The rivers and lakes of Africa are filled with conversations that you cannot hear or take part in. These chats are conducted by fishes called mormyrids or elephantfishes, which can produce and sense electric fields. They use their abilities to navigate through murky waters, hunt their prey, and talk to one another. It’s clearly a successful lifestyle, for there are over 200 species of mormyrid alive today.

Bruce Carlson from Washington University in St Louis thinks that the origin of these diverse species lay in the diversity of their electric songs. Different species of mormyrid communicate with different electric signals, which work as badges of identity. When they’re ready to mate, they find partners of their own kind by listening out for their preferred electric dialect.

The evolution of these diverse signals hinged in turn on changes in the mormyrids’ brains and sense organs. These allowed them to pick up subtler differences in their electric signals and talk to each other in more varied ways. This opened up a world of communication, but it was also the mormyrid equivalent of the Tower of Babel. By gaining the ability ...