#ThrowbackThursday: Reconstructions show that human brains may have evolved more recently than we thought

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The human brain may have evolved much faster and more recently than previously thought, researchers suggest from reconstruction of hominid skulls. By scanning the skull of Australopithecus sediba, one of the earliest complete hominid skeletons, scientists could reconstruct the shape and size of the brain from an endocast of the cranium. Essentially, this means they could use the gaps inside the skull to work out how the brain filled them, right down to some stunning details. Individual lobes of the brain and even blood vessels can be identified, and in total the brain was found to be around 420 cm³, a size comparable to that of a chimpanzee. A. sediba, which lived almost 2 million years ago, has many human-like features, including dextrous hands which were probably capable of precise grip and manipulation, but the endocast shows that the brain was still very much ape-like. The first evidence of simple tool use  appears around 2.5 million years ago, and this would coincide with the appearance of dextrous hands such as those of A. sediba, but it seems that further development of the brain must have come later. There is a slight swelling at the front side of the endocast, which could correspond to modern humans’ Broca’s area, thought to be responsible for language and speech. It’s possible that this bump could foreshadow the evolution of complex communication in hominids, which would otherwise be almost impossible to trace from fossils. And all this potential new knowledge stems from the space where a small-ish brain used to be!

To see how the endocast was made, watch a video here.

Image courtesy of Kristian Carlson. To read more about this work, click here.


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