They found that the gene's activity rose and fell at a steady pace in both unfertilised and fertilised eggs.

BBC: Body clock 'set before birth'

First, their eggs are fertilised externally.

ECONOMIST: Animal behaviour: Truth in advertising | The

Given a suitable chemical kick-start, such re-nucleated cells will begin dividing as though they were eggs that had been fertilised in the more traditional manner.

ECONOMIST: An embryonic development

In the current issue of Nature, Frank McKeon of Harvard Medical School, and his colleagues, report that a gene well-known to suppress tumours evolved from one that stops mammal eggs with lots of mutations getting fertilised.

ECONOMIST: Human fertility