A friend of mine decided to get a group of children in her care a fish tank and guppies as a “class pet.” The guppies were soon joined by baby guppies. The babies disappeared, one by one. Turns out, guppies are known for this shit.
It's common scientific wisdom that parasite resistance comes from repeated exposure to a parasite. But a new study has turned this idea on its head. Guppies who were removed from rivers swarming with parasites actually evolved an improved parasite tolerance in just a few generations. Here's how it happened.
You'll notice right away that choosing the correct side without counting the fish individually is pretty tough. This difficulty stems from the fact that humans can only assess relative quantities by snap judgment under certain conditions. Take away six fish from the right-hand side, for example, and this task becomes…