Charles Darwin, author of On the origin of species (1859). Copyright Royal Society.
By Royal Society Science Books Prize winning author Nick Lane
What is evolution and why does it occur?
Evolution is change: change in populations over time. It’s practically impossible to stop small changes – mutations – from taking place in genes. Most of these don't make any difference. Harmful mutations are weeded out by natural selection, while beneficial ones are preserved. Over millions of generations such changes give rise to complex adaptations like eyes and wings.
What evidence is there for the theory?
The best evidence lies in the sequences of genes and the biochemistry of cells. All life is related, from bacteria to humans, and the relationships computed from gene trees correspond closely to those unravelled from shared anatomical structures in living organisms and from the fossil record. The distribution of species in islands and across continents, the intricacies of embryo development and the retention of vestigial structures (like the appendix) only make sense in the light of evolution. Likewise ageing and disease.
Are we continuing to evolve?
It is impossible to stop change, so we are undoubtedly continuing to evolve in some ways. But those ways might not be very interesting. Our brains can’t get any larger, as a baby’s skull only just fits through the mother’s hips; unless everyone has a Caesarean section, that's it. But the human mind may evolve in more subtle ways, related to urbanization or the use of computers.
What is the strangest thing about human evolution?
Human evolution is strange in many ways, and it's hard to separate cultural evolution from its biological roots. Perhaps the single most important and mysterious biological root is consciousness. We know a great deal about the brain but much less about the mind. How the firing of neurons generates ‘feelings’, whether pain or pleasure, right or wrong, is the hardest and strangest question in biology.
Nick Lane’s Life Ascending was the winner of the 2010 Royal Society Prize for Science Books. Visit: royalsociety.org/science-books