Tag Archives: evolution

McCarthy Muddles the Origins of Language

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Here’s an old but interesting bit of news. A few months back Cormac McCarthy wrote an article for Nautilus on the nature of human language. It was a largely speculative, rangy piece, enjoyable and thought-provoking in its own way. A few months later he wrote another article addressing some of the criticisms spawned by the original.

McCarthy’s most interesting claim is also his most misguided. He argues that language is an invention of humans, rather than the cold, reductive calculus of biological evolution. This is true, insofar as we are concerned with the specific forms of language and the representational significance of individual words. It seems very unlikely, however, that it is true of the capacity for language itself.

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The Righteous Mind: Religion, Cooperation, and Evolution

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I’ve read a book.

In perfect candor, this is a feat I’ve accomplished once or twice in the past, but it never fails to stoke a certain sense of accomplishment and smug self-adulation. After all, I’ve forsaken untold hours of watching TV and playing video games in favor of an identical amount of time spent turning pages and reading words. Basically, the sort of opportunity cost only saints are meant to bear.

In this case, the book came with the additional reward of containing a surfeit of the sort information the late French pedant Claude Levi-Strauss might have called “good to think”.

Without further delay, the book: The Righteous Mind, by social psychologist Jonathan Haidt. I won’t go so far as to give an exhaustive review – suffice it to say that the book was good and you ought to read it, providing as it does a succinct and provocative run-down of research into the psychological underpinnings of our moral and political inclinations.

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…By Any Other Name – Why the Concept of Punctuated Equilibrium is More a Matter of Skilled Branding than Scientific Revolution

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fossil_dinosaurs

Branding is typically thought of as a concept whose applicability is largely confined to the world of business and marketing. However, branding can be important even within the cloistered halls of academia. Nowhere is this more obvious than in the remarkable stamina displayed by Stephen Jay Gould and Niles Eldredge’s concept of punctuated equilibrium. The product of the parochial perspective of professional paleontologists, punctuated equilibrium does two things: restates a point evolutionary biologists had been aware of long before Gould and Eldredge made up a catchy new name for it, and leads to some altogether outlandish ideas concerning the nature of selection.

Gould and Eldredge came up with the idea of punctuated equilibrium in the late 1970s after observing that the fossil record displayed long periods of stasis, interrupted by relatively rapid sequences of change. Specimens from single species recovered from rock formations spanning millions of years often display the same basic range of variation. Then, in the blink of a geological eye, observable changes measurably shift the range of variation, suggesting a rather rapid bout of evolution.

This pattern seems to contradict the standard view outlined by Darwinian or “phyletic” gradualism. In this view, evolutionary change occurs at a more or less constant and more or less glacial pace. The transition from bony fish with fins adapted to swimming to bony fish with fins adapted to swimming and crawling occurred as a result of tens of millions of years of steady evolutionary change. This type of thinking seems a natural byproduct of a perspective that holds that evolutionary change occurs as a result of changes in the frequency of genes within a given population produced by random mutations forced through a sieve of selective pressures.

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Sequence of tetrapod evolution.

As phrased, it is easy to see why Gould and Eldredge thought the standard view might be flawed. Empirical evidence derived from the fossil record seems to unambiguously contradict the gradualist position. What Gould and Eldredge missed in formulating their ideas is that this view of gradualism is at best a caricature of the modern understanding of evolutionary processes. True, evolution is sometimes – almost dogmatically – viewed as a sluggish process. But evolutionary biologist had become aware of the fact that evolutionary change occurs at varying rates long before Gould and Eldredge put forward the idea of punctuated equilibrium.

Evolutionary change, as understood in the modern synthesis, is a product of four fundamental processes: natural selection, gene flow, genetic drift, and mutation. The rate of evolutionary change varies in light of the frequency and intensity of those processes. Consider for example two populations, whimsically named Population A and Population B. Populations A and B experience the same selective pressures, but Population A lives a rather monastic lifestyle, isolated high in some mountain valley. Population B, on the other hand, is rather promiscuous – its members spend a lot of time mating with members of neighboring populations. According to the principles of the modern synthesis, Population A will evolve more rapidly than Population B because Population A accumulates mutations without the buffering effects of gene flow. In principle, one can tune the four dials of natural selection, gene flow, genetic drift, and mutation up or down for any given hypothetical population and achieve differing rates of evolutionary change.

This is all rather humdrum, boilerplate evolutionary biology. It’s dogma today and was at the time Gould and Eldredge came up with the notion of punctuated equilibrium. Indeed, Sewell Wright had laid bare these very principles in his shifting balance theorem, formulated some forty-five years prior to the publication Gould and Eldredge’s seminal papers on punctuated equilibrium. Elsewhere, the idea of long term evolutionary stasis had been explored through John Maynard Smith’s forays into game theory, resulting in the concept of evolutionary stable strategies. As elaborated by Dawkins, evolutionary stable strategies implicitly involve statistically stagnant gene complexes – and therefore stable populations – because mutations are actively penalized by selection (1976; 1982).

Really, a lot of the fuss over Gould and Eldredge’s ideas boils down to marketing. Punctuated equilibrium is a beautifully coined term, at once fluid, memorable, and imbued with the electric hum of scientific novelty. It’s a lot more gratifying to say or write “punctuated equilibrium” than it is to say or write “evolutionary change can occur at a variety of rates depending on the strength of the underlying processes”. Punctuated equilibrium, with its inherent suggestion that generations of Darwinists had gotten things fundamentally wrong, provided excellent fodder for headline-hungry popular periodicals.

