Thursday, June 17

Mo Infants, Mo Problems

Thanks to a colleague for haphazardly pointing this out to me: an interesting bit of research managed to surface on the front of the Science Times from Tuesday. The article discusses male-infant interactions in a variety of species, but most notably, primates.

The main citation of the Times article is a recent publication in Animal Behaviour from Julia Fischer's Cognitive Ethology Group. I know a few of these people: its solid research. Alas, I don't know so much about the everyday behavior of Barbary macaques - though they are the only primate species to have a wild population in Europe, on Gibraltar.
Gall time!
In my rendition of a previous near-death-experience, I mentioned a hitherto unexpected behavior where old Chester forcibly "played" with a nearby infant who was handily playing nearby. At the time, I was only able to come up with a paper which examined male monkey's treatment of dead infants (how was it easier to study their handling of dead infants rather than live ones?). Fischer's paper was what I was actually looking for, it just didn't exist yet.

These studies feed into the nebulous domain sometimes known as "monkey economics." A related paper which investigates baboons, was published a few years ago in Animal Behaviour as Infants as a commodity in a baboon market. Baboons, nay monkeys, nay primates love babies. Why they love babies so much is unclear, but they sacrifice a great deal of time and effort in the form of grooming the mother in order to be able to handle and/or grunt to the infant. Its a fascinating paper which explores the details of these interactions, from which a market has emerged. In short, the fewer young infants in the troop, the more demand there is for them, and the greater "price" a mother can charge for another female to handle her infant. However, someone like Lottie can always pull rank and handle the baby with a minimal amount of grooming in return.

The paper focuses exclusively on female-infant interaction, which is no surprise, since the female baboons spend all day grooming each other and grunting to babies. The males are a lot less involved with the infants. They prefer to herd the troop, aloofly hang around the periphery, or lay about. In the last case, females will often approach and groom the male in order to strengthen or maintain a reciprocal bond with the powerful male.

Barbary macaque males are intensely social with their infants, likewise among female baboons. How do the Chacma males fit into this picture? Again, as I described in the near-death-experience, the use of the infant appeared to diffuse tension between the two... or redirect it elsewhere.

A similar incident occurred more recently, and this time around, I wasn't directly in the line of fire. It occurred in a another troop between the alpha male (not quite as secure in his position as Aaron) and a young adult male, perhaps only a couple years younger than the alpha. The younger male has been growing like a weed, but still lacks the experience; possible the drive of the current alpha. I missed any lead-up to the incident, what I saw and heard, was the younger male come charging down a hill full tilt directly at the alpha, who was sitting a few feet up in a tree. The younger male was grunting like an express train, and clutching a screaming infant to his chest throughout the charge. It happened to suddenly, out of nowhere, but the alpha made no response. The younger guy just charged into the thicket under the tree, and I believe passed straight on by. I lost sight of him then, and am unsure what became of the infant and his carrier.

In both these instances, it seems like when the infant is brought into play by the lower ranked male, the higher ranked baboon will act ignorant of the lesser baboons offense. The infant is sort of like a shield, a bit of insurance against reprisal. My next question, is the male afraid of incurring the wrath of the females by messing with the male and infant, or does the infant appeal to the male's adoring baby-sense?

Very recently, I was pleased to discover a 2003 Nature article which specifically addresses paternal behavior in Savannah baboon (not Chacmas, but very close). Its a Letter to Nature, so it is brief, but its a wonderfully descriptive study which lays the foundation for expansive research into the how and why of male-infant relationships among baboons.

I'd like to see the Barbary macaques in action, since its adorable to see the musky males toss the babies about, sometimes carelessly as if they don't know their own strength. Perhaps the behavior would lose some of its magic were it to become common-place as it is in Barbary macaques, but there's just something constantly comical about the males in primate species where a large sexual dimorphism exists.

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