i get mail…

… well, at least, the newspaper does. Last week, on the 200th anniversary of Darwin’s birthday, our local paper’s Science & Technology page ran a story about Darwin & about evolution. (It was written by David Riddell, one our excellent local free-lance science journalists, & was based on an interview with yours truly (blush). I’d link to it except I can’t find it on the paper’s website…)

Anyway, I subsequently looked forward with considerable interest to the ‘letters’ column in the evening paper. Last time the paper ran an evolution story I got called all sorts of things – ‘delusional’ among them. I’m always a little amused – & bemused – how, when something stirs people up, they often go for the person & not the idea that they dislike.

But back to the paper…

It seems that, while  the advancement of science is wonderful, evolutionary ideas and Charles Darwin have only indirectly helped the cause. Yes, experimentation to falsify a theory is good science, but not when false conclusions are reached.

Evolution is said to be driven by natural selection & mutations ovr millions of years to produce ever more complex life from an original single cell. But all the experimentation has only shown variation within groups, & never a mollusc-to-man type of evolution.

There’s a problem with that statement, & it hinges partly on a mischaracterisation of evolution & partly on the conflation of things operating at two different timescales. Evolution usually does take a long time. (One of the difficulties in teaching about it lies in the problems we have with visualising just how long that time is. ‘Deep time’ can be a hard concept to grasp.) Even ‘punctuated equilibrium’ – long periods of stasis punctuated by bursts of evolutionary change – is rapid only on the geological timescale. That’s not to say that you can’t get rapid evolution: plant speciation as the result of polyploidy can be a fast process.

But evolutionary biologists have been experimenting for only a hundred years or so. (For plant & animal breeders it’s longer, dating back to around the birth of agriculture.) Those 10 decades are far too little time to see the sort of change the letter-writer seems to want.  But we most certainly do have hard evidence of the evolutoin of different ‘groups’ – think of the appearance of amphibians, for example, or mammals, or hominins. (The ‘mollusc-to-man’ bit is a straw-man argument: suggesting that’s what evolutionary biologists say in order to then pull it apart.)

Natural selection & mutation never produce an increase in information & almost always information is lost.

This is a common – & erroneous – creationist claim. Mutations are simply changes in the DNA sequence. They can change the information carried by that sequence – for good or ill, or to no effect whatsoever. Some mutations can result in duplications of a gene, or a whole chromosome – I would have thought this would represent an increase in ‘information’? Anyway, once a gene’s duplicated, as long as one copy remains functional the other can accumulate further mutations without necessarily impacting on the organism’s survival. That mutant form may have a selective advantage at some future point in time. It’s likely that the range of human haemoglobins (the adult & foetal forms, and myoglobin, for example) arose in this way.

In the interview I talked a bit about the in-body evolution of populations of cancer cells. As I said in an earlier post, chemotherapeutic drugs act as strong selection agents: those tumour cells with some degree of resistance to the drugs survive & reproduce, & eventually the drug becomes useless because the cell line has evolved resistance. The paper’s correspondent comments, however, that the resistance either already existed in some cells or mutations have only altered information by error, but never has information been added. The cancer cells would probably disagree (if they could). If the ability to metabolise the cancer drug, or resist it in some other way, arises in a cell line through mutation, then that is definitely novel information. Carl Zimmer talks about a great example of this, describing the experiment by Richard Lenski & his research team that demonstrated the evolution of a citrate-metabolising gene in a population of E.coli.

And finally, the genetic variation between groups of species is so great that it can be shown that evolution is just mathematically impossible even if a mutation added information. Huh?  It’s the similarlities in gene sequences that show us how living things are interrelated! At the level of deep homologies, the basic body forms of flies & humans are controlled by similar ‘homeotic’ genes. The base sequences of mouse genes & human genes are about 85% the same. It’s been said that we share 60% of our DNA sequence with bananas…

I must go & write my letter to the editor 😉


3 thoughts on “i get mail…”

  • I have often wondered if part of the “mutations can only lose information” “error” on the part of creationists lies with a mixing word meanings, playing on the “popular” meaning of a word in the same way that ‘theory’ is often misused by creationists too.
    “Mutants” are constantly seen as negative in science fiction movies, etc., giving them a negative meaning to the general public. So, while meaningless in terms of science, “mutants are negative” has a resonance to the general public perhaps? What do others think?
    As you say, “mutations” should be read as “change”, without any loaded meaning.
    The silly thing is that even the movie “mutants” are often better adapted than their “normal” counterparts, often as horribly effective predators! And they often have very obvious new processes.
    I think you last point is worth putting in newspaper letters, etc., as it a “factoid” that’s probably not as widely known as it ought to be. You and I know that you can see very obvious similarities in genes across huge gaps in evolutionary time.

  • (i tried this yesterday, but perhaps the internet ate my comment. Sorry if it’s a repeat)
    I thought you might be amused to learn that Darwin really did think humans evolved from molluscs. Erasmus Darwin actually thought everything evolved as a result of specialisation of the simple molluscan form. He went so far as to have a crest made up witht the motto E Conchis Omnia – From shells, everything. His grandson’s evolutionary thinking was rather more grounded in evidence…

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