Start the Week is at the Hay Festival for a discussion about what has made homo sapiens so successful. The historian Yuval Noah Harari looks back a hundred thousand years ago when at least six human species inhabited the earth and explores why only one came to dominate. Science was a key breakthrough and Beth Shapiro pushes at the limits of knowledge with her book on how to clone a mammoth. The writer Colm Tóibín reveals how much he owes past writers in his introduction to the enigmatic American poet, Elizabeth Bishop, while Owen Sheers explores the themes of loss and redemption in his latest novel. Producer: Katy Hickman.