Neanderthal brains measure up to ours—literally

(When we talk about “intelligence,” we’re describing something complex and, frankly, rather nebulous; it’s impossible to truly quantify, but that hasn’t stopped generations of scientists from trying. Researchers who study cognition break it down into specific areas: attention, inhibition, cognitive flexibility, speech production and comprehension, working memory, and episodic memory. Some of these abilities are associated with particular sections of the brain, but these relationships are often complicated.)

So when we look at brain size and intelligence, the differences between human brains are relatively small compared to the differences between a human brain and any other great ape brain. For example, our closest relatives, chimpanzees, have brains measuring just 400 cubic centimeters on average; the average adult human brain occupies about 1,350 cubic centimeters. (And there’s a wide range, from about 1,100 to 1,500 cubic centimeters.)

So total brain volume is “empirically the best indicator of behavioral and cognitive abilities in primates,” but only if you compare different primate species. Within species, the differences are not pronounced enough to matter.

If you compare, for example, crows to dolphins, you need to take into account the size of the brain relative to the size of the entire animal, which scientists call the encephalization quotient; According to Schoenemann and colleagues, this is less relevant for primates, where it’s all about size.

It is with this in mind that a group of early hominids called Australopithecus afarensiswhich lived about 3.2 million years ago, had a brain of about 500 cubic centimeters. That’s a big enough difference that we can assume they were cognitively more like chimpanzees than us. On the other hand, the average group of Neanderthals had a brain capacity that matched that they performed about the same on cognitive tests as their counterparts. Homo sapiens neighbors.