You might think a zorse is something from fantasy fiction, grazing in fields alongside a unicorn. But it’s really a zebra-horse and it may live in a zoo near you. The same goes for a liger (lion-tiger), beefalo (buffalo-beef cattle), and, of course, a mule (donkey-horse). Some of these hybrids are the results of people tinkering with genetics. But some are as naturally conceived as they come. The New York Times reports that some of these hybrids may even adapt to conditions in which neither parent may fare as well.

Liaisons between species is not uncommon in the animal kingdom. As the NY Times reports, “biologists estimate that as many as 10 percent of animal species and up to 25 percent of plant species may occasionally breed with another species.” But as in the case of mules and zorses, the hybrid offspring is often sterile and the end of the evolutionary line. Further, the hybrid will also be greatly outnumbered and may not be able to compete with the two parent species for food.

But not all hybrids are sterile. In fact, there is evidence that some hybrids may actually do better in certain situations than their parent species. Biologists have analyzed the history of species and other hybridizations to determine how the hybrid genes have been passed along as an improvement to the gene pool. A successful hybrid may even create a third new species of animal and/or plant.

The NY Times cites the example of a 400-pound gray female bottlenose dolphin named Punahele. Punahele lived at the Hawaii Sea Life Park in the 1980s, sharing her pen with a 2,000-pound male false killer whale. She gave birth to a wolphin with 66 teeth. The bottlenose has 88 teeth and the false killer whale has 44 teeth. Certainly, the wolphin would be at a disadvantage with a pod of false killer whales —but at an advantage amongst dolphins.

Experts have looked at the hybridization of humans, with the possible crossing of Neanderthal and modern man some 270,000 to 440,000 years ago. Biologists in Leipzig recently provided the first detailed analysis of the Neanderthal genetic sequence, proving that Neanderthals did mate with humans. As the NY Times reports, “the Leipzig scientists assert that the interbreeding did not occur in Europe but in the Middle East and at a much earlier period, some 100,000 to 60,000 years ago, before the modern human populations of Europe and East Asia split.”

Biologists also estimate that about 1 percent to 4 percent of the DNA sequence of Europeans and Asians came from Neanderthals mixing with Homo sapiens. This does not include Africans, who are free of Neanderthal genes. How have the Neanderthal genes benefit humans? Experts believe that they better enabled modern people to adapt to new climates and lands.

For further reading:

Animal hybrids may thrive where their parents don't
Ligers, beefalos and wolphins, oh my! Experts look at how hybrids evolve.