News Digest

Who are you calling pigs? Hippo ancestry finally unveiled

If you’ve ever wondered where hippos originally came from, a team of French researchers now have the answer for you. A great-great grandfather of the hippopotamus likely swam from Asia to Africa some 35 million years ago, long before the arrival of the lion, rhino, zebra and giraffe, researchers said Tuesday. Analysis of a previously unknown, long-extinct relative also confirmed that cetaceans - the group to which whales, dolphins and porpoises belong - are in fact the hippo’s closest living cousins.

The origins of the hippopotamus have been a mystery until now. Now we can say that hippos came from anthracotheres - an extinct group of plant-eating, semi-aquatic mammals with even-toed hooves.

Fabrice Lihoreau, a palaeontologist at France’s University of Montpellier and co-author of the study

Until now, the oldest known fossil of a hippo ancestor dated from about 20 million years ago, while cetacean remains aged 53 million years have been found. Scientists had long lumped hippos with the Suidae family of pigs based on palaeontological finds, but DNA later suggested they were the kin of whales instead. Now the remains of a 28-million-year-old animal discovered in Kenya has provided an important piece of the puzzle, according to a study in the journal Nature Communications. Named Epirigenys lokonensis (“epiri” means hippo in the Turkana language and Lokone after the discovery site), it was about the size of a sheep, weighing in at 100 kilogrammes (220 pounds), which is about a twentieth the size of today’s “common hippopotamus”, a sub-Saharan giant.

We filled a gap in the evolutionary history of the hippo, bringing us closer to the point of divergence from their modern-day sister group of cetaceans.

Fabrice Lihoreau