DAVE DAVIES, host:
This is Fresh Air. I'm Dave Davies, senior writer for the Philadelphia Daily News, filling in for Terry Gross. Our guests on today's show want to know what baboons have to say each to other and what's going in their minds as they scream, grunt, and wahoo. They recorded vocalizations of wild baboons and analyzed what they communicate. That's the subject of their book "Baboon Metaphysics," which is now out in paperback. Dorothy Cheney and Robert Seyfarth are a husband and wife team who've studied baboons in Botswana since 1992. They both teach at the University of Pennsylvania where Cheney is a professor of biology and Seyfarth, a professor of psychology. They spoke with Terry Gross last year. By listening to baboons, they're learning about the rules of the game in baboon society.
Professor DOROTHY CHENEY (Biology, University of Pennsylvania; Author, "Baboon Metaphysics"): One of the things that's been intriguing to us about baboons is that they live in these very complex societies that are composed of multiple family lines, individuals of varying degrees of competitive ability, and dominance ranks, and so on. They seem to know a huge amount about each other's social relationships and each other's dominance ranks. So that social complexity, on the surface anyway, appears to be very similar to that of a very complex human society, and yet they're not humans. So the question is what differentiates us from them, and what sort of selective pressures might have gotten us from an organism that looks like a baboon to an organism that looks like us.
TERRY GROSS, host:
Well, let's listen to some of the vocalizations that you've recorded of baboons, because these are just amazing to listen to. And we're going to start with grunts. We're going to hear six different baboons back-to-back with the basic grunt sound. So what should we be listening for?
Professor ROBERT SEYFARTH (Psychology, University of Pennsylvania; Author, "Baboon Metaphysics"): Well, as you go through this tape you're going to hear the calls of six females. Each one of them gives two grunts. And you'll notice that the grunts of any one female - the two that she gives - sound alike, but they sound very different from the next animal who's different from the next animal and so on. So that you can easily imagine that if you were a baboon living all your life with these different individuals, you very quickly learn to recognize, oh, that's Helen. Oh, that's Sylvia, and so on.
GROSS: OK. So here it is - six female baboons back-to-back grunting.
(Soundbite of baboons grunting)
GROSS: Now, were they all recorded together at the same time? Is that a conversation we heard?
Prof. CHENEY: No, not in this particular case. But you could easily have a conversation like that because a typical social interaction might involve a female walking up to another who has an infant grunting, and that female with an infant grunting back. So you do get these kinds of vocal exchanges. And the vocal exchanges are actually most common when animals are embarking on a potentially dangerous move through deep water, for example. And they're given almost as a sort of exchange to a kind of negotiate. Are we really going here or not? Are you keeping an eye on me or not? I mean, that's an anthropomorphism. But there are sort of looks exchanged between animals as they give these grunts. It's as if they're checking to see what each other's intentions and motivations are.
GROSS: We have a scream we're going to hear, a baboon's scream. When do baboons scream?
Prof. CHENEY: Well they scream when they're involved in a fight, and typically the screams are given by a lower-ranking animal to a higher-ranking animal. I should have added earlier that when we're talking about rank in adult females, rank is not determined by size or age. It's determined entirely by who your mother is. And so when you're looking at a dominance hierarchy of females, there could be 26 females ranked in a hierarchy where female one can supplant or cause to move away female two and female two can cause three to move away and so on down the line. What you're really looking at is groups and clusters of families where females one through four could be mother, daughter, and sister. And then female five belongs to an entirely different family so that a lot of these fights and altercations and kind of negotiations that I was talking about involve not just individuals but entire families.
GROSS: Well, let's hear a baboon scream.
(Soundbite of baboons screaming)
GROSS: Now that really sounded like a bird to me.
(Soundbite of laughter)
GROSS: Do you hear that a lot when you're out in the wild with the baboons? Do...
Prof. SEYFARTH: You do, and what you often hear is you hear a sequence of calls. Say from over somewhere behind a bush you hear one animal giving a threat grunt to another animal, and the other animal is screaming. And this is what baboons hear all the time. And this is what we wonder, what do they know? What sort of information do they get when they hear these calls? And the interesting thing is that you can use these sequences to show that the baboons know something about each other's ranks. So if we take - from our library of calls - the threat grunt of a high-ranking female and play it followed by the scream of a low-ranking female.
