I’ve read Steve Jones’ books and enjoyed them — so I’m really baffled by this bizarre report of a talk he gave. It’s either a massive example of misreporting, or Jones has a solid grip on everyone’s ankles and he’s straining to pull our legs right off.

He claims human evolution is over. The reason? Because not enough fathers over 35 are having children. That’s bad because mutations are the source of evolutionary novelty, and older fathers are more likely to have accumulated errors in the replication of sperm, and therefore pass on more mutations.

This is because cell divisions in males increase with age. “Every time there is a cell division, there is a chance of a mistake, a mutation, an error,” he said. “For a 29-year old father [the mean age of reproduction in the West] there are around 300 divisions between the sperm that made him and the one he passes on – each one with an opportunity to make mistakes.

“For a 50-year-old father, the figure is well over a thousand. A drop in the number of older fathers will thus have a major effect on the rate of mutation.”

This is true, but it makes no sense. It’s not as if younger fathers produce no mutations — they generate plenty. It’s a difference in degree, nothing more, so we still have plenty of new mutations percolating into the population. And of course, over most of human history parents have been relatively young, since you couldn’t count on living to the age of 35.

And then there’s this odd argument.

Another factor is the weakening of natural selection. “In ancient times half our children would have died by the age of 20. Now, in the Western world, 98 per cent of them are surviving to 21.”

That makes even less sense. Natural selection is going to eliminate variants; by reducing its effects, we permit more mutations to persist in the population. One moment he’s complaining that fewer mutations are being produced, the next he’s complaining that the mutants are thriving. Which is it?

I’m thinking Jones must be making some colossal joke here, or maybe he’s testing his audience to see how much illogic and absurdity they will accept. That’s the only way I can explain these strange claims.

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I see that Larry Moran has just thrown up his hands in exasperation at all the errors.

There is good cause to be aggravated by some of James Watson’s recently expressed views, but he’s still an interesting fellow who made a significant contribution to our understanding of biology; and E.O. Wilson, of course, is always cool. So here they are together in an interview with Charlie Rose, discussing the significance of Charles Darwin:

(It was a little too gushy at the beginning — Darwin certainly did get some things very wrong! — but it’s still the kind of conversation it’s fun to hear.)

Last weekend’s bloggingheads was an interesting discussion between John Horgan and Brian Ferguson on the unfortunate misconception many people have about human evolution — the simplistic idea that evolution is always about selection for individuals who are better at killing their competitors. It doesn’t work that way! Ferguson discusses the interesting and obvious idea that the data does not back up the notion that being a great warrior is generally a good strategy, because being a great warrior also greatly increases the likelihood that you’ll end up dead.

Evolution is about whatever works, and often cooperation is a winning tactic.

Tony Sidaway discusses a unifying property of theistic evolutionists: the desire or need for there to be some kind of universal plan for their existence. It’s not an attitude I understand very well; I don’t think it makes life better to believe that there is some ineffable teleological intent behind the events in your life, and no one ever bothers to explain why it would be preferable to be a pawn to a cosmic puppetmaster. Their reasoning also tends to be incredibly bad, as can be seen in the article by Mark Vernon that inspired Tony’s musings.

The work of Conway Morris, and now many others, is showing that evolution keeps coming up with the same solutions to natural problems. One of the better-known examples is that sabre-toothed cats. They evolved on at least three different occasions along independent Darwinian paths. And yet they look almost exactly the same. Dozens of examples of convergence have now been documented across a wide variety of biological phenomena, from animal and plant physiology to molecular biology.

Convergence raises the possibility of directionality in evolution. This is anathema to the old school. Strictly speaking, even to talk of adaptations being advantageous is to risk a false sense of teleology. The sense of “advantage” only comes because we have hindsight. As Stephen Jay Gould put it: according to this interpretation of evolution, if you re-ran the “tape of life”, life would look very different.

Convergence challenges this, because in a way, evolution has already re-run the tape of life several times, and it looks strikingly similar.

The argument from convergence is wrong and makes no sense, yet somehow it appeals to smart people like Simon Conway Morris and Ken Miller, who have both made it themes in their books. Convergence occurs, of course, but “dozens of examples” is not very impressive and does not imply that this is a dominant mode of evolution. The examples also exhibit the constraints of contingency; yes, several mammals have evolved saber teeth, which seem to be tools for a particular kind of predation that involves deep tearing to induce bleeding in prey. If we get away from mammals, though, it doesn’t appear very often, if at all. Raptors, for instance, probably used an overdeveloped claw in the same way. Convergence is often a consequence of limitations in anatomy and physiology that make a narrower range of solutions to common problems available.

Another good example is the eye. Eyes have independently evolved multiple times, and we do see examples of convergence — molluscs and vertebrates have simple camera eyes that are not related by ancestry. It’s not because of some master plan, however, but because using a lens to focus light on a sheet of photoreceptive cells is a simple, easily evolved strategy for putting an image on a neuronal array. This is a case where physics itself imposes some limitations on how a receptor organ can function. At the same time, though, life explores a wider set of solutions than we can imagine. Mollusc and vertebrate eyes differ in all the details of their development and anatomy, and obviously enough, other organisms, such as arthropods, have put together radically different solutions with compound eyes. Did a god have a plan that involved eyes forming as orbs with single lenses? Why? And does that make dragonflies satanic, for defying the plan?

Vernon is also completely wrong. The tape of life has not been replayed, except in a small scale and with historical limitations. You could argue, I suppose, that the Permian and Cretaceous extinctions represented a catastrophic rewinding of life’s tape for large terrestrial animals, but do note that each produced different solutions. Dinosaurs became ascendant (in a megafauna sense) after the Permian, but very different vertebrates took over after the Cretaceous.

It’s all very peculiar. This particular breed of teleologist seizes upon small functional similarities in organisms, tooth size or body shape or color pattern, and declares that because two species independently generate similar solutions to common problems, it must be because there is a guiding force producing these solutions. They want the guiding force to be a deity, but unfortunately, Darwin long ago identified the force as short-term local adaptation to environmental forces, nothing more, no grand planner, no deep purpose, and these instances of convergence provide no evidence otherwise.

There must be some psychological need in the teleologists that I lack. I don’t feel any a priori requirement that complexity and adaptation and similar solutions must be driven by any kind of master blueprint, and I find any kind of deterministic explanation for earth’s history to be personally horrifying (not that that is an obstacle to such explanations being true, but it does confuse me that some people think such an answer to be desirable).

We are each our own individual engines of purpose, operating in a hostile universe where randomness can shape our fates. There is no grand scheme behind our existence, other than the same function that all our ancestors had: to order our local environment to allow each to survive and to make the world a little better for our progeny. And that’s enough — that’s all that is needed to make a rich, diverse, living planet, and it’s all I need to live a satisfying life.

Another bit of distortion from Ray Comfort: he claims now that I was asked to present the very best evidence for evolution, and that all I could come up with was some “little infolding of the gut”. If you’ve come here from Comfort’s ignorance zone, here are the details of the evolution of lizards of the genus Podarcis.

What Comfort cannot comprehend is that there is no one absolute make-or-break piece of evidence for evolution — evolution is a conclusion from the totality of the evidence. There are thousands of cases that demonstrate that the principles of evolution work and are useful for understanding the natural world; there are no cases where creationism has improved our understanding.