Bullet ant image by Benoit Guenard

Science is full of ideas that people somehow accept to be true, just because people say it’s true. We’ve all heard wonderful just-so stories that are waiting to be dispelled by data.

Let me tell you about three myths.

The first myth was that gastric ulcers are caused by stress. All kinds of medical treatments were predicated on this notion. When a researcher figured out that gastric ulcers were caused by bacterial infection, it was considered so outlandish that he had to infect himself to convince the medical research community. (In 2005, the Nobel Prize was awarded for this finding.)

For the second myth, consider the three-toed sloth. For about a century, it’s been said they specialize on Cecropia leaves. One twist on the story is that that the trees are tastier to sloths because they have weaker chemical defenses, because the plants are defended by ants. Then, in the 1970s, two biologists radio-tracked sloths for a couple years in Panama and found that yes, they eat Cecropia, along with many other plant species. If you track them with radio collars, then you get to see that they are not Cecropia specialists.

The people who radio-tracked the sloths did not receive a Nobel Prize. Continue reading →