Rubisco and the tendency towards perfection

The effects of scala naturae in the way we think about the evolutionary process are profound and harmful. As a shameful example, it comes to my mind the ludicrous concept that “man came from monkey”. No evolutionary biologist would assert such a thing, neither using the strict and monophyletic sense of the word “monkey” (only the old world monkeys) nor in its most broad, paraphyletic and incorrect sense (all primates but man). Using the word “monkey” in its strict sense, I always like to say to my students that man did not come from monkey, and that the reverse is also incorrect, i. e., monkey did not come from man: we can only say that man and monkey share a common ancestor. Continue reading

Selection and cultural transmission

When I was about to conclude the chapter on selection of my book I came across a problem of definition I’ve never thought about before. Almost without planning, leaving the ideas flow freely to the paper (actually, to the hard disc), I had begun to write about a defensive behaviour found in certain African elephants (which I’ll describe in detail below), when I found myself between a rock and a hard place: how to correlate the concept of cultural transmission to the concept of selection currently used by the vast majority of evolutionary biologists? The rock would be deleting all paragraphs regarding cultural transmission; the hard place would be changing the definition until they fit my needs, something a science writer should refrain from (freely) doing. Continue reading

Gene fossilization and cavefish

When I started teaching biology, and that was a long time ago, I didn’t know most of what I know today about the theoretical framework of evolutionary biology, and I was not properly prepared for a lot of questions from students. Mea culpa. That unpreparedness led me to take certain paths in the classroom that, today, certainly I wouldn’t. The theme of this short post is exactly an example of this. Continue reading

Can you really get in the way of evolution?

A few years ago, I was talking with a friend of mine about stranding of cetaceans. It’s been a long time since I stop to research on this subject, which has interested me a lot when I started to study biology, and so I’m not aware of the further developments and the latest favoured hypothesis about this phenomenon. I remember, however, having read that the amount of worms found in many of the stranded dolphins and whales was higher than normal for those particular species. Regardless of whether this parasitic infection was cause or consequence of organic changes leading to stranding, one of the assumptions at the time was that the large amount of worms in some way would interfere with animals’ orientation, which ends up stranding. I said that to my friend, and her answer is the reason I’m writing this post. She said “but if we rescue and save these stranded dolphins, won’t we be preserving animals genetically susceptible to worms, which will thus propagate their bad genes? I mean, by saving these animals, are not we getting in the way of evolution, since these animals would necessarily die?” Continue reading

What does evolutionary trend mean?

The subtitle of this blog is no foresight, no way back. For those who don’t know it, this quote if from the famous British biologist Maynard Smith. I think it’s time for explaining a little better what this phrase means, because it is an essential introduction to the subject being treated in this very post: biological evolution is not teleological, i. e., no evolutionary changes occur aiming an ultimate end, or a predetermined destination whatsoever. Evolutionary changes occur, that’s it. And sometimes not even that: changes themselves are not a natural need, that is, a population can be maintained for an indefinite period of time without major evolutionary changes, even if the environmental conditions have been modified in this period. Evolution can occur: it is not, however, an obligation. Continue reading

A non-existent antagonism

The original text of the 1st edition (1859) says:

From the facts alluded to in the first chapter, I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts, and disuse diminishes them; and that such modifications are inherited. Under free nature, we can have no standard of comparison, by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals have structures which can be explained by the effects of disuse.

The excerpt, as you can easily see by the publication date, is from Charles Darwin, not from Jean Baptiste de Monet (aka Chevalier de Lamarck). Continue reading