Your saliva contains an enzyme called amylase, made by the AMY1 gene, which digests starch. Modern humans whose ancestors were farmers have more copies of AMY1 than people whose ancestors stayed as hunter-gatherers. This digestive boost may have helped start farming, settled villages and modern societies.
A few people have mutations in a gene called FOXP2. As a result they struggle to grasp grammar and pronounce words. That suggests FOXP2 is crucial for learning and using language. The modern FOXP2 evolved in the common ancestor of humans and Neanderthals: Neanderthal FOXP2 looks just like ours.
All great apes have air sacs on their vocal tracts, which let them make loud bellows. But humans don’t, because the air sacs make it impossible to produce different vowel sounds. Our ancestors apparently lost them before we diverged from our Neanderthal cousins, suggesting the Neanderthals could also speak.
Nobody knows when our ancestors learned to control fire. The oldest direct evidence comes from Wonderwerk Cave in South Africa, which contains ashes and burned bones from 1 million years ago. But there is evidence hominins were processing food even earlier, and that might have included cooking with fire.
For humans, childbirth is difficult and dangerous. Unlike other primates, mothers almost always need help. This is because walking on two legs means a narrow pelvic canal for the baby to pass through, while our heads have grown. To compensate for harder births, human babies are born small and more helpless.
Modern humans belong to a group or “genus” of animals known as Homo. The oldest known Homo fossil, found in Ethiopia, is 2.8 million years old. The first species was probably Homo habilis, although this has been disputed. Compared to their ancestors, these new hominins had much larger brains.
A gene called SRGAP2 was duplicated three times. As a result, our ancestors had several copies, some of which could evolve freely. One of the mutated copies turned out to be better than the original. It seems to have caused our brain cells to extrude more spines, allowing them to form more connections.
Humans are the nearly-hairless apes. No one knows why, but it happened 3-4 million years ago. That’s when pubic lice evolved, which could only infest us once our other body hair was gone. Exposed to the Sun, our skin darkened. From then on all our ancestors were black, until some humans left the tropics.