Changing Times, Changing Faces: The Extinction of Homo neanderthalensis
Writer’s comment: In taking his Biology 10 course, I was thoroughly impressed by Dr. Allen Marr’s continued enthusiasm for all aspects of his chosen field. When beginning an assigned paper on human evolution for his class, I tried to bring some of that same feeling to my essay. Along these lines, I took an aspect of the subject about which I was curious--namely, the disappearance of the Neanderthals--and attempted to utilize topics we had covered in class (such as mitochondiral DNA and genetic variance in populations) to draw my own conclusions on the matter. Ultimately, I admit I only scratched the surface on the wealth of new research regarding the demise of Homo neanderthalensis and the subsequent rise of Homo sapiens sapiens. Still, the information I learned in writing “Changing Times, Changing Faces: The Extinction of Homo neanderthalensis” and my interest in biology which Dr. Marr kindled will stay with me for the foreseeable future.
Instructor’s comment: In BIS 10, Biology for non-science majors, students were given the opportunity to write a paper investigating some area of science. With such a broad choice of topics, William Baker chose a fascinating and dynamic topic: the extinction of Homo neanderthalensis. William successfully presented several relevant ideas concerning not only the environmental conditions influencing Homo neanderthalensis, but also the more social aspects of their extinction. Without a doubt, William has written a stylistically and structurally superior paper displaying an impressive depth of analysis.
—Raina Petrov, School of Veterinary Medicine
It is fascinating to consider that once there were different species of humans living together on our planet, beings that walked and breathed like us, but whose descendants failed to survive into the present. Perhaps the most interesting of these variants is Homo neanderthalensis, a group of hunter-gatherers who lived in Europe and western Asia during the Pleistocene epoch. Despite the pejorative use of the term “Neanderthal” in the modern vernacular, Homo neanderthalensis was “the closest relative we have in the entire known human fossil record” and a highly successful species whose adaptations and close social structure allowed them to exist successfully for some 150,000 to 170,000 years (Tattersall 1995: 10). However, even with their remarkable resilience and adaptive abilities, the Neanderthals (alternately called “Neandertals” in some scientific circles, based on the original German designation) were not immune to changes in the world around them: about 30,000 years ago they all but vanished from the archaeological scene, replaced in fossil evidence by the “fully modern human,” or Homo sapiens sapien.
What could have led to such sudden, drastic, and disastrous changes in circumstances as to push a once-prevalent species like the Neanderthal into quick extinction? Were these ancient humans simply unable to deal with the shifting conditions of their environment, the unlucky losers in the vast and complex evolutionary game of natural selection? Or was the fate of Homo neanderthalensis directly linked to the rise of our own species, the outcome of a clash between similar but distinct human lineages that resulted in the fall of one and the rise of the other? Ultimately, the study of the end of the Neanderthals remains largely speculative, and no one set of satisfactory answers explains their extinction; the result, then, is an intriguing puzzle of archaeological evidence, biological observations, and behavioral theory. More fundamentally, analyzing the extinction of Homo neanderthalensis forces us as human beings to examine the reasons behind the growth and eventual dominance our own species, a development that may have been the result of brutal conquest rather than some kind of fated or evolutionary preeminence.
Before discussing the demise of the Neanderthals, however, let us delve deeper into the material and social characteristics of these remarkable individuals. In the most basic physical sense Homo neanderthalensis was quite different from Homo sapiens sapien, and these distinctions have led most researchers to categorize the two groups as wholly different species. (Such a view is by no means universal, though, and there are plenty of paleoanthropologists who classify the former group as a subspecies, Homo sapiens neanderthalensis [Tattersall 1995: 10].) Many of the more striking contrasts with the modern human lie in the face and cranium of the Neanderthal. Brow ridges (“bony ridges above the eyes”), forward teeth in the lower jaw, a “receding forehead,” the absence of prominent chin, and a “distinctive shelf or protrusion at the back of the skull” known as an “occipital bun” are all frequently noted characteristics of the species (Price and Feinman 2001: 109, Wong 2000: 100, Tattersall 1995: 13). Taken together, these attributes generally give the face of Homo neanderthalensis an “elongated” or “protruding” appearance and may have been related to increased chewing ability (Price and Feinman 2001: 109, Tattersall 1995: 12). The teeth, interestingly enough, have been one of the most important features in gaining greater insight into the behavior and lifestyles of Neanderthals. Among recovered Neanderthals of all ages the teeth are “often heavily worn,” leading to the inference that the mouth was often utilized in “grasping or heavy chewing” (Price and Feinman 2001: 109). Furthermore, diagonal scratches across the front teeth suggest that meat was often held “in the teeth and a stone knife was used to cut off a bite-size piece at the lips,” with the knife slipping occasionally and creating the unique markings (Price and Feinman 2001: 109).
