This section is 2 min long, with soundtrack (see also "SILENT CLIPS")

Chapter size: 19 MB (.mpg) or 3.5 MB (.mov).

Topics and Behaviours covered: eating, food and nutrient diversity, specific appetites, salt and protein deficiency, climbing (see commentary below).

Chapter commentary:
(numbers in bold refer to behaviours also shown in the silent clips)

By now rats have learned to exploit food in the more remote places, and climb on small branches with dexterity. Well, at least almost!(1)

The rats’ diet has also become far more varied than the food pellets that were their staple in captivity. An apple (1), a snail, a stray egg, even a dead bird (2), all were devoured by the colony. But this diversity poses a problem since foods vary in their nutrients content.

How do the rats know how to select a balanced diet? (3) They are helped by another ability evolved by their omnivorous wild ancestors: In addition to having learned whether some foods are better than others, rats possess, like humans, some specific appetites, allowing them to compensate for specific deficiencies in some proteins or salt.