So let's say Sylvia is a high-ranking female and Hannah is a middle-ranking female. We play Sylvia's threat grunt and Hannah's scream. Then that's the sort of thing that happens all the time. And animals don't usually respond, but if we dig into our library and get two different calls, Hannah's threat grunt and Sylvia's scream, and we put them together in a sequence, and we play that the animals will look toward the speaker and try to figure out what is going on. They have a very strong response, because that sequence suggests that Hannah is threatening Sylvia who we all know to be higher ranking, and this violates their existing knowledge. Baboons respond with surprise to anything that signals that the dominance order isn't exactly what we know it to be which suggests that they really understand the rank relations that exist among others.
GROSS: So, you have these hidden speakers in the wild, and you play back baboon sounds for the baboons to see how they respond?
Prof. CHENEY: Exactly.
GROSS: Pretty interesting. Well, let's get to another baboon sound, and this is what you describe as wahoos. Do you want to describe what wahoos are?
Prof. SEYHARTH: Well, in baboon society, as Dorothy said, the females are born and they live in the same group throughout their lives, and they live in this hierarchy of matrilineal families where the mothers and their sisters and daughters all retain really tight relationships with each other - lots of grooming, support, and alliance and so on. When males get to be fully adult size sometime around seven or eight years old, they leave the group where they were born, and they go often miles away and join another group where they have to fight their way to the top of the male dominance hierarchy.
But as in so many animals, there's a lot more displaying and posturing than there is actual fighting. And one of the real clearcut and obvious displays that male baboons give to each other is this wahoo call. It's one of the loudest calls that any terrestrial animal makes, and males make it in sort of contest where one male will start wahooing, and the other will respond, and then the males will run up into trees and leap from branch to branch while giving these wahoos.
GROSS: And they're just kind of showing off.
Prof. SEYFARTH: They're showing off and...
GROSS: For each other.
Prof. CHENEY: And they're showing off, but also these are not just displays of complete bravado because in order to sustain this very loud rapid calling rate as you're racing through the trees, you have to have pretty good stamina. And so males seem to use these sorts of displays to display and also to assess each other's stamina and competitive ability, so that they actually serve a function that allow males to assess whether or not they want to escalate the display into a real physical fight.
GROSS: Let's hear a sequence of three different baboons doing wahoos.
(Soundbite of baboons wahooing)
Prof. CHENEY: So these are very loud when you're actually in the wild with them.
Prof. SEYFARTH: Yeah, they're really loud. And you notice that there is that sort of wa-hoo, and it's a sort of two-part call. And if - as Dorothy says, the calls are kind of a contest to see who's the most powerful. Who can wahoo the loudest, the longest, the fastest, and still not be out of breath.
GROSS: Now, you refer to the importance of rank in baboon society. And there's also calls for low and high-ranking males that you've recorded. Would you explain what we're about to hear with these calls?
Mr. SEYFARTH: Well, what you're going to hear is a wahoo from a high-ranking male, and he's high ranking so right now, he's at the top of the hierarchy, and he's in great physical shape and everyone if deferring to him. And contrast that with wahoo of a low ranking make who's at the bottom of the hierarchy. He may be very old. He may be wounded. He's in not so good shape. And listen to the different wahoos, and you can really hear the difference between one, the high-ranking male that really is powerful and has a long hoo, and the other one that's pretty pathetic, really.
GROSS: Here we go.
(Soundbite of a high-ranking baboon wahooing)
(Soundbite of a low-ranking baboon wahooing)
Mr. SEYFARTH: So, when you hear the first one, wahoo, and then the second one, the hoo is completely gone, wa. And that's the best that that low-ranking male can do. And it sounds much less impressive than the high-ranking males.
DAVIES: Robert Seyfarth and Dorothy Cheney, authors of the book, "Baboon Metaphysics." More after a break, this is Fresh Air. Our guests are Dorothy Cheney and Robert Seyfarth. They've been studying wild baboons in Botswana since 1992. Their latest book is called "Baboon Metaphysics: The Evolution of a Social Mind." Terry spoke to them last year.
