Homo Sapiens Made Eye Contact with Dogs to Dominate Neanderthals
(p. C6) In the space of just a few thousand years, as we spread through the region, we killed off the apex predators: first the Neanderthals and then, over time, cave bears, cave hyenas, lesser scimitar cats, dholes, mammoths and woolly rhinos, among other animals. How did we manage this? According to Ms. Shipman, we enlisted the help of dogs.
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Ms. Shipman devotes the final third of her book to exploring a fascinating range of evidence--genetic, archaeological, anthropological--that provides substantial support for this theory. She never proposes that the alliance of humans and dogs alone led to the extinction of the Neanderthals. In all likelihood, she writes, the mere presence of humans, a competitive new predator in the Eurasian ecosystem, was an important stressor, as were climate change and perhaps even infectious diseases brought by humans from Africa. But the domestication of dogs, she suggests, significantly tipped the balance: "The unprecedented alliance of humans with another top predator (wolf-dogs or a kind of wolf) may have been the final stress that pushed Neanderthals and many other species down the slippery slope toward extinction."
So how did humans manage to domesticate wolves while their Neanderthal cousins, so similar in so many ways, did not? Here Ms. Shipman gets imaginative. Modern humans, she writes, have recently been shown to be the only extant primates whose irises are surrounded by white scleras--the whites of our eyes. We're also the only primate to have eyelids that expose much of our scleras. What evolutionary advantage could this have possibly given us? "The white scleras and open eyelids," she proposes, "make the direction of a person's gaze highly visible from a distance." Having white scleras allowed us to communicate subtly at a distance among ourselves and with our new best friend, dogs, a biological advantage that may have made all the difference as we competed for prey with Neanderthals--who, if they were like every other primate we know of today, had dark scleras.
Most animals, including apes and wolves, don't make eye contact with humans; nor do they gaze at faces for long. Dogs, on the contrary, are excellent gaze-followers, a trait that scientists believe we selectively bred into them during their domestication. Once we had teamed up with dogs, we were unstoppable.
For the full review, see:
(Note: ellipsis added.)
(Note: the online version of the review has the date March 20, 2015.)
The book under review, is:
Shipman, Pat. The Invaders: How Humans and Their Dogs Drove Neanderthals to Extinction. Cambridge, MA: Belknap Press, 2015.