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Evolution triumphs over photosynthesis

In general, I don't want to waste time responding to tired old creationist criticisms of evolutionary theory that have already been refuted elsewhere (such as here or here) -- criticisms backed by new data would be another story -- but I do need to address one issue that could undermine my ability to find a paper to discuss each week. Some creationists have suggested that scientists are increasingly rejecting evolution. Actually they've been saying this for a long time. Is my paper pipeline drying up?

As a scientist, my own impression is rather different. The main change I've seen over the last 20 years has been an increase, not in the percent of research biologists who accept the basic principles of evolution (never quite 100%), but rather in the percent of research that explicitly uses those principles in trying to understand life on earth, past and present. In other words, rather than just asking "how does photosynthesis work?", more scientists are now asking questions such as "how many times did this type of photosynthesis evolve, when, how, and why?"

But personal impressions can be misleading, so I went looking for data. I searched Science Citation Index for papers with "evolution" in the title or abstract. That gave a lot of papers on evolution of stars, etc., so I limited the search to papers that had both "evolution" and "species." This leaves out a lot of evolution papers -- for example, some medical researchers are more likely to report the "emergence" of antibiotic resistance (from a hole in the ground, presumably) -- but I'm mainly looking for trends over years. What I found was more than a 100X increase in evolution papers per week, between 1975 and 2005.

Could this just reflect an overall increase in biological research over this period, or maybe an increase in the availability of computer-searchable abstracts? To test these hypotheses, I used papers with "photosynthesis" as a control. Photosynthesis papers increased also, consistent with an overall growth in research, but much less than evolution papers did. Photosynthesis papers outnumbered evolution papers 20:1 in 1975, but by 2005 evolution papers outnumbered photosynthesis papers by more than 2:1. So the scientific importance of evolution is increasing relative to photosynthesis, but both are very active areas of research. I'll have plenty of papers to choose from.


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Well, you know, photosynthesis is just a theory.


Part of the problem is a redefinition of the word "photosynthesis." It used to include carbon fixation (Calvin cycle) but today the definition of "photosynthesis" has been restricted to the electron transfer reactions that yield NADPH and the proton gradient.

This is a good thing, since carbohydrate synthesis is not coupled in any way to the light reactions except for the fact that the products of photosynthesis (ATP and NADPH) are used in the Calvin cycle.

I'm not sure what fraction of people who might use "photosynthesis" in an abstract know about this change. Do you want to try repeating my analysis with some other term as an internal control? Respiration, maybe?

I wonder if I might not look for poorly used words in the title of my next paper: this may yield more cites since the manuscript will be competing with fewer others...

I'm not sure if you're implying "evolution" or "photosynthesis" is poorly used, but you're right that titles are important. Years ago, someone partially duplicated work that I had done and failed to cite me, even though my paper had been in a journal where he regularly published. When I complained, he pointed out that the title of my paper didn't reflect the contents very well, and he was right.

Oops, with "poorly used", I meant 'not often used' and was certainly not implying anything wrong from authors or people using photosynthesis or evolution in titles... Best is to read "rarely used" or "barely used" instead. The point is that in choosing more carefully words in titles, this may make papers more apparent in the huge body of science literature... (i.e. the title should both fit the content of the paper and increase its fitness in the pool of manuscripts).

Well, that's also pointing out how difficult wording choice could be, considering English is not the mother tongue for many scientists.

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