GROSS: In addition to studying baboon vocalization, baboon language, one of the things that you've been doing in the wild is collecting baboon feces. What can you learn by analyzing their feces?
Ms. CHENEY: One of things that's been really interesting about the developments in poop - I guess you would call it - is that it's now possible to extract hormones from fecal samples. And as a result, you can - in our particular case, what we're looking at is a stress hormones, glucocorticoids, and one of the beauties of a poop samples is, of course, you can gather a fecal sample without actually stressing the animal by capturing it or having to draw its blood.
And so, one of the things these fecal samples do is they allow us to measure stress, and it gives us - in a sense, we can interview the animal almost by asking her what's causing you stress? How do you alleviate stress? And so, it's a wonderful tool that allows us to, actually, delve more deeply into the baboon social structure and look at how animals deal with the many challenges that they face in their environment, including predation, infanticide, rank upheavals, and so on.
GROSS: And so, what does stress out baboons?
Mr. SEYFARTH: Well, there are three things that are really important for both females and males. And the first is predation. There are months in which lions attack baboon or leopards attack, and the collection of these thousands of poop samples from 22 females over several years has shown us that in months when there are predator attacks, everyone's glucocorticoid levels are higher. So, they're under a little bit more stress. It would appear. If a female is taken by a predator of course, everyone's glucocorticoid levels go up. But the individuals whose glucocorticoid levels go up the greatest are the victim's relatives, the members of her matrilineal family or her closest grooming partners.
GROSS: Well, that's interesting because it shows that family matters, that there's a special connection between family members in a baboon world?
Mr. SEYFARTH: It is and collecting these fecal samples tells us something that we wouldn't otherwise know. I mean everybody looks like they're under stress after a lion attack, but the fecal samples, the glucocorticoid tell us that really under stress are the relatives of the victim. But then, of course, in the next few weeks and months, animals' glucocorticoid levels go back to baseline, and we were interested to see how these is achieved, and the females who a lose a close relative or close grooming partner who have their sort of network of friendships disrupted, they show an interesting pattern.
They increase the number of other females that they groom with. As if they're seeking out new friends to reestablish a nice tight grooming network. And that's interesting because the same sort of thing happens when the females are faced with the potential of infanticide. When a new male comes in he often tries to kill the small infants of females in the group at a time. And the females respond by forming a tight bond with another one of the males in the group kind of friendship. And the females who are able to do that, their glucocorticoid levels don't go up as much as everyone else does who doesn't form a friendship.
GROSS: You use the word, infanticide, why do new males in a group try to kill the infants?
Ms CHENEY: Well, from a male's perspective, an immigrant male's perspective, it makes a lot of sense. In baboon society, all females breed regardless of their relative ranks, but that's not true of males. The males who achieve the most matings are the - is a dominant male, the alpha male, and the other males really don't do so well. The problem is, there's such a high turnover in the alpha male position that a male can only expect to be alpha male for about six or seven months - maybe up to a year at most. So, a male coming in to a group faces a dilemma. There are all these infants in the group.
Mothers are not going to start cycling again or become sexually receptive until those infants are weaned. Typically an infant is nursing for over a year, and pregnancy lasts for 6 months. So the chances that a male will be able to retain his alpha position for long enough before these females become sexually receptive again is very small. So from a male's perspective, coming in and trying to kill the infants of lactating females makes sense. After all, these are not his infants. And if these infants are killed then the female resumes sexual cycling soon. From the female's perspective, this represents a significant loss in her reproductive success, so of course they resist it.
GROSS: So, does the new alpha baboon want access to like every female baboon? I mean, it's not enough that some of them are already accessible. He has to kill the babies of the mothers who are lactating?
Ms. CHENEY: In the sense, yes. If a male comes into a group, there may not be that many cycling females present in the group. The odd thing when you look at a group of baboons like this is you can see this new male come in, and he becomes - he's infanticideal - you know, you can't help but as an observer respond negatively to this because - horrible thing to observe. For a while you go through this period where you absolutely hate the male even though you're supposed to remain objective.
