penecontemporary australopithecines due to the teeth, which fell outside the known range of A. africanus, with very large incisors. Also, the large brain size and shape of the hand suggested a closer affinity with Homo.

In January 1964, the team announced the new species Homo habilis. The name was suggested by Raymond Dart, and means "handy man," in reference to this hominids supposed tool making prowess.

Leakey believed that habilis was a direct human ancestor, with erectus out of the picture. While H. habilis is a generally accepted species, they opinion that it was a direct human ancestor seems to be in question.

There are now at least two species of early Homo (whether habilis and rudolfensis or an undescribed species) living prior to 2.0 myr. In adddition, H. erectus (which is almost universally accepted as a direct human ancestor) continues to be pushed further back into the paleontological record, making it possible that it is the first Homo ancestor of modern humans.

Other problems include that some people see KNM-ER 1813 as a near perfect erectus, except for its small brain and size. It could be an erectus that was at the small scale of a wide variation of traits, or it may belong to ergaster (another problematic species, early erectus are usually the same specimens attributed to ergaster), which some believe to be the ancestor of erectus.

The questions are far from solved, and new specimens are needed. Homo habilis may be a direct human ancestor, a dead-end side-branch that lead nowhere, an invalid species whose designated examples belong in other species, or Wolpoff may be right, and all these species are basically part of one highly variable widespread species.

Diagnostic Features

It is particluarly hard to list the features of Homo habilis, because the specimens attributed to habilis (and the reasons the material was placed there) vary widely. The species is a mishmash of traits and specimens, whose composition depends upon what researcher one asks. The simplest way to describe the general features is to describe specimens that are generally considered habilis by most people, and list their relevant traits.

OH 7 is the type specimen of habilis, and the first material attributed to the species. The specimen consists of a nearly complete left parietal, a fragmented right parietal, most of the mandibular body (including thirteen teeth), an upper molar, and twenty-one finger, hand, and wrist bones. The remains belonged to a 12 or 13 year old male. The brain size attributed to this specimen varies, ranging from 590-710 cc. P. Tobias and G. von Koenigswald used three traits to set habilis apart, as a transitional species between A. africanus and H. erectus:

Expanded cranial capacity (relative to africanus).

Reduced postcanine tooth size. The presence of a precision grip (determined from the hand bones present in OH 7), which provides the anatomical basis for tool-making. General features of the specimen seems to support these three traits (whether or not it is transitional from africanus to erectus:

Larger cranial capacity (though very problematic). Tobias gives an estimate of 647 cc, Holloway gives an estimate of 710 cc, and Wolpoff has estimated it at 590 cc. Molar megadontia is gone, with molars longer than they are wide. The P3 is smaller and more asymmetric.

The P4 is much more similar to the P3. Metacarpal 1 and trapezium is much less interlocked, which allowed more movement. The distal phalanges have apical tuffs. OH 8 - a fairly complete foot - was found nearby OH 7, and was initially determined to be from another individual.

This was due to the fact that OH 7 was known to be from an adolescent around age 12, and the foot seemed to be of a more advanced age, due to the presence of arthritis in the specimen. However, the partially gnawed remains have arthritis die to a sustained injury, and the actual age runs close to OH 7, making it likely they are from the same individual (many researchers consider this part of OH 7 now, rather than OH 8). The remains show clear signs that this was an obligate biped, including:

Presence of digital shortening. Enlargement of the hallux, as well as being fully abducted. Alignment of digits 2-5. Thickened metatarsal shaft with a humanlike cross-sectional shape.

A fully developed double arch to the lower surface. Mechanically set up for efficient weight transmission at the ankle. While it shows definite obligate bipedalism, the specimen also has a marked tubercule for the tibialis posterior muscle, an invertor of the foot that could be usefull for climbing.

So it is possible that while this individual was an obligate biped, it still spent some time in the trees (which goes well with paleoecological evidence that suggests that various hominid species spent most of their time in marginal woodland environments). From the talus, H. McHenry calculated an estimated weight of 31.7 kg. Using the various estimated brain size, one gets brain/body weight ratios of:

Wolpoff: 590 cc brain = 1.86%

Tobias: 647 cc brain = 2.04%

Holloway: 710 cc brain = 2.24%

Even using the smaller brain estimate, this is one of the largest relative brain size for any male hominid up to the time period this individual lived (1.75 myr). When compared to primate allometry, the OH 7 brain size is at the top of the allometric expectations within non-human primates.

This is a large brained specimen relative to its body size.

Another relatively complete habiline specimen is OH 13 - "Cinderella". This is a poorly preserved and fragmentary specimen of a 15-16 year old female habilis, dating to a little younger than 1.66 myr. This makes it one of the most (if not the most) recent habilis specimens known. The material consists of the mandible and the maxilla, several teeth, pieces of the cranial vault, and some postcranial elements, including a small piece of proximal ulna.

This specimen (along with OH 16) were the object of much inaccurate brain size estimations, which originally lead to the two being classified as H. erectus. More recent estimates put the brain size at around 500 cc, and along with an estimated body size near that of AL 288-1, gives this specimen a relative brain/body weigth ratio similar to OH 7.

The case of OH 16 is a tragic one. The specimen was discovered nearly complete near the end of a field day, so the position of the find was marked and roped off. The next morning the researchers were horrified to discover that a herd of cattle had charged through the area, and completely crushed it. Some of the specimen's features include:

Very large teeth (close to australopithecus in size). An uncertain brain size, but probably larger than OH 7. The individual was age 15-16 when they died. The individual had very bad caries on one side of its jaws (very unusual in ancient specimens), which lead to differential chewing on the other side, causing it to develop a huge temporalis muscle on that side.

Cranial bone markedly thinner that erectus. Dramatic differences in the supraorbital torus and the nuchal torus that distingish it from erectus. These features (the last two shared with OH 13) seem to indicate that the specimen is a habiline, and not an erectus specimen, as was attributed by J. Robinson.

OH 24 ("Twiggy") is the most australopithecine-like of specimens attributed to H. habilis, and may be more highly correlated with A. africanus. The specimen was found completely fractured, and cemented together in a coating of limestone. R. Clarke was the researcher who went through the long and painful process of reconstruction, but over 100 small fragments could not be placed in the reconstruction.

Hence, the specimen is extremely distorted, making an accurate estimate of its brain size very difficult, though Holloway has given an estimate of 590 cc (many researchers believe that number is too high). Several features caused this specimen to be placed in habilis, including:

Increased cranial capacity over australopithecines (though some doubt this estimate).

Less postorbital constriction. Elongated molars. Absence of postcanine megadontia.

Large front teeth relative to the postcanines. A broad and short cranial base. Anteriorly positioned foramen magnum. Less convex and bulging zygomatics, and more vertically oriented. A distinct maxillary notch. While these features seem to support the notion that it is not an australopithecine, several other features do not support the habilis distinction. For example:

Lacks a salient anterior nasal spine. Lacks broad nasal bones. Lacks nasal bone peaking caused by the internasal angle. Lacks the projection of the middle and top of the nose away from the face, shown by expanded and outward projecting maxillary bones to its side (i.e., maxillary pillar eversion). While this specimen does not seem to be an australopithecine, it also does not seem to fit perfectly into the classic habilis mold.