This wouldn’t detract too much from Gould and Eldredge’s work, were it not for their clear attempts to paint their ideas as revolutionary. Their initial 1977 paper even goes so far as to cite Thomas Kuhn’s The Structure of Scientific Revolutions, suggesting they thought their ideas rather more auspicious than they appear through the sober lens of retrospection. In balance, what they did was quite beneficial. The then banal realization that evolutionary change was not ubiquitously gradual was widely known among evolutionary biologists, but frequently missed by the inexpert. Giving the general concept a name greatly increased its public visibility, spreading the word as it were to many who would have otherwise persisted in ignorance.

Phyletic gradualism (top) vs. punctuated equilibrium (bottom)

Phyletic gradualism (top) vs. punctuated equilibrium (bottom)

Gould and Eldredge’s greater sins were to completely abandon the potential for evolutionary change to occur along a gradual gradient, and, more severely, suggest that species level selection plays a prominent role in shaping long term evolutionary trends. Concerning the former, Gould and Eldredge pointed out that gradualism seemed to demand steady orthogenetic selection, such that traits were more or less guided in a steady direction by consistent – but very small – selection pressures over the course of millions of years. Selection pressures of these kind would be swamped by other factors, so it was unrealistic to presume they were meaningful, especially in light of fossil evidence to the contrary (Dawkins 1982). Problematic is that their assessment fails to recognize that gradual evolutionary change can be produced by a mix of countervailing forces. In no scenario is it actually realistic to presume a stable but mild selection pressure is the only force exerted on a biological population. A strong selection gradient may be counteracted by high levels of gene flow or low levels of mutation, resulting in a net rate of evolutionary change identical to what one would expect under conditions of weak selection alone. As Dawkins points out (1976, 1982), much evolution is a result of organisms evolving in response to pressures exerted by other organisms, resulting in evolutionary arms races. The selective dynamics underlying evolutionary arms races are precisely the kind that would produce steady directional change.

In making their case against gradualism, Gould and Eldredge also greatly oversimplified the nature of the evidence. Fossils provide an excellent record of long term change, cataloguing the results of evolutionary processes over the course of millions of years. Yet it’s worth remembering the fossil record is primarily one of morphological change in hard tissue. Soft tissues like skin and stomachs and brains are only occasionally preserved in the fossil record. Moreover, behavioral change – surely relevant to any claim about the nature of evolutionary processes – can only be studied indirectly. Gould and Eldredge’s reliance on the fossil record implicitly grants preference to morphology as the only meaningful stage for observing evolutionary change, ignoring the fact that a fossil sequence that shows little change in limb length over the course of millions of years might disguise important changes in soft tissue and, critically, behavior. Put simply, the long term evolutionary stasis Gould and Eldredge saw as a basis for punctuated equilibrium is largely a product of what kinds of information do and do not fossilize.

Which brings us to their gravest sin: the claim that punctuated equilibrium shines light on the fundamental role of species level selection in shaping evolutionary processes. This again seems a product of the parochial perspective of a person who spends most of their time looking at fossils. These are necessarily low resolution records, revealing trends that play out on the scale of tens of thousands to millions of years. Little wonder, then, that the most pronounced signal of evolutionary change in the fossil record will often be that left behind by speciation events. Gould and Eldredge seem to have mistaken the locus of evolution for the locus the selection. Populations evolve, individuals do not. That is precisely what we see in the fossil record. From here, it is easy to slip into the trap of thinking selection is operating on level of populations.

The problem here is that populations evolve as the result of differential selection operating on either the individuals that comprise the population or, more fundamentally, the individual alleles whose frequency provides the definitional basis of evolutionary change. Evolutionary processes can be abstracted to involve the differential proliferation of replicators, bits of information that have sufficiently high levels of longevity, fidelity, and fecundity to be sensible to selective forces (Hull 2001; Dawkins 1976 & 1982). Candidates for the unit of selection must meet those criteria. A sufficiently short nucleotide sequence passes muster. But does a species?

Species do seem to last a long time, so perhaps we can tick one box in favor the species as replicator position. But it’s difficult to see how a species can display either fidelity or fecundity. Species do not reproduce – the individuals of which a species is comprised do. Whatever fidelity or fecundity is exhibited by a species is a product of processes that occur at the level of individuals. Speciation events are not good candidates for instances of species reproduction, because – by definition – they involve a species changing into something else. In that case fidelity seems compromised. When we turn to fecundity, the argument for species level replication seems just as dubious: parent species don’t sire lots of copies of themselves.

On geological time scales, speciation seems to occur in the blink of an eye. But selection operates on timescales that make most speciation events appear gradual. Even if we grant the already suspicious claim that species can coherently serve as replicators, the fact nonetheless remains that selection operating on replicators with a faster turnover rate will swamp the effects of species level selection (Dawkins 1982). That is, individuals reproduce and introduce novel mutations into the gene pool at the rate of generations. Depending on the species, that can be anywhere from days to decades. Speciation, by comparison, occurs at a relatively glacial pace. Populations become reproductively isolated and evolutionarily distinct on a scale that must be measured in anywhere from millennia to millions of years. The idea that some selective pressure operates on the species as a whole, when all evolutionary change is a product of the differential reproduction of the individuals within that species, is far-fetched at best.

