Of the many peculiarities that enable the modern giant panda (Ailuropoda melanoleuca) to adapt to life as a bamboo eater, its extra ‘thumb’ is the most celebrated yet enigmatic. In addition to the normal five digits in the hands of most mammals, giant pandas have a greatly enlarged wrist bone — the radial sesamoid — that acts as a sixth digit, an opposable ‘thumb’ for manipulating bamboo. In a new paper published in the journal...
