Form and Function

(I included the famous quote that ends with "form ever follows function" in the header of this blog. I've frequently heard "form follows function" in reference to evolution and if forced to guess, might have attributed the quote to Darwin. Turns out the phrase was made famous by renowned late 19th/early 20th Century architect Louis Sullivan. Who knew?)

I'm working on the endless task of decluttering our household, and today I was making some hard decisions about which books to keep ("All of them!" my mind screams) and which to donate to the library. One that made the cut to keep was The Beak of the Finch by Jonathan Weiner. It follows the work of Peter and Rosemary Grant on the subject of natural selection within Darwin's finches (specifically the ground finches, genus Geospiza) in the Galapagos. Their findings on speciation and genetic variability over short time frames have more to do with the study of evolution than anatomy or physiology, but the relationship between beak size/shape and food sources are a perfect example of the relationship between form and function.


1. Geospiza magnirostris - Large ground finch - large "crushing-type" beak, feeds on large seeds
2. Geospiza fortis - Medium ground finch - smaller "crushing-type" beak, feeds on smaller seeds
3. Geospiza (now Camarhynchus) parvula - Small tree finch, small and narrow beak, feeds on insects
4. Certhidea olivacea - Warbler finch - long and narrow beak, feeds on insects

The thick and powerful beaks of the ground finches are perfect for crushing the hard exterior of seeds in order to access the edible fruits within. And the longer and narrower beak of the tree and warbler finches are suited to picking insects from crevices where they may hide.

* There is a great drawing of adaptive radiation amongst the finches here.
* There is a nice summary of the Grants' work here.