Return of the reproducing condors and regenerating frogs

This week we replay a couple of recent favourites: Claire reveals the surprising observation of parthenogenesis, aka 'virgin birth', in the endangered California condor (Gymnogyps californianus), and explains how this is possible, and why the chicks are male thanks to bird sex chromosomes being different from ours; and Stu tells us how it's possible to get frogs to regrow amputated limbs, raising the possibility of humans also regenerating from damage.