They are the most widespread and abundant equid in the world today, although their welfare depends on conservation programs aimed at maintaining their habitat and preventing overhunting.
Bovids, equids and, in particular, canids, were put to work by H.sapiens; felids always took a slightly different view of the matter, but were indulged for their rodent-catching talents.
The study is in the journal Proceedings of the Royal Society B. Various ideas have been tossed around in the last 150 years about the African equids' stripes.