In 2010, a team of paleo geneticists at the Max Planck Institute for Evolutionary Anthropology, led by biologist Svante Pääbo, published an astonishing result—they had managed to sequence the Neanderthal genome and found that there had been interbreeding between Neanderthals and West Eurasian humans. In a sense, the field of paleogenetics had come of age. Paleogenetics, or the science of using genetics to study ancient humans and other populations, relied heavily on advances in technology to extract and sequence genomes since the Human Genome project. This new book by David Reich, a member of this team, is a popular exposition of the revolutionary potential of paleogenetics to understand humanity’s origins and ‘histories’.
The workhorse of paleogenetics is the DNA molecule—a helix-shaped molecule which is the blueprint for life. It consists of arrangements of four bases denoted by the letters, A,T, G, and C whose ordering determines the coding of amino acids and hence the production of different proteins in a cell. During replication, sometimes there is an error in the copying of the bases and a wrong base is added to the new DNA strand. These errors or mutations are what form the basis on which natural selection operates. Interestingly, the rate at which mutations accumulate in a genome is constant over generations, allowing us to determine how long back two segments shared a common ancestor. What we have is a kind of biological stopwatch.