The Role of Cannibalism in the Extinction of the Neandertals

About 800,000 years ago, Homo heidelbergensis, living in Europe and Africa, gave rise to a number of future human types, including Homo sapiens (us), Neandertals, Denisovans, and others. Geneticists claim that the lineages of Homo sapiens and Neandertals had a common ancestor until about 588,000 years ago, when these two kinds of humans became isolated from one another and proceeded to evolve separately.

Homo sapiens continued to evolve in Africa, mostly likely East Africa. Homo sapiens skeletons have been described as gracile—and in the language of anthropologists, this means tall, thin, and built for heat dissipation and running. Neandertal skeletons are described as robust: short, stocky, and built for heat retention. Neandertals continued to evolve and thrive mostly alone in Western Europe and Asia until they went extinct about 30,000 years ago. The proposed reasons for their extinction range from pure chance to climate change to demographics (group size) to war with Homo sapiens.

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Much has also been made of the coupling of Neandertal extinction with the entry of anatomically modern Homo sapiens into Europe at the beginning of the Neandertal extinction. Some anthropologists believe it is a mere coincidence, primarily because there is little or no evidence for war or direct competition between these two human types. These “twist of fate” anthropologists further argue that Neandertal brains and behavior were the absolute equivalents of modern Homo sapiens (I will call them Neandertal apologists).

However, many anthropologists believe that it was a competition for resources, and not direct conflict, that led to Neandertals’ extinction. Some argue that small but significant cognitive differences between these two human cousins were the reason that Homo sapiens could extract greater resources from the same environments (Wynn, Overmann, & Coolidge, 2016).

Could Cannibalism Have Played a Role?

Spanish anthropologists Jordi Augustí and Xavier Rubio-Campillo (2016) conducted a virtual experiment to study factors underlying the extinction of Neandertals. In their experimental model, they included the location of the group with a definitive home range (where resources are collected), the size of the group, cannibalism (in order to eliminate competition and gain additional resources), and the chance that a group will fracture in two (fission). What their computer model revealed was provocative.

From a game-theory point-of-view, cannibalism appears to be an optimal way to obtain resources. Here, it is important to distinguish between two kinds of cannibalism: endocannibalism and exocannibalism.

Endocannibalism is where a group eats its own members. This type of cannibalism can be practiced for nutritional reasons—that is, if a group is starving and very young or very old members might be eaten in order that the effective (i.e., working and reproductive) members of the group may survive. Endocannibalism may also be practiced for religious or symbolic reasons after a group member’s death. Notice that in the former case, it might be considered murder, and in the latter case, it might represent reverence for the dead.

Exocannibalism, in contrast, involves eating members from other groups. Exocannibalism might be practiced to eliminate competition from a group’s resources (food, shelter, etc.), to frighten away other groups, and/or for symbolic or nutritional reasons.

Augustí and Rubio-Campillo found that when resources were plentiful, neither endo- nor exocannibalism would be necessary to survive. However, when resources were scarce and/or the environmental conditions were difficult (e.g., extreme cold), cannibalism may have been an optimal trait. In the latter conditions, groups that favored exocannibalism could gain additional resources, prevent their own extinction, and reduce competition by other groups.

In their final virtual model, they added an additional "type of agent," that is, non-cannibalistic anatomically modern humans entering Europe about 40,000 years ago. At the end of this simulation, the group practicing exocannibalism had gone extinct. Their simulation led them to the conclusion that the cannibalizing groups were excluded from resource-rich areas, and they either lived in places that were arid or very isolated.

It is interesting to note that this describes the exact conditions for the actual Neandertal extinction. In their model, cannibalism becomes an “extremely negative trait,” because although individuals might benefit, the species as a whole does not. It is also important to note that their model assumes that Neandertals practiced exocannibalism only upon other Neandertal groups, and this appears to be the case.

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Evidence of Neandertal Cannibalism

California anthropologist Hélène Rougier (2016) and her colleagues analyzed 99 Neandertal remains from a cave in Goyet, Belgium that dated to about 45,000 to 40,000 years ago. Their analysis showed very clear evidence for cannibalism and even the use of Neandertal bones to resharpen defleshing tools. Roughly one-third of the bones had clear evidence of cut marks, and there were percussion marks (i.e., notches and pits) as well. Not only were these remains cannibalized, but they were found among many other animals, mainly reindeer and horses. There was also a large number of big animal bones, which were processed in the same way as the Neandertal bones.

A review of six other instances of Neandertal cannibalism ranging from 120,000 to 39,000 years ago shows that all were Neandertal upon Neandertal cannibalism. But the mystery deepens: In many of these aforementioned cases, animal bones were also present, bountiful, and processed in the same fashion. That is, cut marks on longer bones were similar for Neandertal skeletons and animals, and the bones were split to extract nutritionally-rich marrow.

Why would Neandertals eat other Neandertals if animals were plentiful? It is known that Neandertals did not restrict themselves to just meat resources—there is evidence that they sometimes ate plants and other non-meat foods. Some Neandertals, perhaps beginning about 120,000 years ago, began practicing cannibalism as an optimal strategy of gaining resources and reducing competition.

However, it may have begun an almost 80,000-year tradition of gustatory cannibalism in some Neandertal groups—that is, some Neandertals simply enjoyed the taste of Neandertal flesh. It also seems unlikely that the practice began in each Neandertal group independently over 80,000 years, but it was more likely that it was a tradition passed down through generations of Neandertals.

So, why did they do this? One theory: Neandertal's olfactory bulbs were smaller than modern Homo sapiens, so they may have had a lesser ability to discriminate among different smells, particularly smells like burning human flesh, which firefighters uniformly describe as horrible and very stinky.

The extinction of our closest human cousins will always remain a great mystery, but it touches on so many other mysteries—such as whether brain differences matter, how important is the sense of smell in human evolution, and will future Homo sapiens be replaced?