As Dawkins points out (1982), species level selection also finds itself tripped up by one of the very arguments Gould and Eldredge leveled against gradualism. Gradualism seems to demand slight but consistent directional selection. We’ve already discussed the problems with this, but consider the idea when turned to species level selection for complex adaptations. A demand is placed not only on directional selection for a trait, but directional selection on many traits that might not be genetically intertwined. Species level selection falls into the same orthogenetic trap Gould and Eldredge had laid for gradualism, but does so far more deeply and devastatingly.

Species level selection is a chimera. Any given instance of speciation marks a point at which all the interesting change has already occurred at the level of individuals and genes. None of which is to say speciation and extinction aren’t evolutionarily important. They most certainly are. Rather, the crucial point is that selection can’t operate on the level of the species because selection pressures can’t make it that far up the chain. By the time a selection pressure becomes sensible at the level of the population or species, it has already been taken care of by adaptations expressed on the level of the individual. If we picture selection as hierarchical process, the most navigable of selection pressures will never even been sensed by genes. Behavioral plasticity and learning will take care of them. If an organism proves too developmentally inflexible, a beneficial mutation resulting in a slight adaptive advantage (these produced at the rate of generations) will take care of the problem. By the time a selection pressure made it the level of the species, individuals within the population will have had tens of thousands of chances to deal with it, and chances are, they already will have. Populations and species evolve as a result of the aggregate effects of selection on individuals and the genes they carry.

In the final analysis, punctuated equilibrium is a concept well worth keeping. It seems to make the notion that evolution is not merely a steady trudge into the future considerably more digestible by taking the concept embodied by the phrase “evolutionary change can occur at a variety of rates depending on the strength of the underlying processes” and compressing it into a simple, memorable term – “punctuated equilibrium”. But it’s worth remembering that punctuated equilibrium – as formulated by Gould and Eldredge – overstates the case against gradualism, misrepresents the evidence presented by the fossil record, and makes a grossly misleading – and flatly incorrect – argument about the nature of selection. Let’s use punctuated equilibrium to remember that sometimes evolution can happen very fast and discard the rest.

References and Further Reading:

Dawkins, R. 1976. The Selfish Gene. Oxford University Press

Dawkins, R. 1982. The Extended Phenotype. Oxford University Press

Hull, D. 2001. Science and Selection. Cambridge University Press

Gould, S. J. & N. Eldredge. 1993. Punctuated equilibrium comes of age. Nature. 366

Gould, S.J. & N. Eldredge. 1977. Punctuated equilibria: the tempo and mode of evolution reconsidered. Paleobiology 3 (2): 115-151

Kuhn, T. 1962. The Structure of Scientific Revolutions. University of Chicago Press

Maynard Smith, J. & G. R. Price. 1973. The logic of animal conflict. Nature 246 (5427): 15–8.

Wright, S. 1932. The roles of mutation, inbreeding, crossbreeding and selection in evolution. Proceedings of the 6th International Congress of Genetics: 356-366.

A Creationist Physician Insists There is No Conflict Between Science and Religion – Here’s Why He is Wrong

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Chaudry

Kashif N. Chaudry, physician and – apparently – cosmologist.

Physician and human rights activist Kashif N. Chaudhry seems to have an awfully high opinion of his rhetorical skills. Indeed, Chaudry makes no less lofty a claim than to have demonstrated that “no conflict exists between science and faith”. Not content to rest in the shadows of this inimitable accomplishment, Chaudhry has decided to tackle the question of ultimate causation, insisting that atheists – rather than religionists – make the bolder of claims by suggesting that the universe simply sprang into existence, unfurling randomly out of cosmic nothingness.

Chaudhry is confident that science is on his side, but his argument in this regard is perplexing at best. After a careful reading of Chaudry’s argument, the thoughtful reader is left with two options for understanding his approach: either he does not understand the process of scientific discovery – the ways in which evidence is wielded to corroborate of falsify claims – , or he is being deliberately disingenuous, using a caricature of scientific practice to convince the credulous that faith, as oxymoronic as it might seem, bests reason when it comes to the problem of cosmic origins.

Chaudhry begins his bizarre attack on atheism by posing a question about causation. He asks his readers to picture a random chocolate bar and explain its origins. To simplify (or confuse – I’m still not sure which) the matter, he gives three options for potential explanations for the chocolate bar’s existence:

  1. Through the help of an external force or agency. Isn’t that common sense?
  2. Magically appeared out of “nothing”. Ever watch Disney cartoons?
  3. It could either have come into existence through an external force or have appeared “out of thin air”. We can never  be wholly sure since we did not witness the exact moment when the bar came into existence.

His approach here is curious, but not altogether unprecedented. Axiomatically speaking, the clear answer is option three. This, however, flies in the face of all measures of practically and, indeed, scientific practice. The central thrust of his argument is that causation is a central component of all satisfactory explanations. This is “common sense”, insidiously deployed. No one is going to seriously argue that the chocolate bar did not have a maker, because that type of thinking is at the core of how we perceive the causal relationships between human artifacts and human agency. Chaudhry is attempting to guide the incredulous into a corner they can’t escape from without proclaiming something he can twist into acquiescence to faith.

What Chaudhry is missing, through deliberate obfuscation or excusable ignorance, is that science and common sense are not synonymous. Science, in fact, is a method for navigating around the traps common sense sets for us when thinking about complex phenomena. Causation certainly appears to be at the heart of everything, but – scientifically or axiomatically speaking – it’s difficult to get beyond the word appears. This is an insight that dates back to David Hume, who argued that causal relationships can be inferred, but never directly observed or – in colloquial scientific parlance – “proven”. Hume’s recognition is at the root of the so-called problem of induction, a problem with which both practicing scientists and philosophers of science have been grappling ever since.