Perhaps it fits more closely with rudolfensis, or an undefined penecontemporary species. Another option may be that the distorted reconstruction is blurring a clear species designation. For now, a clear designation is up in the air.

The last specimen that I am going to discuss is OH 62. Publicized widely as "Lucy's Child" by Johanson, it is a very scrappy collection of 302 boen fragments. Portions of the maxilla (which permitted identification as habilis), parts of the femur, and upper limb bones.

The entire specimen is problematic, and raises many questions as to sexual variation and behavior. The most controversial aspect of the specimen was the Johanson et al. calculation of a humero-femoral index of 95%.

The material was far too sparse to calculate such an index, but even using their own estimated range of possible lengths for the incomplete femur, they should have computed an index quite close to the A.L. 288-1 value of 83.8%. It is unclear why Johanson et al. calculated the index in the manner they did, and it is generally not accepted in any form at all.

Conclusions

Homo habilis is a very complicated species to describe. No two researchers attribute all the same specimens as habilis, and few can agree on what traits define habilis, if it is a valid species at all, and even whether or not it belongs in the genus Homo or Australopithecus.

Is one of the more problematic of somewhat accepted species designations currently tossed around in anthropological literature.

Each individual researcher that sees ergaster as a valid taxon sees different specimens as belonging or not belonging to the taxon. Many researchers deny any validity to the species at all.

On the whole though, most researchers see too little difference between ergaster and erectus to form the basis of a species of the former, separated from the latter. As a general rule of thumb, one can consider most attributed ergaster specimens to be early erectus geographically confined to Africa (however, this is not a hard and fast rule).

The taxon ergaster was first described in 1975 by C. Groves and V. Mazak. The specimen attributed as the type specimen was ER 992, an isolated mandible. Since then, other specimens have been attributed by various authors to ergaster, with most researchers placing the same fossils in erectus.

The most significant feature of ergaster, is that those who see it as a valid taxon, tend to see it as more closely resembling modern H. sapiens than does H. erectus.

They tend to see ergaster as a direct ancestor of modern humans with erectus being an evolutionary dead-end. Many Out of Africa supporters use this taxon as evidence that Asian and European specimens did not contribute genetically to the modern human genome, but this claim is very weak.

Diagnostic Features

The type specimen for ergaster is KNM-ER 992. Groves and Mazak claimed that the mandible was significantly different from H. erectus to deserve its own species designation. However, they did not compare it to H. habilis, and the

mandible may actually belong to that taxon.

The specimen showed some periodontal disease, as seen by absorption of bone around the roots of the teeth. The mandibular symphysis also shows strong markings for the digastric muscle (important for swallowing and vocalization), which some people have interpreted as proof of language by this time.

One of the most spectacular and important paleoanthropological finds in recent years was the Nariokotome Boy (KNM-WT 15000), by a team of researchers led by Richard Leakey and Alan Walker.

This find represents the most complete early hominid ever found, with almost the entire cranium, and most of the postcranial material intact. This specimen has been attributed as a male ergaster by some, though most place it in H. erectus, and that is where it will be discussed in detail. Other specimens that have been attributed to ergaster include KNM-ER 3733, SK 847, and KNM-ER 3883.

Several researchers have tried to define the difference between ergaster and erectus, P. Andrews and B. Wood among the more prominent. P. Andrews defined seven autopomorphies that were characteristic of erectus, but which ergaster supposedly lacked.

However, G. Bräuer have shown that these are not autopomorphies. For example, some erectus do not possess these features, while some ergaster and some habilis do. Also, some of these autopomorphies are not independent traits, and should not be considered separately (e.g., frontal keel and parietal keel). B. Wood lists seven traits that link ergaster with H. sapiens, and that distinguish ergaster from erectus:

Increased cranial breadth across the parietal bones. Increased occipital bone length. Broader nasal bones. Broader nasal opening. Shorter cranial base. Greater development of the mandibular symphysis. Narrower M1s and lower canines. However, these synapomorphies have been convincingly challenged by showing them to be present in erectus populations from Asia.

Also, more recent analyses by other researchers seem to indicate that even if ergaster specimens are considered as a different taxon than erectus, the erectus material is still closer to modern humans cladistically.

Conclusions

In short, H. ergaster does not show significant promise of lasting as a separate taxon due to several factors. I has not been shown to be significantly different from erectus to require the designation of a new hominid species, and it has not been shown to be closer to modern humans morphologically as has been claimed by some. At this time, ergaster basically means early H. erectus from Africa.

These included the Neanderthals, and Homo erectus. In the early 1960s, this began to change, and human ancestry began to be populated by many different players. Accordingly, erectus is one of the better known members of genus Homo, especially in terms of its well-established place in paleoanthropology. This has begun to change, however, and now some question both the validity of erectus as a species, and its place in human evolution.

Some (e.g., M. Wolpoff) claim that erectus is an invalid taxon, though few accept this iterpretation at this point in time.

Others believe that the material previously attributed to erectus should be split into several different taxons: Asian and later African material remaining as erectus (with erectus not contributing to modern humans), early African material as ergaster, and European material as heidelbergensis.

In this description of the species H. erectus, the material that has been attributed as ergaster and erectus in the above splitting scenario will be covered, with the heidelbergensis material discussed under the page dedicated to that species.

The species was named by Eugène Dubois (originally designated as Pithecanthropus erectus) in 1894, after his 1891 find from Trinil, Java, in Indonesia (Trinil 2). Dubois was inspired by A. Wallace's conviction that the origins of modern humans might lie in Southeast Asia. Dubois enlisted as an army surgeon in the Royal Dutch East Indies Army,

and searched for fossils in Sumatra.

He had little success in Sumatra, but found unearthed a thick mineralized hominid skull near the bank of the Solo River in Java. Dubois made his find public a few years later, and was met by derision from the dominant British paleontological hierarchy. Dubois was disillusioned, and this important find actually spent some time in a box underneath the floorboards of Dubois' home.

The material was later associated with the Chinese material from Zhoukoudian, and renamed Homo erectus. Except for modern Homo sapiens, erectus was the most far ranging hominid to have existed. Material that has been attributed to erectus has come from South Africa, Indonesia, and England, and just about everywhere in between, covering the entire continents of Africa, Asia, and Europe. The European material will not be discussed here (it is discussed under heidelbergensis), but the rest of the material will be covered here under erectus.

Diagnostic Features

The dates for erectus have become earlier and earlier, while habilis remains have been found in later and later deposits, making a lineage involving habilis ancestral to erectus increasingly unlikely. Specimens that are considered erectus are dated very securely to at least 1.8 myr, and fairly securely to 1.9 myr. The question of this species evolutionary destiny is under some disagreement.

