Third unanswered question about evolution for BBC Focus

Here is the third and last “unanswered question about evolutionary biology” that I discussed in a short BBC Focus essay.  (#1 is here and #2 here). I’m putting this up because the second and third questions appear only in the print version.

How much of our behavior reflects our evolutionary past? What does it mean to be human? Part of the answer involves knowing which of our behaviors were instilled in our ancestors by natural selection.  This is the purview of the popular field of “evolutionary psychology.”

Unfortunately, its popularity—as measured in books and articles that give Darwinian explanations for everything from homosexuality to music—is not a sign of scientific rigor.  It turns out to be hugely difficult to determine what portion of our modern behavior was adaptive in our ancestors. For one thing, our culture is far more elaborate than that of any other animal, being transmitted instantly from individual to individual through emulation.  Is men’s preference for young, curvy women a function of past evolution in favor of choosing mates with marked reproductive potential, or is it simply a function of what we see on the covers of magazines?  These debates are important.  How much of gender difference in academic performance, for example is due to genetic evolution versus cultural differences between males and females? It’s hard to tell because it’s unethical and unpalatable (not to mention impossible) to settle the issue by raising children in completely gender-neutral environments.  And since many of our behaviors evolved thousands or millions of years ago under unknown conditions, we’re often forced into speculative historical reconstructions, cynically known as “just-so stories.”

Some of our behavior is clearly due to natural selection. Eating, sleeping, and copulating all promote our survival and reproduction.  The greater choosiness of females than males in finding mates, predicted by evolutionary theory and seen in most animals, is also borne out by psychological tests. We favor kin over non-kin, an evolutionary prediction met in many animals. And the human penchant for sweets and fats, now a maladaptive taste, was probably a valuable asset to our fuel-starved ancestors on the savanna.

But when you read evolutionary explanations about why gentlemen prefer blondes, or why so much of the world is religious, always ask yourself two questions. First, could these traits be culturally influenced and not genetic?  More important, what is the evidence for whether these behaviors were favored in our ancestors by natural selection? My own standard for judging whether our behaviors represent evolutionary adaptations is this: employ the same rigorous scrutiny used by biologists when deciding whether studies of behavior in nonhuman species should be published in scientific journals. By those lights, much of “pop” evolutionary psychology doesn’t pass muster.


  1. jimroberts
    Posted July 29, 2012 at 5:14 am | Permalink


  2. Cody Porter
    Posted July 29, 2012 at 6:35 am | Permalink

    Well put! It’s nice to hear a sobering critique of evolutionary psychology, as it often seems to be a bit too ‘hand-wavy’ for my taste.

    Oh, and I was totally anticipating that the third question would be in regards to why species exist at all.

  3. gbjames
    Posted July 29, 2012 at 7:00 am | Permalink

    “First, could these traits be culturally influenced and not genetic?”

    Very often the more likely possibility is they are both. Which provokes consideration of how much of one vs. the other.

  4. Posted July 29, 2012 at 7:05 am | Permalink


  5. MAUCH
    Posted July 29, 2012 at 7:28 am | Permalink

    Wouldn’t one guideline be for whether a claim is scientific be whether a test can be made to prove it’s validity. Without that it is pure conjecture.

    • Posted July 29, 2012 at 8:24 am | Permalink

      It behooves you to read my take on evolution. It will save u a lot of insignificant rhetoric.

      • andreschuiteman
        Posted July 29, 2012 at 8:46 am | Permalink

        Your ‘take on evolution’ is mere ignorant twaddle copied from Ray “Banana Man’ Comfort, or a similar moron.

      • Posted July 29, 2012 at 8:57 am | Permalink

        Could you have used “chance,” “random,” or “accident” a few more times?

        THAT is rhetoric. You’re trying to appeal to peoples’ emotions by implying that evolution says we’re mere accidents, maybe even mistakes. Horrors!

        Natural selection is not random. Please study a legitimate text on evolution.

        Also it wouldn’t hurt to hire a professional web-page designer.

      • suwise3
        Posted July 29, 2012 at 9:47 am | Permalink

        humblepaul / The electric orange headline you use on your blog hurts people’s eyes. It just does. (There are studies on that.) Please take that into consideration if you want people to even be able to read your stuff…

      • gbjames
        Posted July 29, 2012 at 10:49 am | Permalink

        What I got out of your URL was the deep irony of your nym.

      • HaggisForBrains
        Posted July 30, 2012 at 2:59 am | Permalink

        It behooves you to read my take on evolution.

        Very humble!


    • Posted July 31, 2012 at 12:05 am | Permalink

      The shortest definition of evolution that I know:

      “The non-random selection of random mutations.”

