Nature Other

Evolution, ID, Carl Zimmer, monkey-men and suchlike. Again.

I’ve just added The Loom to the linkroll. The Loom is the blog of Carl Zimmer, who wrote the excellent and rivetingly eye-opening Parasite Rex, as well as the excellent but marginally less riveting At the Water’s Edge. They’re both worth reading, but the parasite one would be my recommendation just because the subject matter is that bit more unusual. Anyway, I was reading a long discussion in the comments about how to sell evolution to the public, and it reminded me a of a point I’ve been meaning to make for a while.

The ID movement’s current Big Idea is a rather technical attack on the mechanism of natural selection. It looks good because they appear to be engaging with biologists on their own ground, rather than relying on appeals to scripture. On the other hand, the point which seems to have the most visceral appeal to the public is the question “do you believe that you are descended from an ape?”

But there are two questions here. The idea of ‘evolution’ – that all form of life on earth share common ancestors, that Ivory-billed Woodpeckers are similar to Pileated Woodpeckers because they are actually related to each other, and yes, that we are descended from apes – is independent of natural selection. There were evolutionists before Darwin. And the weight of evidence for evolution is overwhelming.

An analogy: Newton said that a dropped apple falls to the ground because all objects are attracted to each other by gravity in proportion to their mass. Whether that’s true or not, the apple still falls. Someone who rejected Newtonian mechanics would not therefore expect apples to float in midair; apples definitely fall, and the only question is why.

Even if IDists have found a fatal flaw in natural selection*, it doesn’t make any of the evidence for evolution disappear. We are definitely descended from apes (and reptiles and fish and little wormy things). Natural selection is by far the best explanation we have for how it happened, but the evidence for evolution is now so strong that if natural selection was disproved, we would need another evolutionary explanation to replace it.

*they haven’t

Nature Other

Vatican Starman Slams ID!

“The Vatican’s chief astronomer said on Friday that Intelligent Design Theory isn’t science and doesn’t belong in science classrooms.”

The ‘Vatican’s chief astronomer’? I wonder if CERN has a head priest who can be consulted for a theological perspective on particle physics.

I don’t suppose the Vatican astronomer is empowered to define the Catholic Church’s theological stance on all scientific issues, even though he *is* an astronomer. So why is this news? Because the media prefer a story with an obvious hook, however fundamentally pointless, to a subtle but informative one.

The link came from Claudia.

Culture Nature

‘The Mating Mind’ by Geoffrey Miller

I’ve just read The Mating Mind: How Sexual Choice Shaped Human Nature by Geoffrey Miller. The book’s argument is that many of the typical characteristics of human behaviour are best understood as products of sexual selection. Sexual selection is the process where you start with some ancestral bird species where the females have a bit of a thing for longer tails, and a few thousand generations later, they’ve evolved into peacocks. I suppose there are two key insights I’d take from the book, neither of them completely new to me but worth being reminded of.

The first is this – it’s easy to think of natural selection as being driven by adaptations for survival, with sexual selection being almost cosmetic in its effects. It doesn’t matter how good-looking you are if you starve, die of disease or get eaten by a lion before you get a chance to breed. But from an evolutionary perspective, there’s no point in living to a ripe old age if you can’t attract any sexual partners. Both scenarios are evolutionary dead-ends. Also, selection is not necessarily an either-or process (either you survive or you don’t; either you breed or you don’t). Rather, it’s driven by differential rates of reproductive success. And within a well-established species, it’s easy to see how the biggest single factor in determining reproductive succcess will often be the ability to attract a mate. The results of sexual selection will often appear cosmetic – coloured feathers, or an attractive song – but that’s just because those are the things a potential mate is able to perceive. It doesn’t mean that sexual selection is a less powerful force than ‘normal’ natural selection. In a sense, this is an obvious insight; anyone who has ever heard a nightingale or a blackbird singing must be aware of how much effort it is costing them, and there are few more spectacular adaptations than the plumage of a bird of paradise. And just because sexual selection mainly operates on external features, it doesn’t mean that it is limited to those features. Applied to humans, it doesn’t have to be limited to skin colour, breast size and hip-waist ratios. There’s no reason why it can’t also operate on people’s ability to hold a conversation, or dance, or sing. The only requirement is that there must be some genetic component.

The other insight is that anywhere in nature where we see an oganism with a physical feature or behaviour that doesn’t seem to have any survival benefit, it’s worth considering sexual selection as the explanation. Natural selection is inherently thrifty – we should never expect to see energy being expended without there being some reason for it. If that reason isn’t survival, pretty much the only other possibility is an attempt to attract mates, either directly or via increased status. And sexual selection can take almost any form. There are reasons why some adaptations are more likely than others, but the process is essentially arbitrary; once some trait becomes associated with sexual attractiveness, it’s a self-sustaining trend. The explanation is almost too powerful – you can see how it would become a lazy assumption faced with anything slightly unexpected, but as far as I can see, it’s very difficult to disprove. Geoffrey Miller certainly sees sexual selection everywhere – he uses it to explain sport, art, poetry, music, language, dancing and indeed just about everything that makes us human.

I find this argument moderately persuasive, I must admit. As ever, there are questions about which human behaviours can really be seen as written into our genes; can music making really be seen as an evolved trait? Or sport? They seem to be human universals, so it’s not a ridiculous idea, but I’m still slightly wary about making the assumption. But for more obviously evolved traits, like language, it seems very plausible that sexual selection would be the principle driving force.

