If you are interested in the brain, and you find yourself at a book fair where all the books are dirt cheap, you tend to pick up anything related to the brain. So, I have that every year when the annual book fair takes place in Maastricht. As a result, many books are left lying around for a few years, so that I forget about them. For example, the other day I found ‘Big Brain’ by Gary Lynch and Richard Granger in my closet. A book about how human brains got so big in our evolutionary history and how that relates to intelligence.
I had an idea that this book might be one of those gems where you get a fundamental new insight. Indeed, it begins with a description of the so-called ‘Boskops’, a species of people who would have lived tens of thousands of years ago, and which were found and named in South Africa. Early in the twentieth century there was much ado about these Boskops (this translates into ‘Forest Heads’ in English). Whether they lived in the forest or not, these heads were gigantic! Based on skull measurements, they would have had a brain size over 30% larger than today's human average. In addition, they would have had small faces and certainly not a larger body than us.
It is not automatically true that a larger brain goes hand in hand with greater intelligence. Elephants have a bigger brain than humans, but although they have notoriously good memory, they cannot be called more intelligent. Similarly, there are more animals with bigger brains than us, yet it is probably fair to say that we win against them on IQ. It is, in short, not about the absolute size of the brain. So how is intelligence related to the brain exactly then?
It turns out that the relative size of the brain, when comparing it to the body, relates to intelligence (or complexity of behavior). In other words, the larger your brain in relation to your body size, the smarter you are. This applies to comparisons between species of animals, not so much to individuals within a species. (In reality the ‘encephalization quotient’ is often used, which is the ratio between brain size and ‘predicted’ brain size for a given body size). Shown below is a graph of animal species where the relationship between brain and body size can be seen.
A couple of things stand out.
First, there is clearly a relationship between body size and brain size. This was to be expected, of course, because what would a mosquito, for example, do with a brain as big as that of an elephant?
Second, there are fundamental differences between categories of animals. For example, fish and reptiles (and dinosaurs) score significantly lower as a group than mammals when it comes to brain-body ratios. So, are they dumber? Probably yes. (By the way, this explains why I used to find my goldfish so utterly boring. If you want a dog, you should never get a fish instead.)
Third, apes as a group do score markedly higher and human species (H. Sapiens are us, H. habilis and A. Africanus are extinct former human species) score even above that. Men, as we know them, Homo Sapiens, clearly stands out: you can see a strong deviation of the ‘human cross’ in relation to the linear curve that runs diagonally upward and represents the general relationship between brain and body size. Dolphins, by the way, have a remarkably high brain-body size ratio. That fact was probably the inspiration for the opening of the movie ‘Hitchhikers Guide to the Galaxy’ (for me the highlight of the movie): ‘So Long And Thanks For All The Fish’.
Going back to our Boskops: these people had brains 30% larger than ours, without a larger body size. That's about the same magnification as our brains compared to the brains of H. Erectus, an early human species that could certainly be called primitive. How evolved must those Boskops have been? So, in the 1920s to 1950s, the discovery of the Boskop skulls was cause for much discussion. Were we Homo Sapiens not the most intelligent species to have walked the earth? Were the Boskops superior beings? Where had they gone? Understandable questions. Fascinating questions.
The authors of ‘Big Brain’ begin their book by asking why we haven't all heard of the Boskops. After all, the fact that they existed is a world-changer. They briefly indicate that it might raise too many difficult questions, that people found it an unpleasant idea, that there wasn't that much evidence after 1950....
However, unfortunately, a quick Google search is enough to paint a different picture. An expert John Hawks shrugged hard at the idea. There has been evidence that the whole thing is really just a misunderstanding. Indeed, the skulls found were disproportionately large, but not so large that one should automatically assume a new species existed. They will just have been statistical ‘outliers’, people from the ‘normal’ human species who had exceptionally large heads. That happens. There is always variation around an average. Humans also have an average height, but when future anthropologists discover the skeleton of soccer player Peter Crouch, they will be mistaken if they make that into a new human species. Not to mention the tallest human in the world (2.51 m). In any case, according to Hawks, there is no very strong evidence that there was a species of humans that had, on average, much larger brains than we do.
Too bad -- it was a nice idea. But it is now possible to extract DNA from old bones, to analyse whether a bone comes from one species, another species, or perhaps a new species. I say throw that Boskop in the grinder and let’s find out! Secretly, then, I do hope that there was another species of human, a human with superior cognitive abilities that didn't survive until today. Wouldn't that be exciting? Would it change your worldview?
Author: Tom de Graaf
Adaptation and translation: Melanie Smekal
