Nested, or hierarchically arranged, mutualisms allow ecosystems to support more species than they otherwise would. But in this and other contexts, the growth of such networks could carry a heavy price

John Maddox, who died on 12 April, was editor of Nature during 1966–73 and 1980–95. He transformed the journal from a collegially amateurish publication into one that was challenging and professional in its assessment of science and in its journalistic reportage

Asteroids are much 'redder' than meteorites (which come from asteroids); the accepted explanation is 'space weathering', though the actual processes and timescales involved have remained controversial