Charles Snowdon, a professor of psychology at the University of Wisconsin-Madison, found something surprising when he looked at cotton-top tamarins in long-term relationships (adult tamarins are monogamous): They had corresponding levels of oxytocin. If one had a high level, so did the other; if one had a low level, the other did, too. Overall, however, tamarins’ oxytocin levels are all over the map.
As regular readers of this blog will remember, the hormone oxytocin has been linked to our desire to connect with others and sense of trust. Tamarin partners that had high levels of oxytocin did more cuddling and grooming and had more sex than the tamarin pairs with lower levels of the hormone did. Might the frequency of these behaviors and the levels of oxytocin be directly related?
Snowdon thinks so. And he points out something really fascinating:
Males in a high-oxytocin relationship were more likely to initiate cuddling, and females were more likely to initiate sex. These males were initiating the behavior that the female needed for high oxytocin, and the females with high oxytocin were initiating the behavior that male partner needed for high oxytocin.
Check out this video of one gorilla hitting another and then running away, leading to a chase.
This kind of play might be a way for young gorillas to test how far they can push their behavior and how members of their group will respond to unfair situations, preparing them for more serious interactions like conflicts over food, say researchers who studied gorillas in natural settings. As they write in their paper:
The subjects, that hit their playmates unequally prior to a play chase, significantly more often moved first to run away than their playmates. Therefore, the current study provides, to our knowledge, first empirical evidence that non-human species may try to maintain their competitive advantages when responding to inequities. These findings suggest that humans are not unique in being sensitive to inequities when they have the advantage and the disadvantage … and in their ability to modify their responses to these situations accordingly.
Females who had the strongest, most stable, and longest-lasting relationships with other baboons lived significantly longer than those whose social ties were more fragile and unpredictable. To illustrate their findings, the researchers divided the baboons into three groups according to the quality of their relationships with others. Members of the least sociable group lived from about 7 to 18 years; the middle group lived from about 9 to 25 years; and the friendliest group lived from 10 years on up, as some were still alive when the study ended.
Such findings in a nonhuman primate, the authors write, “suggest that the human motivation to form close and enduring bonds has a long evolutionary history.”
It appears male topi antelopes in Kenya’s Masai Mara National Reserve improve their chances of having sex with female antelopes by tricking them—using the snort that signals a predator is nearby. (Both female and male antelopes snort when they see a predator to tell the predator it has been spotted and should go away, since it cannot outrun an antelope over long distances.) Here’s the really fascinating thing: The male topi antelope almost exclusively issues “false” alarms in the presence of a female antelope in heat—and when it appears she’s about to leave his territory. The male will snort while looking in the direction she’s headed, making her think she’s going toward the danger. As Wiline Pangle, a visiting scholar at Ohio State University, explains in a write-up of the research:
It’s almost amusing to us. The female hears the snort and thinks, ‘oops, there is a lion.’ She steps back, and the male comes around and mates. It’s striking.
On average, the researchers say, the males earn nearly three additional mating opportunities by using a false snort to delay a female’s departure from their territory. For their part, the females are in heat for only one day a year—which may help explain why they don’t catch on to the deceptive behavior. Plus, they’re safer erring on the side of caution, given the high potential cost of thinking a “true” alarm is “false.”
The researchers conclude in their paper that:
Although firm statements about intentions behind behaviors are notoriously difficult to make, our study does identify a parallel between animals and humans in their capability of using false signaling to deceive mates, a finding that hints that their communication may be less fundamentally different than widely assumed.