Guns, Germs, and Steel

The first chapter presents a whirlwind account of human evolution. 11,000 BCE is a useful starting point for discussing how the world’s continents developed. It was at this point that village life began in some areas and the Americas started to be peopled; geologists term this the Recent Era. However, Diamond’s purpose in this chapter is to establish whether some continents already had a head start.

Human beings trace back to hominids that lived in Africa; hence, we can ascertain that human evolution began on this continent too. Human history commenced around seven million years ago when these hominids split into three populations, a third of which evolved into humans. Diamond charts the stages of this evolutionary process, explaining that, by around 2.5 million years ago, these hominids had achieved an upright posture and increased in body size and brain size. These proto-humans are categorized as Homo erectus, but their brain size was still barely half of our own. Even so, they were the first human ancestors to spread beyond Africa, with fossils having been found on the Asian island of Java.

Fossils also demonstrate that, by around half a million years ago, the human skull had developed to the extent that it can be classified as our species: Homo sapiens.