The BBC has highlighted a fascinating study in today's article "Neanderthal large eyes 'caused their demise:'"
A study of Neanderthal skulls suggests that they became extinct because they had larger eyes than our species. As a result, more of their brain was devoted to seeing in the long, dark nights in Europe, at the expense of high-level processing. This ability enabled our species, Homo sapiens, to fashion warmer clothes and develop larger social networks, helping us to survive the ice age in Europe. Neanderthals are a closely related species of human that lived in Europe from around 250,000 years ago. They coexisted and interacted briefly with our species until they went extinct about 28,000 years ago, in part due to an ice age. The research team explored the idea that the ancestor of Neanderthals left Africa and had to adapt to the longer, darker nights and murkier days of Europe. The result was that Neanderthals evolved larger eyes and a much larger visual processing area at the back of their brains. The humans that stayed in Africa, on the other hand, continued to enjoy bright and beautiful days and so had no need for such an adaption. Instead, these people, our ancestors, evolved their frontal lobes, associated with higher level thinking, before they spread across the globe.
For a novel about how Neanderthals and the early Homo sapiens may have co-existed during the Ice Age, try Jean M. Auel's Clan of the Cave Bear:
When her parents are killed by an earthquake, 5-year-old Ayla wanders through the forest completely alone. Cold, hungry, and badly injured by a cave lion, the little girl is as good as gone until she is discovered by a group who call themselves the Clan of the Cave Bear. This clan, left homeless by the same disaster, have little interest in the helpless girl who comes from the tribe they refer to as the "Others." Only their medicine woman sees in Ayla a fellow human, worthy of care. She painstakingly nurses her back to health--a decision that will forever alter the physical and emotional structure of the clan. Although this story takes place roughly 35,000 years ago, its cast of characters could easily slide into any modern tale. The members of the Neanderthal clan, ruled by traditions and taboos, find themselves challenged by this outsider, who represents the physically modern Cro-Magnons. And as Ayla begins to grow and mature, her natural tendencies emerge, putting her in the middle of a brutal and dangerous power struggle. Although Jean Auel obviously takes certain liberties with the actions and motivations of all our ancestors, her extensive research into the Ice Age does shine through--especially in the detailed knowledge of plants and natural remedies used by the medicine woman and passed down to Ayla. Mostly, though, this first in the series of four is a wonderful story of survival.
By the way, Cro-Magnon is an old-fashioned term for the early Homo sapiens which are now known as "European Early Modern Humans."
UPDATE: there's a good review of Clan of the Cave Bear over at the Book Addict Blog.