Animal studies have shown them to affect neurological and reproductive behaviour.

ECONOMIST: Fire retardants may affect female reproduction

For, in their reproductive behaviour, people share something with fish that they do not have in common with many of their fellow mammals: men often invest heavily in their children.

ECONOMIST: Birds do it, bees do it | The

The advantage is that almost all the members of the colony can direct their energies towards foraging for food in order for the whole community to survive, rather than indulging in physically exhausting mating and reproductive behaviour.

BBC: NEWS | Health | Clues to stress-infertility link

So Dr Wildt's group is, for example, using a test-tube assay to measure hormone patterns in the faeces of endangered clouded leopards, and correlating these to behaviour under stress with a view to improving reproductive efficiency.

ECONOMIST: Endangered species