To be fair, this is a point that is rarely made explicit outside the cloistered circles of scientifically oriented philosophers. But it is a recognition critical to understanding the rigorous practices that drive the process of scientific discovery. This is precisely where the sometimes tortured language of “failing to reject the null” comes from when testing hypotheses. The fact of the matter is that scientific certitude remains the strict province of falsification. Outside of that, science is a search for confidence, not proof – particularly as the word “proof” is colloquially understood.

What Chaudhry is getting at with his chocolate bar example (though I’m not sure he knows it) is a probabilistic understanding of evidence. And, in the case of the mysterious chocolate bar, this is not unreasonable. Chocolate bars did not exist before humans invented them. Every chocolate bar anyone has ever eaten has been a product of deliberate human action. It therefore makes good sense to think the mysterious chocolate bar is like all other chocolate bars, rather than a novel phenomenon deserving of novel explanation.

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Graphical illustration of scientific understanding of the origins and evolution of the universe.

That Chaudhry’s understanding of proof is at best colloquial is amply illustrated when he springs his trap by replacing “chocolate bar” with “the Universe”, arguing that the Big Bang – the point at which the universe began what appears to be its perpetual expansion from an infinitely hot, dense point – must have some external cause. This may be true. It may also be true that causation is illusory, a product of humanity’s peculiar evolved psychology and insufficient knowledge concerning the inner workings of reality. But to insist that, because causation is a fundamental component of other scientific explanations, it must underwrite an understanding or, more pragmatically, acceptance of the Big Bang sets up a philosophical straw-man.

Graphical illustration of origins and evolution as modified by Chaudry. Yes, that is Ludovico Mazzolino's 16th century rendering of the Christian God, but the basic idea applies.

Graphical illustration of origins and evolution as modified by Chaudry. Yes, that is Ludovico Mazzolino’s 16th century rendering of the Christian God, but the basic idea applies.

Chaudhry wants to get around the obvious problem of infinite causal regression by invoking a positively mystifying tactic, one that fundamentally undermines his entire position. Cause and effect relationships, he argues, are a product of the physical laws that characterize the post-Big Bang universe. Prior to the Big Bang, the notions of space and time in which we anchor our notions of causation become incoherent. Fair enough. Why then does he think it reasonable to insist that the Universe must have an ultimate cause and that to think otherwise is nonsensical? Having spent most of his essay arguing that the Universe must have an ultimate cause in the currently unknowable conditions preceding the Big Bang, he upends his defense of Islamic creationism by pointing out that causation, prior to the Big Bang, might very well be a completely erroneous concept.

Close inspection of Chaudhry’s argument reveals a clear discontinuity between the phenomena behind the presence of chocolate bars and the Big Bang. Theoretical speculation concerning the possibility of multiple (possibly infinite) universes aside, it is clear – from an empirical standpoint – that the Big Bang is a singular event. Consider another example for purposes of illustration. All life forms with which humans are familiar are the product of evolutionary processes, well-explained by neo-Darwinian theory. It therefore makes sense for a researcher, upon discovering a previously unknown organism, to feel very confident in believing that it is a product of those same processes, explicable in the same ways.

This is not the case with something like the Big Bang. Cosomologists do not have a plethora of big bangs to study, nor do they have solid information concerning what – if anything – preceded the Big Bang for which they do have empirical evidence. It is not even clear that what preceded the Big Bang is explicable using the tools of modern physics. As Chaudhry illustrates, our common sense understandings of causation might not even apply.

The fundamental point is that, scientifically speaking, when it comes to the conditions that preceded the Big Bang, it’s presently impossible to move beyond speculation. Consequently, the best way to greet the question of ultimate causation – of prime movers or ex nihilo spontaneous generation – is with resolute agnosticism.

And this is precisely the position adopted by anyone whose atheism is grounded in reason. Atheists who come to a position of disbelief or substantiate their disbelief through a process of rational inquiry tend to avoid making overly confident claims concerning what existed prior to the Big Bang. As far as I am concerned, the only argument against the sort of amorphous, hands-off prime-mover endorsed by milquetoast deists the world over is one based in superfluity. That kind of god has no explanatory merit – the universe looks the same whether you posit its existence or not.

However, Chaudry wants to go beyond the kind of soft spiritualism at the heart of deism. Not only was the Big Bang the product of some external cause, but he knows what it is. How? Well, I guess he just believes really, really hard. Spoiler alert: this ultimate cause is not only a god, but the God depicted in the Koran. How fortuitous that Chaudhry happened to be born into a family and culture that stamped that belief on him from birth. Shame for the rest of us.

This, I think, is where we get to the atheistic assertions that really trouble Chaudhry and stimulated his ill-conceived journey into the weeds surrounding ultimate causation, prime movers, and ex nihilo creation. Atheists do make strong assertions concerning the existence of particular gods, because the increasing specificity of elaborate religious beliefs inevitably leads to claims that can be tested against empirical reality. An ardent religious apologist, Chaudhry insists that there is no conflict between science and religion. That atheists think otherwise is what really irks him. He supports this claim through a very selective and highly imaginative reading of the Koran.

Chaudhry himself offers a number of illustrative examples of this point in a previous blog, “How Science Brought Me Closer to God”.

Chaudhry argues that the Koran preempted Copernicus, Kepler, and Newton in describing planetary motion, quoting:

And He it is Who created the night and the day, and the sun and the moon, each gliding along in its orbit (21:33).

