The details about Neanderthal behaviour remain highly controversial. From their physiology, Neanderthals are presumed to have been omnivores, but animal protein formed the majority of their dietary protein, showing them to have been carnivorous apex predators and not scavengers.[1] Although very little is known of their social organization, it appears patrilines would make up the nucleus of the tribe, and women would seek out partners in neighbouring tribes once reaching adolescence, presumably to avoid inbreeding.[2] An analysis based on finger-length ratios suggests that Neanderthals were more sexually competitive and promiscuous than modern-day humans.[3]
The quality of stone tools at archaeological sites suggests Neanderthals were good at "expert" cognition, a form of observational learning and practice – acquired through apprenticeship – that relies heavily on long-term procedural memory.[4] Neanderthal toolmaking changed little over hundreds of thousands of years. The lack of innovation may imply a reduced capacity for thinking by analogy and less working memory. Researchers have speculated that Neanderthal behaviour would probably seem neophobic, dogmatic and xenophobic to modern humans,[4][5] but nevertheless having a considerable degree of rationality.[6] There is genetic evidence that supports interbreeding with Homo sapiens, language capability (including the FOXP2 gene), archaeological signs of cultural development and potential for cumulative cultural evolution.[7] Few Neanderthals lived past the age of 35.[8]