Did you know that rats will save a drowning rat?

Everybody hates the humble rat but, according to researchers in Japan, this much maligned creature has a Good Samaritan side. 

The scruffy dweller of sewers and rubbish dumps will help a brother in distress.

Nobuya Sato and his team at Kwansei Gakuin University divided a box into two compartments separated by a transparent partition. Water was poured into one of the compartments while the other remained dry. A rat, placed in the water, could be seen by another from the dry side of the partition. The wet individual had to tread water to stay afloat but it wasn’t in danger of drowning; there was a ledge to which it could cling. It could only leave the water, however, if the observing rat opened a door in the partition. Rats placed on the dry side soon learned how to do this and released their wet companions.