Those who accept the validity of egaster usually consider erectus an evolutionary dead-end that went from Africa into Asia, and went extinct there. Those who see erectus as a modern human ancestor, either see the Asian specimens as a dead-end side branch, or see all the ergaster, heidelbergensis, and erectus specimens as belonging to Homo sapiens.

This view has some validity in that these species are usually considered "chronospecies" due to anagenesis. Some researchers do not support the concept of anagenesis as a valid mechanism of speciation, since there is a "fuzzy" area where the transition between species occurs, whereas in cladogenesis (the splitting of a species into two new species or the branching off of one species from another) there is a "clear" boundary.

However, the method of speciation is the same in both, since beyond the moment of the split in cladogenesis, the transition to new species is by anagensis. So this is really a matter of semantics and differing ideologies. In any case, erectus shows clear trends in the modern direction, and I personally think that the most parsimonious answer is that erectus is an ancestor of modern humans, and not an evolutionary dead-end. However, that is just my personal opinion.

There are specimens from a wide time span and a vast geographical area that have been attributed to erectus. The traits of these specimens are very similar, and show a trend toward the modern human condition. Some of the trends linking erectus with sapiens includes:

An increase in brain size (erectus approximately 900 cc., sapiens approximately 1350 cc.).

A reduction in postcanine dentition, and a correlated decrease in jaw size. Vertical shortening of the face. Shortening of armbones (especially the forearm) to come to a very humanlike limb proportions (postcranial proportions are very similar to tropically adapted modern humans).

The development of a more barrel-shaped chest. The formation of an external nose. Reached modern human size in terms of height. One of the most important erectus specimen is the Nariokotome boy, KNM-WT 15000. This specimen was discovered by a team led by R. Leakey and A. Walker at Nariokotome, Keny, in 1984.

This is the most complete ealy human skeleton ever discovered. The specimen was dated to 1.6 myr, and is considered by some as ergaster, but to most researchers it is definitely erectus. The relative completeness of this specimen allowed detailed examination of the anatomy of erectus, and has led to many influentual ideas about this species. Some of its important features include:

Is the skeleton of a 10-12 year old individual (generally considered male). The teeth are unworn. Shovel-shaped incisors. Was 5'3" (168 cm) tall at death, and may have been as tall as 6'0" (183 cm) if it had reached maturity. Resembles a very robust modern human from the neck down.

A 880 cc. brain (estimated that its mature brain size would be 909 cc.). Brachial and humero-femoral index in the modern human range. Had relatively small (compared to modern humans) thoracic spinal canal diameter. Smaller cervical and lumbar swellings (relative to modern humans).

External projecting nose. Longer vertebral spines (relative to modern humans). An elongated femoral neck. A narrow biilliac breadth. The narrow spinal canal has been an issue of much speculation. Some contend that this means that KNM-WT 15000 had small intercostal muscles (used for fine air control during speech in modern humans).

However, this was a juvenile and the neurocanal size may have increased by 30% by maturity. Also, even though it has a small canal size relative to its body size, it is still within the modern human range (albeit, at the bottom).

This is a very tenuous piece of evidence that has been used to make very specific statements about early human capacity for speech.

Considering it is within the human range at all, it makes it unlikely that this would have prevented the capacity for speech, and since it is a juvenile specimen, sweeping statements about the species capacity for language based on this trait is very weak.

A very important specimen (especially in terms of the history of paleoanthropology) is KNM-ER 3733. This fairly complete cranium is responsible for sinking the single species concept as a hard and fast rule. The specimen was found by a team led by R. Leakey at Koobi Fora, Kenya, in 1975.

The specimen has been dated to approximately 1.75 myr. This is usually considered the remains of a female due to the decreased level of robusticity compared to conspecifics such as KNM-WT 15000. Some of its key features include:

Is a mature adult specimen (known from the closed cranial sutures and the erupted M3s). A low cranial vault (characteristic of Asian erectus). Some keeling along the midline of the cranium. A round torus across the occipital bone. A cranial base that is wider at the base than at the top of the cranium. Possible evidence of alveolar torus. An 848 cc. brain.

Moderately sized postcanines and large anterior teeth. Clear evidence of an external projecting nose. Double-arched supraorbitals. Another African erectus specimen is KNM-ER 3883. This specimen is thought to be a male from the same population that ER 3733 came from. It was found in the same area, Koobi Fora, Kenya. It has been dated to approximately 1.57 myr and is the best-preserved early male cranium. Some of its features include:

Roughly equivalent brain size to ER 3733 (minimally 804 cc., but likely larger). Clear evidence of an external projecting nose. Projecting nasal bones, which tend to be convex and relatively wide.

Margins of nose everted laterally (deviate laterally). Presence of anterior nasal spine. Clear angulation of margin of nasal floor and premaxillae. A forehead flatter than ER 3733 with less of a supratoral sulcus separating it from the top of the supraorbitals.

Much larger mastoids than ER 3733. A slightly developed nuchal torus. Well-developed supraorbitals that are not double-arched. The erectus specimens from China were some of the first hominids that were discovered.

The various specimens from Dragon Bone Hill, in the cave of Zhoukoudian were discovered in the late 1920s; however, all but two teeth that were sent abroad for analysis were lost in the chaos of WWII. The material included five skullcaps, several cranial and facial fragments, eleven mandibles, and 147 isolated teeth.

This material was used for the reconstruction of "Peking Man" by F. Weidenreich. A newer reconstruction has been made by I. Tattersall and G. Sawyer that uses fragments that are assumed to be male, as the original reconstruction used both male and female remains.

The newer cranial reconstruction results in a larger cranial capacity with a more massive and projecting face, with a broader taller nasal region. This new reconstruction is more similar to erectus from elsewhere in the world. The material has been dated to approximately 400 kyr to 500 kyr.

The five skullcaps have a mean cranial capacity of 1043 cc. The supraorbital torus on the reconstruction is smaller than that of OH 7 or Sangiran 17 from Java. The Zhoukoudian occipital bones are strongly flexed with a broad torus across the bone's width. The skullcaps are also characterized by flat, thick, rectangular parietal bones. The facial bones are massive, and the mandibles are very robust. The Asian specimens show some general differences from African erectus, including more robust ridges of bone with the walls of the skull greatly thickened.

The Javanese specimens are a source of great controversy. No specimen from Indonesia has been found in a well-dated locale. Often, they have been found by locals and bought by researchers or interested laypersons. More than one specimen has shown up in the hands of an interested layperson, for that person to be told by a paleoanthropologist that it is a fake. The older dates (ranging near 1.7 myr) are very controversial, and very tenuous.

For example, the Modjokerto child was discovered by a hired workman in 1936, and the specimen was "dated" decades later by looking at the material that adhered to the cranium, and matching that matrix to a strata based on the information of where the specimen was found, finding a strata that matched the material taken from the specimen, then dating the samples of stratum that were assumed to be where the specimen originally came from.

