I missed the deadline for Cause Exploration Prize submissions. However, I am not bothered about the prize, I just want to put forward the case for focussing some attention on the domestication of zebras. Here is the case in a nutshell - other should please feel free to take the ideas and develop them as they wish. 

• Horses (and similar animals) have been a major source of power for agricultural, industrial and transport uses throughout human history. I focus on transport but similar considerations apply to other uses of horses.
• In the event of a disaster which made mechanised transport impossible then humans would likely return to the use of horses, especially for transport. Fortunately, there is a reasonably large number of horses and people who know how to train, manage and breed horses (e.g. farms, the British Army).
• Horses are ill-suited to conditions in sub-Saharan Africa (e.g., tsetse fly). In the event of mechanised transport becoming unavailable to humanity as a whole or to sub-Saharan Africa in particular then humans there would not be able to fall back on the horse as an alternative.
• Zebras, however, have evolved to endure conditions in sub-Saharan Africa. If the zebra were domesticated then its power would be available to people living there. 
• The domestication of the zebra therefore represents an insurance policy which would mitigate the worst effects of a disaster rendering mechanised transport unavailable in sub-Saharan Africa. The thought process here is similar to the well-known recent suggestion that coal deposits should not be exhausted in order that re-industrialisation can take place if needed: if humanity is returned to pre-industrial conditions then the more resources available to humanity at that time, the better. 
• The domestication of the zebra is likely nowhere near as difficult as has been widely reported, e.g. in Guns, Germs and Steel. Here https://www.youtube.com/watch?v=etV8YAnyjcE is a link to a video of a woman confidently riding an evidently tame zebra. (The YouTube channel from which this comes, 4hoovesnstrips, shows more examples.) 
• This http://messybeast.com/history/working.htm is a link to a set of resources showing the successes that colonial powers and hobbyists had in domesticating zebras in the late 19^th and early 20^th centuries, before mechanised transport became more cost effective than continuing the domestication project. Examples include:
  • Multiple photographs of men and women riding zebras.
  • A photograph of a zebra being ridden by a man while jumping a fence.
  • Excerpts from books written around the turn of the 20^th century explaining how to break in zebras. E.g. “Of all asses, the mountain zebra (see Fig. 122) is the most difficult to break; as he is sulky, stupid, and has an almost immovable neck. I have found the Burchell’s zebra, which is more nearly akin to the horse than any other ass, comparatively easy to break.”
  • Examples of zebras used for pulling carts or carriages. Some examples are no more than aristocratic japes or publicity stunts, but others include mail coaches and similar commercial enterprises.
  • Zebra hybrids bred in German East Africa used to pull gun carriages.
• Modern gene-editing techniques are likely to make it even easier to develop tame zebra varieties suitable for human use than the older selective breeding and training techniques. 
• The domestication of the zebra, so long as presented as beneficial to the animals themselves, is likely to be a reasonably popular project. A large number of people like horses and animals that look like horses. Many 18/19 year olds would be happy to work on a zebra farm in southern Africa in their gap year at their own cost. 
• Related: bringing back the quaggas would appear to be sensible. There are indications from the material at the link above that quaggas were likely even better candidates for domestication than zebras.