“Thinking again?” the Duchess asked, with another dig of her sharp little chin.
“I’ve a right to think,” said Alice sharply, for she was beginning to feel a little worried.
“Just about as much right,” said the Duchess, “as pigs have to fly….”
It seems that creationists/ID advocates aren’t the only folks discontented with Darwin’s theory of natural selection, as I have been hearing murmurings that some scientists are considering genetic changes to be far more important to evolution. It’s been difficult to find details about this “phantom menace” to Darwin’s theory, some adherents jokingly claiming that they would not present their ideas without wearing full body armor, but now Rutgers philosophy professor Jerry Fodor has published an article entitled “Why Pigs Don’t Have Wings” in the London Review of Books that presents his personal complaints about natural selection. Many other more capable bloggers (like Jason Rosenhouse, and Larry Moran, thus far), have already addressed Fodor’s somewhat incoherent piece, but given that the article was written by someone on my own “turf” I think I should throw in my $0.02 as well.
Fodor’s essay is a bit complex as it seems to stem from his distaste for evolutionary psychology (a sentiment I largely share), the pathway that led him to pen the current article being presented in an article listed as “forthcoming” on his CV site called “Against Darwinism” (although from this post from March 2007 at OmniBrain, it appears that it has already been released). Indeed, it seems that the problems Fodor experienced with the claims of evolutionary psychology led him to doubt natural selection as an evolutionary mechanism in general, and he writes;
So the claim turned out to be that there is something seriously wrong with adaptationism per se. Having gotten that far, I could have rewritten this as straightforwardly a paper about adaptationism, thereby covering my tracks. But I decided not to do so. It seems to me of interest to chart a route from being suspicious of Evolutionary Psychology to having one’s doubts about the whole adaptationist enterprise.
Perhaps the London Review of Books article is the paper specifically about adaptationism mentioned in the somewhat sloppy paper I just cited, but new article is not easy reading by any means. I’m not much of a fan of opera so I’ll skip the first section of Fodor’s writing, but at least he makes the distinction that science tells us of what is and not what ought to be. It is in this section that he reveals what his major problem with adaptationism is;
What’s wrong with us is that the kind of mind we have wasn’t evolved to cope with the kind of world that we live in. Our kind of mind was selected to solve the sorts of problems that confronted our hunter-gatherer forebears thirty thousand years or so ago; problems that arise for small populations trying to make a living and to reproduce in an ecology of scarce resources. But, arguably, that kind of mind doesn’t work very well in third millennium Lower Manhattan, where there’s population to spare and a Starbucks on every block, but survival depends on dodging the traffic, finding a reliable investment broker and not having more children than you can afford to send to university. It’s not that our problems are harder than our ancestors’ were; by what measure, after all? It’s rather that the mental equipment we’ve inherited from them isn’t appropriate to what we’re trying to do with it. No wonder it’s driving us nuts.
This paragraph effectively forms the basis of Fodor’s objections to natural selection, the idea that our minds were essentially molded out on the savanna where being aware of a lurking Dinofelis, finding enough food to eat, and keeping other males from disrupting a consortship with your mate were the main concerns. There can be little doubt that what occurred in our evolutionary past shaped the present characteristics of Homo sapiens, but Fodor is right to point out the absurdity of thinking that people alive today are all repressed hunter gatherers that are befuddled by their own technological, societal, etc. creations. Still, even though I think Fodor is justifiably irritated by some of evolutionary psychology’s claims, he takes things a bit too far and seems to be a bit out of his depth when it comes to the actual science of evolution.
While Fodor claims that he embraces one aspect of what he calls the Darwinian synthesis (common descent), he rejects the mechanism of natural selection, effectively divorcing himself from Darwin’s ideas nearly entirely. What made Darwin significant and important (along with, lest we forget, A.R. Wallace) was that he provided a mechanism for evolution; evolution as an idea of “transmutation of species” preceded Darwin and various mechanisms (like the attainment of acquired characteristics) were proposed prior to On the Origin of Species.