It is methods like this that dates that are very early come from. Specimens like Sangiran 17 and Trinil 2 have been dated to approximately 800 kyr and 400 kyr, respectively.

The best preserved hominid cranium from Java is Sangiran 17. This specimen was discovered by a farmer at Sangiran, Java, Indonesia, in 1969. Sangiran 17 has been an important specimen for those who accept the multiregional hypothesis that has erectus moving into Asia early, and evolving into Homo sapiens with gene flow being maintained between various African, Asian, and European populations.

In Indonesia, this hypothesized lineage begins with Modjokerto, moves on through Sangiran 17, the material from Sambungmachan, Ngandong, all the way through present day Javanese. Some of the traits that are cited to link this lineage together includes:

A long relatively flat frontal bone. A projecting face with massive, flat zygomatics. A zygomaxillary tuberosity at the base of the zygomatics. A rounded edge to the bottom at the eye sockets.

The lack of a clear demarcation between the nasal region and the lower face. The Sangiran 17 specimen itself shows several other features that distinguish the Indonesian material from other populations of erectus. Many of these also fit into the multiregional model. These features include:

Very thick cranial bones which are flattened along the sides of the braincase.

A maximum cranial breadth at the base of the cranium. A reduced development of the frontal and parietal lobes of the brain, though more developed elsewhere (Sangiran 17 is at the high end of the erectus scale with an approximate 1029 cc. brain). Prominent muscle markings along the sides and back of the cranium.

Conclusions

Homo erectus (or the various species which may be subsumed under that appellation) are extremely important in the study of modern human origins. The Middle Pleistocene is where the modern human postcrania develops, the modern cranial features begin to develop, and significant increases in brain size occur.

It is also important because many behavioral changes occur in this time period, e.g., much more developed lithic industries, the controlled use of fire, regular meat-eating, hunting, etc.

This is where the things most people consider "human" start to develop to the point where most people would recognize these pattern of anatomy and behavior as human. This is also a dynamic time in the evolutionary perspective caused by these species, with the recent well-dated Dmanisi remains in the Republic of Georgia, dated to 1.7 myr.

This mandible (Mauer 1) validated Otto Schoetensack's conviction that there would be Pleistocene human remains found in the quarry amid the more common rhino, bear, elephant, bison, deer, and horse remains.

Schoetensack published an extensive monograph on the mandible a year later in which he designated it to a new species of hominid, Homo heidelbergensis. Schoetensack named a new species without justifying it by describing the unique anatomical features of the species.

Along with this lack of morphological comparisons and differentiation from other known species, the lack of older specimens (and just about any specimen at all for a long period of time) kept heidelbergensis from becoming accepted among paleoanthropologists.

However, though Schoetensack did not justify his species designation, there are features that set Mauer 1 apart from Neanderthal and H. sapiens. The age of the specimen also creates a distinction, as it dates to appromiately 500 kyr. With a wealth of newer discoveries in the last 30 years, the species designation if heidelbergensis has been revived.

The validity of heidlebergensis seems to be current among many researchers at this time, but it is by no means universally accepted. Many researchers argue that heidelbergensis is invalid, and is simply a chronospecies (though, that is exactly what some proponents argue for, among those who see anagenesis as a valid speciation event).

In this overview of the species, I will be making the distinction of heidelbergensis from erectus based on both age and geographic location.

Starting with the null hypothesis that all the ergaster, erectus, and heidelbergensis are members of the same variable species that differ by age and geography, I will discuss heidelbergensis as those specimens occurring later, and occurring in Europe and Africa.

I will discuss erectus as those specimens occurring earlier and in Asia and Africa. My personal convictions are not contained in this partition of the specimens, as I am trying to give a current overview of popular opinion in the field while noting obvious fallacies in some species designation (as per antecessor).

Diagnostic Features

Due to the fact that there have been so many different specimens attributed to the erectus offshoots, it is difficult to create a list of features that differentiate heidelbergensis from erectus or H. neanderthalensis.

In general, heidelbergensis specimens show a continuation of evolutionary trends that occurred in the Lower Pleistocene into the Middle Pleistocene. Along with changes

in robustcity of cranial and dental features, there is a marked increase in brain size from erectus to heidelbergensis. Some of the features of Middle Pleistocene Homo that shows these trends include:

An increase in brain size (early Homo approximately 900 cc, heidelbergensis specimens approximately 1200cc). A shift from the widest part of the brain case from the cranial base to the parietal regions. The rear of the cranial vault becomes more vertical. A gradual reduction in cranial robusticity. A decline in postcranial robusticity also. A tendency for a shift from shorter more robust stature to taller more leaner bodies.

The increase in brain size may have also come with an increase in brain complexity, although this is difficult to determine from endocasts, and may have to remain supposition only. However, the increase in absolute size, and the change to larger frontal and parietal lobes indicate that there may have been a reorganization of the functional anatomy of the hominid brain.

The increase in size itself indicates changes in behavior that lead to the ability to more easily acquire nutritional resources.

This is due to the high nutrition requirements of brain tissue, especially during development.

There is increasingly more convincing evidence in the use and control of fire, and in the hunting of animals for food. This time period is important for many reasons, and may be the time period when more modern behavior began to develop.

The type specimen of heidelbergensis is Mauer 1. This specimen shows a host of both primitive and derived features that, in general, have been accepted as proof of ancestry to the Neanderthal line.

The specimen was discovered in 1907 in the Mauer sand pits near Heidelberg, Germany. The exact age of the specimen is uncertain, but it dates at least as old as 400 kyr, and possibly as old as 700 kyr. However, a date of 500 kyr is generally accepted as most likely. Some of the traits that distinguish this specimen include:

A sloping symphysis that contains two mandibular tori on its inner side (primitive).

An especially broad ramus (primitive).

An M2 that is larger than the M1 (primitive).

A very robust mandible (primitive).

Taurodont molars (derived).

A reduced M3 (derived).

Dramatic buccal cusp dominance in the P3 (derived).

Another Middle Pleistocene hominid that may or may nor be attributed to heidelbergensis is the Bodo cranium. Bodo was discovered in 1976 at Bodo d'Ar, Ethiopia, in the Middle Awash Valley. The specimen is important because of its age (600 kyr), and its suit of features.

The cranium is extremely robust and sports the biggest face known among hominid specimens. Acheulean tools were found near the site with the remains of hippos, baboons, and antelopes, indicating that Bodo may have been butchering animals for meat, and may have even hunted them.

However, Bodo himself was also the victim of butchery, as seen by the distinctive cutmarks on several parts of the cranium. Bodo has also been at the center of infighting among scientists, and, as such, has had relatively few publications describing it. Some of the features that distiguish Bodo include:

Approximately 1100cc brain. A broad massive face. An extremely broad nose (the largest of any Pleistocene hominid). The lower nasal margin is guttered. Robust zygomatics that angle backwards from the nasal margins. An expanded maxilla, and an associated lack of a canine fossa (though there is a very shallow fossa lateral to the nose). A long sloping frontal bone.

