It has been proposed that the age of the Earth deduced from lead isotopes reflects loss of lead into space at the time of the Moon's formation rather than partitioning into metallic liquids during core formation. Here it is shown that lead partitioning into liquid iron depends strongly on carbon content and that, given a core carbon content of about 0.2%, there is evidence of strong partitioning of lead into the core throughout the Earth's accretion.

Millions of pounds per year are spent on various 'brain-training' programs; however, the efficacy and performance of these training regimes is still unclear. In collaboration with the BBC, a six-week online study of brain training was conducted. Although improvements were observed in the specific tasks used for training, in the authors' view there was no evidence that these improvements transferred to other untrained cognitive tasks.

Proper functioning of the brain requires a balance between the formation of excitatory and inhibitory synapses, but how this is achieved during development is unclear. Here FGF22 and FGF7, two fibroblast growth factor cell–cell signalling molecules, are shown to promote the formation of excitatory and inhibitory synapses, respectively, through their effect on epilepsy in mice. These findings should inform other neurological and psychiatric disorders involving defects in synapse formation.