Some spider species eat their siblings, especially when food is scarceDavid VILLA/SCIENCEIMAGE CBI CNRSA species of spider avoids cannibalising its siblings while they are alive, but does not seem to have qualms about eating its brethren as soon as they die. This suggests some spiders come to tolerate one another by learning to recognise a chemical or mechanical life signal, which could be a key piece to understanding the evolution of rare social spiders.Raphal Jeanson at the University of Toulouse in