The Tweet: By socializing we out-lived bigger brained Neanderthals. Explains why tweeting has made my brain smaller.
Guessing Intelligence From Brain Size
Deducing intelligence level from brain size is an idiot’s errand yet some modern humans feel up to the task. Count me in. Much is being made of Gerald Crabtree’s article Our Fragile Intellect in the journal Trends in Genetics. Crabtree writes,
New developments in genetics, anthropology, and neurobiology predict that a very large number of genes underlie our intellectual and emotional abilities, making these abilities genetically surprisingly fragile.
I would wager that if an average citizen from Athens of 1000 BC were to appear suddenly among us, he or she would be among the brightest and most intellectually alive of our colleagues and companions, with a good memory, a broad range of ideas, and a clear-sighted view of important issues. Furthermore, I would guess that he or she would be among the most emotionally stable of our friends and colleagues. I would also make this wager for the ancient inhabitants of Africa, Asia, India, or the Americas, of perhaps 2000–6000 years ago. The basis for my wager comes from new developments in genetics, anthropology, and neurobiology that make a clear prediction that our intellectual and emotional abilities are genetically surprisingly fragile.
And I would wager that if such an average Athenian were to suddenly appear among us it is highly likely he would be a boring buffoon. He wouldn’t know anything about the Beatles, the Simpsons or the original Star Wars trilogy. He wouldn’t know how to use a computer, drive a car or cook an ethnically diverse meal. And he wouldn’t speak modern English (or modern Greek for that matter). He would have to learn it all from scratch and there’s no guarantee, no matter how big his brain might be, that he would learn it.
Taking into account that he is an AVERAGE ancient Athenian (or African, American, Asian) not a super-human Athenian, he might give up learning about modern life for the same reason we give up on our New Year’s resolutions before the arrival of February: it requires too much of us emotionally.
This is no small consideration as our emotional and social intelligence most likely gave us the advantage over the bigger brained, physically stronger Neanderthals thousands of years ago. They had brains and brawn but we had the ability to share information, cooperate, innovate and drive the Neanderthals to extinction.
Imagine instead of a Athenian, a Neanderthal were to be magically transported to modern times. The big brute would be better at fighting off lions and snakes, foraging for food and beating the crap out of a modern human competitor. But he would not be able to write out an effective resume, pass a job interview, flirt with a fellow employee, woo her into marriage and make babies. If he doesn’t get around to procreating, that big brained Neanderthal can say goodbye to his genes.
Just because our average ancient Athenian has a bigger brain doesn’t mean he’ll walk as a genius among us. Intelligence is not directly proportional to the amount of brain mass crammed into a cranium.
Intelligence is related to the ability of a brain to store and deliver useful ideas and behaviors. Sometimes a smaller brain with more connections can be better at delivering results.
Imagine a circle with one vertical and one horizontal line inside it. Now imagine a smaller circle with a bunch of squiggly lines inside it. The smaller circle would make a better brain because it has more connections and can hold more information. It has greater neuronal complexity.
Or better yet, for a more real world example, consider this: would you rather have a computer from 1978 built around a chip containing 29000 transistors or a computer from 2012 built around a chip half the size containing 29 million transistors? I thought so.
Why are some brains bigger than others? One reason is large animals have more body mass than small animals. The greater the body mass, the bigger the muscles needed to move that mass. Big muscles require a proportional amount of brain mass, hence large animals have big brains.
An elephant is one of the largest animals on the planet and its brain weighs six kilograms. But I’m not about to trade in my small brain for an elephant brain. I’m no Einstein but my puny brain could probably beat an elephant’s brain in Jeopardy. Probably.
Furthermore, brains are highly active areas of the body, human brains especially so. Our neurons are firing away while processing data from our senses. This constant neuronal activity burns energy like a Hummer burns gas with our brains slurping up to twenty per cent of the food energy we ingest. With that much energy consumption it pays to make brains smaller and more efficient. Again, brain size doesn’t directly correlate with intelligence. Smaller brains could be better, more efficient processors.
Another reason the average ancient Athenian might not be “the brightest and most intellectually alive of all our colleagues” is because there are more people are alive today on the planet than were in ancient Athens.
Any complex trait such as intelligence varies across a population. The greater the number of individuals in a population, the greater the likelihood of an increased number of individuals at every point of the intelligence range. That’s why there are more geniuses living now than there were in ancient Athens. Heck, there are probably more geniuses living in modern Athens than there were in ancient Athens. It’s a pure numbers game.
A last point to consider is that intelligence is also affected by the number of good ideas our brains are exposed to. The more good ideas they have as a jumping off point, the more good ideas they will generate. Modern humans are part of a robust network of ideas that can produce many, many more advanced ideas than the idea network of ancient Athens.
The intelligence of an ancient Athenian would be hampered by not having been exposed to the scientific and political ideas of the last two millennia. And the ancient Athenian may not have the cognitive bandwidth to pick up and assimilate those ideas wholesale in adulthood.
So what about an average ancient Athenian baby instead of an average adult? If such a baby were to be transported to modern times and grow up being exposed to modern ideas, would that kid be the smartest cookie in the class? The answer is a resounding maybe. Remember we’re talking about an average ancient Athenian baby. Statistically speaking some modern kids will be smarter than the average Athenian kid.
If instead of an average baby, we were to take the smartest baby born in the entire ancient world and match it against the smartest baby born in the modern world, the modern kid could possibly be smarter because more kids are born today. More kids born means a greater likelihood of the birth of an off-the-scale smarts baby.
The same goes for modern adults too. A bigger adult population means a greater chance of an off-the-scale smart adult alive today. Hence, if we magically transported Euclid himself to modern Cambridge, there is no guarantee he would be able to understand what’s bouncing around in Stephen Hawking’s head.
Neuronal complexity, network effects, and a bigger global population all increase the likelihood that we can find lots of people today who will be much smarter than the average ancient Athenian.
Profressor Crabtree, I’ll take your wager any day of the week ’cause I’m no dummy.