This 21,000-mile trek is a seven-year experiment—a slow march across the world on foot to retrace our ancestors’ global migration http://on.natgeo.com/2nM92pF

This 21,000-mile trek is a seven-year experiment—a slow march across the world on foot to retrace our ancestors’ global migration http://on.natgeo.com/2nM92pF 

https://twitter.com/NatGeoTravel/status/939932788056346625