A mule is a biological hybrid, an offspring of a male donkey and a female horse. According to a new paper, all of this cross-pollination has real benefits: mules are significantly smarter than either of their parents. No regression to the mean here:
Six of each animal were shown sets of two food buckets, each marked with a different symbol.In order to gain access to the food, the animals had to pick the correct bucket. The mules learned to discriminate between more pairs of symbols than the horses or donkeys, and did so more consistently.
The scientists argue that the intelligence of mules results from their genotypic diversity. It’s long been recognized that such diversity can produce improved physical characteristics – mules are also stronger than their parents – but this study suggests that diversity also has cognitive benefits. And there’s no reason to think that the hybrid principle is limited to mules. So go out and rescue a mutt and marry somebody with an entirely different set of recessive genes.