Testosterone and its effects on evolution – go to https://archaeologynewsnetwork.blogspot.co.uk/2016/06/when-it-comes-to-e… … another kind of change to the pure Darwinian model of evolution is being suggested – and one that involves testosterone levels. Animals with high testosterone have an edge on those of their own species with a more relaxed attitude to mating, display, and the competition for food resources. Testosterone may have influenced size, plumage (colour and display), and bouts of agression (particularly when it boils down to who gets at the lady of the species). Presumably testosterone would have played a part in human evolution too.
At https://archaeologynewsnetwork.blogspot.co.uk/2016/06/how-butterfly-got-… …. researchers found that by tweeking a few genes they could make certain patterns on butterfly wings disappear – or change colour. Variation is the engine of evolution and butterfly wing designs are a defence mechanism as well as a means for one variety to identify its potential mate rather than chasing after a different variety of butterfly and wasting valuable energy. Makes sense and it can be changed simply by eliminating the odd gene or rearranging them.