Why’d the zebra evolve its stripes? Perhaps because stripes seem to keep off horseflies, a new study suggests. There’s good evolutionary reason to escape the ravages of horseflies, at least for horses and their relatives; though flies are just annoying pests from the human perspective, horsefly-bitten horses can grow skinny and have trouble producing milk for their young. And as soon as baby-making is affected by something in the environment, adaptation isn’t far behind.
Other research has shown that horseflies prefer to land on black horses instead of white, which got Gabor Horvath, author of the recent study, thinking about how they’d react to black-and-white specimens, such as zebras. Of course, actual zebras can be hard to experiment on, as The Economist notes in an article on the research:
[Real zebras] insist on moving around and swishing their tails. The team therefore conducted their study using inanimate objects. Some were painted uniformly dark or uniformly light, and some had stripes of various widths. Some were plastic trays filled with salad oil (to trap any insect that landed). Some were glue-covered boards. And some were actual models of zebra. They put these objects in a field infested with horseflies and counted the number of insects they trapped.
Government and big business try to build a massive industrial project in a protected space. Wildlife defenders rise up to save the threatened reserve. This starkly drawn plot line sounds like the simplistic basis of a hundred Disney films, but in this case the drama is playing out for real in Tanzania.
The government of Tanzania would like to build a highway that connects the commercial activity on the country’s coastal eastern side to the inland and more remote west. That highway, however, would cut right through the plains of Serengeti National Park, and right through the annual migratory path of the millions of gazelles, zebras, and wildebeests that head from Tanzania to Kenya and provide a gorgeous visual staple for nature films.