      If you had actually bothered to read any good books (Why Evolution Is True by Jerry Coyne or The Greatest Show On Earth by Richard Dawkins) then you would see that YOUR definition of evolution has no validity in it what so ever; worse, you are happy to disseminate incorrect information to your readers under the guise of ‘religious truth.’ You should be ashamed of this.

  6. CJ
    Posted July 29, 2012 at 8:12 am | Permalink

    If Men’s preference for young, curvy women is simply a function of what we see on the covers of magazines; i will join a cult and never again take evidence seriously :-)  To me, the right question is whether there is any evidence of cultures where men don’t prefer young, curvy women, and if so, is there evidence that that is not culturally influenced?

    • Posted July 29, 2012 at 9:07 am | Permalink

      I live in a culture where the standards of beauty are quite different from the ones I grew up with in the USA. Here (Ecuador) more corpulent women are favored (kind of like the big-bottomed shape of many stone-age carvings of women). Of course, this difference in preference could still be either cultural or genetic. But don’t assume that your culture’s preferences are universal.

      • CJ
        Posted July 29, 2012 at 10:35 am | Permalink

        Are these more favored corpulent women older?

        Call it an educated hypothesis based on what i’ve learned from the many males i’ve met and observed from cultures all over the world. Of course i could be wrong. But i just wouldn’t bet on it, or think it simply a function of what is seen in magazines.

        Don’t assume that i would assume that my cultures preferences are univeral….JK

        • Gregory Kusnick
          Posted July 29, 2012 at 11:13 am | Permalink

          But you did assume that in formulating your “right question”, which explicitly asserts a universal preference for young, curvy women as the null hypothesis.

        • Posted July 29, 2012 at 11:14 am | Permalink

          OK, sorry, that was an unwarranted inference from your comment.

      • Posted July 29, 2012 at 12:16 pm | Permalink

        What CJ said. There are some aspects of attraction that are culturally highly variant, men’s idealized preferences for BMI in women, something not just variant between cultures, but historically as well. There was an theory that there was nevertheless an ideal 0.7 waist-to-hip ratio in women that was nevertheless was a universal in spite of cultural differences in BMI preferences, but research has found at least one indigenous group in the Amazon that does not conform to this.

        However, sexual attraction to younger partners, especially by men, does seem to come up time and again cross-culturally, with no counter-examples of “gerontophilic” societies where the aged are considered the sexual ideal. (Note that there may indeed be a small number of gerontophilic individuals in any society, but it’s never a general pattern.) There are many examples across cultures where younger partners are sought out by older people who have sufficient wealth, power, and/or prestige to outweigh their declining physical comeliness.

        That would seem to indicate a cultural universal, and the Darwinian underpinnings of it should be obvious, namely, that younger people are more fertile and also chromosomal defects accumulate in people over 40. While it may not be possible to observe the conditions of early evolution directly, observations of *genuine* cultural universals coupled with a clear selective advantage for that behavior can make an evolutionary explanation much more than a “just so story”.

  7. RWO
    Posted July 29, 2012 at 8:26 am | Permalink

    Is the current 30+-year (and continuing) cycle of ruthless greed-grab by financial elites just one more historical example of a typical peak cycle of cultural drive based on genetic predisposition, matched with equally cyclical fortuitous opportunity? Or is it possibly primarily due, in this particular present era, to an innate subliminal genetic response to the building imminent threat to survival due to disastrous climate change? For example, if I had the financial means to rapidly build income by disadvantaging hourly employees in a box store or electronics components factory, would I be more inclined to exploit human labor for my own personal benefit because of a survival threat like climate change than I might be otherwise? Could threat of catastrophic environmental change subconsciously result in survival behavior that overrides even innate egalitarian predisposition? How does genetics, immediate cultural imperatives, and free will or the absence of it, fit into the decision process that created the shift in wealth in the US over the previous several decades? How is any or all of this applicable to ongoing political paralysis re climate change?

  8. Bebop
    Posted July 29, 2012 at 8:49 am | Permalink

    The human animal has now reached a point isn’t strictly ruled by its biology and environment anymore. Because of that, it is impossible to just employ the same rigorous scrutiny used by biologists.

    You can’t just ignore the cultural impacts, even if they can’t be measured and precisely be defined.

    We may be biologically speaking the same homo sapiens as we were 50 000 years ago, but we all know that we have evolved since…

  9. Jeff Johnson
    Posted July 29, 2012 at 10:47 am | Permalink

    There is always a tendency for people to go overboard seeking ways to simplify the world or to make one theory explain everything. We often see newspaper articles speculating that a single gene is behind one human trait or another. Of course then always comes the obligatory response dashing hopes by explaining genes don’t work that way…

    The search for silver bullets resembles the fascination long ago with El Dorado, the Holy Grail, or the Fountain of Youth. The perfect diet, the killer app, the right fashion look, etc. are all different types of quests humans chase after.

