Darwinmania!

New York Times blog post (June 17, 2008) from Olivia Judson on the upcoming 200th anniverary of Charles Darwin's birth Feb 12, 2009; also, "July 1 [2008] is the 150th anniversary of the first announcement of his discovery of natural selection, the main driving force of evolution." This was at a meeting of the Linnean Society of London (see yesterday's blog post on the Linnean Society collections) where both Alfred Russel Wallace and Darwin read papers on natural selection. Judson outlines the prior claimants to the concept of evolution and natural selection, and then asks the question, why do we celebrate Darwin over any of these others? it was for On the Origin of Species, published on November 24, 1859.

The reason the “Origin” was so powerful, compelling and persuasive, the reason Darwin succeeded while his predecessors failed, is that in it he does not just describe how evolution by natural selection works. He presents an enormous body of evidence culled from every field of biology then known. He discusses subjects as diverse as pigeon breeding in Ancient Egypt, the rudimentary eyes of cave fish, the nest-building instincts of honeybees, the evolving size of gooseberries (they’ve been getting bigger), wingless beetles on the island of Madeira and algae in New Zealand. One moment, he’s considering fossil animals like brachiopods (which had hinged shells like clams, but with a different axis of symmetry); the next, he’s discussing the accessibility of nectar in clover flowers to different species of bee.

At the same time, he uses every form of evidence at his disposal: he observes, argues, compares, infers and describes the results of experiments he has read about, or in many cases, personally conducted. For example, one of Darwin’s observations is that the inhabitants of islands resemble — but differ subtly from — those of the nearest continents. So: birds and bushes on islands off the coast of South America resemble South American birds and bushes; islands near Africa are populated by recognizably African forms.

He argues that the reason for this is that new islands become colonized by beings from the nearest continents, and that the new inhabitants then begin evolving independently. He then asks: can animals and plants from the continents get to new islands, especially those that are far out at sea? To investigate this, he conducts experiments to see how long seeds from different plants can remain immersed in saltwater and still begin to grow. In short, he tests his reasoning over and over again.

Let's celebrate Darwin's birth this coming February! And then the publication of Origin in November!