Two flavours of evolutionary psychology

In many people’s eyes, evolutionary psychology (EP) has a bad rap. For some it’s methodology is questionable. For others the conclusions unpalatable. I actually tend to think many criticisms of EP are misguided, and either miss the point or attempt to build a straw man only to burn it down. But, I also acknowledge that EP has some criticisms that are clearly worthy of attention.

But I think a lot of the criticisms of EP are really targetted at just one approach to EP, and it's not the only approach one can take. In fact, I find it helpful to distinguish between what I see as two broad streams of EP; two streams that often perceived as being one and the same yet they are different enough to handle the criticisms in very different ways. And they both have significant implications on other fields, such as moral philosophy.

I'd even go so far as to say I was an enthusiastic subscriber of one version, while being but cautiously interested in the other. And I suspect a lot of EP critics would also find themselves in the same boat.

The first stream I call 'leaps and bounds', or 'top down', evolutionary psychology (let's call that TDEP). The other is, predictably enough, 'small steps', or 'bottom up', EP (here, BUEP). The fundamental distinction is between what they are trying to use evolution to explain behaviour.

TDEP is typified by the Leda Cosmides and John Tooby school of thought. Other exemplars would be David Buss, Robert Trivers and other 'sociobiologists' like E.O. Wilson. In my eyes, the common element running through all their research is the observation of behaviour and the positing of evolutionary explanations for it. So it draws a long thread from genes all the way through to individual, or even collective, behaviour.

As such, while the research often starts with behaviour and ends with genes, the theories travel the other way, starting with genes and ending with behaviour. If you get my drift. And this is where many of the criticisms of EP are targetted: at the link between genes and the end behaviours.

Just a few of those criticisms include the difficulty of 'reducing' complex behaviours to one or more genes; the assumption that this approach implies that genes determine behaviour, and the contrary observation that there are very few behaviours that are universal; the idea that genes 'fix' behaviour, not allowing for change or free will etc.

But the other school of thought, BUEP includes researchers like Robin Dunbar, Marc Hauser, Jon Haidt and others. BUEP doesn't necessarily stress the link between genes and behaviours rather than linking genes with faculties. This might seem a trivial difference, given that the faculties themselves (like the language faculty, or Hauser's moral faculty) lead to behaviour, but the key point is the genes enter the picture at the bottom and there is plenty of wiggle room before they hit the dry land of behaviour.

Some might also say this distinction is trivial because BUEP is not really that controversial (although some research in its field could be considered such, like Haidt's work on political sentiments). The idea that evolution has shaped our brains in the same way as our bodies is simple enough. Sure, we aren't born as a tabula rasa, because there has to be a tablet with certain properites to begin with, and evolution shaped those properties.

But even BUEP is important because it reminds us that biology and evolution are important in behaviour, even if they are several steps removed. And BUEP is a foundation of TDEP, so even if you question the findings of the latter, the former can still stand.

I find this distinction useful for my own research into the the implications of evolution on morality. Certainly there's lots to talk about with Cosmides and Tooby's notions of a cheater detection module, or Trivers' talk about a biological basis to altruism. But there's another story that makes even BUEP significant for moral thinking.

First if, as Hauser suggests, evolution has endowed us with a moral faculty that works at the level of sentiments in cahoots with a number of hardwired cognitive heuristics, this could have potentially sweeping implications on morality. For example, if this picture is true, then where do we find our moral foundations? From whence come our 'cardinal values', as Dennett likes to say.

We normally think that our cardinal values - often including things like altruism, compassion, temperance etc - are rationally justifiable, or that they just are. But if evolution sticks its nose into our moral realm, it can stir things up.

If evolution has shaped our moral faculty, presumably because it lent some adaptive advantage to our ancestors, does this mean our values are ultimately reducible to those things that lend a selective advantage? This would be tantamount to a fierce naturalism, and would quickly fall foul of the is-ought problem (which is often called the naturalistic fallacy, although the two are different) as well as claims that it could lead to a form of Social Darwinism. But, if we dismiss such a naturalism, what's left? Do we pluck our cardinal values out of thin air, as suggested by G.E. Moore? Or are we left with moral nihilism, as Richard Joyce believes?

Another moral issue concerns utilitarianism, and that old chestnut of why maximise happiness or pleasure rather than some other value. If it turns out that evolution can provide an explanation for the existence of happiness or pleasure, and they turn out to be simply behavioural motivators to point us towards things that promote our survival - while pain serves the opposite role - then this, too, could ground morality in biology. For, if our biology was different, then so too would be our morality.

All this stems from BUEP, let alone the considerations of TDEP. So even if you have concerns about the leaps and bounds school, if you even but acknowledge that evolution plays some role in our behaviour, even by shaping our cognitive faculties, then there are still important issues that stem from that, particularly in the moral realm.