We started walking on two legs between 6 million and 4 million years ago, tool-making began 2.5 million years ago, and our brains grew dramatically between 2 million and 1 million years ago.
We became bipedal walkers 5 million years ago.
mnli hypothesis: We became bipedal walkers 5 million years ago. premise: We started walking on two legs between 6 million and 4 million years ago, tool-making began 2.5 million years ago, and our brains grew dramatically between 2 million and 1 million years ago.