To begin, Chaudhry is selecting the translation that most closely comports with a scientific perspective, hoping his readers will ignore the fact that there are several others. Each differs – some subtly, some substantively – in the array of interpretations they can be taken to support. But more importantly, the verse seems to be suggesting a geocentric perspective. What, after all, is the sun supposed to be orbiting? Accomodationists – to borrow a term coined by evolutionary biologist Jerry Coyne – might respond with a pedantic parry, crying “surely the Koran is referring the barycenter of the solar system”. Maybe (extreme emphasis on maybe), but that is a mighty long leap that can only really be justified with a liberal sprinkling of imagination.

It certainly does not look like the Koran is offering a perspective that can be harmonized with scientific knowledge. Nevertheless, those still unconvinced might benefit from a further example, again plucked directly from Chaudry’s own arguments. According to Chaudhry, the Koran references the Big Bang:

Do not the unbelievers see that the heavens and the earth were a closed-up mass, then We clove them asunder? (21:30).

Fascinating. The Koran must not only be true, but a scientifically accurate account of creation! Alas, Chaudhry has again chosen his translation carefully. More worrisome, however, is that he appears to have cropped the verse in a manner that reeks of duplicity. The full verse reads:

Do not the Unbelievers see that the heavens and the earth were joined together (as one unit of creation), before we clove them asunder? We made from water every living thing. Will they not then believe? (21:30)

If you squint just right, you might be able to find the Big Bang prefigured in that verse. But it also contains the marvelous insight that every living thing is made from water. Apparently we can scratch elements like carbon, nitrogen, calcium, and potassium off the list of elements that comprise human bodies. So speaks the Koran.

The point here is unsurprising. All religious texts make claims that, interpreted literally, bring them into conflict with a scientific understanding of reality. Just read Chaudhry’s full blog for further examples. (Note the magnanimity with which I am avoiding the clearly perfidious and misleading use Chaudhry makes of quotes from Stephen Hawking – a self-described atheist – to supported his religious claims).

Some religionists take a softer stance, arguing that religious texts like the Koran are populated with metaphors and similes – stuff that can’t be taken literally and meanings that can only be accessed through subjective interpretation. That is certainly true, but brings up the thorny question of how one goes about finding an interpretation in accord with the design of the Creator. I would humbly suggest that the design of the Creator is hard to differentiate from the vicissitudes of culture and individual psychology.

In any event, theists that adopt the religious-text-as-metaphor stance frequently advocate for a more amorphous perspective on deity. Chaudhry describes his god as follows:

“The concept of God as explained in Islam is that of a Spiritual Being, a conscious Creator who provides for man’s needs, expects man to serve His creation, and to whom we are all accountable in the end.”

That certainly seems better than the atheistic straw-man Chaudhry is anxious to wash his hands of. Yet it still places the concept of deity in direct conflict with a scientific understanding of reality. Evolution is not the work of “a conscious creator that provides for man’s needs”. Such teleological thinking is antithetical to an understanding of a fundamentally directionless process clearly guided by nothing more miraculous than contingency. Three billion years of evolutionary processes did not unfold for the purpose of building humans – we do not occupy such a privileged place at the pinnacle of creation. Humans are, in a very real sense, an evolutionary accident, and the processes that built us will continue to operate long after we have gone extinct.

Science and religious faith are irreconcilable. That does not mean they can’t sit precariously together in the same mind. It’s just a trick that takes either a willful avoidance of critical thought, a lot of intellectual gymnastics, or – in Chaudhry’s case – a willingness to bend the truth. Religion can only coexist with science so long as people like Chaudhry run around frantically plugging the leaks in the partitions that prevent scientific reason from permanently dissolving blinkered adherence to ancient superstitions.

Evolutionary Psychology Isn’t Done Evolving Yet

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Editorial_cartoon_depicting_Charles_Darwin_as_an_ape_(1871)

Caricature of Charles Darwin from The Hornet, ca. 1871.

Rejecting evolutionary psychology (EP) is tantamount to rejecting evolution. Or so goes the argument put forward by evolutionary psychologist Glenn Geher in a recent Psychology Today editorial. As Geher writes, there does seem to be some disconnect involved in accepting evolution, on the one hand, and rejecting evolutionary psychology on the other. It’s the sort of about-face that seems dependent on a certain amount of cognitive dissonance. For many – particularly in the humanities and social sciences – this incongruence is probably very often politically or ideologically motivated. Rightly uncomfortable with the sort of late 19th and early 20th century typological thinking – sometimes crudely justified by a slipshod invocation of Darwinian ideas – that contributed to classist and racist social agendas, many rebel against the notion that human behavior is biologically determined.

eugenics-cropped

This is peculiar for a number of reasons. For one, it seems to demand either a rejection of all Darwinian accounts of behavior or a vaguely vitalistic assertion that human behavior is governed by forces distinctly different from those that shape the behavior of other animals. The problem here is that the differences between humans and our animal cousins are largely differences of degree, not of kind. This leaves the task of identifying the point at which an organism becomes a creature ungoverned by fitness-enhancing imperatives a matter of arbitration.

To the extent that Geher is rebutting the position represented by the Standard Social Science Model, I tend to agree with him. For many, the notion that humans are more or less infinitely plastic hasn’t lost its allure. It is, after all, appealing to think that we are born a blank slate. Unfortunately, this is mostly a product of wishful thinking.