All this information, in turn, leads anthropologists to venture more general conclusions about the technology and cognitive capabilities of Neanderthals (e.g., Why use your teeth unless you had failed develop more intricate knife technology?). This attitude is reinforced by evidence from archaeological sites: it is generally thought that Neanderthals were limited to devising Mousterian tools, most notably hand-axes since members of the species probably did not posses a “[sufficiently] sophisticated understanding of the material” to become proficient in bone-working (Tattersall 1995: 161). Do these less than flattering appraisals of the intelligence of Homo neanderthalensis contradict the fossil record, which displays evidence of large craniums? Not necessarily: although the members of Homo neanderthalensis actually tend to have larger brains than modern humans (1500 ml rather than 1400 ml), that is no guarantee of intelligence, as David Tattersall pointedly notes in his book The Last Neanderthal: “we should not be mesmerized by this feature. . . . Although Homo sapiens and Homo neanderthalensis had brains of similar size, so do virtually any other pair of closely related primate species” (1995: 11).
The descriptions of the Neanderthals from the neck up would seem to suggest a bias in information regarding their physiques; in reality, the entire bodies of Homo neanderthalensis tell quite a story. With “barrel” chests, “heavy limb bones,” and “heavy muscle attachments” (particularly in the shoulder blades, neck, and back of the skull), the short (typically 63 to 66 inches in height), compact Neanderthals were well-suited to their harsh environments (Price and Feinman 2001: 110). The powerful bodies of these individuals, it seems, could often make up for their lack of more sophisticated tools, allowing them to get closer to their prey than could later human species. Furthermore, the bodies of Homo neanderthalensis (“similar to that of the Eskimo”) might have been well suited for extensive travel over inhospitable areas, a necessity in tracking migratory prey for suitable sustenance (Price and Feinman 2001: 110). More fundamentally, though, the generally “stocky” composition of the Neanderthals almost certainly played a role in heat retention (decreased surface area to volume ratio, for example), allowing individuals to stay warm “more effectively in the extremely cold weather brought on by glacial cycles” than any taller, thinner contemporaries (Wong 2000: 100). (There is a reason, after all, that the Pleistocene is referred to as the “Ice Age.”)
Describing the traits of individuals, however, fails to reveal the whole story of the Neanderthals since their group interactions seem to have been of the utmost importance in their success and longevity. The members of Homo neanderthalensis tended to stay in comparatively small tribes of “perhaps ten or a dozen adults at most, plus children of various ages” (Tattersall 1995: 158); these tight social structures allowed for a greater ability to travel over inhospitable countryside looking for resources. Generally, the archaeological record suggests that Neanderthals variously engaged in a pair of food-gathering methods, the choice of which depended on geographic and climatic considerations. In the “circulating-mobility pattern,” a cluster of individuals would periodically move their campsites as they ranged over a territory; this approach would have been particularly effective in areas with scant resources spread throughout a large physical area (Tattersall 1995: 155-156). By contrast, the “radiating-mobility strategy” involved establishing a central location from which “forays to temporary satellite camps near important resources” could occur; the resources in a given region, then, would be used to their optimal potential (Tattersall 1995: 156).
