One of the Greatest Mysteries in Human Evolution

Neandertals went extinct about 30,000 years ago. They lived successfully in Europe, Asia, and Africa for hundreds of thousands of years. Homo sapiens left Africa about 70,000 years ago and entered France about 55,000 years ago and Germany about the same time. Many anthropologists see the entry of Homo sapiens into Europe and the Neandertal extinction as no mere coincidence—that is, Homo sapiens moving into Europe had something to do with the Neandertal extinction. This video reveals one possibility for the Neandertal extinction: They had a penchant to cannibalize each other.

There is little or no evidence that the two human cousins fought with each other. However, one provocative hypothesis is that Neandertals, when they were alone in Europe and Asia, cannibalized each other. Further, in some sites, Neandertals processed deer, their carcasses, and their bones just like they processed the bodies of other Neandertals. They would split the bigger bones of deer and other Neandertals to obtain nutrient-rich marrow. In one site, they ate the bodies of two young juvenile Neandertals and even scraped out the skull of a child for its brains.

When Neandertals were alone in Europe, cannibalism would serve at least two purposes: One, it would reduce competition for limited resources. Neandertals hunted big and small game animals, and we know they had a variety of food types. However, they needed larger meat sources because of their thick (robust) bodies. It is estimated that Neandertals needed about 35 percent more calories than the thinner and taller bodies of Homo sapiens (described as gracile). But these large meat food resources are not always plentiful and/or available. Given times of limited food sources, eliminating the competition of other Neandertals might be an effective strategy. A second hypothesis is that eating other Neandertals might also be an additional source of food.

There were also brain differences between these two human cousins that might have caused subtle cognitive differences that were visible to natural selection. First, Homo sapiens might have had neuronal differences in their frontal lobes with the recent gene discovery of TKTL1. This gene is responsible for the generation of neurons in the frontal lobes of human children, but Neandertals lacked this gene. Homo sapiens also had a larger cerebellum, which contains about 80 percent of all the brain's neurons. The cerebellum not only tweaks fine motor movements but also refines thoughts just like motor movements. The cerebellum has also been linked to creative ideas and innovation. Interestingly, the olfactory bulbs in Homo sapiens have also been shown to be larger than in Neandertals, and genetic studies have shown that Neandertals may have had a lesser ability to distinguish smells than Homo sapiens. Finally, Homo sapiens had expanded parietal lobes, which have been shown to be responsible for episodic memories (like movies), constructive mental simulations (thought experiments), sense of self and others, mathematics, and autonoesis (a sense that time is relative, and we can move back and forth in time in our minds).