Evolution of Darwin's Finches Caused by a Rare Climatic Event
Grant, B. Rosemary; Grant, Peter R.
Biological Sciences, Volume 251, Issue 1331, pp. 111-117 02/1993
Abstract:Populations of animals and plants often undergo conspicuous ecological changes when subjected to climatic extremes. Evolutionary changes may accompany them but are less easily detected. We show that Darwin's finches on a Galapagos island underwent two evolutionary changes after a severe El Nino event caused changes in their food supply. Small beak sizes were selectively favoured in one granivorous species when large seeds became scarce. The effects of selection were transmitted to the next generation as a result of high trait heritabilities. Hybridization between this species and two others resulted in gene exchange, but only after the El Nino when hybrid fitness was much enhanced under the altered feeding conditions. These observations imply that if global warming increases the frequency or severity of El Nino events on the Galapagos, microevolutionary changes in animal and plant populations are to be anticipated.
Now I suppose your wondering, what on earth does this have to do with diet and exercise? I am so glad you asked. I often hear from various sources that many of the problems associated with our health are due to the fact that we don't eat the way our paleolithic ancestors did. In conversation, I have been know to reply, "Darwin's Finches". This generally leads to a puzzled expression that might be similar to the one you had when you first read the above abstract and wondered where this is going. When reading/talking/hearing about the virtues of the paleo diet keep in mind that in less time then it has taken human beings to develop agriculture, dairying, and to figure out how to make beer, the finches have colonized the Galapagos, adapted to completely new food stuffs, and developed into several distinct species. In fact, they even evolved over the course of the relatively short time span of one "El Nino" to adapt to the change in food supply. Now, with all that in mind, are we to believe that human beings are incapable as a species of successfully incorporating into our diet, the most abundant food source available on the planet today? What exactly does that say about our future as a species? Is it really the grains causing the problems here, or just the technology what we have developed to process them. We didn't start developing type 2 diabetes at epidemic levels until recently. Grains have been around for 10-15 thousand years as part of our diet. The preponderance of that time they would have been eaten in a relatively whole state, or if ground, not finely ground like today. Additionally, the bread, porridge, and other grain products eaten, would have been fermented and not leavened by industrial yeast. Not only have grains suffered from industrial food processing. Are some of the processed meats, say chicken nuggets, available today any better for us than processed grains? And the ever popular Velveeta cheese, mm mm yummy goodness. This stuff has only been part of our diet for about fifty years. In all likelihood this is what we have not adapted to. More importantly, do we really want to?