    Yet even this tendency to seek the solution to all our problems must be based on our evolutionary history. Perhaps much of human progress came because at some point a byproduct of various brain capacities was that natural human longing, that curiosity, that drive to find that one perfect or highly valuable tool or food source or dwelling place or plant or whatever that would (seemingly but not actually) change everything, that would be the holy grail of explanation or pleasure or comfort or power or popularity.

    We can’t pick out one cause of religious faith, or why men or women find one type more or less attractive, or many other cultural phenomenon. Certainly we can’t always look for a proximate genetic or evolutionary explanation for all cultural artifacts, such as the sounds of particular words, or the kind of music, brand of deodorant, or style of car one likes.

    Yet at some ultimate level every cultural phenomenon exists because of some combination of human appetites, needs, or wants that at their root must arise from aspects of human nature that are in fact part of our evolutionary history. We didn’t evolve a taste for hamburgers, but we have a taste for hamburgers because of certain appetites we did evolve.

    While direct causal links between adaptive features and cultural norms may be impossible to single out or identify, at some level it is evolution and the adaptive traits of human nature that determine or at least limit the scope of what humans like or don’t like, what we do and don’t do, what we find good and bad, i.e. human culture is shaped by what humans essentially are, which is shaped by evolution and natural selection.

  10. candyliz2003
    Posted July 29, 2012 at 1:01 pm | Permalink

    Given my very limited education in evolutionary biology I would like to ask a question:
    Traits passed-on can be both beneficial and/or unfavorable in the survival of a species. As previously pointed out – while the craving for high-carbohydrate sustenance would be beneficial to a being surviving on foot on the great plains, a similar being using public transportation in a metropolis would not benefit from the same high-carb diet. Is it possible that some traits are the very ones that will doom the continuation of a particular species? Preference for curvy blondes could mean less likelihood for the survival of the genetic material of a male making that choice than were his preference to be for the more sturdy, corpulent brunette with better child-bearing capabilities – in other words – do some cultural influences (if that’s where “choices” are born) serve to drive a species to it’s extinction just as they might be likely to weed-out negative traits through natural selection? Or, in another fashion, Are there “suicide genes”? (I recall the parasite that causes ants to climb to unsafe places where they will be eaten – are there in-born traits like this?)
    (I hope that made sense to someone.)

    • Posted July 29, 2012 at 2:17 pm | Permalink

      To reply generally, I don’t think we need to posit “suicide genes” to explain behaviors or desires that could prove deleterious in a modern human. Adaptations are context-dependant. What works in one context may not work so well in another. I just don’t think natural selection has had enough time to re-adjust our behaviors or desires, not to mention we now have the ability to subvert or neutralize natural selection.

      Specifically, is there evidence that curvy blondes are less reproductively fit than “corpulent brunettes”?

      (As an aside, is hair color really as relevant as this “curvy blonde” meme implies? It seems to me physique would be the main thing.)

      • candyliz2003
        Posted July 29, 2012 at 2:37 pm | Permalink

        Sorry, I added “hair color” as a simple – though culturally cogent – example. You’re correct that I was going more for emphasis on physique as the better choice for breeding.
        I still wonder about traits that would work in opposition to the positive of natural selection, i.e., a “suicide gene” (sorry, for the label – I don’t know what else to call it). Is there such trait that would doom a species? Would nature seek to purposely breed a species into non-existence on it’s own (not through human interference a la dog breeds that require human help in sustaining a breed – like French Bulldogs)?

        • Gregory Kusnick
          Posted July 29, 2012 at 6:25 pm | Permalink

          Nature has no purpose and doesn’t seek anything. Nor does natural selection care about the good of the species; it simply favors genes that increase the chances of their own propagation in their current environment.

          If the environment changes, a gene that was once beneficial may become detrimental, and bad luck of that sort could have the effect of dooming an individual or an entire species, but calling it a “suicide gene” on that basis implies an overarching purpose or plan that doesn’t exist.

          • Jeff Johnson
            Posted July 30, 2012 at 9:55 am | Permalink

            We could say that nature seeks a few things: increasing entropy, equilibrium energy states, path of least resistance (minimize hamiltonian), following geodesics, and a variety of other special distributions of energy and allowed quantum states, things I once knew a good deal about but the knowledge has decayed over the last 30 years.

