Once upon a time, several million years ago, our ancestors, yours and mine, were primates swinging through branches in the heat of Africa. They shared a common primate ancestor with gorillas. Then two million years ago something happened and some of these ancestors came down out of the trees and began to walk on their hind legs. Homo erectus, the first hominin, came into being. This is the way current scientists tell the story.
Perhaps it was a climate change, perhaps it was an expanded population, or perhaps it was an evolutionary mutation that prompted this new behavior. Once walking the earth became the norm, new discoveries were made. Observing animal predators bring down large game inspired a new diet. At first our hominin relatives moved in to finish off the carcasses left by animal predators. They made basic stone tools to help release the remaining meat. They discovered fire and learned that cooked meat was easier to digest.
Those hominins living in the lush Rift Valley of East Africa continued to evolve. 200,000 years ago, hominids with larger brains, Homo sapiens, came into existence. Significantly for us, the ancestry of all of us, you and me, can now, through DNA testing and analysis be traced back to one woman in East Africa, mitochondrial Eve. She lived 170,000 years ago and is the mother of us all. Each of us owes our existence to her and to the continent of Africa that produced her. Another woman, Rebecca Kahn, was the first scientist to identify mitochondrial Eve in the late 1980s. Mitochondrial DNA is passed from mother to daughter (and sons) and can be used to determine generations and date mutations that occur.
Among our hominin ancestors, two cultures grew up in Africa, an inland culture that survived by developing hunting tools and methods for killing large animals and a coastal culture that fished the sea. The inland culture followed the animals into South and West Africa and into Eurasia, becoming Neanderthals in Europe and Denisivans in Asia. Then expanding deserts blocked the northern path to Eurasia.
100,000 years ago, nurtured by a high protein diet, the brains of our hominin ancestors in Africa expanded. They developed language along with the capacity to plan and to cooperate in executing plans. They created more tools and developed art. Shell necklaces found in caves of South Africa are among the oldest art forms ever found.