A thick browridge with a fery deep temporal fossa. A remarkably flexed cranial base. A flat sloping anterior face on the mandibular fossa, that is the result of emphasis on anterior tooth loading. The cave site of Arago, at Tautavel, France, in the eastern Pyrenees mountains has yielded the remains of many hominids, with the cranium Arago XXI the most complete.

Due to its size and robust facial features, Arago XXI is generally considered a young male, though some consider it female. The dating of the material is problematic, with a wide range of dates being claimed. Henry de Lumley considers the material to be approximately 400 kyr, though it is much more likely that the material dates 200 kyr to 300 kyr. Arago 21 is fairly complete, lacking only the temporal and occipital bones. Some of its distinguishing features include:

An approximately 1166cc brain.

Broca's cap and other speech areas are well-developed. Evidence of an extensive right parietal association area. Evidence of right-handedness from an asymmetric endocast. Lacks a frontal boss. Presence of marked parietal boss. Presence of an angular torus. A low broad sagittal keel. A deep supraorbital sulcus. A short and prognathic face, with an expanded maxilla. The material from Petralona is very similar morphologically to the Arago material.

The Petralona 1 cranium was discovered in 1960, hanging suspended from a stalagmite in a cave of Katsika Hill, in Petralona, Greece. The specimen has a very ambiguous morphology, which led to several different species attributions. It was originally attributed to neanderthalensis, and was later classified as erectus, but it falls much closer to the morphology of the various heidelbergensis specimens, especially Arago XXI.

The specimen was originally thought to be approximately 70 kyr, as young as many Neanderthal specimens, and later estimates put that number at closer 700 kyr. However, ESR dating has given a date of between 247 kyr and 127 kyr, though some researchers estimate its likely date to be around 300-400 kyr due to its morphology. Some of its features include:

A large brow ridge - a double-arched supraorbital torus. Lacks a canine fossa. An open occipital angle. A 1220 cc brain estimate. A massive face, though it is non-projecting. A prominent transverse torus.

There are many other specimens that can be (and have been) attributed to heidelbergensis, and they generally have all the same common traits that have been mentioned for the specific specimens discussed above. Material from Apidima, Kabwe, Steinheim, Atapuerca, etc. can be and have been designated as heidelbergensis, or erectus. In general, there is a decrease in robusticity, an increase in brain size, and a tendency towards more derived features of neanderthalensis or sapiens.

Conclusions

There is no real question as to whether or not heidelbergensis is a chronospecies, it is. The validity of it depends on whether one accepts anagenesis as a valid method of speciation. H. heidelbergensis specimens are generally Middle Pleistocene hominids in Europe or Africa (though some specimens from Asia such as Dali have been designated to heidelbergensis by a few individuals), with the major difference from erectus being spatial.

The material was found in a limestone quarry near the city of Düsseldorf. The material recovered consisted of a skull cap, two femora, the three right arm bones, two of the left arm bones, part of the left ilium, and fragments of a scapula and ribs.

These fossils were recovered by the quarry workers and set aside to be given to a local teacher and amateur naturalists, Johann Karl Fuhlrott. Fuhlrott suspected that these bones represented unique pieces of the human past, and left the description of the material to anatomist Hermann Schaaffhausen.

The find was announced jointly in 1857, two years before Darwin's On the Origin of Species. While this find was the beginning of paleoanthropology, it was also the beginning of a long debate that is just a vigorous today as it was a hundred years ago.

German scientist R. Virchow claimed that it was the skeleton of a diseased Cossack cavalryman, with thick browridges developed from constantly furrowing his brow in pain.

Even when the validity of remains attributed to Neanderthal were no longer in such question, the description of Neanderthals was still full of controversy. M. Boule and H. Vallois were the most prominent of those who believed that Neanderthals had no place in modern ancestry.

These two supported the idea that Neanderthals were more apelike than human, were of simian intelligence, and walked in an apelike gait.

These perceptions were based on both the misinterpretation of the La Chapelle-aux-Saints specimen as typic of the species (this specien was an older individual with chronic arthritis throughout its body), and on the prejudices of these researchers, who refused to accept any evidence that related Neanderthals closely to modern Europeans.

The Feldhofer remains were not the first Neanderthal remains discovered, but the first one recognized as belonging to a separate species. The Engis child from Belgium was the first Neanderthal deiscovered, in 1829, and the second discovered was the Forbes Quarry find from Gibraltar in 1848.

The species name of neanderthalensis comes from William King, who first named the species in 1863 at a meeting of the British Association, and put it into print in the Quarterly Journal of Science in 1864. This species is the focus of more argument among the academia of paleoanthropology than any other.

Today, most researchers follow a multiregional view which has the European Neanderthals interbreeding and being absorbed by invading populations, or to have been marginalized by invading Homo sapiens until they died out, leaving no genetic legacy to modern humans.

There are some (C.L. Brace most prominently) that think that the Neanderthals evolved in place into modern Europeans with little or no genetic influx from African populations, but few accept this argument.

Currently, the pendulum has swung to general support for the Out of Africa II model of people like C.B. Stringer, especially in the public. However, current research is cutting both ways, with sites such as Vindija and Lagar Velho seemingly giving support to Neanderthal assimilation models.

Also, there is much research into the genetics of Neanderthals versus modern humans, most of which point to a 700 kyr separation of the two species. However, these genetic studies are seriously flawed, and newer studies that are theoretically sound need to be conducted before the results are taken as gospel.

Diagnostic Features

The Neanderthals were a very distinct group from earlier, later, and contemporary populations. They possessed several traits that have been used either as indicators of Neanderthal ancestry, or as autapomorphic Neanderthal traits. Some of these traits include:

An occipital bun. A suprainiac fossa. Position of the mastoid crest. Position of the juxtamastoid crest. Position of the mastoid process. The supraorbital torus. The supratoral sulcus. A receding frontal. Presence of lambdoidal flattening.

Many of these traits are not autapomorphies, but are positioned differently in Neanderthals relative to other populations, and probably cannot be used to distinguish the European Neanderthals as anything more than a population that may or not belong to earlier or contemporaneous demes.

In 1978 A.P. Santa Luca published an extensive study of Neanderthal traits and came to the conclusion that there were four Neanderthal autapomorphies which could be used to distinguish Neanderthals from contemporary sapiens populations. These traits included:

The presence of a suprainiac fossa. A mastoid crest located behind the external auditory meatus. A juxtamastoid eminence located behind the mastoid crest, and often larger than the mastoid process. An occipital torus (a horizontal occipital torus with uniform vertical dimensions with little occipital protuberance).

Santa Luca applied these criteria to most of the Neanderthal-like specimens that were known at the time and attributed specimens to Neanderthal or not based on these traits.

