Friday, February 22, 2013

What is an "evolutionary perspective?"

Proponents of evolutionary studies (EvoS) claim that an evolutionary perspective makes it possible to make sense of a broad range of different disciplines.  In fact, in more private moments I've heard claims that disciplines outside the hard sciences are primarily atheoretical and that the lack of a unifying framework has hindered their progress.  Instead, the thinking goes, these different scholarly traditions lumber along with each generation doing nothing more than finding clever ways of discrediting the generation before, with no lasting body of theoretical or empirical work to build from.

Naturally, EvoS advocates claim that evolution can save the day.  Taking an evolutionary perspective, they propose, makes it possible to unite vastly disparate scholarly traditions and to make sense of an otherwise chaotic intellectual landscape.  At first blush, this seems plausible, perhaps even compelling.  Or at least it does if you're trained in the life sciences where evolutionary theory does important work.  As Dobzhanzsky is so often quoted as saying, "Nothing in biology makes sense except in light of evolution," so how could taking an evolutionary perspective not shed light on all the other things that life has managed to create? 

Underneath all this enthusiasm, however, is one rather glaring problem.  Namely, what does it mean to take an evolutionary perspective?  For that matter, what is an evolutionary perspective in the first place?  In all the years I've been associated with EvoS I can’t recall anyone ever articulating exactly what they mean by this and I'm coming to find that rather deeply troubling and problematic.  Underneath it all is an implication that evolutionary theory is a single thing, a unified set of principles by which life can be understood.  With a bit of training in how to use the "evolutionary toolkit," the story goes, all of life's mysteries can be revealed and that holds as true for culture, economics, psychology, literature, etc. as it does for biology. 

As someone trained in evolution, though, I have to ask just what is this toolkit we’re all supposed to have?  Is it simply Darwin's recipe of mixing inheritance, variation and selection?  Is that the simple logic that scholars should rally around?  In biology, the answer would seem to be a rather resounding no and it has been since the Modern Synthesis.  At the very least, then, taking an evolutionary perspective should include things like Mendelian inheritance, mutation and population genetics.  However, we can’t stop there.  As the Extended Synthesis is demonstrating, no evolutionary toolkit would be complete without also including topics such as evo-devo, phenotypic plasticity, multilevel selection, epigenetics, niche construction, robustness and evolvability.  In seeking conscilience, though, we’re trying to explain human behavior, too, so what are we to make of culture?  Cultural evolution is an obvious answer, but this hardly represents a unified perspective.  While not necessary at odds with one another, gene culture coevolution is nevertheless a fundamentally different discipline than evolutionary psychology, which is itself hardly a single theoretical framework, and these both offer very different approaches, methodologies and preoccupations than human sociobiology, behavioral ecology and memetics.

As best I can tell, then, there is no single evolutionary perspective, no single evolutionary toolkit.  Rather, the study of evolution has led to a rather dizzying array of specialized disciplines, each asking different kinds of questions about different kinds of phenomena.  Sure, there are varying degrees of overlap between many of these fields.  However, I doubt that many specialists in, say, niche construction, would be so bold as to claim expertise in evolutionary psychology simply because both fields can trace lines of intellectual thought back to Darwin.  Yet I have heard similarly bold claims, both publicly and in private, about what EvoS can bring to nearly every intellectual tradition imaginable.  If "applying an evolutionary perspective" is nothing more than arguing by analogy from biological principles, then to a limited extent I suppose this is true.  However, I can hardly blame those who have been trained in rich intellectual traditions with deep histories outside the Darwinian aegis if they find the application of biological analogies less than compelling or far from illuminating.

All that said, I remain cautiously enthusiastic about EvoS.  As a program it does have the capability to facilitate dialog between disciplines and to foster unique interdisciplinary research programs.  However, until we’re able to articulate a consensus about what this "evolutionary perspective" is that we all seem to take for granted, the ability of EvoS to bring about any kind of conscilience will remain a distant and rather fanciful dream.

Monday, February 18, 2013

Religion and Parasitic Memes

It's an obvious fact that organisms do not exist in isolation.  Every individual organism, no matter how simple or complex, must navigate a world of other organisms.  Often, these interactions are antagonistic such as in predator prey dynamics.  However, individual organisms also form positive relationships with other organisms in complex webs of mutualistic benefit.  Perhaps the most startling examples of this come from mammalian studies that have shown the majority of cells contained within a mammal's body are not mammalian cells at all.  Put more plainly, most of the cells in your body aren't human!

