The Beak of the Finch: a story of evolution in our time by Jonathan Weiner.

This is about empirical studies proving some of Darwin’s most important concepts. Weiner tells the story of Rosemary and Peter Grant, evolutionary biologists, who spent years in the Galápagos islands observing Finches. Their objective was to observe, witness evolution in real time. And they did. The book explains what and how they did their observations and most importantly how they came to their conclusions. One aspect I liked about the book is that the author takes its time going back to Darwin’s original ideas providing historical and scientific context. I particularly liked some segments where Weiner explains Darwin’s conflicting ideas, having been a religious person, and following Milton’s ideas and then realising about the reality of evolution. The Grant’s studied the shape, and sizes of the finches' beaks in all their varieties. Compared their eating and mating habits with their beaks and were able to draw connections. They found out that the islands have so many finch varieties so every variety could have different food sources, usually seeds. The kinds of seeds a finch can eat depends on the shape, size and strength of their beaks. The Grant’s noted that during the wet seasons all finches feasted on all kinds of seeds (the ones they could eat), but during dry seasons each variety would focus on their speciality. Finches would die when their special seeds were scarce. Just a tiny variation in the length of a beak would make a bird unable to open a seed and eat it. In hard times (draughts) hundreds of birds would die and the ones who survive would reproduce more. You can call this natural selection. This way finches would adapt to the kind of foods which are available at some point in time. This and sexual selection, females selecting males with particular characteristics (e.g. with long or deep beaks) would determine how variations happen. So variations -> natural selection + sexual selection.