Excerpt from A Primate's Memoir by Robert M. Sapolsky, plus links to reviews, author biography & more

Leah had given birth to a whole line of strapping, confident sons. In various social species of animals, either males or females pick up and move to a different social group around puberty -- one of those incest avoidance deals. Among baboons, it's the males who get this undefined itch of wanderlust, and Leah's sons were raising havoc far and wide throughout the troops of the northeast Serengeti. Devorah was her first daughter in quite some time, maybe even ever. She was just hitting puberty, and Solomon was going wild about her. Devorah was highly desirable by any male baboon's standards. She was well fed, in good health, and thus very likely to conceive and carry through her pregnancy. And once the kid was born, no one was going to mess with it; it would survive. From the standpoint of evolutionary theory, of leaving as many copies of your genes in future generations as possible, all that jazz, this was one highly desirable young primate. I never thought that Devorah was a big deal (unlike Bathsheeba, whom I had a crush on, and who was soon to meet a tragic end at the canines of that bastard Nebuchanezzar), but she certainly did not lack for confidence. When male baboons who are getting along well run into each other and want to say howdy, they yank on each other's penises. I think it is, in effect, their way of saying, "We're getting along so well, I trust you so much for this one second, that I'm gonna let you yank on me." Like dogs rolling on their backs to let each other sniff at their crotches. Among male primates, this means trust. All the guys did it to the other guys that they were pals with. And in addition, Leah and Devorah would do penis-grab greetings on males. Only females I ever saw do it. I saw Devorah pull this off on Nebuchanezzar, around the time he first joined the troop. He comes sauntering along, having just spent the morning causing trouble and feeling pretty good about himself, passes this little ol' lady and her young daughter, Leah and Devorah, coming the other way, don't reckon he knows them yet, but he does the male baboon equivalent of tipping his hat -- flashing his eyebrows -- and this young thing reaches over, and, well, she just yanks his balls, good solid heft, and goes walking on with the old biddy. Nebuchanezzar actually crouched to get a better view of her departing rear end, perhaps to be certain that she wasn't really some fella who just came past.

Thus, Devorah was sailing through puberty without a care, without a hint of acned insecurities, Solomon just waiting for her to smell a little sexier, get a slightly larger estrus swelling, perhaps, before starting to squire her around. Such was not the destiny, however, of poor Ruth, also going through puberty at that time. Hers was the more usual adolescence. She was from an obscure, low-ranking lineage and had the constant, swiveling, nervous movements of someone who gets dumped on a lot. Years later, in middle age, she would still have an anxious hyperadrenal look, and her umpteen kids would have the same frazzled edge to them. But this year, her major problem was that she was slowly being driven mad by estrogen. Puberty had hit, and she was getting estrus swellings and steroids were poisoning her brain, and all she could think of was male baboons -- but no one was interested in her. For about the first six months when they start cycling and getting estrus swellings, female baboons are probably not yet really ovulating; the system's just warming up. Almost certainly, to the males, this translates as the female just not quite yet smelling sexy enough, the estrus swelling on her rear not quite yet having that irresistible glint in the African twilight.

Meanwhile, poor Ruthie was in hormonal limbo and going bonkers. She was after all the big guys, and no one would even look at her. Solomon would step from out of the bushes and sit down in the field, and Ruth would be up in a flash, scurrying over from whatever she was doing to stick her tush in his face, as per the custom of female baboons in estrus, in the hope that he would do something more than sniff. No dice. Or ol' Aaron, another adult male, would be trying to accomplish the simple task of walking over to the fig tree, and Ruth would be all over him, running two steps ahead to stop and present; he'd pass, she'd spring again and try it from a different angle. How I remember Ruth best is from the summer of 1978: standing, preening, presenting her behind, arching her back every which way, looking back over her shoulder to gauge the effect, trying to get that perfect irresistible pose, panting with the sheer pleasure of the proximity to Solomon, who sits there, the thug, distractedly picking his nose and ignoring her.

Copyright © 2001 by Robert M. Sapolsky.