“That innocent little word ‘to'”

It seems the editor-in-chief of the review journal BioEssays shares my concerns about using teleological language when discussing evolution. He calls it anthropomorphic rather than teleological, which is probably a better way of putting it – likely, the reason we think of evolution in teleological terms in the first place is because we do things for purposes, and we are biased to think of everything as if it had a human mind. The word “anthropomorphism”, I think, gets to the root of the problem.

In his short opinion piece “We need a new language for evolution… everywhere” (BioEssays 33:237), Andrew Moore discusses how language (including “that innocent little word”) can subtly lure scientist and layperson alike into this dangerous trap.

I especially like this bit:

Another concept that arises from the ‘anthropomorphisation’ of evolution is the ‘problem’: in other words, an organism or system evolves towards what we, retrospectively, identify as a barrier, or ‘problem’ that had to be ‘solved’, and we wonder how it was overcome. Nature doesn’t solve anything.

(It’s a point I’ve never quite articulated to myself, so these remarks were something of a lightbulb moment for me.)

Moore doesn’t just tear down the old language. He provides a table listing some common turns of phrase that give entirely the wrong impression – and offers alternatives that, for the most part, aren’t clumsy at all. (I’ve got to say, though, that calling the alternatives “new-speak” is a tad ironic in an article about using the wrong language, IMO.) Interestingly, one of his “replacements” still sounds teleological/anthropomorphic to me. Instead of “innovation of evolution”, he suggests using “product”, and my first thought upon hearing that word tends to involve factories. Just goes to show how difficult it is to get rid of deeply ingrained thought patterns.

Still, kudos to Moore. For bringing the problem to the fore, and for suggesting specific ways of solving it.

Pretty Reapers

Did you know proteins were beautiful?

Of course, many of them are just vaguely potato-shaped lumps of joined atoms. But when a few of these lumps get together, the most amazing shapes can emerge. Such as these:

Structural models of different forms in various views

What the molecule actually looks like

These are models of a fruit fly apoptosome, a huge multi-protein complex that plays a role in programmed cell death. (Programmed cell death, or apoptosis, is not as bad as it sounds. It’s used to remove damaged cells, to sculpt body parts during development, and other decidedly useful things.) The top image shows the structure of the apoptosome in the stylised language of molecular biology – spirals, ribbons, loops etc. indicate the way the protein is folded in that region. The bottom image gets closer to what the molecule would look like, although what the blue shapes represent – electron clouds – are kind of hard to picture in a realistic way. (The pictures are from Yuan et al. (2011) Structure of the Drosophila Apoptosome at 6.9 Å Resolution. Structure 19:128-140)

The folly of hindsight

Recently, I’ve been re-reading Life on a Young Planet. As I said before, it’s an excellent book. It is beautifully written, cleverly structured, and the author is obviously knowledgeable about the subject (which, sadly, isn’t always true in popular science). Most importantly, it emphasises the process of science, as opposed to the actual knowledge gained through that process. “How do we know what we know?” is a question at least as important to Andrew Knoll as “What do we know?” As he so eloquently puts it, “[t]extbooks may portray science as a codification of facts, but it is really a disciplined way of asking about the unknown.” This is an attitude I share with him, and probably a big part of the reason the book has such a special place in my heart.

So, I was surprised to discover on this re-read that Knoll falls into one of the most common traps of talking about evolution: teleological thinking. In Chapter 11, “Cambrian Redux”, he writes that “[f]orty million years after the Cambrian began, evolutionary way stations still played a major role in the ecology of marine environments.” He is discussing the Cambrian explosion, of course, and here he is talking about stem groups of living phyla living alongside the crown groups [1]. I don’t think he means to convey a sense of goal-orientation, but the wording does exactly that. It sounds as if, say, Anomalocaris was just something evolution had to pass through to get to arthropods, not a successful animal in its own right. It suggests that the eventual supplanting of these now-extinct lineages was meant to happen.

