Surely it's destructive and illogical? For a few animals, the risk of being eaten by relatives is just one of the natural hazards of life. The fierce sibling rivalries of foetal sharks and surprising parental strategies of burying beetles have long perplexed scientists. Dr Jane Goodall grapples with ruthless chimp motivations, in an investigation that leads disturbingly close to humankind. Sequences recorded here for the first time reveal the logic of selfish strategies, deeply embedded in nature.

Surely it's destructive and illogical? For a few animals, the risk of being ...