However, what specific “resources” were favored by Homo neanderthalensis? The original conclusions among most researchers, notions which persisted into the 1980s, were that Neanderthals “were hunters, subsisting mainly on meat gained by raiding the herds of grazing mammals” that lived on the wide plains of Europe and western Asia (Tattersall 1995: 148). (Images of Neanderthals taking down massive woolly mammoths with spears persist into the present.) While that conception of Homo neanderthalensis has not been completely dismissed (recent evidence from a dig in Croatia suggests Neanderthals “were skilled hunters capable of killing even rhinoceroses”), the more current thesis suggests that Neanderthals had much more varied food sources, scavenging much of the year, hunting “only the smallest mammals,” and altering methods of food collection “widely with the environment and the changing seasons” (Wong 2000: 102-103, Tattersall 1995: 148). Whatever the exact composition of their diet, though, the Neanderthals displayed in their approaches towards subsistence the same characteristics that seem to have guided them throughout their time on Earth--stubborn, pragmatic survival.
From all the available evidence, it would seem the Neanderthals were well suited to their environment and their lifestyle, both in a biological and a cultural sense. What factors, then, led to their extinction? That word--“extinction”--is somewhat tricky: when applied to a pre-modern context, the term often suggests the demise of a species based strictly on environmental phenomena (e.g., climate changes, ecological disasters, the absence of a steady food supply, etc.). As I suggested earlier, one might suppose that Homo neanderthalensis was the unfortunate victim of natural selection, or “the survival and reproductive success of individuals or groups best adjusted to their environment, leading to perpetuation of genetic qualities best suited for the environment” (Thomas 1998: 429); in other words, the times and conditions changed, the Neanderthals failed to change with them, and as a result they were left in the wake of evolution. While the exact circumstances of Neanderthal extinction remain obscured, the prevailing theories on the matter center not on relationships with the environment but rather on the intrusion about 45,000 years ago of unwelcome intruders in eastern Europe and western Asia: namely, Homo sapiens sapiens. In a mere 11,000 years (about 43,000 to 32,000 years ago), modern humans swept across Europe from the west and wiped out Homo neanderthalensis. The great importance of this development cannot be underestimated. “With the arrival of the behaviorally modern Homo sapiens the world faced an entirely new phenomenon,” Ian Tattersall writes in The Last Neanderthal, “one from whose impact it is still reeling, and of which the Neanderthals were among the first to bear the brunt” (1995: 198).
But while the effect of the arrival of Homo sapiens sapiens on the Neanderthals is clear, the exact mechanism by which that usurpation took place remains obscured. A particularly controversial notion is the idea that modern humans did not destroy the Neanderthals but rather mated with them: “Did Neanderthals disappear into the gene pool of modern-looking humans, as smaller numbers of Neanderthals interbred with larger numbers of Homo sapiens sapiens?” (Price and Feinman 2001: 119). The basis for the evidence behind this claim is that many modern humans of the era seem to have taken on some characteristics of Homo neanderthalensis (“many of the features that characterize Neanderthals are also seen in the early modern Europeans that follow them”) and, reversely, that many late Neanderthals take on traits of their contemporary Homo sapiens sapiens--“more modern-shaped brow ridges and the slight presence of a chin on their mandibles” (Wong 2000: 100). As one might suppose, such a claim is quite controversial and flies in the face of several long-held beliefs--for example, the notion that Neanderthals and modern humans belonged to separate species, as only members of the same species can mate successfully. Although the theory in question has many detractors, author Ian Tattersall, curator of the Department of Anthropology at the American Museum of Natural History, offers the most virulent condemnation of the theory that I came across. “There is no convincing biological evidence in [Europe] for the intermixing of Neanderthal and modern morphologies,” he notes with a palpable sense of annoyance in The Last Neanderthal, “and if Homo neanderthalensis and Homo sapiens were indeed different species, as the anatomical distinctions between them so strongly suggest, they could not have interbred successfully, certainly not over the long term” (1995: 199).
Genetic evidence would seem to further bolster the notions of Tattersall and his like-minded colleagues. In July of 1997, researchers at the University of Munich conducted experiments on a short stretch of mitochondrial DNA from a Neanderthal sample and compared it to the mitochondrial DNA of living human beings. The result? The difference between the mitochondrial DNA of the Neanderthal and that of the modern human proved to be “considerably greater than the differences found among living human populations” (Wong 2000: 100-101). While this information would seem to resolve the debate, some paleoanthropologists will not abandon the interbreeding hypothesis. Instead, they point to the recovery in Portugal three years ago of the skeleton of a four-year-child with an apparent blend of Neanderthal and modern human characteristics; certain researchers believe such combined traits “could only have resulted from extensive interbreeding between the two populations” (Wong 2000: 101).
