Little brain, lots of art

The world of human evolution is in turmoil these days. A team of paleontologists believes they have found ceremonial burials from 240,000 years ago, long before our species, Homo sapiens, came into existence. I say ceremonial because, according to these authors, it would not be simply a matter of putting the corpses underground, but of leading them through a labyrinth of tunnels dug by nature in the limestone rocks of the Rising Star caves in South Africa. The bodies appear in a fetal position and sometimes with a stone tool next to the hand. The walls feature engraved lines of a vague symbolic appearance.

Most scandalous of all, the inhabitants of those caves had brains the size of a chimpanzee. The species was already known, it is called Homo naledi and constitutes one of the most puzzling mysteries of human evolution.

Our pride of species deceives us. We need to think ourselves qualitatively different from other creatures, but everything we know about biological evolution, which is a lot, forces us to conclude that we are not. The six or seven million years that separate us from the chimpanzee are a geological blink, barely 0.2% of the history of life. The mental faculties of our species have produced poetry and art, science and literature, philosophy and politics, true, but there is no evolutionary time to make all that lace of neural bolillos with very specific and innovative strategies. The great hope of understanding our origins is that they can be explained by something as rude and unsexy as gross increase in size.

And the data added up quite a bit so far. Rounding off a little, the chimpanzee and the australopithecus had half a liter of brain, Homo erectus added another half liter that was enough to invent the tools and Homo sapiens gained half a liter more and became master of the world. A somewhat thick but quite effective story to explain our high capabilities without having had much time for them to evolve.

But then, how do you fit Homo naledi into the scheme? For starters, that a hominin with a half-liter skull lived only 250,000 years ago was already a shock when the species was discovered in 2014. Australopithecines had that cranial capacity, but became extinct millions of years ago. The other known exception is the Indonesian hobbit (Homo floresiensis), of which a dozen fossils have been discovered, but only one skull. And if the South African findings are confirmed now, it would turn out that half a liter of skull would be enough to perform mortuary rituals and even an ancestral form of art. Much of the profession does not fit even in painting. Articles about the Rising Star cave are still in the process of peer review, and scientists such as María Martinón-Torres, director of the National Center for Research on Human Evolution, do not believe it has been proven that the burials are deliberate.

That is the subject at the moment. If Homo naledi is shown to have little brain and a lot of art, we will need new theories about the evolution of the human mind. Maybe it's not all about size after all.

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