This bird at the San Diego Zoo the other weekend kept me entertained for several minutes with its futile attempts to win over a female of the wrong species with its mating ritual – a high-pitched croak accompanied by a quick head bob.

Few things are more amusing than perversions of nature – absurd moments that the razor sharp edge of natural selection is usually so good at excising.

Sometimes, though, a little interbreeding can get the evolutionary engines churning.  Research shows that the divergence of the human lineage from that of chimpanzees may have taken around 4 million years.  That our X chromosomes diverged around 5.4 million years ago means for millions of years our ancestors were interbreeding with those of chimpanzees.

Watching this bird’s futile little dance, though, I find comfort knowing that at least I never tried to have sex with a duck.