More often than not, both halves of the Darwinian synthesis are uttered in the same breath; but it’s important to see that the phylogeny could be true even if the adaptationism isn’t. In principle at least, it could turn out that there are indeed baboons in our family tree, but that natural selection isn’t how they got there. It’s the adaptationism rather than the phylogeny that the Darwinist account of what ails us depends on. Our problem is said to be that the kind of mind we have is an anachronism; it was selected for by an ecology that no longer exists. Accordingly, if the theory of natural selection turned out not to be true, that would cut the ground from under the Darwinist diagnosis of our malaise. If phenotypes aren’t selected at all, then there is, in particular, nothing that they are selected for. That applies to psychological phenotypes inter alia. [emphasis mine]
Again, Fodor’s aim in this piece is made clear; unsettled by the claims of evolutionary psychology he aims to cut the head off the “adaptationist snake”, for if natural selection doesn’t even exert an influence on phenotypes (or frequencies of genes in populations that express those phenotypes) how can it influence our mental evolution? This is significant in terms of Fodor’s point in that he’s not suggesting that natural selection occurs but is not significant, but rather than natural selection doesn’t occur at all (although a more accurate statement might be that he doesn’t consider natural selection at all, regardless of whether it occurs or not). This is clearly absurd and runs counter to direct observations of nature. Take the case of the Blue Moon Butterfly, Hypolimnas bolina, for example. According to research published in Science this past July, a strain of Wolbachia bacteria wiped out 99% of the males of the butterfly species by 2001, but that 1% of remaining males was important in that it was resistant to the bacteria. The resistant males, facing little to no competition for mates, were able to pass on their resistance to the next generation and as of 2005 (about the time of 10 generations) the male/female ratio in the butterfly populations is close to 1:1 again. This is a classic example of natural selection at work, variation already present in a population allowing some members to have greater reproductive success than others (in this case because those that were not resistant to the bacteria died and hence could not mate), passing along the variation that was favorable under the given conditions. I could understand if Fodor called into question the significance of such selection events, but to deny that they occur at all is a bit strange, to put it mildly.
Fodor picks a more abstract example to illustrate his point how strict adaptationism (looking at a particular trait in terms of what it was selected for) doesn’t work. He asks;
…were polar bears selected for being white or for matching their environment? Search me; and search any kind of adaptationism I’ve heard of. Nor am I holding my breath till one comes along.
The question Fodor poses is a bit bizarre in that he doesn’t seem to have fully thought it through. The advantages for an animal being white in a habitat that is primarily that color are clear, but under what circumstances would a polar bear be selected to be white regardless of its ecology? I’m not even going to get into the fact that polar bears have black skin and white hair (something overlooked by Fodor), but it seems that in his attempt to knock down this particular straw man he swung and missed entirely. Fodor then moves on to the subject from which the article gains its name, a discussion of the non-existence of winged pigs, extinct or extant. The airborne ham argument is as follows;
For example, nobody, not even the most ravening of adaptationists, would seek to explain the absence of winged pigs by claiming that, though there used to be some, the wings proved to be a liability so nature selected against them. Nobody expects to find fossils of a species of winged pig that has now gone extinct. Rather, pigs lack wings because there’s no place on pigs to put them. To add wings to a pig, you’d also have to tinker with lots of other things. In fact, you’d have to rebuild the pig whole hog: less weight, appropriate musculature, an appropriate metabolism, an apparatus for navigating in three dimensions, a streamlined silhouette and god only knows what else; not to mention feathers. The moral is that if you want them to have wings, you will have to redesign pigs radically. But natural selection, since it is incremental and cumulative, can’t do that sort of thing. Evolution by natural selection is inherently a conservative process, and once you’re well along the evolutionary route to being a pig, your further options are considerably constrained; you can’t, for example, go back and retrofit feathers.
