Fossil evidence indicates many Malagasy hippos were hunted by humans, a factor in their eventual extinction.

Calves are born on land or shallow water [37] weighing on average 50 kg (110 lb) and at an average length of around 127 cm (4. Two highly acidic pigments have been identified in the secretions; one red ( hipposudoric acid) and one orange (norhipposudoric acid), which inhibit the growth of disease-causing bacteria and their light-absorption profile peaks in the ultraviolet range, creating a sunscreen effect.

When hippos become over-populated or a habitat shrinks, bulls sometimes attempt infanticide, but this behaviour is not common under normal conditions.

It is challenging to study the interaction of bulls and cows because hippos are not sexually dimorphic, so cows and young bulls are almost indistinguishable in the field. Observations on the response of a pod of hippos to a dead juvenile hippo ( Hippopotamus amphibius, Linnaeus 1758)". The most recent theory of the origins of Hippopotamidae suggests hippos and whales shared a common semiaquatic ancestor that branched off from other artiodactyls around 60 million years ago. Small boats can easily be capsized by hippos and passengers can be injured or killed by the animals, or drown in the water. Mitochondrial DNA variation of the common hippopotamus: evidence for a recent population expansion".Huberta became a celebrity during the Great Depression for trekking a great distance across South Africa. It is unlikely to serve a territorial function, as the animals only establish territories in the water.