His analysis seemed to exclude the Eastern Asian and African specimens (Maba, Ngandong, Jebel Irhoud, Kabwe, etc.) from being attributed to H. neanderthalensis, while incuding the some of the West Asian and European specimens (Shanidar, Amud, Tabun, Kebara, etc.) as Neanderthal. In Santa Luca's designation, the controversial Qafzeh and Skhul specimens were firmly placed out of the Neanderthal range.

Neanderthals show a very distinctive craniofacial morphology relative to modern human populations. The Neanderthal face, in particular, is distinctly different from anything that came before or after. This fact has often been touted as evidence that the Neanderthals were a divergent outgroup that left no genetic heritage to modern human populations.

The Neanderthal face is distinctive for its significant midfacial prognathism. Features involved in this prognathism include a very anterior midface, retreated zygomatics, anterior position of the dentition, and the anterior position of the nasal aperture.

Evidence that the zygomatics have retreated is seen in that pre-Neanderthals have the M1 at the root of the zygomatic, with Neanderthals having the M3 at the root of the zygomatic, even though there has been some decrease in mandibular robusticity and postcanine tooth size. Some of the features that can be used to distinguish Neanderthals from modern humans (but not from earlier or conteporary populations) include:

Lack of a canine fossa. Flat zygomatics. Rounded inferior orbital margins. The supraorbital torus projects at midline. Presence of a retromolar space (also distinguishes them from earlier hominids). Retreating mandibular symphysis (no mental eminence). A long low brain case. A suprainiac fossa. An occipital bun. A broad and projecting nose.

Larger cranial capacity (but due to larger body size, Neanderthals are less encephalized than modern humans). Another trait that is being looked at currently as a way of distinguishing Neanderthals in the inner ear morphology. Researchers like Hublin and Spoor are trying to determine if the Neanderthals had a unique inner ear morphology that can be used as a Neanderthal autapomorhpy.

The diagrams below show the difference between modern humans, Neanderthals, and chimpanzees. When comparing the values of S/I, humans generally have a value close to 1, chimpanzees have values greater than 1, and Neanderthals have values less than 1. This is seen in the diagrams below:

The range of traits in Neanderthals is very broad, and specimens can be looked at in three groups: early Neanderthals (approximately 250 kyr to 130 kyr), the Neanderthals that existed during the transition to the Upper Paleolithic (approximately 130 kyr to 45 kyr), and the late surviving Neanderthals ( after 45 kyr). The traits that make up each group will be discussed, along with this will be descriptions of some specific specimens.

Lower Paleolithic Neanderthals

As always in the anagenesis of one species into another, there is a "fuzzy" area which prevents the pinning down a a date when "A" became "B". In the case of heidelbergensis to neanderthalensis, this boundary seems to have the Neanderthals first appearing between 250 kyr to 200 kyr.

The specimens that can be attributed as some of the earlier Neanderthals include material from Pontnewydd Cave, Vértesszöllos, Ehringsdorf, Casal de'Pazzi, Biache, La Chaise, Montmaurin, Prince, Lazaret, Fontéchevade, and possibly the very latest material from Atapuerca.

The material from Pontnewydd Cave, Wales, consists of small bits of a mandible and maxilla that may represent an eight-year-old child and an isolated molar from a near-adult or adult individual. This material has been dated by U-series dating, thermoluminescence (TL) dating, and by the associated faunal remains to approximately 251 kyr to 195 kyr.

However, these dates are quite likely too old, as the material may have been washed into the cave at a later time. The features of the fragmentary remains that links them to Neanderthals include the dominant buccal cusp of the P3 and the taurodontism of the postcanine teeth.

The site of Vértesszöllos, Hungary, is also not very securely dated. The site was originally dated by thorium/uranium dating and association with microfauna to the 400 kyr range, but U-series dating has suggested a much younger date of 225 kyr to 185 kyr. However, the stratigraphy of the sites makes the dating of any of these methods with accuracy to the date of the skeletal material as unlikely, so the real date may be earlier or later.

The remains of two individuals come from the site, a child approximately seven-years-old that is represented by fragments of a deciduous canine, a molar, and a permanent molar, and an adult that is represented by most of an occipital bone. The teeth are very similar to the Zhoukoudian material from China, and the cranial fragment has a Neanderthal-like occipital bun, but the bun is attained by cranial thickening, which is unlike the later Neanderthals.

The cranial fragments gives an estimated cranial capacity of 1300 cc. The material has been attributed to erectus, heidelbergensis, and neanderthalensis by different researchers.

The material from Ehrinsdorf comes from the Fischer and Kämpfe quarries that are near the city. The material has been dated to 205 kyr by U-series dating and to 200 kyr by ESR dating, giving a fairly secure date for the material. The hominid remains consists of a neurocranium and partial endocast, an adult and an adolescent mandible, four parietal bones, a femoral shaft, as well as some associated teeth and postcrania.

The Ehringsdorf H vault has been reconstructed at least three times since the material was discovered in 1925, by F. Weidenreich, O. Kleinschmidt, and E. Vlcek. The most Neanderthal-like reconstruction was done by Kleinschmidt, and the least Neanderthal-like was done by Weidenreich.

However, no matter which reconstruction is used, the material shows many traits linking it to later Neanderthals, not least of which is the large brain size (1450 cc for a female). Ehringsdorf is likely the earliest unquestionable Neanderthal site.

The material from Biache-Saint-Vaast, France, consists of two partial crania, a maxilla and cranial rear of a female individual, and parts of the splanchnocranium and cranial vault of a male.

The site is dated to an estimated 196 kyr to 159 kyr. A brain size of 1200 cc. has been estimated for the female crania. While some features such as the small brain size seem to link these specimens to the Swanscombe cranium, it shows many more affinities with later Neanderthals, including:

A Neanderthal-like occipital bun. A suprainiac fossa. Very small mastoids which do not project below the cranial base. A circular cranial contour when seen from the rear. A thin cranial vault. A lateral maxillary incisor with large marginal ridges, a tubercle, and a well-developed labial crown convexity.

The material from the Bourdeois-Delaunay Cavern at La Chaise has been dated by thorium/uranium dating to approximately 151 kyr. The material from this site consists of a partial fragmentary cranium and mandible, and some other fragments and teeth. There are also specimens from the Suard Cave at La Chaise that are uncertainly dated to the same time period.

These remains consist of a large portion of a cranial vault, an occipital bone, a child's mandible, as well as other fragments and associated teeth. The features that can be distinguished about the material seems to link these specimens most closely to the Biache hominids.

The material from Fontéchevade was once a central piece of evidence to the discredited "pre-sapiens" theory of human evolution. The material from Fontéchevade consists of several cranial fragments from different individuals.

Fontéchevade 1 was claimed to lack the thick browridges of Neanderthals by Vallois, but this specimen is that of a juvenile, and the brows would likely have thickened much in late adolescence and early adulthood. Also, Fontéchevade 2 was said to also show no strongly-developed browridge, but this specimen was missing nearly all of the face and browridge region.