But what's interesting is that once the female he's mated with become pregnant, and they produce offspring of their own, he becomes a doting dad. He protects these infants. He carries them. He lets them jump on his head and so on. And so in some cases, these males who are alpha almost cede their position after they've produced some offspring of their own. They don't necessarily willingly give up the alpha position. But they are now - their efforts are devoted more to protecting their current infants than to fathering additional ones.
GROSS: If you're just joining us, my guests are Dorothy Cheney and Robert Seyfarth, and they're the authors of the book, "Baboon Metaphysics." They've studied baboons in the wild for years, and they've been married for about 30 years. They're also both professors are the University of Pennsylvania. The baboons can climb up into trees and take shelter there. Have there been situations in which you've had to hide from lions or tigers or any other animals of prey?
Mr. SEYFARTH: Everyone has at least one close call story, and my close call story was not watching the baboons, but when I was driving through the National Park to the nearest town for supplies, and I got stuck in an enormously deep rut that I couldn't jack my car out of. So I had to walk back to the nearest ranger post, and I walked into a group of seven lions. And you're always told do not run. If you run, a lion is like a sort of cat with the ball of yarn. It'll go for you, and you won't win. And so, I moved as quickly at a walk as I could, about 15 meters to the nearest tree. And I climbed up the tree, and I was very glad that the tree at that time had knobs and little, you know, things that supported my feet.
And I thought, as I was going up, and I had these lions growling behind me, gee, this is just like climbing a ladder. It's great. And I made it up to the first branch which is about 11 feet off the ground, and then I knew I was OK. And hours later, the lions finally went away, and I got help and about a week later we all went out and decided we would visit this tree and take some photographs and have a picnic. And it turns out that these little knobs and branches that provided me with footholds were only about a 32nd of an inch above the surface. They provided no support, whatsoever. No one could climb the tree. Everyone all fell down. So, I guess, that's the beauty of adrenaline.
GROSS: I know you try to keep like emotional distance from the baboons and not influence their behavior or become too emotionally attached to them. Nevertheless, have you become very emotionally attached to them, and you do see them as beautiful animals?
Mr. SEYFARTH: Yes. And as animals with - each one of them with a unique personality.
Ms. CHENEY: Recently, the oldest female in the group, Sylvia, died. And she was over 25 years old, and she was a real curmudgeon. And when we used to do these experiments that we did on looking at reconciliation, Sylvia never reconciled. She was the second-ranking animal in the group, and her attitude seemed to be, you know, I should be first ranking, and I'm not just not happy about my life in general and neither will you be as long as I'm around. And so she would cut the swath throughout the group and sort of beat up animals and so on.
As she aged, she became a little bit more mellow. And she had a very close relationship with her only surviving daughter. And in a sense, that was the animal that she groomed with the most. And most of the other animals in the group, anthropomorphizing for a moment, really didn't want to be near Sylvia, because she was such a nasty individual. And then this daughter was killed by a lion. And Sylvia's stress levels, of course, or glucocorticoid levels went very, very high and she went - she embarked on a kind of grooming campaign to try to identify a new grooming partner. Nobody would have her. Every time anybody - she approached anybody, animals would run away from her. And so she spent the last few years of her life pretty lonely. And then this past May, at the age of 25, she was seriously injured by a leopard. And she spent weeks off on her own, trying to recuperate and finally did.
During this time, some of the low-ranking animals began to try to challenge her and try, you know, oust her from a relatively high-ranking position at which point, her sister - who otherwise hadn't been paying attention to her for years - supported her and reestablished her bond and refused to let her be fallen rank and so on. So, we all have a great attachment to Sylvia, and when she recently died, I was emailing all of our, former post docs and everybody wrote back saying, oh, Sylvia. One of the interesting things about these animals is that, you don't try to anthropomorphize, but everybody kind of agrees on different individual's personality. So, what's interesting at these personalities has really emerged consistently.
GROSS: I want to thank both of you so much for talking with us about your work. Thank you.
Mr. SEYFARTH: You're welcome.
Ms. CHENEY: Thank you.
DAVIES: Dorothy Cheney and Robert Seyfarth are the authors of "Baboon Metaphysics." They're both professors at the University of Pennsylvania. Terry spoke to them last year. I'm Dave Davies, and this is Fresh Air.
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