# Simple Math Explains Finch Beak Evolution

Image credit: Wikimedia Commons

The variation in the beaks of Galapagos finches famously served as inspiration for Darwin's theory of evolution. The various birds, however, may not be all that different. According to new research in applied mathematics from Harvard University, the finches can be clumped into three major groups.In the course of their research, Otger Campàs and Michael Brenner observed 14 distinct beak shapes that appeared to be unrelated. It took only a few simple calculations, however, to explain the variations. By altering the scale of the beaks—changing the relative length and depth—the researchers saw patterns emerge.

Campàs explained:

It is not possible, however, to explain the full diversity of beak shapes of all Darwin's finches with only changes in beak length and depth...by combining shear transformations (basically, what happens when you transform a square into a rhombus by shoving the sides toward one another), with changes in length and depth, we can then collapse all beak shapes onto a common shape.

This means that the shapes of the birds' beaks are controlled by only three variables: depth, length, and the degree of shear.

Ricardo Mallarino, a graduate student in the Department of Organismic and Evolutionary Biology at Harvard, commented:

This is really significant because it means that adaptive changes in phenotype can be explained by modifications in a few simple parameters...these results have encouraged us to try to find the remaining molecules responsible for causing these changes.

In fact, genetic research conducted on the finches has revealed that two genes are responsible for controlling beak shape: one affecting length and depth and the other influencing scaling.

The findings, researchers said, are a reflection of Darwin's own observations, made 175 years ago, when he said "this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."

Tags: Animals | Birds