The Origin of Modern Humans: The Fossil Evidence, Part 2
Note: In this ongoing series, James Kidder writes about human evolutionary history. Today is part two of a series in which James discusses the evidence for the origins of modern humans by exploring key paleoanthropological discoveries from around the world. Read last week’s post here.
Perhaps the most important early modern human fossils to be found outside of Africa come from the Holy Land, from the Israeli sites of Mugharet es-Skhul and Jebel Qafzeh, in the Mount Carmel region. Mugharet es-Skhul was excavated in the early 1930s and consists of approximately ten individuals, both adult and juvenile (Garrod, Bate, McCown, & Keith, 1939). Three skulls (IV, V and IX) from Skhul are complete enough to study and show a mixed pattern of relationships. Electron Paramagnetic Resonance dates of between 100 and 110 thousand years before the present (ky BP) have been established for the habitation layers at this site.
These hominins are extraordinarily variable in appearance. Skhul V (Figure 4), the most complete of the three is the most modern, with a high forehead and short vault. When compared, statistically, to a known modern human sample of over 2300 individuals (hereafter “modern human sample”) this skull is within the modern human range (Kidder, Jantz, & Smith, 1992). Such is not the case with Skhul IV (Figure 5) and IX, which exhibit very long and low vaults with faces that are pulled out. Visual and metric analysis of these skulls suggests, however, that they are not Neandertal in appearance but are, rather, more similar to the early moderns from North Africa and, thus may represent a general pan-North African/Levantine population or a migrant population of incipient moderns. About the remains from this site, the excavators wrote this:
We are of the opinion that the variability found amongst the fossil people o f Mount Carmel is greater in degree and in kind than is to be observed in any local community of modern times. Had the Mount Carmel people been discovered—not collectively, in one place, but separately, in diverse localities, each excavator would have been convinced that a new and separate form of humanity had been unearthed, so great does one Carmelite individual differ from another. (McCown & Keith, 1939)
Not far from the site of Skhul is the site of Jebel Qafzeh, yielding the other large cache of modern human remains from the region. This site was excavated between 1932 and 1935 and yielded a number of remains including two complete crania, Qafzeh 6 and 9. Smith (pers. comm.) has indicated that skull 9 is likely intrusive while 6 is contemporaneous with the deposits. This skull has been dated by Thermoluminescence and Electron Spin Resonance to between 92 and 101 ky BP. Qafzeh 6 is regarded by most researchers as modern human although we noted some archaic characteristics for it. For one, the skull is long and very wide compared to the modern human sample (Kidder et al., 1992). When included with the Skhul remains, it is clear that a population that was on the cusp of modernity was resident in this area.
The Levant also contains three sites that yielded Neandertal remains, Mugharet es-Tabun, Amud, and Kebara. Of these, the Tabun and Amud sites yielded relatively complete skulls and their morphology differs from the classic Neandertals of Europe insignificantly. When the modern human remains are compared to the Neandertal remains in the area, chronologically, however, a confusing pattern emerges. The best dates for the Neandertals are between 50 and 70 ky BP, which places them after the modern humans in the area. Of additional consternation is that, as discussed above, the archaic traits do not indicate a Neandertal pattern. This seems to suggest that the Neandertals existed in this region to the exclusion of the modern humans.
Also oddly, subsequent to the Skhul/Qafzeh sample, there are no modern human remains in this region until approximately 40 000 years BP, a gap that is explained by Shea and Bar-Yosef as reflecting a failure of the Skhul/Qafzeh moderns to gain a foothold in the region (Shea & Bar-Yosef, 2005). This model effectively argues that, counter to modern sensibilities, the Levantine Neandertals outcompeted the early moderns in the area and drove them out.
It is tempting to regard Europe as an evolutionary backwater in the pantheon of human evolution simply because few (if any) major evolutionary changes originated there. Rather, it just seemed like "a good place to relocate." While it is true that Neandertals developed their peculiar morphology here, other evolutionary trajectories, especially those involving the populations represented by the slightly earlier Sima de Los Huesos remains are murky. Although several genetic studies have suggested that there was a split between Neandertals and other archaic groups around 400 thousand years ago, it is anybody's guess where that occurred, especially given that Neandertal morphology did not appear until between 200 and 300 thousand years ago.
The other primary reason that Europe is regarded as a backwater is that, where modern humans are concerned, the pace of evolution has lagged behind that of Africa and the Near East and the earliest known anatomically modern humans from the region date to no more than 34 to 37 ky BP, some 100 to 160 thousand years after the first appearance of moderns in Africa. The frustration among European palaeoanthropologists resulting from these issues has persisted since the middle-1800s and is, in part, responsible for the Piltdown debacle (See The Lack of Acceptance of Australopithecus and the Piltdown Forgery in this post). While it is quite possible that the whole Piltdown hoax was conceived of as an elaborate prank, that European paleontologists were so willing to claim the purported first modern human as their own clouded the judgments of some, otherwise very thoughtful and professional, minds.
Despite these shortcomings, the amount of effort that has been placed on European palaeoanthropology in the last 200 years has resulted in a wealth of hominin material relating to the appearance of modern humans that is unparalleled in the rest of the Old World, so much so that it would be impossible to describe even half of the most important finds in this review. I will focus, instead on a few sites that provide critical information regarding the trajectory of modern human evolution in this area.
The first modern Europeans appear in the Moravian Karst region of the Czech Republic, at the site of Mladeč. These were excavated in 1925 and, because of the complex cave stratigraphy, have been dated biostratigraphically to before 32 thousand years ago but before 40 thousand (Wolpoff, 2011). Conventional thought is that the skulls date to between 34 and 37 thousand years ago (Laville, 1988). This coincides with the Early Würm/Late Würm interglacial period and they represent, perhaps, one of the first populations to expand into (the now slightly more hospitable) Europe. The fossil material from this site is comprised of six partial to complete skulls and other fragments. While these fossils have been characterized as generally modern, they have been used as evidence by those espousing versions of regional continuity between Neandertals and early moderns in the region based on the presence of archaic traits. For example, while Mladeč 1 and 6 are quite modern-looking, Mladeč 5 (Figure 6) has a very long, low cranium with significant “bunning” at the back of the skull and, from the rear of the vault, is as wide at the base as it is near the top. However, the brow ridges are small and what is preserved of the face (not shown) is modern.
Perhaps the most well-known site in Europe is the site of Cro-Magnon, located in the Dordogne region of France. Excavated in 1868 while a railway was being constructed, the remains from the site, which consist of two complete crania, CM 1 and 2 and the top of a head, CM 3, along with some arm and leg bone fragments, have been dated only biostratigraphically as being slightly less than 30 thousand years old. Cro-Magnon 1 (Figure 7) exhibits modern cranial curvature and possesses a very high forehead but comparison to a sample of known modern humans reveals that cranial lengths and widths are still expanded over the modern condition. The brow ridges, on the other hand, are small, and all of the associated mandibles have large chins. The skulls are short, high and house-shaped from the rear (Pruner-Bey, Lartet, & Christy, 1875).
Dated to approximately the same time period is the Vogelherd site, which yielded only three individuals, one of which was an almost complete skull that is missing the face. The other two remains consist of a partial skull and a humerus. Very little of the Vogelherd 1 cranium is archaic in nature and the skull has a very high forehead, small brow ridges and is quite gracile in appearance. Only the slight protuberance at the back of the head and a slight roundness to the vault suggest an archaic past.
Join us next week for part 3 of this post!
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