Most of the non-human cells taking up space inside the body you think of as you are not harmful.  Indeed, most of them are likely performing useful services that help you to survive and reproduce better.  As such, their biologic interests and yours are closely aligned.  This isn't always the case, though, as anyone who has ever suffered a bacterial infection can attest.  These relationships are unpleasant precisely because the biological interests of harmful organisms and our own are at odds with one another.  Staph doesn't need to worry about your welfare in order to survive and reproduce as long as there are plenty of other bodies in close proximity that it can infect when it's done exploiting yours.  These kinds of antagonistic interactions between organisms is what differentiates parastism from mutualism.  

It is within this context that the concept of memes was born.  A provocative implication of memetics was that cultural information, when considered as consisting of replicators in their own right, might behave similarly to parasites, using hosts' resources to replicate in direct conflict with their hosts' fitness interests.  This could explain why human behavior is often so maladaptive.  It's at once a clever and compelling idea.  Unfortunately, as best I can tell it's an idea that can only be explored within the context of maladaptive behavior.  It's not at all clear to me, for instance, how you could demonstrate selection at the level of memes in cases where memes are mutualistic since selection acting at the level of the individual has equal explanatory power.

Be that as it may, even if memetics can only be explored within the context of maladaptation then it is still a useful idea worth full consideration and there are seemingly endless examples of maladaptive human behavior to explore.  One of the favorite examples that memetics proponents, particularly those that make up the New Atheist movement, like to trot out is religion.  It's no secret that Dawkins, the one who coined the term "meme," is no friend of religion and his career has taken a polemical turn against religion because he believes it to be a parasitic meme, causing people to engage in all sorts of preposterous behaviors that are against their self interest.  He's hardly alone.

There are several problems with this line of reasoning, though.  First and most obviously such arguments generally treat religion as some singular, monolithic thing.  This gives great rhetorical freedom to march out any historical instance of religion behaving badly as an example in support of the hypothesis that religion is a parasitic meme.  However, it's an approach that doesn't give much, if any, empirical traction.  It ignores the fact that different religions are VERY different and even within a particular religious taxon, such as Christianity, there is such incredible variation that different denominations are better thought of as separate species, each of which is comprised of suites of traits that can be adaptive, maladaptive or entirely neutral.  It may be that Quakers display maladaptive traits, but using the excesses of Catholicism during the Crusades as evidence of this makes absolutely no sense, yet the broad brush arguments of many of those in the New Atheist movement seem to be just that undiscriminating.

Such arguments also tend to ignore context.  Generally speaking biological traits only become maladaptive within specific contexts.  Our evolved traits that cause us to find sweet and fatty foods desirable is entirely adaptive in environments where these energy sources are relatively hard to come by.  Only in modern times when these have become available in every corner store do these traits lead to severe obesity with all its associated problems that lead to lower fitness.  Branding Islam as maladaptive because some vanishingly small number of Muslims engage in suicide bombing is a bit like branding the heart as maladaptive because it sometimes leads to cardiac arrest.

This brings us to the last point I'd like to make.  Namely, is religion really maladaptive?  By any definition, this is probably true within certain contexts.  However, is it broadly true?  The answer seems to be no.  The most comprehensive treatment of this topic is Koenig, King and Carson's Handbook of Religion and Health, now in its second edition.  It is a hefty tome of meta analyses that reviews virtually every study that has been done related to religion and health.  I couldn't begin to summarize their findings here but the relevant take home message is that more religious people, on average, live longer and have more children than less religious people.

Now, survival and reproduction are the very sina qua non of biological fitness.  If religion actually can be thought of as being composed of memes then it would seem that most of the time religious memes' interests are closely aligned with the biological interests of their hosts and, as such, cannot be thought of as parasitic at all.  Indeed, if we look at fitness through a strictly biological lens, then the fact that atheists have fewer children and live shorter lives suggests that it is atheism, not theism, that is composed of parasitic memes and needs special explanation from an evolutionary perspective.  I somehow doubt that many within the New Atheist movement would be comfortable with that conclusion, but the best empirical evidence we have seems to point in that direction.