The specimen also shows a shallow sulcus and the back of the top of a supraorbital on the right lateral side, meaning it most likely had Neanderthal-like browridges. Fontéchevade has given as estimate of 1350 cc for brain size.

Middle Paleolithic Neanderthals

The next rough grouping of Neanderthal specimens contains those specimens that date to the Late Pleistocene, between approximately 130 kyr to 45 kyr. These include many of the "classic" Neanderthals, as well as many of the better known specimens.

Sites which are included in this group are: Krapina, Saccopastore, Malarnaud, Altamura, Gánovce, Denisova, Okladnikov, Pech de l'Azé, Tabun, Kebara, Régourdou, Mt. Circeo, La Ferrassie, Combe Grenal, La Chapelle, Amud, Shanidar, Teshik-Tash, and Feldhofer.

The material from Krapina Cave, Coatia, was first discovered in 1899 by K. Gorjanovic-Kramberger. The material from this site is the largest sample of Neanderthals ever found, and is one of the largest fossil hominid samples ever found.

There are more than 850 human fossils from more than eighty individuals at the site , most of whom died between the ages of sixteen and twenty-four years. This material has been dated to approximately 130 kyr.

Many of the remains show evidence of butchery, and many of these remains may be the result of cannibalism, as also evidenced by the presence of concoidal scars, and the lack of carnivore tooth marks.

While the crania that have been reconstructed show some differences from the classic Neanderthal anatomy, and from the Near East Neanderthals, several features clearly link the crania as Neanderthal, including: Low and broad cranial vaults.

Broad, shallow temporal fossae with a low anterior articular face. Prominent continuous supraorbitals with large frontal sinuses restricted to them. Receding foreheads with frontal bossing. Columnar outer orbital margins in a lateral orientation.

A broad upper nasal region lacking any depression at the nasal root. A concave, angled nasal profile. The Saccopastore material from the Saccopastore quarry in Rome, Italy, consist of one fairly complete adult female cranium (Saccopastore 1), and a less complete male cranium (Saccopastore 2).

These specimens were found at different times by different people, and have been dated to approximately 120 kyr, nearly contemporary with the Krapina specimens. The female specimen had given an estimated brain size of 1245 cc, and the male has been estimated at 1300 cc.

While these specimens are undeniably Neanderthal, they do show some differences from the Neanderthals from more northenly sites such as La Ferrassie and Le Chapelle-aux-Saints in France. These differences from the classic Neanderthal anatomy include:

A lesser magnitude of middle face projection. More anterior orientation and greater curvature for the cheeks. A shorter temporal fossae. Better development of the canine fossa. Smaller brain size.

A more rounded occipital bone. A more flexed cranial base. The material from the cave in Teshik-Tash, in the mountains of Uzbekistan, consists of the nearly complete cranium of an eight to nine-year-old child, likely male, as well as many postcranial elements, including one neck vertebra, several ribs, a humerus, the clavicles, a femur, a tibia, and one fibula.

The site is very important in that it is likely one of the earliest instances of purposeful burial, and has been dated to approximately 70 kyr. The skeleton was surrounded by what seems to be purposefully arranged Siberian ibex (a wild goat) skulls.

Also, these faunal remains may be indicative of purposeful hunting, as there are few carnivore bones, and the many goat bones show little to no signs of carnivore activity. While this specimen is that of a young juvenile, he had developed several traits that clearly link it to European Neanderthals. These features include:

A large face and nasal region. A developing browridge. A receding forehead. A long cranium. It lacks a mental symphysis. A large cranial capacity of approximately 1500 cc.

The material from Kebara Cave, Israel, was discovered in several phases of excavations. The first hominid found was the fragmentary remains of an infant (Kebara 1), and in 1983, the better known Kebara 2 specimen was recovered. This material has been dated by both thermoluminescence and ESR dating to approximately 60 kyr.

The Kebara 2 specimen consists of the upper part of a male postcranial skeleton, as well as a mandible, a hyoid, and a single M3. The Kebara 2 specimen is one of the few complete pelves known between the australopithecines and modern humans, however, as with just about every complete fossil pelvis that is currently known, it is from a male individual.

The Kebara 2 individual is estimated to have stood about 173 cm tall, and to have weight approximately 76 kg, significantly smaller than estimates for European Neanderthal specimens of similar height, such as La Ferrassie.

The recovery of the hyoid bone was a very important find, as it disproved earlier theories that Neanderthals and other pre-sapiens hominids were incapable of speech due to the lack of a hyoid. Neanderthals did possess a hyoid, and this scenario of speechlessness based on this bone was discredited.

The individual was between the ages of 25 and 35 when he died, and he can be securely attributed to Neanderthals based on the several features, including the presence of a retromolar space, an the lack of a mental eminence.

The material from Amud Cave, Israel, consist of the fragmentary remains of a male, along with 15 other specimens, two-thirds of which are children or infants. This material has been dated by thermoluminescence to approximately 45 kyr to 47 kyr. Amud 1 is the most complete specimen, consisting of just about the entire cranium, with most of the postcrania present.

This individual was a male, died in his mid 20s, was approximately 174 cm tall, and has the largest cranial capacity of any Levant hominid at 1740 cc. While these remains are clearly Neanderthal, these specimens show more affinity to the Shanidar Neanderthals rather than the "classic" European Neanderthals.

For example, when compared to the European Neanderthals and the Skhul H. sapiens, the Amud material actually shows greater affinity to the sapiens of Skhul than to the European Neanderthals.

The Shanidar Cave, in the Zagros Mountains of Iraq, is also the site of a well-preserved Neanderthal sample. The sample consists of two groups from two different time periods, the earlier group has been dated to approximately 60 kyr, and a later group that has been estimated to date to approximately 46 kyr.

The two samples consist of the remains of nine individuals, two children and seven adults. The Shanidar specimens are the focus of some debate over the possibility that flowers were layed over the grave. Many researchers hold doubts to the validity of this claim, saying that the researchers that led the excavation might have carried pollen in accidentally with them.

However, D. Frayer has pointed out that the pollen was from late spring/early summer flowers, and the excavation was conducted in August, so the debate is likely to rage on. The early group consists of Shanidar 2, 4, 6, 7, 8, 9, and the later group consists of Shanidar 1, 3, and 5.

An early Neanderthal find whose description led to several unfourtunate outcomes is that of La Chapelle-aux-Saints. This specimen was discovered by monks during construction of an abbey in 1908, and the remains were sent to M. Boule, who proceeded to describe the specimen as the "typical" Neanderthal, thus leading to the description of "classic" Neanderthal features.

However, Neanderthals are a highly variable species, and La Chapelle-aux-Saints shows many of the most extreme degree of the Neanderthal features. Also, Boule used the state of the fossil to construct an image of Neanderthals as ape-like primitive creatures, which could not possibly be related to humans.

