The Ancestor's Tale

From Palaeos

The Ancestor's Tale is a book by Richard Dawkins', in which he imagines a backwards 'pilgrimage' in time, during which we humans 'meet' all the other species of organism with which we share a common ancestor (more technically, a most recent common ancestor or MRCA). Dawkins coined the word, concestor, as an alternative to MRCA.

Following the human evolutionary tree backwards, we first meet the concestor which we share with the species that are our closest relatives, the chimpanzee and bonobo. Dawkins estimates this to have occurred between 5 and 7 million years ago. Another way of looking at this is to say that our (approximately) 250,000-greats-grandparent was a creature from which all humans, chimpanzees and bonobos are directly descended.

Further on in Dawkins' imaginary journey, we meet the concestor we share with the Gorilla, our next nearest relative, then the Orangutan, and so on. The MRCA for all living organisms is also known as the last universal ancestor.