300 million years ago, all the landmasses of the earth gathered in one big super-continent we call Pangea.
Life was widespread on this continent, and it diversified further as the tectonic forces broke up Pangea around 200 million years ago, during the middle of what we call the Jurassic period, in the beginning of the era of the big dinosaurs, to create the separate continents we know today.
When India collided with Asia some 50 million years ago, the Himalayan mountain range was formed as ‘fold mountains’, which changed the global climatological patterns in such a way that West Africa changed from lush tropical rainforest into dry grassland savannah.
As the trees disappeared, some of the primates living there were forced to start living on the ground, and eventually some of them began to walk upright, perhaps to better spot dangerous animals across the tall grasses.
Once you are upright, your hands are freed, and can be utilized in whole new ways. It is possible that this led to rapid development of the brain, and, eventually, the use of tools.
Thus starts the evolution towards us, the modern human, homo sapiens sapiens, a sub-species of the family of Simian primates, which includes chimpanzees, gorillas, orangutangs, and us.
Now, there were also other farmers soon after in other areas of the world, developing quite independently of course, in places such as China, Africa, and the Americas. But in some of these cases, we notice that farming did not lead to significant societal development.
Why is that? Jared Diamond proposes that this is a direct consequence of the plants and animals living in those places and climates, and he points out that the vast majority of plants and animals highly susceptible to domestication all originated in certain regions, while the plants and animals of, for example, New Guniea, Australia, and the Amazon, produced comparatively low levels of nourishment, gave poor produce ratios, and the animals could not be used as beasts of burden.
In fact, of the 14 large, domesticated animals, 13 originate in the region that stretches from Europe and the Mediterranean Sea to Asia.