A 3.3-million-year-old fossil with a missing rib tells us a lot about human evolution
Our spinal column is different from that of apes because — yes, you guessed that right — we walk upright on two feet. But when did our distinctive back structure first evolve? The skeleton of an early human ancestor found in Africa shows that some features were already established at least 3.3 million years ago, earlier than previously thought.
The fossil was found to have only 12 rib-bearing vertebrae, the same number as modern humans — and one fewer than most apes. That feature had previously been observed in early humans dated to only 60,000 years ago or later. The findings, published today in the journal Proceedings of the National Academy of Sciences, show that the general structure of our spinal column was already emerging 3.3…
