As an article from the Daily Mail points out, early Homo sapiens had bigger brains than we do. Cro-Magnons, living in Europe perhaps as early as 45,000 years ago, had 10 percent more brain than the average human today. (Neanderthals had bigger brains, too, but, unlike those of Cro-Magnons, theirs grew in a differently shaped skull.)
So does this mean that Cro-Magnons and other big-brained earlier humans were smarter than us? Not necessarily, but it also doesn’t mean that they weren’t smarter.
An expert cited in the Daily Mail article gives a more common opinion:
Dr Lahr thinks that part of the answer may lie in improving efficiency ... 'We may have smaller brains than early humans but it doesn't mean we are less intelligent,' she said.
- our brains are smaller than those of our more-recent ancestors (e.g. Cro-Magnons) and
- we don’t actually have a good definition of intelligence or an understanding of the relationship between brain size and smarts, however defined.
This second issue means that Lahr is technically correct: brain size might change for any number of reasons without affecting intelligence, depending on how we define it. But many researchers do assume that increasing brain size accompanied greater “intelligence” among earlier species in our line, say from Australopithecus afarensis (“Lucy”) to Homo habilis. So why would that association between size and smarts stop once brain size decreases in our species? Could it be that researchers suffer from an emotional stake in our superiority?
(By the way, we could begin to test Lahr’s idea by comparing a series of skulls within various species to see whether it is common for brain size to decrease in this fashion.)
Maybe, as individuals, we actually are less “intelligent” than our ancestors, whether due to dietary changes or to some other cause. For these purposes, let’s consider intelligence to be the combination of our cognitive flexibility and creativity. Flexibility is basically the ability to learn and remember, and creativity is the ability to produce new ideas or combinations of ideas. Why wouldn’t a hunter-gatherer – moving throughout a large and varied landscape and frequently encountering different people, plants, places, and animals – need more intelligence, thus defined, than a sedentary farmer? Or a factory worker? Or a blogger?
If our ancestors were capable of more flexibility and creativity than us, would that make us less valuable?