Fodor is correct in stating that there are certain constraints that would present a farmyard pig from becoming winged anytime soon just as we would not expect to find a pig with wings in the fossil record for as a group they are throughly unsuited to flight. Does this disprove natural selection? Of course not, and merely saying “There are no pigs with wings, therefore natural selection is powerless to cause evolutionary change,” does not follow. Powered flight has evolved at least three times among tetrapods and gliding an even greater number of times, always involving small creatures that were probably arboreal in their habits, structures and habits that may have been present to one degree or another being molded by mutation and natural selection to allow for flight. If Fodor really wanted to make his case he would have taken the time to construct an argument based upon the available fossil evidence present for the evolution of flight in dinosaurs (birds), bats, or pterosaurs, not pick a fantastic example that does not prove anything beyond the author’s ability to create a faulty analogy. It should also be noted that Fodor lists natural selection as purely a conservative mechanism, but this seems to assume that the ecology the organisms find themselves in does not change. If local ecology were constant, if there were no droughts, monsoons, years of high food productivity, years of scarcity, etc. (not to mention larger changes in climate, plate tectonics, etc.) then we could maybe suggest that natural selection would always favor the same traits and therefore do little more than conserve, but differing circumstances require different solutions and natural selection continues to prune the evolutionary bush when groups are too constrained to adapt to ecologies in flux.
We don’t even have to look at nature through the perspective of “deep time” or the geologic record to recognize this; different populations of the same species often have different habits, the Chimpanzees of Mt. Assirik being a primate example. I’ve talked about this population before, but to keep things brief they live in a much drier and open habitat where food availability does not appear to be seasonally predictable (the availability of water being more important). While they prefer the forest and may go about their business alone in such relatively safe areas, they are far more alert when out on the grasslands, traveling between wooded areas in large groups, standing up every now again to look out over the savanna. They also smash baobab nuts on the hard branches of the baobab trees (using the branch as an anvil) but do not crack the nuts by placing them on an anvil and hitting them with another stone like the Tai forest chimpanzees. Clearly the Mt. Assirik chimpanzees are reacting to their ecology in a manner much different from other populations (i.e. Gombe), the constraints of their environment favoring different social patterns and even tool cultures that could be the basis for larger changes through the course of time. Disregarding ecology, then, is absolutely foolish, no matter how much disdain Fodor might have for Darwin’s considerations of the environment in the theory of natural selection.
Back to Fodor’s article, we now must ask the following question; If natural selection does not contribute to evolution, what is the major driving force behind change in populations through time? Fodor posits research from evo devo as the answer, although no actual research is cited to support his view;
So what’s the moral of all this? Most immediately, it’s that the classical Darwinist account of evolution as primarily driven by natural selection is in trouble on both conceptual and empirical grounds. Darwin was too much an environmentalist. He seems to have been seduced by an analogy to selective breeding, with natural selection operating in place of the breeder. But this analogy is patently flawed; selective breeding is performed only by creatures with minds, and natural selection doesn’t have one of those. The alternative possibility to Darwin’s is that the direction of phenotypic change is very largely determined by endogenous variables. The current literature suggests that alterations in the timing of genetically controlled developmental processes is often the endogenous variable of choice; hence the ‘devo’ in ‘evo-devo’.
Changes in development certainly contribute to the amount of variation present in populations, but just because a new variant of a species can be created due to a change in development it does not mean that such a form is immediately established in the group. Whatever variations arise through mutation, changes in development, or other factor, they all are subject to natural selection. Organisms are constrained by biotic and abiotic environments they exist in and are not free to merely take on whatever form may be generated by a change in development or by mutation. There are some traits that do not come under direct selective pressures and change as a result of other changes being made to the organism and natural selection as outlined by Darwin is not the entire story when in comes to how evolution proceeds, but it’s a pretty significant part of it.
If Fodor simply stuck to what aggravated him in the first place, the major problems with many of the evolutionary psychology hypotheses that he alludes to (yet does not cite), I might have found much common ground with his paper. Hypothesizing about such a paper, however, is like hypothesizing about pigs with wings; it does not exist, whatever constraints Fodor himself experienced driving him to try and chuck natural selection in the waste bin without considering it fully. For Fodor, Homo sapiens seems to be a privileged group not touched by natural selection, although how we got to be as we are is left unanswered by the piece. I’m sure we’ll be hearing more from Fodor in the future, though, as the end of the article mentions that a book about evolution without adaptation from him is forthcoming. If the article herein described is any indication, however, I sincerely doubt that Fodor’s book will contribute to what he feels is an upcoming revolution in evolutionary science.