Tuesday, 16 February 2016

Prediction that creationists will crawl out of the woodwork

I predict (and have done so publically) that creationists will be particularly excited by an announcement that research on cockroaches in Australia indicate that evolution is (to an extent) predictable.  Of course I mean old universe, big-bang accepting creationists, not young earth creationists for whom this research might be less appealing.  I go further to suggest that this excitement on their part will be characterised by a deep lack of understanding as to how evolution works.

The research has looked at the genetics of a type of burrowing cockroach.  The ancient cockroaches that came to Australia about 20 million years ago had a similar diet to your average rural cockroach today (the German or American ones), they would forage on the forest floor among the fallen leaves.  The forest conditions would protect them from the sun.

As the rain forest retreated from Australia and the continent dried out, there was less protection from the sun and burrowing became a valuable strategy.  The processes of evolution resulted in speciation and we ended up with an Australian cockroach that burrows up to a metre below the surface.

What the research shows is that this speciation didn't happen just once, it happened maybe as many as nine times.  Now, the question is – what specific misunderstanding is a creationist going to bring to this issue?

I predict that it will be this, the notion that Dr Lo is talking about evolution happening multiple times from one species to one other species (which he isn't).

Think of this way, there is a rainforest cockroach and a dry scrub cockroach and only the latter must be able to burrow to survive.  Initially there is little or no scrub at all, so there is only the rainforest cockroach, then the rainforest retreats.  But the retreat isn't singular and total, it happens in stages, the rainforest retreats a bit, then a bit more and so on.

So, very roughly speaking, a rainforest cockroach can become a dry scrub cockroach.  Naively we might think that this is a once off and as the rainforest retreats the range of the dry scrub cockroach merely expands while the range of the rainforest cockroach contracts.  What Dr Lo is saying is that this is not necessarily the case.  The rainforest cockroaches living in an area which is becoming dry scrub can evolve into a dry scrub cockroach again.  Naively (again) this might be thought of as a repeat of the same evolution that has happened before, that the population of dry scrub cockroaches (DSC) can be increased in two ways: the normal way with DSC birth rate exceeding the DSC death rate die, and by rainforest cockroaches (RFCs) evolving into DSCs.

You can imagine a male DSC meeting a sexy new female DSC at the border between old scrub and newly ex-rainforest.  The male leaps into a standard chat-up routine: "Well, hello there gorgeous, I've not seen you around before!"  And she replies with: "Uh, hello, no you wouldn't have, I've just evolved."

Of course that's not how it works.  Dr Lo was not doing his research on one species of burrowing cockroach (the DSC) and one species of wood-feeding cockroach (the RFC).  His research involved 25 different species.

He's merely talking about how living things evolve to fill niches.  This phenomenon is well known and is highlighted by the similarity in body types between tenrecs on Madagasca and many other types of animals in the rest of the world.

Here's a tenrec:

And here's a hedgehog:

These two creatures fill the same niche and look quite similar, but they haven't merged into the same species.

In the same way, wood-feeding rainforest cockroaches may well have been put under evolutionary pressure multiple times and thus evolved strategies to survive the disappearance of their rainforest – and a clearly successful strategy is to burrow.  So there will be a range of species of burrowing cockroaches – those that evolved out of other burrowing cockroaches which had, at some time in the past, evolved out of rainforest cockroaches and those that evolved "directly" from rainforest cockroaches.  I write "directly" because a transitional process like evolution doesn't really have direct paths of evolution from one species to another, each individual in the process is its own path and species don't change in one generation.

So, basically, I think that some creationists are going to trip over what is in effect a category error.  Because we lump a whole bunch of species together as "burrowing cockroaches", they'll consider this to be an example of one species arising out of multiple speciation events – as if things were evolving according to some master plan.  People who understand evolutionary processes much better than me will try patiently to explain, but their explanations will fall on deaf ears and the creationists will unilaterally declare another victory.

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