For better or worse, humans do share an array of motivations, preferences, and inclinations that are the products of natural selection. Which gets to the more interesting area where Geher might be wrong, or – at least – not entirely right, in his assertion that rejecting evolutionary psychology is equivalent to rejecting evolution. True, the rejection of EP among certain segments of the humanities and social sciences involves a liberal seasoning of cognitive dissonance. But there are also reasons why individuals with an understanding of evolutionary theory and confidence in its ability to unify biological and behavioral phenomena under a single explanatory umbrella might find EP wanting.

On a proximate level, EP seems to fall short of fully explaining the clearly context sensitive expression of human universals, much less the social, ecological, and epigenetic factors that contribute to behavioral diversity. Evolutionary psychology can expose the roots of phenomena like male aggression by pointing to male-male status competition and differential reproductive success (Wrangham & Peterson 1996; Daly & Wilson 1988). But any given case of male violence is contingent upon a variety of environmental factors. In an important sense, placing the explanatory onus on fitness – and therefore the transmission of genetic information – seems to ignore the central dogma of molecular biology. Segments of DNA are transcribed into corresponding strands of RNA which code for protein synthesis, culminating – in terms of behavior – in the production of hormones like testosterone and cortisol that contribute to patterns of aggression. This is a simplification, but the basic point is this: the chain of causation between genes and behavior is long and complicated, and can only be understood probabilistically. Serious evolutionary psychologists are aware of this, recognizing that behavior unfolds at the interface between environmental and genetic inputs. Yet, by placing their emphasis on behavioral adaptation and, implicitly, the genetic variation underlying traits, evolutionary psychologists give short-shrift to other important factors.

The disconnect between biological adaptation and behavior is particularly pronounced in the concept of massive modularity. The massive modularity hypothesis posits that individual behaviors are the product of specialized cognitive algorithms that exist explicitly because they conferred some fitness advantage on members of an ancestral population phrenologicalchart(Tooby & Cosmides 1992). The actual degree of modularity – if any – exhibited by the human mind is a thorny question, far from being resolved. Here, suffice it to say that I’m skeptical that the modularity of the human mind can be properly described as massive or that modularity is necessary to explain most human behaviors. As a heuristic for thinking about the evolutionary roots of behavior and formulating adaptationist hypotheses, modularity has some utility. But as a firm conceptualization of how the mind actually works, it lacks clear empirical support. Neurologically, there is little evidence for the existence of structures corresponding to the cognitive algorithms suggested by modularity. There is no reason to presume that human universals like cooperation or theory of mind need to be accompanied by a corresponding set of specialized cognitive modules. Furthermore, the notion of massive modularity seems to impose a level of rigidity that defies what we know about human behavioral plasticity and ignores the likely crucial but currently poorly understood influence of epigenetic changes. Evolutionary psychologists have countered this argument with a metaphor involving a globe-trotting, context sensitive jukebox, but this argument doesn’t yield any predictions that are sufficient to distinguish it from alternatives (Ermer et al. 2007).

Much explanatory work can in fact be done without assuming the burden of such a highly specialized cognitive architecture. This is particularly true when it comes down to thinking explicitly about the components of humanity’s evolved psychology. Our remarkable facility with social learning, for instance, is very likely the product of natural selection. In concert with our capacity for language – an evolved trait, for sure, though not necessarily an adaptation – social learning provides a generalized mechanism that has served as a scaffold for behaviors shaped by the accumulation and transmission of social information (Alvard 2003; Sterelny 2003). Examples such as this go a long way toward illustrating one of the primary deficits of the EP program: a broad failure to take into account the multiple scales of information that contribute to the construction of the behavior researchers are trying to explain. The genes we inherit from our parents, present in their germ line because of the role they have typically played in building reproductively successful phenotypes, only partially explain any given trait. Maternal effects and environmentally induced epigenetic changes throughout growth and development are crucial. Some behaviors are likely adaptations in precisely the sense intended by evolutionary psychologists, but others involve the dynamic interaction between ecological and social sources of information – places where the boundary between adaptation and non-adaptive plasticity (i.e. plasticity not explicable in terms of heritable genetic information) gets fuzzy.

Critics of EP have also occasionally charged its proponents with being overly adaptationist, in the pejorative sense of the term outlined by Stephen Jay Gould and Richard Lewontin in their 1979 paper, “The Spandrels of San Marco”. I’m typically sympathetic to the adaptationist perspective and find some of the arguments put forward by Gould and Lewontin less than convincing, but in the case of evolutionary psychology, the central criticism is frequently valid. In an exercise limited only by the bounds of imagination, evolutionary psychologists posit the existence of some cognitive adaptation then postulate a set of plausible circumstances that would have selected for it among the mobile bands of foragers ancestral to modern humans. The problem here is twofold. First, testing adaptationist hypotheses can be tricky. In the strict, historical sense of the term, for a trait to be an adaptation it must have a genetic component that proliferated because it contributed to a good solution to a given adaptive challenge, such that it conferred higher fitness on its bearers than conspecifics lacking said trait (Sober 1984). Unfortunately, the adaptive challenges that shaped the trait are, by definition, in the past. If environments have been more or less stable from the point at which the trait became a fixed feature of the population and the point at which the trait is observed, this isn’t much of problem. But if things have changed over the intervening years, researchers are confronted with the issue of adaptive lag  – a result of a disparity between extant circumstances and the circumstances that selected for the trait (Laland & Brown 2006; Dawkins 1982). If adaptations are identified by the increased reproductive success they facilitate relative to a specific set of selective pressures and said pressures are no longer at work, empirically demonstrating adaptation can prove difficult. Evolutionary psychologists are thus left with ubiquity and the appearance of “design” (reasonable, because natural selection is the primary force responsible for the appearance of design in biological systems) as criteria for identifying psychological adaptations. These are heuristics that might point researchers in useful directions, but they do not provide unequivocal measures of adaptation.

