Many of you have already seen reports of Homo fossils recently discovered in Morocco. (NYT: https://www.nytimes.com/2017/06/07/science/human-fossils-morocco.html). It is interesting for a few reasons. One is that it pushes the origins back another 100,000 years to around 300,000. The history of paleontology seems just about always that new discoveries push timelines further back, e.g., people in the Americas, use of fire. These early Moroccans used fire, ate antelope and shaped arrow-spear heads using stone from 20 miles away. Another find is that I used the plural, ‘origins’ indicating that scientists now think Homo arose not just in eastern Africa but in several areas, e.g., south Africa and now northwest Africa. Still another is that the researchers say these fossils represent Homo sapiens, an assertion that will paleontologists will debate a good deal, I am sure. The faces were flat like ours and some other features were similar.
The interesting find is that their brains were about the same size relative to their bodies but were longer and less rounded in shape; our brains have some larger posterior areas that give height and round out our brain’s shape.
Here is my speculation: These areas still to develop probably included the parietal lobe and the part of the temporal lobe. Consider what these enlarged areas help to accomplish. On the left side the P-T (parietal-temporal) junction helps to maintain skilled motor patterns enabling handedness and motoric praxis, (this for right handed people) and just below that is an area involved in lexical memory, i.e., the ‘dictionary’ of words our brain relies on for comprehension (and some for production). On the right side the P-T junction is where Empathy Central lies, or what academics call Theory of Mind. This area supports our social insights and knowledge of others, and this in turn supports social praxis, i.e., socially skilled interactions. These would seem paramount in our functioning and so the later evolution of this neurological substrate fits into this speculative hypothesis. Finally, remember that the long cortical fasciculi, most notably the arcuate fasciculus (see several posts here about that fiber bundle) have their posterior origin in this area and their anterior origin in the frontal motor areas. On the left we know this tract enables verbatim repetition, i.e., mirroring the words heard, and the right I suspect is involved in the empathic mirroring of emotional expressions. Both types of praxis and mirroring are critical in the development of human intelligence. Pretty cool, huh? Well, much more to do today so I will travel on.