Testosterone is a funny thing. We tend to think of it as being responsible for the aggressive and antisocial behavior displayed by males, and in a way this is true. But it’s only part of the story. While testosterone appears to be central to status-seeking, it also correlates with prosocial behaviors such as generosity when such behaviors are appropriate for achieving or maintaining status. There’s more than one way to get ahead and testosterone doesn’t seem to care how you get there as long as you get there.
But testosterone never seemed to be on Burrito’s side. Not surprising, given that he never had the opportunity to learn prosocial behavior from either his mother or a community. He was raised by humans, forced to perform in a circus, and then locked alone in a cage for years. His first experience in a real social group likely came at age 23 when he was housed with six females in a series of four cages in a windowless basement. As a result, his attempts at dominance were marked by spasms of unprovoked aggression with few attempts to form alliances or coalitions. If they could, the girls would tell you he was hard to live with. They certainly told him often – by ganging up on him and putting him back in his place.
We can’t put the blame squarely on testosterone for Burrito’s struggles but we can now see what his life is like when not subjected to its constant demands. Because when Burrito suffered a serious injury to his scrotum last winter, he was surgically castrated. You’d have to squint pretty hard to see a silver lining in such an outcome, but there’s no doubt that his relationships with the other chimps are different now. He threatens and fights less. He plays more. A lot more. He plays all day long.
Would a change like this be as benign or even welcome if he lived in a different social group? If he lived with other males? Probably not. This is by no means an argument for castrating male chimps to control aggression (for so many reasons, but as mentioned above – testosterone does more than promote aggression). I’ve hesitated to even talk about it for fear of being misinterpreted (and, to be honest, for fear of getting too far out of my expertise, for I am not an endocrinologist). But we can all see the changes in him, and you probably have too.
For her part, Jamie has mellowed quite a bit too. Could it also be due to hormonal changes? After all, she’s on medroxyprogesterone to inhibit her estrus cycle in an effort to reduce discomfort associated with a perianal fistula. Who knows. We all change as we get older.
Whatever the cause, these two were never very close in the first 13 years they lived at the sanctuary and now there seems to be more space for them to form a relationship. It’s cute to watch Burrito work his charm on Jamie. She’s not one to let her guard down very often. But he can be very persuasive.