The second problem extends from first. Sometimes the distinguishing characteristic of adaptation is the point in time at which the trait in question evolved. Invoking adaptive explanations is most useful when accompanied by an understanding of the conditions that selected for the trait in question. This makes distinguishing between ancestrally derived and uniquely acquired characteristic essential (Thornhill 2007). At some point, many of the features of the general body plan shared by all tetrapods (amphibians, reptiles, mammals, and birds) were probably adaptations. But these homologous traits evolved as adaptations at some point well before the emergence of any of the aforementioned classes of animals. This is an extreme example, but it points to another flaw in certain veins of EP. Consider, for purposes of illustration, the problem of cheater detection. It has been hypothesized that humans should have some ability to detect individuals likely to defect from social contracts, because these individuals represent free-riders imposing costs on the cooperators they’ve duped. In other words, humans should be able to identify cheaters (Cosmides & Tooby 1992). This is quite reasonable, and, I think, probably true. It also might not be an exclusively human trait, because its advantages should be present whenever survival and reproduction depends on participations within a larger social unit. Considering the amount of cooperating humans do with non-kin, cheater detection may be more elaborated in our line, but it ought to be present in other primates as well.

The problem is not whether human psychology and behavior has been shaped by evolutionary processes. It clearly has, so in that sense EP is based on a truism. There are, of course, those who take issue with this. The distinguished anthropologist Marshall Sahlins, for instance, has spilled considerable ink railing against attempts to develop evolutionary explanations for human behavior, adopting the curious tactic of arguing that evolutionary explanations are false by demonstrating an apparent inability to understand any of them.

The real question is whether or not human behavior has been shaped by evolution in the manner conceived by evolutionary psychologists. There isn’t really an unequivocal answer in this regard, but there is plenty of room for skepticism. Though attempts to formulate Darwinian explanations for human behavior date back to at least Darwin himself, Charles_Darwin_photograph_by_Herbert_Rose_Barraud,_1881a relatively recent proliferation of interest has spawned a number of variously competing and complimentary paradigms. This is a good thing, encouraging the kind of discourse that fuels scientific progress. Though EP has deservedly gained some traction, it’s still too early to dismiss all of its detractors as victims of the sort of tortured intellectual gymnastics exemplified by the proponents of the Standard Social Science Model. Serious evolutionists can – and in many cases should – take issue with a number of the claims leveled by EP without running the risk of being dismissed as intellectual charlatans.

Ultimately, what we are trying to explain through the application of a theoretical paradigm like EP is phenotypes. It should be unsurprising then that an understanding of the forces that selected for specific adaptations in past environments, the adaptive challenges that shaped them into universal components of human phenotypes, can only teach us so much. This point is enhanced when one recognizes that many behaviors aren’t necessarily explicable in the adaptive sense at the heart of the EP program. Behavior is one of those phenomena for which the most interesting explanations might often reside at the proximate end of the explanatory spectrum. This isn’t an anti-Darwinian position. The neo-Darwinian synthesis provides an exceptionally powerful toolkit for understanding and explaining behavior. Maybe, I’d venture to say, one the best. But as our understanding of evolutionary processes deepens, it becomes more and more apparent that there is more at work in shaping phenotypes than the genes that proliferated because of their role in building fit phenotypes in ancestral environments.

References:

Alvard, Michael S. 2003. The adaptive nature of culture. Evolutionary Anthropology. Evolutionary Anthropology 12:136–149

Cosmides, Leda and John Tooby. 1992  Cognitive Adaptations for Social Exchange. In The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Jerome H. Barkow, Leda Cosmides, & John Tooby eds. Pp. 161-228. New York: Oxford University Press.

Daly, Martin and Margo Wilson. 1988  Homicide. Aldine Transaction

Dawkins, Richard. 1982. The Extended Phenotype: the Long Reach of the Gene. Oxford University Press: New York

Ermer, Elsa., Leda Cosmides, and John Tooby. 2007  Functional Specialization and the Adaptationist Program. In The Evolution of Mind. Steven W. Gangestad & Jeffry A. Simpson eds. Pp. 153-160. New York: The Guilford Press.

Gould, Stephen Jay and Richard C. Lewontin. 1979. The spandrels of San Marco and the Panglossian paradigm: a critique of the         adaptationist programme. Proceedings of the Royal Society B. 209: 581-598

Laland, Kevin N. & Gillian R. Brown. 2006. Niche construction, human behavior, and the adaptive-lag hypothesis. Evolutionary Anthropology. 15: 95-104

Newcombe, Nora S., Kristin R. Ratliff, Wendy L. Shallcross, and Alexandra Thyman.2009  Is Cognitive Modularity Necessary in an Evolutionary Account of Development? In Cognitive Biology: Evolutionary and Developmental Perspective on Mind, Brain, and Behavior. Luca Tommas, Mary A. Peterson, & Lynn Nadel eds. Pp. 105-126. Cambridge, MA; MIT Press.

Sober, Elliott. 1984. The Nature of Selection. MIT Press.

