Sunday, February 17, 2013
The Evolution of Emotions
Stephen T. Asma has a very interesting piece on the evolution of emotion in Aeon. Asma is Professor of Philosophy at Columbia College, Chicago. The essay is part travel story and part summary of “the new field of affective neuroscience.”
Asma pushes a number of provocative ideas that seem very plausible to me. One goes like this:
It might seem self-evident to the sentimental pet owner that our fellow creatures have emotions, but science has long been loath to admit it. Yet Jaak Panksepp, professor of veterinary anatomy at Washington State University College, says this is one area where our anthropomorphic tendencies are probably in the right: animals do have complex emotional lives.
This involves the familiar problem of anthropomorphizing animals. Just because a snarling dog looks angry to me doesn’t tell me whether he experiences anger in anything like the way I do. On the other hand, assuming that animals are not capable of emotional states seems to me to reek of dualism; that is, it supposes that human beings possess a soul that is so unique as to remove us from the category of animals. I suggest that the latter leads us further astray than anthropomorphizing animals ever did.
Ethologists who study animal behaviour increasingly accept the idea that fear keeps animals away from predators, lust draws them toward each other, panic motivates their social solidarity and care glues their parent-offspring bonds. Just like us, they have an inner life because it helps them navigate their outer life.
That is the most parsimonious interpretation of the phenomena. A second idea is that human minds emerge from a series of “brains” arranged one atop the other.
Neuroscience has begun to correct the computational model by showing how our rational, linguistic mind depends on the ancient limbic brain, where emotions hold sway and social skills dominate. In fact, the cognitive mind works only when emotions preferentially tilt our deliberations… Our rational mind is truly embodied, and without this emotional embodiment we have no preferences. In order for our minds to go beyond syntax to semantics, we need feelings. And our ancestral minds were rich in feelings before they were adept in computations [my italics].
Our neo-cortex mushroomed to its current size less than one million years ago. That’s a very recent development when we remember that the human clade or group broke off from the great apes in Africa 7 million years ago. That future-looking, tool-wielding, symbol-juggling cortex grew on top of the limbic system. Older still is the reptile brain — the storehouse of innate motivational instincts such as pain-avoidance, exploration, hunger, lust, aggression and so on. Walking around (very carefully) on the Serengeti is like visiting the nursery of our own mind.
I have pointed out here that this hierarchically layered model of the mind was explicitly advanced by Aristotle in his masterful On the Soul. I suggest that Aristotle’s view corrects for both dualism and anthropomorphizing. It presents an embodied mind that allows the human being full ontological status without divorcing it from its animal origins.
Asma has some criticisms of evolutionary psychology.
Evolutionary psychologists have tried to apply Chomsky’s module idea to almost every other mental activity. What kind of food we like, what kind of spouse we’re looking for, our phobias of snakes and spiders, our preference for certain kinds of stories, even our ability to detect cheaters in a group: all have been attributed to specialised programs in the brain. This neat, formulaic explanation of human psychology plays well in the popular press, but it seems less convincing as we learn more about brain development and early human ecology.
Its chief rival is the school of ‘general intelligence’. According to this view, the neocortex is a highly flexible, general problem solver. Our environment selected for a mind with reliable pattern recognition and prediction powers, but it didn’t give us specific modules for thought contents or behaviors. As affective neuroscience advances, this scenario comes to look more credible, albeit with a surprising twist. It seems that even the emotional springs of the limbic system — our fear, care, rage and so forth — are more pliable and open-ended than we previously thought…
This criticism seems to be confused. Evolutionary psychology does seek to identify evolved psychological mechanisms, but it hardly insists that these mechanisms are inflexible. Mental schema for distinguishing kin from non-kin, allies from enemies, have to be flexible and responsive to context. Moreover, flexibility seems to come chiefly from having a considerable number of distinct mechanisms that may be drawn upon in a pinch, each one of which enables novel responses in novel contexts. The whole point of the layered theory of mind advocated by Asma is that human intelligence depends on a lot of prepackaged software, something that is very different from any notion of “general intelligence.”
Another death-knell for old-school evolutionary psych might be sounding from the field of hominin-era climate studies. A vital premise for the modular theory is that our minds evolved in an extremely stable, unchanging environment. If our current minds are a mishmash of Pleistocene adaptations, then the conditions that shaped our brains must have been very consistent, or else natural selection couldn’t sculpt each module to fit our perennial environmental challenges. But it now appears (thanks to the work of paleoanthropologists such as Rick Potts) that the environment was anything but stable during the brain boom. In fact, it was precisely the climate chaos of this era that created our multipurpose, problem-solving minds.
Again, there seems to be some confusion. Human beings share some of our genetic heritage with all other animals. Tool box genes are one example. The layered theory of mind that Asma advocates tells us that we share significant parts of our brain’s architecture with other animals, including reptiles. That means that some parts of our environment have not changed significantly over the course of evolutionary history. Just as the astonishing stability of ants over millions of years points to an environmental niche that was very stable, so the presence of reptilian architecture in the human brain suggests that some environmental challenges have been persistent for very long periods of time.
No doubt the environment of evolutionary adaptation was subject to a lot of changes, due to climate and other factors. Regardless of those changes, our ancestors still had to find mates and allies. Females had to make sure their investments were as secure as possible and males still had to make sure they were investing in the right offspring. If evolutionary explanations are worth anything, it is because some things change while others do not.
I look forward to more from affective neuroscience. It certainly looks like the right idea.