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The term RNAi — short for RNA interference — crops up again and again in biology research these days. This is in part because of its power as a laboratory tool, and in part because it is a widespread natural phenomenon.
What determines how long we will live? Studies of simple organisms, single cells and mammals hint that certain shared principles underlie ageing, and raise the possibility of devising ways to extend life — if we want to.
Why, when the human race shows comparatively little genetic variation, are cultural differences so widespread and enduring? Thinking about cultures in terms of biological species provides some provocative answers.
A neglected mathematical theory is enjoying new popularity, thanks to its relevance to network dynamics in biological systems. The beating of a leech's heart is just one example that has a mathematical basis in ‘groupoid theory’.
