Now, the results of what started as a home experiment by evolutionary biologist Hopi Hoekstra, now at Harvard, are starting to show how this process works. Working with Oldfield mice that construct elaborate burrows with escape tunnels and deer mice that construct only simple tunnels, Hoekstra has homed in on the genetic loci involved. It turns out that they are modular, with 3 genetic loci responsible for the long tunnels and a fourth for the escape hatch. The next stage will be to engineer deer mouse with the advanced tunnelling genes of the Oldfield mice and watch the digging.
This kind of pick and mix modularity controlled by very few genes has been observed in body traits (eg butterfly wing patterns) but this is the first time it has been seen in behaviour. The fact that complex organs and behaviour can be pick-and-mixed like this and switched relatively easily by genetic switches clearly makes evolutionary adaptation less of a mystery.
Nature, 2013, 493, pp. 402-5