If the general consensus in the anthropological community is against the interbreeding hypothesis, however, then what could explain the mechanism by which Homo sapiens sapien usurped Neanderthals in Eurasia, especially in a mere 10,000 years (a heartbeat in evolutionary terms)? The most popular theory is perhaps the least appealing: simple, brutal conquest, either by actually wiping out the Neanderthals group by group or by pushing the species out of its desired habitat into less hospitable regions farther north (Price and Feinman 2001: 118-119). Interestingly, this thesis is based largely on supposition rather than hard fact or intense observation. Indeed, many researchers are perfectly willing to accept and condemn the “invasion” of modern humans on the species’ subsequent record of violence and warfare (Tattersall 1995: 203).
In reality, though, certain bits of physical evidence directly contradict the theory in question. Artifacts recovered from sites in Europe dating back to about 38,000 years ago would suggest that Homo neanderthalensis was in possession of more advanced Homo sapiens sapien technology (“multiple long, thin blades from cylindrical cores,” “tools from bone and antler”) “before the arrival of fully modern humans” in Neanderthal-controlled regions (Price and Feinman 2001: 119). How could this be possible in the context of the “conquest” supposition? Furthermore, the varied levels of remains in many French archaeological sites, coupled with the rugged terrain of Europe and western Asia, imply that the takeover of Neanderthal regions by modern humans could not be as swift and uniform as many researchers would like to believe; instead, it was “a gradual and fragmented process,” a realization that raises the issue of how pockets of Neanderthals failed to survive, isolated from the modern human invasion by remote geographic location (Tattersall 1995: 202). After all, the movement of Homo sapiens sapiens was random and based on the survival of each particular group or “tribe”: as a species they lacked the overriding social structure needed to systematically and consciously eliminate Homo neanderthalensis on such a large scale. Despite the tantalizing and contradictory nature of much of this information, it seems a large number of paleoanthropologists are willing to accept this thesis based on only a general notion of genetic superiority--namely, that fully modern humans “held some cognitive advantage over Neanderthals” (e.g., language, symbolic thought, complex bone and antler tools) that allowed them to outdo their genetic “cousins,” thereby becoming the preeminent human species on the planet (Wong 2000: 103).
A “cognitive advantage”--is that all that explains the extinction of a thriving, seemingly resilient human species? In the end, the lack of true answers regarding the demise of Homo neanderthalensis is also what makes studying these individuals so intriguing. The Neanderthals appear to have been well-adjusted to their environment in several ways, from their loose, tribe-like social structure (ranging quickly over large areas), to their broad diet (moving from large prey to plants and smaller animals as the situation dictated), and their own bodies (short, compact, powerful, and warm). How, then, did extinction find these highly adaptive beings? Shouldn’t “natural selection” have discriminated against a species ill-suited for its environment? With this inconsistency in mind, are we forced, as many researchers suggest, to turn to ourselves, the “noble” Homo sapiens sapiens, as the culprit in the disappearance of Homo neanderthalensis? Neither the “interbreeding” nor the “conquest” hypothesis is completely convincing since there is evidence to dispute both theories--genetic testing in the former and technological remnants in the latter. Still, the mere suggestion of human culpability in the extinction of our closest ancient ancestors carries with it disturbing implications about our tendencies towards violence, control, and warfare, even some thirty millennia in the past.
Price, T. D. & Feinman, G. M. (2001). Images of the past. Third ed. Mountain View, California: Mayfield Publishing Company.
Tattersall, Ian. (1995). The last Neanderthal: The rise, success, and mysterious extinction of our closest human relatives. Hong Kong: Macmillan.
Thomas, David Hurst. (1998). Archaeology. Third ed. Fort Worth, Texas: Harcourt Brace.
Wong, Kate. (April 2000). “Who were the Neandertals?” Scientific American. 98-107.