Thursday, May 30

The Most Unusual Looking Creatures in the World

Several people have recently directed my attention to a set of images floating around the internet, described as "animals you didn't know existed." Its a nice set, but I did know about most of them, even things like the markhor, babirusa, and the dhole (which I only recently discovered). I wrote about the snub-nosed monkey previously; the main reason no one knows about it is because it was only discovered 2.5 years ago.

However, there were plenty of animals I did not recognize. The arthropods on the list are bizarre and were previously unknown to me. Same goes for dolphins on the list. That Irrawaddy fellow is quite a looker. Just what we all needed: a dolphin that appears as creepy as dolphins actually are.

Yet, the most striking animal among the bunch, for me, was the sunda colugo. I thought I'd seen every strange looking primate species there was.
I once spent a long night on Long Street with my colleague, Bellerica. We ended up at Neighborhood, probably my favorite low-key drinking establishment in Cape Town. It was her first time there, and I knew she'd be taken by the collection of old animal books published by Life in (I think) the 60's.

She recognized just about every creatures in those books, or at very least all of the primates. Which was certainly more than I knew. I found myself at a considerable disadvantage, with minimal zoological foundations to rely on. It was an informative experience for me, and she certainly enjoyed the old books and the photos within.

The sunda colugo is often known as the sunda flying lemur, even though it isn't a real lemur. It actually isn't even a real primate, which might explain why I've never heard of them before. They are from the order Dermaptera, which sits alongside order Primates within the mirorder Primatomorpha. Even tarsiers, lemurs, and lorises are primates, even if they're prosimians, and thus not monkeys.

Sunda colugos aren't called "flying lemurs" for nothing. They can glide like flying squirrels, using flaps of skin stretched between their arms and legs. They can soar a hundred meters and lose only ten meters of altitude, turning in the air to control their course all the while. Like many creatures who glide, they spend the majority of their time in the forest canopy, and like many other creatures who live in the canopy, they subsist on leaves, and supplement with other nutritious plant materials they come across.

I am reminded of gibbons, the lesser apes, who also live in this part of the world and spend their lives among the treetops. Gibbons aren't doing very well for themselves these days; most species are endangered, many critically so. Fortunately, colugos have proved adaptable. Their population is not as strong as it has been, but they are doing fine.

Thursday, May 23

Is there really such a thing as a spandrel?

While engaging in a bit of background research for last week's post, I stumbled upon a discussion of spandrels on one of my favorite blogs. When discussing the validity of evolutionary theories and evolutionary psychology in general, spandrels come up fairly often because they are usually red herrings. If a trait is a spandrel, and did not develop in an adaptive way, applying adaptive logic to it in order to justify your theory could undermine your work.

The article I linked to mentions the spandrel of blood color. As far as anyone knows blood doesn't appear red for any adaptive reason, it's just the color imparted by the iron element in hemoglobin. But hold on: the redness of inflamed or swollen tissues is absolutely used adaptively, in primate reproductive swelling, which I can't seem to stop referring back to.

The swellings themselves are certainly not spandrels; in baboons the swellings appear on their rumps, but in geladas swellings appear on their chests. Geladas are perhaps best knows by this trait, having been nicknamed the "bleeding heart baboons" (another of my favorite blogs). In each species the swellings appear in the most visible location. If these traits are adaptive and rely upon the redness of blood, can blood color still be a spandrel?

The real answer is that it doesn't really matter. Adaptive traits and spandrels are all evolving in concert with each other over the course of thousands and millions of years. None of these traits are independent, they are all inexorably intertwined (which is exactly why there are so many adaptive traits that rely on the bright redness of blood function). This is one of the most important lessons of ethology.

Gould and Lewontin, the the creators of the spandrel theory, wished to classify traits as spandrels or not spandrels. Spandrel traits can be found along all avenues of evolutionary biology, not just psychology. For instance, reproductive swellings in primates rely on both biology and psychology. Given the previously discussed risks of misapplying evolutionary psychology, focusing on spandrels just isn't a particularly useful or efficient way for an evolutionary psychologist to spend their time.

Thursday, May 16

Tell Truths, Not Stories

On either side of a recent conference in London, where participants discussed the possibility that "human ancestors were exposed to a period of semiaquatic evolution", a number of voices have taken aim at the so-called Aquatic Ape Hypothesis. The AAH attempts to grapple with some interesting ideas, like why fish protein and fat is so important to our health, notably brain development, or why infants have an instinctual ability to swim, which disappears between 4 and 6 months. According to the mainstream theories of recent human evolution, these facts don't make a whole lot of sense.

It has been pointed out by many journalists (see the infamous Space Ape Hypothesis) that the AAH is still kind of ridiculous. Henry Gee points out the most crucial of flaws in the AAH, and more importantly, faulty underlying reasoning. For instance, sinuses, proposed to aid the theoretical Aquatic Ape in maintaining buoyancy underwater, are found in all mammals.

The AAH debate has been warmed over by a million people, both qualified and unqualified, over the course of decades. We don't need another tiny voice in that mix; I don't have anything to add about the AAH. But, the AAH represents much of what is wrong with evolutionary psychology, and points to a core issue that I've argued and discussed with many of my peers over the past several years: How do you make any progress in evolutionary psychology without creating a bunch of baseless just-so stories?

The short answer is, Slowly, and with a lot of hesitance.

When a psychologist found that that individuals who worry the most about social rejection are most likely to act out in response to rejection cues, what she found was truth. This is a fact of human psychology. There aren't any such facts about ancient psychology because we have no prehistoric psyches to work with, only archaeology, non-human primates, and modern humans.

