Back in December I asked readers to submit questions and promised to answer at least the top five (by votes).
This part’s question is from Tim McCollough.
P. Z. Myers has equated EP with adaptationism and that it ignores other mechanisms of evolution. Does EP rely overly on adaptationism?
I am going to assume that Tim’s question is not a distortion of the position of P.Z. Myers [EDIT: Tim has said in the comments that his question is not a just summary, so take my reply as a reply to his formulation and not necessarily to Myers’s writing]. I do not read his blog, and I will not now, because his immediate response to my critique of Rebecca Watson’s talk was to insult me personally and to disparage my motives. Such behavior disqualifies anyone from my attention when it comes to serious academic discussion.
Much like deniers of climate change, evolutionary psychology denialists rehash tired old arguments which have been effectively dispatched over and over again. For example, read the short rebuttal from the Center for Evolutionary Psychology (CEP) here, or read a fascinating 1996 exchange between Steven Pinker et al. versus Stephen Jay Gould here (pdf).
The CEP notes that even in 1966, influential luminaries like George C. Williams knew better, and wrote so:
Evolutionary adaptation is a special and onerous concept that should not be used unnecessarily, and an effect should not be called a function unless it is clearly produced by design and not by chance. When recognized, adaptation should be attributed to no higher a level of organization than is demanded by the evidence.
I have a peer-reviewed paper in the current edition of the journal Quarterly Review of Biology in which my co-authors and I review the arguments against adapationism before testing a specific adaptationist hypothesis and presenting evidence that does not support it. One of my co-authors on that paper is Elliott Sober, a distinguished philosopher of biology who has written extensively about the epistemology of evolution and about adaptationism (Elliott has many great books and papers; I would recommend Evidence and Evolution and Philosophy of Biology). So I am versed in criticism of adaptationism— I am one of its published critics.
The question Tim raises is a weak criticism because it includes as premise the idea that “other mechanisms” can explain the ultimate origins of mind features that we study. To say that evolutionary psychology is over relying on adaptationism is like saying that walking overly relies on legs. In Part 1, I reviewed some of the fruits of adapatationism. I would invite P.Z. Myers or anyone to produce a similar list, reviewing the findings of ultimate causes of mind features from non-adaptationist mechanisms. I think that we would all be very interested in seeing that.
When it comes to explaining how life on Earth started and then diverged into current forms, adaptationism is the only game in town. No biologist has proposed a coherent alternative hypothesis to natural selection in which the origin of the complex functional features of living things can be explained. It is not that evolutionary psychologists (or biologists) ignore other mechanisms of evolution, or more insultingly, that we just have not heard about them— it’s that they are not useful in finding answers to our questions.
I do not read the blog of P.Z. Myers, so I do not know which he spends time on. I will discuss genetic drift and happenstance. Wiki genetic drift if needed, I will not explain the definition here. Drift can have a huge effect on the frequency of an allele in a population, which is the most basic definition of evolution. That said, we still always need to understand the effects of natural selection in order for any postulated drift scenario to make sense. For example, the Pennsylvania Dutch exemplify the founder effect. A small, reproductively isolated group in which the descendants reflect the particular genetic hand of the founders and not a more diverse population. As a result, recessive genetic disorders are much more common among some populations therein, such as polydactyly, having an extra digit or digits. One must understand the founder effect to explain such phenomena, as well as more mundane features such as specific frequencies of hair or eye color in that population.
Drift is not possible unless selection is absent. So even at the start, we have to think about possible selective pressures. Recessive disorders that result in sterility or young mortality will be filtered out quickly. Genes that significantly impact reproductive success will also be filtered over time. Next, drift hasn’t told us anything about where those alleles came from or why they were present in the original population to begin with. Drift might tell us about the frequency of brown hair in contemporary populations of the Pennsylvania Dutch, but not why the trait brown hair evolved, not why hair itself had evolved. Drift just does not explain the origins of design features. We will always need mutation and selection for that. Drift can tell us about bottlenecks, instances where genetic variation can sharply decrease. In other words, it can sometimes inform us what the stage upon which adaptation acts looks like. That’s important and evolutionary psychologists know this and generally include it in their considerations. Indignant reminders add nothing to the science, and I would invite P.Z. Myers or anyone else to prove otherwise.
Random events and conditions are significant in determining the course of evolution, and no evolutionary psychologist would deny it. The asteroid that ended the reign of most dinosaurs almost surely permitted the rise of the mammals, including ourselves. The first animals to reach and colonize the geologically young Galapagos Islands had no predators to fear or adapt to, making them behaviorally different from mainland cousins or hypothetical versions of themselves that could have landed on older lands that do have predators. These events are part of the ecology in which selection pressures are considered. They are part (where appropriate) of any good adaptationist account.
There are smaller random events, as well, of course. A positive mutation arises, but by the nature of mutations only one individual has it. That person can randomly die or fail to reproduce because a beneficial mutation is not a guarantee of success, only a statistical improvement. Perhaps some genes are like Betamax versus VHS, where the superior version fails to catch on. This is all interesting, but it doesn’t help us understand evolutionary changes that do happen and why. As with drift, happenstance events tell us about the ecological world in which selection can act. It isn’t helpful understanding that mammals took over former niches held by dinosaurs without understanding how selection caused those animals to adapt to those new niches and subsequently interact in new ecologies.
What if, by random accident, Elvis’s parents never met and he had never been born. This would surely have changed the history of rock music as we know it. Perhaps this did happen, but with respect to some other musical person who we don’t know because they were never born. Now I ask you, what does this thought exercise gain us? Do we understand how rock music grew and changed any better or why? Is there any real insight offered? Land animals would never have existed if the Earth (by random chance) happened not to have any dry land. Dry land is a random-factor “cause” of the evolution of land animals. Does this observation help us understand the evolution of land animals? With our hypothetical what-if ideas in hand, can useful hypotheses now be generated and investigated which could not have been otherwise? I do not aim at knowing what might happen but did not, but at knowing what did happen and why.
Stay tuned for questions 3 & 4 in the next part:
Evolutionary psychology is an inter-disciplinary study so you have to rely on evidence derived from anthropology, psychology, ecology etc. What problems can arise from this situation? 5 votes. Submitted by Chas Stewart.
What, in your opinion, is the most surprising or unintuitive result evolutionary psychology has provided, and what is the evidence for it? 6 votes. Submitted by qbsmd.