Roughly 2% of humans suffer from obsessive compulsive disorder, but a lack of animal models has impeded research into this condition. Could a genetically engineered mouse model provide an exciting lead?

Ageing populations raise the spectre of crippling healthcare costs. Extra spending on medical research might bring healthier, happier older people who work (and pay taxes) for longer. Is that a good investment?

Statistical analyses of the networks formed by plant–animal mutualisms can now take account of the relatedness of the players on either side. How helpful is this innovation for understanding network dynamics?