The sons of Adam: spirit, not blood

A few years ago a statistical geneticist at Cambridge’s Sanger Institute, Luke Jostins, posted the chart above using data from fossils on cranial capacity of hominins (the human lineage). As you can see there was a gradual increase in cranial capacity until ~250,000 years before the present, and then a more rapid increase. I should also note that from what I know about the empirical data, mean human cranial capacity peaked around the Last Glacial Maximum. Our brains have been shrinking, even relative to our body sizes (we’re not as large as we were during the Ice Age). But that’s neither here nor there. In the comments Jostins observes:

"The data above includes all known Homo skulls, but none of the results change if you exclude the 24 Neandertals. In fact, you see the same results if you exclude Sapiens but keep Neandertals; the trends are pan-Homo, and aren’t confined to a specific lineage…. "

In other words: the secular increase in cranial capacity for our lineage extends millions of years back into the past, and also shifts laterally to “side-branches” (with our specific terminal node, H. sapiens sapiens, as a reference). This is why I often contend as an aside that humanity was to some extent inevitable. By humanity I do not mean H. sapiens sapiens, the descendants of a subset of African hominins who flourished ~100,000 years before the present, but intelligent and cultural hominins who would inevitably construct a technological civilization. The parallel trends across the different distinct branches of the hominin family tree which Luke Jostins observed indicated to me that our lineage was not special, but simply first. That is, if African hominins were exterminated by aliens ~100,000 years before the present, at some point something akin to H. sapiens sapiens in creativity and rapidity of cultural production would eventually arise (in all likelihood later, but possibly earlier!)...

Gene Expression