Do the eyes have it?

One of the classic conundrums in paleoanthropology is why Neandertals went extinct while modern humans survived in the same habitat at the same time. Mellars and French compared the number and sizes of Neandertal and modern-human archaeological sites, as well as the density of tools and the weight per square meter of prey animals, represented by fossils, in those sites. There is no shortage of hypotheses. Some favor climate change, others a modern-human advantage derived from the use of more advanced hunting weapons or greater social cohesion. Karen Lupo of Washington State University conducted a similar study among the Bofi and Aka forest hunters of the Central African Republic. A study by Hiromi Kobayashi and Shiro Kohshima of the Tokyo Institute of Technology showed that modern humans are unique among extant primates in having highly visible white sclerae surrounding the colored irises of their eyes, as well as eyelids that expose much of the sclerae.