What can we then say? Still quite a bit. Example: incest avoidance. Animals avoid mating with siblings and other close relatives because of the dangers of incest. There are many mechanisms spread across the kingdom that work to prevent incest from happening; in baboons, males disperse to a new troop to avoid reproducing with their relatives. In humans, we come to recognize those who we grow up in close company with as family members. This frequently applies to childhood friends of the opposite sex, and was a major problem for the sustainability for the Israeli kibbutz system. This is a psychological mechanism, born from an evolutionary need. It is respected enough to have been named. It is called the Westermarck effect.

Ultimately, the validity of evolutionary psychology lies with the validity of all science. If your findings aren't logically sound, other scientists will see through them, and you won't get published. Modern science has an additional tool: statistics, which allows us to falsify theories with varying degrees of confidence. Like any other field, statistics isn't perfected, but it is a powerful tool.

Unless your argument against evolutionary psychology is that all evolutionary psychologists are deranged, there is no particular reason to target evolutionary psychology. Evolutionary psychology is like psychology which is like all of science. There is fraud, there are charlatans, and sometimes just honest people get things wrong. We do what we can about that, but we don't disavow the entire field. 

If you would like to read more about the AAH itself, esteemed professors and bloggers John Hawks and PZ Meyers recommend that you go here. The site is more than just a discussion of the AAH, it is an informative primer for any interested in the logic of evolutionary psychology.

Thursday, May 9

Ruminations on a conversation between primatologists

 A couple years back I had the privilege to hear Robert Sapolsky speak. It was a detailed talk, but given how much I know about his research already, there wasn't a huge amount of new information for me to learn. However, I did pick up on something he only briefly mentioned, and eagerly looked forward to asking him about it after the talk. I said to him:
"The baboons I've seen in the bush are very thin and spend almost all day every day foraging, so they have little time to engage in social interaction except mornings and evenings. You said that your olive baboons have the entire day to socialize; how is this possible?"
Dr. Sapolsky explained that the savanna his baboons live on is a paradise, ripe with easy to find food and moisture. Of course, other baboons could and do live under different conditions. But his baboons were lucky, and their fortune was certainly part of what made them such a great study group.

I haven't thought about this conversation much recently. That is, until I encountered a recent article in National Geographic. In this article, the author asked many of the same questions that came to mind when I heard Sapolsky speak: 'what on earth do these baboons feed on?…and where do they go to drink and sleep?'

Olive baboons are widely spread species in Africa, and while they are known to inhabit arid regions, the Chalbi Desert (the area discussed in this article) is dryer than most other such regions. I am most familiar with baboons sleeping in trees, but in wilder areas where there are more predators (notably leopards), high, steep cliffs are baboons' favored sleeping grounds.

I'm not sure that the authors of the Nat Geo article knew all of this (or much of any of it), but they may have found all the answers they needed, at least for this group of baboons. The troop in question spent a lot of time around doum palm trees, which provide water rich fruit, and shade. Apparently these baboons spend a great deal of the daytime in the doum palms' dense shade. I've seen baboons rest under cover during the heat of the day, but never to the extent found by the authors, in the Chalbi Desert.

These baboons don't live like Sapolsky's monkeys, that is for sure. Their environment does not seem to be able to sustain a large population, but it does seem to be able to support a small one consistently. All this speaks for the remarkable flexibility of baboons. They, like many other species of monkeys; chimpanzees and of course humans, can adapt themselves to survive (and possibly even thrive) in a myriad of different environments. They may not live the most healthy lives, but they will survive to reproduce, and keeps their genes alive.

Oh, and if you were wondering about the truth of Sapolsky story, well have a look at this.
The girl (okay, friend) waiting with me to talk to Sapolsky thought it was a really clever idea that I brought a book for him to sign
Okay, you probably weren't doubting me, but I'm allowed to be boastful on occasion.

Thursday, May 2

Vervets: the Forbidden Circle

I lied. The second article on vervets did not appear in Science, but in Current Biology. Other than that, I stand by my earlier statement: this is an unusual and thought provoking article, and it happens to be about vervet monkeys.

In this experiment, the authors created a locked container which contained appealing food. The subjects, a troop of vervet monkeys, could see inside and smell the food, but they could not get at it. Only a single low ranking member of the troop was trained in how to open the container.

Without needing to read the paper, I could tell you how things would start out. The dominant individuals in the group would mess around with the container, carrying out all kinds of violent acts in an attempt to force the thing open (which would all fail). Once the alpha got tired of this, it would go do something else and the second rank individual would make similar attempts to open the container. This is a common scene among the baboons, when they're trying to get into a locked storeroom or car.

In order for the monkeys to get at and eat the food inside the container, all dominant individuals would need to exhaust their own interest and wait. They were also required to stay a safe distance away from the container, somewhere between 10 and 15 meters. Only when the dominant individuals were a safe distance away would the monkey trained to open the container actually open the container.

It took most of these troops a few long trials to begin to understand that they would need to show restraint. But after they picked up this notion, the process went surprisingly smoothly and quickly, and the trained monkey would invariably be allowed to open the container. Unsurprisingly, the subject group that was experienced in raiding garbage bins and picnics took much longer to get over the fact that only a single low ranked individual could open the container. The authors go into great deal of game theory, but I will leave that by the wayside and get to the conclusions.

There are a number of fairly impressive accomplishments included in this paper. First, that the authors were able to train a wild vervet, to essentially be a confidant in their experiment. It is kind of incredible. Second, their main results show that these monkeys are capable of restraint on group and individual levels. Monkeys are notoriously bad at self-control, but this shows the power of reinforcement learning. I can't imagine any of the monkeys I've worked with, in captivity or the wild, being trained to show these levels of restraint. So kudos to the authors, and kudos to vervet monkeys.