About Rationally Speaking

Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Sunday, August 27, 2006

Rapid evolution, even if you don't believe it

I'm often asked how come we can't show evolution happening right now, we always have to rely on historical records for which, you know, “nobody was there to see it.” Well, a recent study by Aaren Freeman and James Byers at the University of New Hampshire, published in Science (11 August 2006) demonstrates how quickly evolution can occur.

Freeman and Byers studied the invasion of the Asian shore crab along the northeast coast, and the response by one of its prey species, the blue mussel. Observations in the field had shown that blue mussels growing in the presence of the predator develop thicker shells, which protect them from the crab's attack. If the crab is not around, the mussel doesn't increase the thickness of its shell, presumably because it would be wasting energy that could be channeled into other directions, like reproduction (this sort of condition-dependent response is called phenotypic plasticity, and I have devoted most of my scientific career to studying it).

Since the shore crab is new to the northeast, how quickly did the blue mussel evolve its ability to respond to the invader? Less than ten years. The crab had been initially documented in New Jersey around 1988, and has since spread to most, but not all, the coastline between North Carolina and Maine. Freeman and Byers therefore sampled mussels from areas where the crab had already arrived and from locations were the invader had still not made an appearance. Sure enough, only the mussels taken from the invaded coastline were capable of the adaptively plastic response, which therefore has to have evolved in less than a decade.

Ah, yes, I can already hear the classic creationist remark: “but it's still a mussel, isn't it? I mean it hasn't turned into another species, like, say, a whale, or a banana.” That sort of statement shows such a profound ignorance of both science in general and evolutionary theory in particular that it would be laughable – if it didn't come from adult individuals with the aim and possibly the power of plunging our country's public education back into the Middle Ages.

You see, most evolution is just like the example of the blue mussel and the shore crab: day to day struggle for survival, where small but significant changes make all the difference for the protagonists involved. Just like mountains form by small incremental movements of the earth's surface, so major differences between species emerge over long periods of time. Too long, apparently, to be contemplated by small minds whose horizon is limited to the 6,000 years or so allowed by the Bible.


  1. Great article, Max, but I can hear the creationist objection now: it's just "micro-evolution" (as you observe, they want "non-dogs to come from dogs"). These people will never learn.

  2. Even today new species are being born and documented.


    While most new species comes from selective breeding, the more unusual path is inter-species breeding. One prime example is Man's creation of the poor mule. Crossing a horse and a donkey produces a superior "beast of burden" that is usually sterile.

    While true that dogs don't come from non-dogs, dogs did come from dog-like creatures that evolved from simpler forms of life over the life of this planet. Just as a mule is different and distinct from either of it's parents, it is produced from those parents.

    As for the mussels. I have to wonder if that genetic feature was already part of the species that is re-asserting itself, just as humans who live and work in the sun get a darker skin, does living with this predator thicken the shell?

  3. It's not even just the narrow biblical time-frame of 6,000 years that anti-evolutionists are stuck in, but the even narrower space of a human lifetime. The major chages that are wrought by evolution (such as birds from dinosaurs, or fish becoming air-breathing land creatures) take many hundreds or thousands of years, as we all know--rendering creationists' complaints of lack of first-hand human observation a lame strawman argument.

    The ironic thing is, speciation that can and does occur withing a time-frame comparable to a human lifetime are dismissed by creationists as "microevolution"--an artificial distinction only creationists make. The bottom line is that creationists set up their own definitions as to what constitutes evolution (definitions that reflect their lack of scientific understanding), and then set impossible standards of proof which only proves (in their fevered imaginations) that evolution is bogus.

    This reminds me of something I was reading in Answers in Genesis (gotta keep up with what the enemy's up to). A writer was pointing out how a creationist should debate a scientist about evolution. First off, this writer says, is to never ever let a scientist set the terms for a scientific debate. (Translation: Let your ignorance be your guide.)

  4. http://www.greenapple.com/~jorp/amzanim/crossesa.htm

    isn't working for me Eric. I want to check out that page; can you please verify and repost the URL? Thanks.

  5. Bananas won't evolve into anything, because they are perfect just the way they are!

    http://www.youtube.com/watch?v=Y4yBvvGi_2A ... video of some ID scientists explaining.

  6. Here's another Creationist argument, God is just trying to trick us to test our faith.


  8. My father was a preacher and on the side of his notes he used write'weak point,shout' You don't have to shout annonymous except if your point is weak.

  9. Nice article dude. Hate to break it to you but your rapid evolution idea is simply called "adaptation." The genes for this phenotypic plasticity were pre-existing, and were merely selected for in the crab's new environment.
    This is plainly a variation of a phenotypic character.
    Ya i realize im just a mindless creationist in your eyes. However, i'm three days away from obtaining a bachelors of sience in biology (and a minor in chem) so i dont consider myself to be "profoundly ignorant" in the realm of biology.
    Im not here to endlessly argue about this issue, but i would like to pose a few questions:
    what is energy, time, life, death? How are they imparted on lifeless matter?
    what came first: the DNA that codes for the protein or the protein that makes up the DNA?....the enzymes produced by life or the enzymes without which there can be no life?
    These are conundrums that cannot be explained by any mindless, purposeless, and gradual process. Rather, an intelligent designer is irrefutably required to attest for these ever present phenomena.

    Science, while of utmost importance and relevance, has the ability to deal only with the "how" and is simply out of its element when attempting to explain the "why." Science needs to realize its limitations and accept them.

  10. Caleb,

    the combination of characteristics that I find astounding among creationists are perfectly displayed by your post: ignorance, cockiness, and irrationality. In order:

    a) Ignorance: phenotypic plasticity is a genetically-based phenomenon, and adaptation requires both genetic change and natural selection. I should know, my professional career is about studying plasticity.

    b) Cockiness: you may be about to get a BS in biology, but are you so confident that that is sufficient background to brazenly go up against a professional biologist with two PhD's in the field and 25 years of experience? Really?

    c) Irrationality: what on earth do your questions on DNA, energy and so forth have to do with the article on which you were allegedly commenting?

    Yes, you are indeed, and unfortunately, yet another "mindless creationist."


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