As mentioned yesterday, Jebel Irhoud documents an early African Homo sapiens. The specimen represents mixture of archaic and modern features, such as an elongated braincase compared to the face and teeth, respectively. In a new paper published in Science Advances, researchers Simon Neubauer, Jean-Jacques Hublin and Philipp Gunz used CT scans to create virtual endocasts that approximate brain size and shape and compared them to other endocasts of various fossils and present-day humans. Their findings as outlined in the image below show that in the last 300,000 years or so, our brain shape changed to a more globular one from a elongated archaic form.

Brain shape evolution in Homo sapiens: brain shape of one of the earliest known members of our species, the 300,000… [more] © MPI EVA/ S. Neubauer, Ph. Gunz (License: CC-BY-SA 4.0)
Brain shape evolution in Homo sapiens: brain shape of one of the earliest known members of our species, the 300,000… [more]
© MPI EVA/ S. Neubauer, Ph. Gunz (License: CC-BY-SA 4.0)
Two areas, the parietal lobes and the cerebellum bulged recently. Both areas function in spatial orientation, the parietal more aligned to the higher functions while the cerebellum more towards the lower ones, like coordination and balance. Curiously, these shape changes evolved some time between 100,000 and 35,000 years ago and independently of brain size — with endocranial volumes similar even the oldest Homo sapiens fossils from Jebel Irhoud falling within present-day variation of brain size. These changes parallel the gradual emergence of behavioral modernity as seen from the archaeological record.

One thought on “The Modern Human Cerebellum & Parietal Lobe Evolved Recently

  1. That sapiens’ globular skull form is different from the elongated and flattened skull of earlier Homo is known for a long time. But assuming that what is decribed as “parietal bulging” implies that H.sapiens has better “orientation, attention, perception of stimuli, sensorimotor transformations underlying planning, visuospatial integration, imagery, self-awareness, working and long-term memory, numerical processing, and tool use” than Neanderthals seems to be a modern form of phrenology. There’s no evidence that skull form influences brain functions. In fact, Neanderthals often had larger brains than we have, and in my opinion there are much better explanations of why the earlier lang & flat skull form was lost in H.sapiens, boogl e.g. “Ape and Human Evolution made easy 2018 Verhaegen”.

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