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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