On the whole, though, I found the parts of the book about human behaviour less interesting than those about sexual selection generally. I’ve read about sexual selection before but to have it treated in depth as a subject in its own right was helpful. For example, the classic examples used to illustrate sexual selection involve dramatic sexual dimorphism, as with the drably-plumaged peahen, or the difference in size between male and female elephant seals. But Miller points out that those are a special case where a few successful males account for the vast majority of offspring. Even in species which form largely faithful pairs, there is an advantage in being able to attract the best (healthiest, most fertile) mates. In that situation, the effects of sexual selection will be less dramatic, but will still be present. For example, in bird species where colourful plumage is found in both sexes, they have traditionally been referred to as ‘species markers’; Miller suggests that these could still be the results of sexual selection.

So I would have liked more of the book spent on sexual selection in general, with more illustrative examples from other species, and slightly less of the human stuff at the end. But it’s a good book, and I recommend it.

Culture Nature

‘The Ancestor’s Tale’ by Richard Dawkins

I’ve just read The Ancestor’s Tale by Richard Dawkins. The book traces back human descent to the earliest forms of life as a ‘pilgimage’, marking the points where other branches of our family tree ‘join’ us; the first rendezvous is with the chimps, then the other apes, then the rest of the primates and so on back to the simplest forms of life. At each rendezvous, Dawkins picks out one or two species from those who have joined, and tells their Tale, which is used to illustrate some point about natural selection – the Peacock’s Tale is used as an occasion to talk about sexual selection, for example. Some of these points are theoretical, others deal with practical issues like the difficulties of dating some of the points on the tree, or interpreting fossil evidence.

The approach allows him to touch on all sorts of different aspects of biology and build up an overview of evolutionary science, while also maintaining a kind of narrative structure. If you’ve read some of his other books, many of the preoccupations and some of the examples are familiar, but there are always enough surprising bits of information to keep you interested (in many plants, the thread-like roots are actually created by a symbiotic fungus). The family tree is interesting in itself; I was surprised to learn that we are more closely related to sea urchins than to snails and bees, for example. Or if that relationship is a bit distant: We are more closely to trout than trout are to sharks. That is, we share a common ancestor with trout which is more recent than the common ancestor of the trout and the shark. We and the trout both have bony skeletons; the shark is cartilaginous.

It’s a big fat book, and occasionally it drags a bit, but on the whole I found it absorbing and Dawkins’s prose is (nearly) clear as ever. So I’d recommend it.


teaching ID alongside natural selection

I do actually think there’s an argument for teaching about the idea of Intelligent Design alongside natural selection.

Or, to be more exact, in teaching natural selection in the context of ID.

That’s not because I think ID is a valid alternative to NS. It’s clearly not. On the contrary, school biology lessons ought to be teaching a very basic version of what biology is as a professional discipline, and natural selection is the unchallenged theoretical basis of academic biology, the context by which all data is understood.

So why teach about ID, if it’s a bad theory?

I found a lot of science teaching boring at school, even though I was generally interested in science and good at it (I could easily have ended up studying Maths or Chemistry at university instead of English Lit). I am still interested in science and still read a lot of popular science and science history. So why was it so dull at school? What you get from reading a biography of Darwin, which you don’t get from a typical school lesson on biology, is a sense of the interaction and development of ideas. At school you get taught the answers without being told what the questions were. Insights which brilliant men slaved over for decades are presented as though they were obvious and trivial, and all the excitement is drained out of the subject.

A non-biology example. Everyone knows the anecdote about Newton watching an apple fall and having the idea for gravity; but all they take from it is that Newton saw an apple fall and thought “there must be a force that makes apples fall”. But the *important* insight is: the force that makes the apple fall is the same as the force that keeps the Earth circling the sun. Not that long before Newton, people thought that the movement of bodies on the Earth needed to be understood completely differently to ‘superlunary’ bodies. Someone as brilliant as Gallileo tried to explain the movement of the planets in terms of an inherent tendency they had to move in circles, while a falling apple was being moved by a completely separate force. What Newton did was come up with four simple laws – the laws of motion and the inverse square law of gravitation – which taken together are enough to explain not just the orbits of the planets and the falling of an apple, but the movement of all objects. The entire universe becomes one system. As Pope put it,

Nature and Nature’s laws lay hid in night:
God said, “Let Newton be!” and all was light.

That kind of historical understanding of gravity is no use to an engineer, but for most people, who will leave school and never use physics again, it’s a lot more important than being able to calculate the speed of a falling body or the period of oscillation of a pendulum. I also think the historical context helps you learn the science, because knowing how the ideas developed helps you remember them.

In the case of biology, Intelligent Design was the reigning theory before Darwin. An intelligent designer is a good way to explain the complexity of living things. The reason that Darwinism is important is that it provides a materialist alternative to ID. That’s one reason why Richard Dawkins keeps harking back to creationism in his books – he recognises that it is the only competing theory for the complexity of life. A book like ‘The Blind Watchmaker’ is one long engagement with the idea of an intelligent designer because ID is the context which makes Darwinism important.

So, if I was trying to teach evolution, I’d be tempted to start with ID as the context before moving on to natural selection and pointing out all the things that NS (and evolution) can explain that ID doesn’t – like the fact we have an appendix, the way that animals tend to live in the same geographical areas as their relatives, that all mammals have the same bodyplan and so on.

Teaching ID as a viable alternative to natural selection, on the other hand, is completely insane.