Being the top dog — or, in this case, the top gelada monkey — is even better if the alpha male is willing to concede at times to subordinates, according to a study by researchers from the University of Pennsylvania, the University of Michigan and Duke University.
Alpha male geladas who allowed subordinate competitors into their group had a longer tenure as leader, resulting in an average of three more offspring each during their lifetimes.
The findings, collected from data during a five-year period ending in January 2011 through the University of Michigan Gelada Research Project, were published in theProceedings of The Royal Society.
The research was conducted by Noah Snyder-Mackler, then a graduate student in the Department of Psychology in Penn’s School of Arts and Sciences. He collaborated with Thore Bergman, assistant professor of psychology at Michigan, and Susan Alberts, professor of biology at Duke.
Cooperation is surprisingly common among wild animals, the researchers said. While it makes evolutionary sense for animals to help their kin, it is harder to explain cases where competitors — especially unrelated adult males — join forces. This conundrum is particularly hard to explain because mating is generally a zero-sum game in which males can only reproduce by stealing mating opportunities from each other.
Why would an alpha male allow other males to be a part of his unit, if they will inevitably decrease the probability that he will pass on his own genes? The researchers felt there must be a reason since this kind of behavior is observed in many species.
“For example, in some species unrelated males will sometimes tolerate the presence of one another and, in rare cases, form bonds and even appear to cooperate,” Snyder-Mackler said.
To understand why potential rivals might team up, researchers compared the fitness consequences for dominant male gelada monkeys living in single- or multi-male groups. They found that, although subordinate males father some of the offspring in multi-male groups, dominant males gain a lifetime fitness benefit because the subordinate aids in defense of the group from other males, thus extending the dominant male’s reproductive career.
Even more tantalizing is evidence that the subordinate males that are allowed to mate stay around in the group for much longer.
“This suggests,” Bergman said, “that the alpha males may allow the subordinate to reproduce as a ‘staying incentive’ for defending the group, a payment for their services.”
While it is not yet clear that a willing exchange is occurring — subordinate males may simply steal some chances at reproduction — the evidence is strong that subordinates confer some benefit to the leader.
“These findings demonstrate a benefit of forming multi-male groups in a predominantly single-male system, an important step in the evolution of sociality among unrelated competitors,” Bergman said.
I bet you can raed waht tihs syas, eevn tohguh smoe wrods are sracbmled.
In his PhD thesis, Graham Rawlinson of the University of Nottingham showed that if one jumbles a word’s interior letters, but preserves the positions of its boundary letters, people can still read the word with more ease than one might expect. Language standardizes the position of letters in words—what linguists call orthography and what is more colloquially known as spelling —but clearly the human brain can handle a little disarray.
But what if you have no idea how to spell? What if you have never seen written words before? What if you are a baboon? For the first time, scientists have taught baboons to tell the difference between English words and strings of letters that do not spell real words. The researchers conclude that—without any prior knowledge of written language —the primates learned to identify individual English letters and what kinds of letter combinations differentiated true English from nonsense words. The new findings suggest that some of the ways human brains understand written language do not depend on previous experience with written words or spoken language. Instead, when learning to recognize letters and words, our brains may co-opt circuits that evolved to recognize objects in our environment.
Jonathan Grainger of Aix–Marseille University in France and his colleagues trained six baboons to distinguish four-letter English words from nonsense strings of three consonants and one vowel. The baboons sat in front of a touch screen on which either a real or nonsense word appeared followed by an oval and a cross. Using wheat pellets as rewards, the researchers trained the baboons to touch the oval when a real word appeared and the cross when the letters formed only gibberish. One and a half months later, the baboons had learned to distinguish as many as 308 true English words from nonsense strings with nearly 75 percent accuracy. The study is published in the April 13 issue of Science.
Remember, the baboons have no idea what any of the words mean. As far as anyone can tell, all the baboons know is that there are two categories of patterns on the screen: pressing the oval in response to one category and the cross for the other earns a wheat pellet. But Grainger and his colleagues also see evidence that the monkeys are not simply memorizing which patterns correspond with either the oval or cross. Over time, the baboons got better at distinguishing the true words from nonsense. At first, hundreds of trials were required for the baboons to learn that, say, “wasp” and “feet” belong to one category and that “tokl” and “tezp” belong to another, but the more time they spent in training, the faster they differentiated real and made-up words, making fewer mistakes.
Biologists Tom Struhsaker, Colin Chapman, and Theresa Pope and surgeon Jeffrey Marcus, director of Duke’s Cleft and Craniofacial Program, described the discovery in June of this female baboon in Kibale National Park, Uganda who appears to have been born without an upper jaw or the dog-like snout of her species. Struhsaker, Chapman and Pope watched and photographed her for a half hour before she moved away. She probably had one pair of upper molars, but it remains unknown how she fed. And with one nursing juvenile and a pregnancy, she’s apparently not a social pariah.
The next time you’re struggling to relate, think like a baboon. Once again non-human primates are making monkeys out of us and our ideas about uniquely human abilities. Turns out baboons can solve analogy problems—yes, like those scary questions in the GRE Verbal Section.
Analogies are all about relationships. Cat is to kitten as dog is to puppy, rain is to dampness as sun is to heat, etc. To make an analogy, you have to understand the relationship between a pair and then relate that to another pair. Most of us use analogies all the time, and because of their link to language, we thought we were the only living beings that could do it. Not so, apparently.
