Posted by: brian | January 28, 2009

Speaking of evolution

A couple of weeks ago I saw a piece on Discovery.com called “Fruit Flies Put Evolution in Reverse.” [Sidebar: OMDog, “Tiny Test Subject!” Mr. Tusks, come quick!] The article opens with this paragraph:

If you could put an animal in a time machine and send it back to live in the distant past, would its DNA evolve in reverse, returning to the genetic code of its ancestors?

The answer, unsurprisingly, is “No.”

Modern-day fruit flies are the distant descendants of an original group that had been harvested in the wild back in 1975.

Really? The entire species evolved from that particular group? You mean to say that fruit flies in the wild are extinct? Let me grab a couple of bananas & leave them on my counter for a week. I’ll get back to you.

This is horribly sloppy science writing, and, sadly, is not unusual for Discovery.com’s News section. My best guess is that they meant that all fruit flies used in genetic research are descended from that one group. Or maybe all fruit flies used for ALL scientific research? Is there no examination of the species in the wild?

Over the following decades, 500 generations of flies grew up in different environments.

Different groups of insects were starved, exposed to greater humidity and so on in various experiments, and as a result developed specific characteristics, molded by these conditions.

Classic Darwinian evolution.

Henrique Teotonio and colleagues put these various populations back into the ancestral environment and let them reproduce for another 50 generations.

They then took a close look at a telltale stretch of DNA, on Chromosome 3, to see whether “reverse evolution” had taken place.

The answer: Yes, it had, but only up to a point.

Did Mr. Teotonio and his colleagues put ALL of the existing fruit flies back into that ancestral environment? Or did they just use members of each population? Again, the writing is terribly weak here.

So, the fruit flies “reverse evolved.” What exactly does that mean?

Once the flies had adapted comfortably to their new environment, the backwards-winding clock of evolution came to a halt, according to their paper, published on Sunday in the journal Nature Genetics.

“Reverse evolution seems to stop when the populations of flies achieve adaptation to the ancestral environment, which may not coincide with the ancestral [genetic] state,” said Teotonio.

In other words, the flies evolved – regular evolution occured, wherein the flies adapted to their new environment. It may have been the same environment they lived in originally, but for these flies, 500 generations removed from that environment, it was a NEW environment, and they adapted to it.

They did not “reverse” evolve. That term doesn’t make any sense, and that a scientist would use it is sad, because it muddies the subject. Yes, it’s nice to use clever wording to get attention from others, but when that wording is misleading, science as a pursuit suffers.

Please, Mr. Teotonio, call it what it is. It’s evolution. Period. Not reverse evolution, not lateral evolution, not circular evolution, not tangential evolution. It’s just evolution.

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