Shaking hands hasn't been so popular in social distancing Covid times, but it is a widely accepted gesture that has existed for thousands of years. The handshake ritual Is deeply embedded in a range of cultures and it's not just the exclusive domain of humans. Chimpanzees and bonobos also shake hands. The ancient social gesture has so captivated paleoanthropologist and evolutionary biologist, Ella Al-Shamahi, that she's written a book about it - The Handshake - A gripping history.