"As the Sahara grew even harsher, people began to look east for a way out. Which would bring them here – to the Gates of Grief. To perhaps one of the most important events in all the long story of mankind. Because DNA evidence is quite clear. There was only ever one successful migration out of Africa and everyone of us – every single person outside of Africa – is descended from one of the people who made that one crossing. Estimates put the number at around two hundred to two hundred and fifty people. That's how closely we are all related. Something we should remember sometimes."