But sometimes -- actually quite often -- Bow will do something that seems so characteristic of humans, that it takes one's breath away.
I dropped a Kleenex on the floor by accident yesterday, and as I was cleaning up the potty, my back turned to Bow, I heard him blow his nose -- loudly! I turned around, and there he was, blowing his nose and then looking at the tissue.
Did I teach him how to do this? No. But I did use a tissue in his presence many times, and when he was little, and he had a cold, I used to wipe his nose. Is this "natural" behavior for a chimpanzee? Well, they certainly don't have facial tissue in the wild, but I would not say that it is unnatural. In fact, it is no more natural for a human than for a chimpanzee. Do you think I have had disposable facial tissues all my life? My mother sent me to kindergarten with a cloth handkerchief! Facial tissue is a new invention.
So what is natural? It's natural for all of us to learn to use the cultural artifacts that we have in our environment. Bow picks up Kleenex and the alphabet with the same facility as a human. I didn't invent facial tissues and neither did Bow. I didn't invent the alphabet and neither did Bow. In fact, the alphabet was only invented once in all the history of mankind. Everybody else borrowed it. Having a writing system is not a uniquely human thing. Using the writing system that everybody else drops in our laps is natural for humans -- and no less natural for chimpanzees. The veneer of civilization is something we all pick up, like a dropped Kleenex.
What doesn't make sense to me is to call it one thing when a human does it and something else when a chimpanzee does it. But there are lots of experts who do just that. There is the fellow who made a career out of suggesting that chimpanzees may react to seeing just the same as humans, but they don't understand seeing in the same way. So when they hide behind a tree, they do it for a different reason from the reason a human might have to hide behind the tree. The human knows that you can't see him, because the tree blocks your vision. But the chimpanzee only hides out of instinct!
There has been a long tradition for researchers not to attribute mental states and emotions to chimpanzees, even when the reaction is pretty much the same as ours to the stimulus. A human is sad, but a chimpanzee can't be, because he is just a chimpanzee. A human is amused, but a chimpanzee displaying amusement must never be described that way. Different words for the same behaviors have to be employed. A researcher who breaks these rules is considered to have lost his scientific objectivity.
Under our cross-fostering experiment, I call myself Bow's adoptive mother. All I mean by this is that while I am not his biological mother, I have served him in the capacity of a mother all his life. One "expert" told me that because Bow is a chimpanzee and I am a human, I can't be his adoptive mother. At most I am his surrogate mother. The last time I checked, in ordinary parlance, a surrogate mother is a woman who carries another woman's child in her womb. I never did that for Bow, so I am not his surrogate mother. I am just his adoptive mother. But this person was working so hard to make the point that chimpanzees and humans are different species, that he was willing to break the language to come up with a different word for the same relationship.
Don't get me wrong, Bow is a chimpanzee. He does belong to a different species from me. I am not in denial about that. When the mowers came yesterday to cut the grass, Bow went into a characteristically chimpanzee display.
When he does this, Bow is showing us the parts of being a chimpanzee that are hard-wired and not open to cultural mediation.
But then there are the other behaviors, which are very much like our own. I am not suggesting that Bow has become more human by living among humans. I think, instead, that humans and chimpanzees have more in common than many people are comfortable admitting, including many researchers and self-appointed chimpanzee spokesmen.
An experiment in cross-fostering has at its base the desire to learn which behaviors are due to enculturation, and which are hard-wired. A very large percentage of human behavior is learned rather than inborn. The same is true for chimpanzees, although it may not be exactly the same percentage or exactly the same behavior.
In German, they have two different words for eating, "essen" when a human does it, and "fressen" when a non-human does it. It is part of the identity politics of differentiating us from them. In Hebrew when a woman gives birth, she "יולדת". When a dog gives birth, she "ממליטה". It's an understandable human move, to want to mark how special we think we are by creating a whole different vocabulary for those in the out-group. But it's not scientific or objective.
When Bow blows his nose using a Kleenex, it's the same as when I do it. It's not "natural", because it is culturally mediated, but the action is the same.
In order to be objective in our attempts to understand chimpanzees, it is important to use the same words for the same behaviors. It is important not to engage in identity politics and suggest that every action has a different meaning when performed by a non-human.