Jul 22 2010

The Animal Connection

We often take our relationship with animals for granted, but humans are unique in their ability to form working relationships with other species. (There are animals that have formed symbiotic relationships, but nothing compared to the multifarious use of animals by humans.) Humans nurture other species, feed and protect them, have guided their evolution in a process of domestication, and can communicate with them to a limited but useful degree. In exchange we use animals for protection, companionship, as a renewable food source, as a source of milk for our children, to provide wool for clothing, to perform strenuous manual labor, and for transportation of goods and people.

Anthropologist Pat Shipman has written a paper and an upcoming book hypothesizing that our relationship with animals was a key component of recent human evolution. Working with animals, she argues, evolved out of our knowledge of animals as prey and predators. Our ancestors intently learned about the animals in their environment, so that they could better hunt prey and avoid becoming prey themselves. This animal knowledge base then allowed them to exploit those same animals. Acquiring and passing on a complex knowledge base requires language, and therefore the benefits of animal knowledge became a key component of the selective pressures in favor of language itself. Those ancestors that were better able to form relationships with animals had a significant advantage over those who did not.

Let’s take dog domestication, for example. This was a long process, and what we can say at this point is that the dog genetic line split from the wolf line about 100,000 years ago. It is unclear what role, if any, humans had in this original split. One hypothesis is that some wolves began following human hunters to scavenge. Those that were less threatening to the humans were more likely to survive at the edges of human activity, until eventually you have a wolf transitioning to become a dog. At some point humans became involved in the process, feeding the proto-dogs in exchange for their service as an alarm system and protection against other predators. The oldest dog fossil dates to about 32,000 years ago, although this fossil still has some wolf-like features. The earliest example of clear human-dog cohabitation dates to about 14,000 years ago. Genetic evidence suggests that dogs are evolved from Middle Eastern wolves, although there was likely a contribution from Asian wolves which might have been an independent domestication.

Today we use dogs for companionship, as an alarm system, for protection, herding, hunting, and transportation. I use my dog to keep squirrels away from my bird feeders and deer away from my garden.

The advantage to our ancestors of using animals is clear. It is easy to imagine the extreme advantages to early tribes of humans if they had large hunting dogs at their sides, or horses to ride, or farm animals as a convenient food source, or even just cats to keep away the vermin.

But Shipman is making a further argument – the advantage of communicating knowledge about animals was significant enough to become an important factor in our own evolution. As evidence for this she writes:

“Though we cannot discover the earliest use of language itself, we can learn something from the earliest prehistoric art with unambiguous content.  Nearly all of these artworks depict animals.  Other potentially vital topics — edible plants, water, tools or weapons, or relationships among humans — are rarely if ever shown,” Shipman said.  She sees this disproportion as evidence that the evolutionary pressure to develop an external means of storing and transmitting information — symbolic language — came primarily from the animal connection.

That is an interesting argument. The fact that our ancestors focused their art almost entirely on the depiction of animals is certainly worthy of some explanation. But Shipman makes a tricky inference. It is also true that animals are often beautiful and fascinating creatures. It is easy to understand the artistic obsession with animals without invoking any other explanation. In order to interpret the implications of the disproportionate focus on animals in early art we would need to know the role of art in early human culture. Was it used to depict useful or important aspects of human life, or things that were thought to have a spiritual connection, or simply the most interesting things available in the environment?

I look forward to reading Shipman’s book to see how she further develops this argument. Regardless of the true implications of this observation about early human art, and the precise role that animals played in driving human evolution (specifically with language and tool use, as Shipman argues), there is no question that animals were vitally important to the success of humans as a species. I see the formation of useful relationships with other species as just one of many skills that our ancestors developed to help them survive and thrive, but perhaps one that deserves more attention.

Incidentally, I took two courses on human evolution with Pat Shipman while I was an undergrad at Johns Hopkins. She was an excellent teacher and helped further my interest in the science of evolution. She is now an adjunct professor of biological anthropology at Penn State University.

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