Richard Dawkins called this “the conceit of hindsight” and complained about it at length in the introduction to his (also really good) book The Ancestor’s Tale. Dawkins characterises such thinking as “seeing the past as aimed at our own time, as though the characters in history’s play had nothing better to do with their time than foreshadow us.” (In this particular case, he’s talking about ordinary history, as a prelude to introducing the same problem in evolutionary history.) It’s a very common way of thinking about evolution (just look at any of the traditionalmarch of progressimages), and it’s also totally wrong.

If you’ve been in prolonged contact with creationists, you’ve almost certainly encountered conspicuous examples of this common misconception. Types of questions I’ve personally seen include “what use is half a wing/[insert transitional feature here]?”, “why didn’t all X evolve into Y?”, and “how did X know they were evolving into Y?” At the heart of each lurks the idea that evolution works towards goals. That it doesn’t seems to be one of the most difficult aspects of evolutionary theory to grasp, and it’s especially hard to escape when we are looking at the past.

Simply put, evolution has no foresight. Rather than working towards something, the process always reacts to something. Rather than looking ahead, it constantly lives in the present, though it’s often saddled with the baggage of the past. The kinds of things that cause mutation (such as replication errors, radiation and chemical damage) have random effects [2]. Moreover, the processes that sort among mutations, such as natural selection, are similarly blind. Because the mechanisms of evolution are not thinking entities, the only traits that get passed on are traits that help their owners reproduce in the here and now. Any long-term trend is the outcome of repeated rounds of selection on the same traits. Evolution has no goal in the same way a snowflake doesn’t aim for your nose, though in retrospect you can perhaps reconstruct the path it took to get there.

That’s the problem with history: we are looking back on processes whose outcomes we already know. It’s so tempting to view the preceding events as mere stages in a journey aimed at those outcomes. After all, we humans work with goals in mind all the time (ironically, nowadays we might use evolutionary principles to attain those goals!). Unfortunately, viewing evolution in this way can lose sight of the process by focusing on the endpoint – and then people start asking about half wings.

It’s important to remember that the ancestor of the wing was not “half a wing”. It was just a modified arm that had some advantage over its ancestor, e.g. large feathers to help a dinosaur keep her eggs warm, or (closer to “wingness”) glide from tree to tree. These animals weren’t half-functional fliers, they were fully functional at whatever they were doing. If an alien scientist looked around in a Middle Jurassic forest, it might have marvelled at the exquisite gliding adaptations of small dinosaurs much like Microraptor [3], but it surely wouldn’t have focused on how bad they were at flying.

(Also, always remember that when you are the only one who can do something, by definition you’re the best at it!)

I wish we could just drop the teleological language altogether. It’s surprisingly difficult even when you actively try, though. It could be something about the way language works (at least the two I know well). Somehow, it seems much easier to say things like “X evolved to do Y” in them than to give a more accurate description of the evolutionary process. I’m sure that says something profound about human minds…


[1] In systematic jargon, a crown group is the last common ancestor of all living members of a group, and all of its descendants (including extinct ones). The corresponding stem group (stem groups are always relative to a crown) includes anything extinct that’s more closely related to the crown group in question than to any other living lineage. For example, all non-avian dinosaurs were stem birds.

[2] We have to be precise about the meaning of “random” here. Some mutagens cause very specific mutations. “Random” refers to their fitness effects, not the chemical changes that happen or even the places where they happen (though the latter is largely random, except for trivial constraints). The same mutation in different parts of the genome can be beneficial, harmful or have no effect at all, and conversely, the same is true for different mutations at the same spot – and all of this is uncontrollable. If you keep your study organisms in a hot environment, they won’t suddenly start producing more mutations that make them heat-resistant. That’s the main thing we mean when we say mutations are random.

[3] Microraptor itself is Early Cretaceous – birds were already around when these guys inhabited the forests of China. The first part of the Jurassic – i.e. the time between early dinosaurs and Archaeopteryx – doesn’t have a great record of dinosaur fossils, so most of what we know of the origin of birds comes from relatives of birds that persisted alongside birds later on. However, a few very bird-like fossils are contemporaneous with, or older than, Archaeopteryx. Like Microraptor, some of these creatures have long leg feathers (unlike Microraptor‘s, theirs aren’t very aerodynamic) , so that may be something ancestral for the “birdy” lineage.