The Vadoma tribe lives deep within the confines of western Zimbabwe. Derogatorily referred to as the “ostrich people," the Vadoma suffer from a rare genetic condition called ectrodactyly, which affects one in four children within the population. Ectrodactyly, or “lobster claw syndrome,” can affect either the hands or feet. In the case of the Vadoma, the middle three toes are absent and the two outer ones are turned inward.
Ectrodactyly is an inherited dominant genetic mutation. Some have theorized that the mutation may have adaptive benefit if it aids in tree climbing. It's more likely, however, that the defect remains prevalent in the Vadoma because of a small genetic pool among the Vadoma. It is against tribal law for members to marry outside the group.
Ectrodactyly occurs at lower rates throughout the world and can be caused by a number of human gene defects, a common one being a mutation of the 7th chromosome. It is also associated with hearing loss. Though ectrodactyly itself is fairly rare, occurring in 1 in 90:000 births, limb defects occur in roughly 1 in 1000 births, only slightly less then the rate of identical twins.