I love pistachios and Charles Darwin. Since today is Darwin’s birthday (or more accurately, the anniversary of his birth on February 12, 1809, the very same day as Abraham Lincoln), I intend to enjoy both. Darwin and pistachios are linked forever in my mind by my favorite science writing metaphor ever. It comes from Jonathan Weiner and his unforgettable book, The Beak of the Finch, which brings to life Darwin, his famous finches, and the decades long studies by Peter and Rosemary Grant of Princeton University of continuing evolution on the Galapagos Islands. Weiner describes how dry or wet climate cycles favor certain beak shapes by making food accessible to one shape over another on the volcanic terrain. Weiner writes, “Watching the birds combing the dry lava for Tribulus seeds is like watching people hunt through a bowl of pistachio shells for the last unopened nuts, the ones that were thrown back as too tough to crack.”
I have never looked at a bowl of pistachios since without thinking about natural selection. This is the supreme achievement in science writing—to embed a metaphor in the public imagination that makes a complicated concept unforgettably vivid. Weiner’s pistachios do more to reveal the “grandeur of this view of life,” as Darwin put it, than all the diatribes against wrong-headed Creationism together.
It being Darwin’s birthday, the Grants are back in the science news as co-authors on a new paper with lead collaborator Leif Andersson of Uppsala University in Sweden, who did whole genome sequencing of 120 individual birds representing all 14 of the recognized species of Galapagos finches plus two closely related species. The genomic results largely support Darwin’s original interpretation of their descent but with some unexpected taxonomic rearrangements and evidence of extensive hybridization between some species. The study identifies the gene ALX1 as the source of the finches’ pliant facial morphology. ALX1 has analogs right through the vertebrates into fish and mammals. Defects in the ALX1 gene in humans is linked to facial malformations.
All of which shows the breathtaking insight of Charles Darwin that all living things are related, that all living things are changing, and that the experience of life shapes all life. Darwin had no inkling of modern genetics and yet 206 years after his birth, whole genome sequencing of the Galapagos finches shows that he read the beak of the finches correctly.
So pass that bowl of pistachios. There are bound to be a few more morsels to be cracked by the serious Darwinian.
About the Author:
John Fleischman was the ASCB Senior Science Writer from 2000 to 2016. Best unpaid perk of the job? Working with new grad students and Nobel Prize winners.
