▪ Neutron stars are born in the violence of a supernova, but one in a binary system may have formed when a white dwarf collapsed without exploding. A gentle birth would explain why the pair moves slowly.

Physical Review Letters, February 11

▪ In mice, inflammation permits prions to enter organs not normally infected. It bolsters the theory that people with an existing illness may be more likely to get infected with mad cow prions when those brain-destroying particles are encountered.

Science, February 18

▪ Foxes being bred in Siberia read human social cues as well as domestic dogs, even though the trait was not explicitly selected for. Evidently, social intelligence can rise simply when fear and aggression decrease.

Current Biology, February 8

▪ An enzyme called kisspeptin, produced by the kiss-1 gene, activates the puberty gene GPR54, a finding that may help those with hormonal development problems.

Proceedings of the National Academy of Sciences USA, February 1