            I apologize for having rambled at length here, but I guess I hope someone else might find interesting that things that seem interesting to me, or that someone more knowledgeable might explain why these ideas aren’t interesting.

            Phase transitions show us that nature seems to prefer certain states when an assemblage of particles reacts to influx or outflow of energy. I say “prefer” in the sense that it allows and encourages them to exist because of what me might call natural mathematical or combinatorial relationships. We could say that certain thermodynamic states are “fittest” and are mathematically “selected” because of the properties they exhibit as they transition between higher and lower energy levels or states.

            There is of course no seeking as in wanting, but there is seeking as in the fact that given certain initial conditions, certain types of outcomes are probable or even required according to natural laws, just as a non-buoyant object tossed into air or water seeks immediately to minimize its gravitational potential. We might even say that such simple deterministic systems display the illusion of will, analogous to how the human brain does, even to the extent that it generates the experience of powerful emotions to enforce that will to survive or encourage arrival at states of comfort and well being.

            Life certainly seeks to survive, but one must say that is independent of anything nature “cares about”. Nature is indifferent toward life or death, as the prevalence of stars seems to confirm, and as evolution’s readiness to toss out unfit individual experimental organisms also confirms, yet metabolism and replication viewed as collective forces seem to seek to perpetuate themselves.

            In the way resonance expresses in membranes or crystals what one might call discrete preferred or amplified energy states, so metabolism and replication may be considered a kind of resonance for a system of certain proportions of atoms structured in certain combinations of chemicals reacting to a constant influx of solar radiation.

            It seems very odd that life, given that it exists in the open system of earth with continuous energy input from the sun seems to seek to reduce entropy. It is as though certain inputs of energy into certain systems prefers to generate patterns we like to think of as order because they store potential energy that has utility for us, more so than other patterns we like to think of as random and not useful. And it is quite odd we have the intelligence to look for these certain types of systems and preserve and use them.

            It is ignorance of the fact that nature does all these things that seem intentional without the need for any intervention by an intelligence that causes people to appeal to deities for an easy explanation, while at the same time causing them to grossly undervalue the creative power, capability, and beauty of “just a bunch of mere random chemicals”.

            • Gregory Kusnick
              Posted July 30, 2012 at 11:06 am | Permalink

              While you make some good points, my point was that candyliz is imputing an agency to nature that doesn’t exist. Agents have goals and purposes, but nature is not an agent; it’s just what happens.

              In that sense I think it’s overstating it to say that nature seeks to increase entropy. In fact the evolution of a thermodynamic system shows no preference for one microstate over another, nor do the laws of particle physics have a preferred direction of time. All interactions are reversible, and high-entropy microstates can evolve into low-entropy microstate as easily as the other way round.

              The reason that entropy increases is purely probabilistic, arising from the fact that high-entropy microstates vastly outnumber low-entropy ones (and also from the fact that we find our universe in a state of anomalously low entropy). So nature does not seek to increase entropy any more than a pair of tumbling dice seeks to come up seven; it’s just that there are more ways to make seven than any other number.

  11. emmageraln
    Posted July 29, 2012 at 3:33 pm | Permalink

    Reblogged this on emmageraln.

    • candyliz2003
      Posted July 29, 2012 at 4:03 pm | Permalink

      I don’t understand. What is the “re-blogged” reference?

      • Gregory Kusnick
        Posted July 29, 2012 at 6:36 pm | Permalink

        Apparently there are people who have blogs without ever writing anything original on them; they just copy posts from other blogs.

        And, inexplicably, WordPress seems to have a feature that makes this easy, and leaves behind these annoying “reblogged” comments in the blogs being plagiarized.

        • candyliz2003
          Posted July 29, 2012 at 7:09 pm | Permalink

          Thank you, again.
          Seems you’re pretty handy to have around. :D

  12. Posted July 30, 2012 at 5:07 am | Permalink

    candyliz2003 and Gregory Kusnick

    Plagiarism is using someone else’s work and presenting it as one’s own, instead of properly documenting its source.

    As you will see, if you go to emmageraln, the blog owner always gives proper credit for the posts she reblogs.

    • Gregory Kusnick
      Posted July 30, 2012 at 8:41 am | Permalink

      Fair enough; “plagiarized” was hyperbolic and I withdraw it.

      I stand by “annoying” however.

  13. Posted July 30, 2012 at 5:20 am | Permalink

    @Unfortunately, its (“evolutionary psychology”) popularity—as measured in books and articles that give Darwinian explanations for everything from homosexuality to music—is not a sign of scientific rigor.

    There is or was “literary Darwinism,” which seems to have disappeared. It certainly is a way to ruin Jane Austen’s novels.

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