But Shipman takes it a step further and argues that our unique ability to empathize and form bonds with other animals drove our evolution to such a degree that it played a central role in the invention of stone tools, language and symbolism, and domestication. In short, that it made humans human. She calls this trait the animal connection, and in addition to her initial review paper, has made it the subject of a new book.
According to Shipman, the adoption of a more carnivorous diet by the genus Homo about 2.6 million years ago required this former prey species to start depending on accurate observations of other animals to obtain more meat. Thus, a selective pressure arose favoring those hominins capable of understanding and empathizing with non-hominin species, which made them more effective hunters. This led, in turn, to the development of stone tools, used not just for hunting, but possibly also for anatomical study of carcasses. From there, the need to share complex information about animals led to the invention of language, and eventually reached ultimate fruition with the domestication of canids about 32,000 years ago.
Her thoughts about dogs are insightful: if the point of domestication was to make meat-acquisition easier, as has generally been supposed -- that is, if it was meant to reduce the risks of hunting by simply growing our own meat at home -- why then were wolves the first animals to be brought into human society? Wolves (who later became dogs) eat a lot of meat on their own, and are dangerous predators in their own right. From the perspective of evolution, domestication of a predator is maladaptive: it uses up a lot of your resources and calories, poses a danger to your offspring, and competes with you for food. Shipman maintains that animal domestication was essentially the invention of "living tools," an extension of our ability and desire to shape our environment to our needs. In this model, domesticated canids became extensions of our spears, an effective way of defending our homes and acquiring larger prey to feed more people. Ultimately, this allowed us to support larger, more settled populations and invent agriculture.
"Clearly," Shipman argues:
humans who handled and lived with animals more successfully accrued a selective advantage in performing tasks that humans without animals could not achieve. Domestication was reciprocal, as the animals in turn selected for behavioral or physical traits in humans, such as better communication with animals and the continued functioning of lactase into adulthood....
In this phase, the animal connection gave a selective advantage to humans who had better abilities to observe, to communicate, and to make a new sort of living tool. These abilities pre-adapted humans to live in higher densities and more permanent settlements, as happened once domestication of plants and stock animals occurred.My initial reaction to Shipman's idea was to ponder the paradox it highlights. According to her hypothesis, our capacity to empathize with, love and care for other animals as though they were members of our own family arose in within the context of increased meat-eating by our distant ancestors. In other words, the ancient roots of animal rights ideas may lie in the birth of the one behavior by which all animal rights people are horrified.
To me, it's an excellent demonstration of exaptation. We evolved the capacity to empathize with other animals so that we could more effectively exploit them; but it is that very capacity that now allows some humans to ponder the folly of our ways and espouse animal liberation on the basis of our natural capacity for empathy.
In other words, animal exploitation and animal liberation may be two applications of a single evolutionary trait: our ability to make cross-species connections with other animals!
There's a lot to think about here, and I'm certain this won't be the last we hear of Shipman's hypothesis. Based on the responses in her review paper, the idea has received a generally positive reception among her colleagues. I look forward to reading her book and getting a more in-depth treatment. In light of her ideas, it will be interesting to see where she stands on current animal issues.