Sterelny, Kim. 2003. Thought in a Hostile World: The Evolution of Human Cognition. Malden, MA: Blackwell Publishing

Thornhill, Randy. 2007  Comprehensive knowledge of human evolutionary history requires both adaptationism and phylogenetics. In The Evolution of Mind. Steven W. Gangestad & Jeffry. A. Simpson eds. Pp. 31-37. New York: The Guilford Press.

Tooby, John. and Leda Cosmides. 1992 Psychological foundations of culture. In The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Jerome H. Barkow, Leda Cosmides, & John Tooby eds. Pp. 19-136. New York: Oxford University Press.

Wrangham, Richard and Dale Peterson. 1996  Demonic Males: Apes and the Origins of Human Violence. New York, NY: Houghton Mifflin Company.

GOP Presidential Hopefuls Resoundinngly Reject Science and Constitutional Values

Posted on by Standard Reply

A recent Salon article provides a synopsis of the views the GOP’s current 2016 presidential hopeful hold regarding evolution. In aggregate, they take a bold stance against science and reason, which should come as a surprise to absolutely no one. Jeb Bush holds the most enlightened view by a considerable margin, accepting evolution on the one hand and arguing that it should not be a part of school curricula on the other. Compared to his fellow presidential hopefuls, this is a remarkably intelligent and nuanced position, but it still ultimately boils down to sycophantic pandering to the far-right religious zealots the GOP depends on to remain competitive. That anyone holding any of the views expressed by the GOP’s potential 2016 candidates – even Bush’s milquetoast appeals to the lowest common denominator – has some chance of securing the presidency is exceptionally disheartening.

The worst offenders – Ben Carson, Mike Huckabee, Rick Perry, and Rick Santorum – have adopted a position in abject opposition to all measures of rationality and evidence, essentially casting their lot with emotional/ideological preferences rooted in flimsy interpretations of ancient myths and, I suspect, deep fears regarding their own cosmic insignificance. The sad thing is that there is a significant proportion of the U.S. electorate that finds this sort of vehemently stubborn,  fact-averse religious fanaticism appealing. According to a recent Pew poll, some 31% of Americans reject the reality of human evolution. This is disconcerting, but offset by the 35% or so (depending on who you ask – Gallup comes up with a different number) who recognize that evolution by purely natural means in the best explanation for human origins. Still, the 31% who more or less reject everything the best evidence and most coherent theory tells them regarding the origins and diversity of life on the earth should not be written off.

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Pew survey results on acceptance of human evolution. Ideally, the public views would mirror those of AAAS scientists.

Not being a Jedi master/mind reader, I can only speculate about the motivations behind the GOP candidates’ stated beliefs. I get the impression that the four gentlemen mentioned in the previous paragraph aren’t being anything less than genuine. They are religious fanatics, pure and simple. The actual beliefs of the other candidates are harder to discern, clouded as they are in the nebulous miasma of obfuscation and pandering that seems to follow career politicians wherever they go. All of the candidates endorse some breed of “teach the controversy” nonsense (read: allow Christian creation myths to be taught in science class), and obsequious attention to the right-wing base seems like a plausible motive. Though the 31% of the population that rejects evolution aren’t likely to decide an election on their own, it’s worth noting that their votes aren’t evenly distributed. Results of a Gallup poll indicate that 58% of Republicans endorse the Creationist view that humans were created by god within the last 10,000 years, as opposed to 41% for Democrats. Consequently, pandering to anti-evolution religious zealots is essentially mandatory for anyone hoping to secure a chance at the Republican presidential nomination. The relationship between religious belief and party affiliated tells a similar story. 64% of white Protestants reject evolution; 67% of white Evangelical Protestants are registered as Republicans. The exact degree to which these two subsets of the white “I find reality intensely unsettling” demographic overlap is unclear, but I suspect it is considerable.

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In any event, the outlook for modern Republicans with presidential aspirations is bleak: grovel at the feet of superstitious troglodytes or lose. But perhaps I’m being too partisan in my analysis. Certainly the fact that Republicans can’t win an election without pandering to the one of the most stubbornly ill-informed subsets of the modern American populous should be properly viewed as stain on their party: the only way they can maintain their brand is to sell snake-oil to eager dupes. More disconcerting, however, is that any member of any party has to invest energy in either placating or pleasing society’s most grossly ignorant factions. No one who expresses any of the views enumerated in the Salon article should have a chance of becoming the president of the United States – or any other 21st century, for that matter. The answer, of course, is not to disenfranchise the ignorant. Rather, it is to work to eradicate ignorance by remedying the flaws in our educational system and the broader social milieu in which it rests that have allowed that ignorance to persist. In a supposedly advanced, modern society with near-instant access to endless information, the proportion of the population that rejects evolution, believes GMOs are unsafe, thinks vaccinations are dangerous, or any number of the hair-brained, lunatic fringe notions that have taken up residency in the popular consciousness should be 5% or less.

From this perspective, there is some reason to be hopeful. The proportion of the population that accepts naturalistic evolution is up to 19% (from 15% in 2012) even as the percentage of the population that takes the nonsensical creation myths of the Bible serious has dropped to 42% (from 46% in 2012). Slims improvements, to be sure, but I’ll take them enthusiastically. Viewed through properly rose-tinted glasses, this is a silver-lining that can be magnified, unfolding into a future in which presidential candidates don’t have to pander to religious zealots, and sincere religious nuts don’t even register as even far-shot options for the presidency. Maybe it’s a long shot, but I’m not quite prepared to abandon hope.

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