Beyond Boule's prejudices regarding the pattern of human evolution, the fact that the specimen was that of an arthritic "old man" (aged at between 40 and 50 years of age), which further skewed the description of Neanderthals as a species. This specimen has all the traits of the "classic" Neanderthal, for example, the large brain size (1625 cc), the heavy supraorbital torus, etc. This specimen is dated to approximately 50 kyr.

Another early discovery of Neanderthal remains came in 1909, when the remains from La Ferrassie were first uncovered. This site is dated to approximately 50 kyr, and has yielded the remains of seven individuals.

The best known is La Ferrassie 1, the nearly complete skeleton of a middle-aged male Neanderthal, also discovered was a fairly complete adult female specimen, and five juvenile specimens ranging from prenatal to ten years of age. The remains seem to have been purposely buried. The La Ferrassie 1 specimen (along with La Chapelle-aux-Saints) founded the description of the "classic" Neanderthal anatomy, with such features as:

A receding forehead. A long low cranial vault. The base of the skull is wider than the top of the skull. Prominent double-arched browridges. Midface prognathism. Retreated zygomatics. A weakly developed mental eminence. A retromolar space behind the M3. Large cranial capacity (over 1600 cc).

Early Upper Paleolithic Neanderthals

The late surviving Neanderthal sites have started to become better known in recent years, and new discoveries and new dating have clouded the supposedly clear picture of replacement of Neanderthals by incoming H. sapiens populations. This is an exciting field of research at the moment, and only time will tell which evolutionary model os better born out by the evidence.

Sites of late surviving Neanderthals are those that date to after 45 kyr, and especially those dating to after 35 kyr. Sites that are on that list include: La Quina, Zafarraya, Hortus, Vindija, Kulna, Šipka, Saint Césaire, Arcy-Sur-Cure, El Castillo, Bñnolas, Devil's Tower, and Le Moustier.

The cave site at l'Horus in southern France has yielded about 50 hominid fragments which date to the latest part of Würm II. Most of the remains are pieces of jawas and teeth, but there are some cranial fragments and postcranial remains mixed in as well.

These remains have been claimed as evidence that the late Neanderthals were not evolving towards the modern human condition, but have also been used to claim that they were evolving in the modern human condition.

What can be said is the remains show several Neanderthal features (e.g., a poorly developed mental eminence), but also show soe reduction in the anterior dentition relative to earlier Neanderthals. The material has been interpreted as the remains left in a hyena den.

The site of Vindija is becoming a very important site in the debate over assimilation versus replacement of the Neanderthals. There are several layers to the site, and the material in them dates from 42 kyr to as late as 28 kyr in the upper layers.

The Vindija hominids have been put forth as a population that derives from both Neanderthal and incoming sapiens populations, or an influx of gene flow into the Neanderthal populations of Europe.

The remains from the earlier level (G3) date to approximately 42 kyr, and are contemporary with the l'Horus remains. In support of the assimilation theory is evidence that these Neanderthals were evolving in a way that was leading them to the modern human condition. For example:

A reduced midface prognathism and a less projecting upper face. Thinner and less projecting supraorbitals. A narrower nasal aperture, more prominent nasal spine, and a smaller facial height below it. A reduced breadth for the anterior teeth. The absence of ossipital bunning.

Thinner cranial bones. Definite presence of a mental eminence (though not prominent). Some early criticisms attributed these modern affinites to the specimens being subadults or smaller than "normal" Neanderthals, but the remains have been well-reviewed, and seem to be full adults whose size compares favorably to earlier Neanderthal populations.

The most recent stratigraphic level from Vindija (G1) dates to approximately 32 kyr, and has been claimed to be late surviving Neanderthals with modern human affinities, as well as the remains of modern human beings, with no affiliation to the European Neanderthals.

This question is directly involved with the split bone points that have been found in this level, since these have been identified as Aurignacian, which have generally been considered a H. sapiens industry.

If the points are associated with the human remains at the site, it means that either the Aurignacian industry was transmitted to the Neanderthals from incoming humans, or the industry developed independently in both populations. The human remains from this level seem to definitely be of Neanderthal affinity, as seen when they are compared to the earlier remains from the G3 level.

The remains of the Saint-Césaire skeleton was discovered at a limestone cave at Pierrot's Rock, near Charente-Maritime, France, in 1979. The remains consist of the right half of a skull, some ribs, a shoulder blade, two arm bones, and fragments of a kneecap and the tibias which have been dated to approcimately 36 kyr. At one time, it was considered the last surviving Neanderthal. The specimen shows many definitive Neanderthal traits, such as:

Absence of a canine fossa. Presence of a retromolar space. Lack of a mental eminence. Some consider the Saint Césaire skeleton as showing evidence of a transition of the Neanderthals to a more modern human-like form.

Others claim that the differences between the sapiens populations in Europe and the late surviving Neanderthals is so great to preclude the possibility of an ancestor/descendent relationship since the timeframe is so short. Some of the features that have been claimed to show affinities to modern Europeans include:

Central and lateral supraorbital thinning. A reduction in the thickness of the supraorbital torus. A reduction of midfacial prognathism. Reduced anterior tooth size. Smaller, lower appearing orbits. Smaller zygomatics. A markedly narrower nose. A flattened rear surface of the mastoid process.

The material from the Chatelperronian levels of the Grotte du Renne at Arcy-sur-Cure, France, has been dated to approximately 34 kyr. This material consists of isolated teeth with definite Neanderthal like affinities, and a child's temporal fragment whose inner ear morphology links it to Neanderthals rather than modern humans.

The importance of Arcy-sur-Cure is in the association of these remains with personal adornment articles that were similar to those from Aurignacian sites nearby. This is yet another link between the Neanderthals and the Aurignacian industry that discredits the idea that the Neanderthals were not associated with that particular industry.

What may be the latest surviving Neanderthals currently known comes from the Zafarraya Cave, near Andalucia, Spain. The upper levels of this site have been thorium/uranium and C14 to approximately 27 kyr, and the sequence may extend as late as 25 kyr. Material from the site include a nearly complete mandible, a mandible that has been burnt, a partial os coxa, a femur, and an upper incisor.

The femur shows affinities with both Neanderthals (thick cortical bone, circular midshaft cross-section), but also shows affinities to later Europeans (development of a pilaster, thin femoral neck dimensions, shaft expanded anteriorly-posteriorly). The complete mandible more closely links this material to Neanderthals, with features such as:

Small teeth with a very robust mandibular corpus. A vertical symphysis with a mental trigone. A slight mental eminence. A mental foramen positioned under the P4. A gap between the front of the ascending ramus and the back of the third molar.

Moderately large anterior teeth.

Conclusions

The eventual fate of the Neanderthals in the modern human phylogeny is still a much questioned issue, and a vigorously debated one. However, one thing is certain, the issue is not as cut and dry as many supporters of the Out of Africa II theory oftentimes claim.

It seems highly unlikely that the Neanderthals contributed absolutely nothing to the modern genome, but whether they left a large heritage in modern humans or an insignificant one is a question that might not be answered satisfactorily for a long time.