In a study published in Psychological Science, Franklin & Marshall’s Roger Thompson and Joël Fagot of the Laboratoire de Psychologie Cognitive gave 29 baboons their very own analogy test using visual cues. Each baboon watched a touch screen reveal two shapes with a specific relationship. The next screen presented two pairs of shapes. Baboons received a reward when they correctly identified a pair that related in the same way as the first.
Not only did six of the baboons learn how to use analogies to earn a reward, but when taking the test again a year later, the baboons acquired the skill faster than the first time around. This suggests that they could remember how to make analogous connections.
By now, I know of few people who haven’t seen the movie, Mean Girls. But in case you haven’t, here’s what you should know about it: the story is essentially an explanation of social cliques and aggressive teenage girl behavior. As a study recently published in Behavioral Ecology suggests, this agonistic behavior between females in cliques is not exclusive to human primates, but is found in our non-human primate kin as well.
Over 18 months and 1027 interactions, Huchard and Cowlishaw (2011) discovered a correlation between sexually receptive female baboons and female-female aggression in groups. In female baboons, sexual receptiveness is typically a period in which individuals are estrous, or “in heat.” A way in which a female can display this information is through sexual swellings, or a swelling of the perineal skin, which indicates ovulation. Additionally, females with wider sexual swellings are perceived as “sexy,” as they attained sexual maturity earlier and generally have more offspring that survive (Domb and Pagel 2001).
With that in mind, enter female-female competition. Female-female competition is thought to occur more often under circumstances where resources for success in reproductive factors might be limited: for example, yielded access to food resources inhibits successful gestation or production of milk or helpful mates that provide more access to resources through social rank.
In the study performed by Huchard and Cowlishaw, sexual receptiveness was perceived to be the driver of aggressive behaviors as sexually receptive females received the most aggression, while lactating mothers received the least. It is thought this might be a tactic to delay conception; thus, females who have already conceived or have offspring would be more likely to receive access to resources and thereof prevents competition. Females who eat less (or would have limited access to food resources) also tend to have less reproductive success (Altmann and Alberts 2003). In addition, it is also possible by inflicting the cost of aggression onto sexually receptive females, the stress may make it more difficult to conceive or support a pregnancy (Beehner et al. 2006). Therefore, by being aggressive to these sexually receptive females, pregnant females or females who have offspring are conserving their resources and limiting the competition.
While no reports of any baboons getting thrown in front of buses have been reported yet, if it does happen—be sure to check the sexual swelling for the baboon version of Regina George.
If you’re a baboon, being in charge gives you a lot of advantages: you have better access to food, you get more action from the ladies, and your kids tend to grow faster and live longer. Low-rankers, meanwhile, must expend more time and energy to get food and mating opportunities. It makes sense to assume that the baboons at the bottom of their hierarchy might experience more stress than their high-ranking relatives.
But life at the top of a baboon troop isn’t all fun and games, since the alpha male must constantly struggle to maintain his social position. A new study in Science shows that alpha males suffer from much more stress than the second highest-ranking baboon, and tend to exhibit the same amount of stress hormones as baboons much lower in the hierarchy.To study stress in a group of wild savannah baboons, the researchers collected 4,000 fecal samples from 125 adult male baboons over nine years in Amboseli, Kenya. Their goals were twofold: to determine how stress differed between high- and low-ranking baboons, and to assess whether this pattern changed in times of upheaval. The scientists tested each fecal sample for a group of hormones called glucocorticoids, which can indicate how much stress each baboon was dealing with at the time.
The researchers found that, with one notable exception, glucocorticoid levels decreased as rank increased; in other words, low rankers experienced much more stress than higher-rankers. The exception, however, was the alpha male’s stress levels, which were just as high as those of the low-ranking baboons. While the males that ranked second through eighth seemed to enjoy relatively low-stress lives, the alpha male experienced just as much stress as the baboons ranking ninth through fourteenth.
One of the most unexpected finding of this research is that the alpha males’ glucocorticoid levels were so different from the second-ranking males’. Two of the study’s other findings may account for the immense amount of stress that the highest-rankers experienced: they had a 17 percent higher rate of aggressive encounters with other baboons and they spent 29 percent more time mating than lower-rankers did. These physiological costs of maintaining the top spot are likely responsible for the sky-high stress levels exhibited by alpha males.
The stress patterns were consistent, no matter which individual held each rank; the study ran long enough for baboons to spend time at several different social ranks, and stress levels were a product of rank, rather than of consistent individual hormone profiles. In times of instability within the troop, this pattern didn’t change, but all the baboons’ stress levels went up a bit.
While short-term bursts of glucocorticoids are beneficial and can help individuals cope in stressful situations, lengthy exposure can be harmful. Over the long term, high glucocorticoid levels are known to suppress the immune system. In the study, alpha males exhibited much higher parasite loads than the baboons just beneath them in the hierarchy.
The researchers also noticed another interesting trend in their data: the alpha males tended to turn over more often than expected, and weren’t able to monopolize access to the troop’s females. Meanwhile, the second-ranking males managed to secure more matings than their rank suggested. While not directly tested, it’s possible that high stress levels negatively affected the health and performance of the alpha males, causing them to fall short of their reproductive potential.