Why are some people smarter than others?

Factual Questions
1

And I mean people in general not nonsensical stuff about races. Is it something physical, something to do with differences in the brain itself? It surely can’t be environmental, too many dumb rich people and smart poor ones for that to be true. On the other hand it can’t be genetic, geniuses rarely spawn geniuses and many a moron has sired a really intelligent kid.

So if it is some difference in the brain what exactly is it? Is it size, the bigger the brain the smarter you are? Or is it like the penis, it’s not the size that matters it’s what you do with it?

My own grey matter, such as it be, needs a little help with this one!

2

If it’s not at least partly genetic, then why aren’t chimps as smart as humans?

How could humans have evolved to be as intelligent as we are if there was no genetic component?

It’s clearly both, since environmental factors such as nutrition have been shown to play a role. And don’t think that the two (nature and nurture) never interact in certain circumstances, either. It needn’t be a clean dichotomy.

3

Before you can answer the question of why some people are smarter than others, you need to define what you mean by “smarter”. People have been trying to define intelligence forever, and still cannot come up with a consensus. Plus, there are many types of intelligence, not all or which are measurable. Why do you think IQ test are so controversial?

4

Yes, smart is one of those words that it’s almost impossible to define. But on the other hand we all know a smart person when we meet one. Go figure.

5

Well, yeah. I mean, imagine you take two babies – identical twins – and you (a) place one of them with a family who’ll make sure he receives the best private education that money can buy, and you (b) shoot the other one in the head.

6

I think genetics does indeed play a big part, at least as a starting point. After that it’s just like athletics; the more you exercise the brain, the better it gets.

Knowledge doesn’t just appear in ones brain. Knowledge is acquired through education and experience. I’m pretty sure that if I had the drive and determination I could have been a lot more successful in life. Hey, I’m not complaining. I earn a very good living, but if it wasn’t for my like of slacking off and partying I could have really excelled.

Wayne Gretzky used to get up in the morning and spend an hour skating in the back yard rink before school each day in the winter. When he got home from school he spent time on the rink till supper. He ate, and then went back to the rink until bed time. He did this every day and all day on weekends for what, maybe 4 or 5 months a year. He no doubt had a predisposition genetically for athletics, but he practiced as much as he could as often as he could.

Now, imagine reading for knowledge an hour in the morning, five hours in the evening, and all day every weekend, especially in your formative years. How damned smart would you be by the time you were 16?

7

You’d be pretty knowledgeable. But I don’t know if you’d be smart.

8

You could as easily ask why some people are tall and others are short.

Every feature of humans is subject to
A) genetic variation
B) epigenetic variation
C) environmental variation
D) Social variation

The old “nature versus nurture” debates are 17th century science. We now know it’s all of the above in an endlessly varying mix.

As to smart people having average kids, or tall people having short kids, understand that by and large you don’t carry only the genes to make clones of you. If you have brown eyes that doesn’t mean every descendant of yours forever will have brown eyes.

Simplifying mightily, each of us carry the genes to make pretty much every kind of possible human. We as individuals only use a small subset of the genes we carry. So we’re able to create kids that aren’t clones of us, even after you consider the fact your kid is a mix of you and your partner’s genes.

A better analogy than “you are your genes” is there’s a gigantic deck of many millions of cards. At conception you draw a “hand” of a couple thousand of those cards.

Some of which are discarded and some of which are doubled or trebled during gestation. Depending on luck, food supply, weather, pollutants, etc. This process creates the fetal you.

Then you’re born and luck, food supply, weather, pollutants, etc. continue to work on you. As does your parents’ childrearing skills and social habits for good or ill.

With the end effect that you learn how to play some subset of your cards in the game called “society at your time and place.” You may be skilful or not. Or ref panache45, skilful at some things and sucky at others.

All in all “genes are destiny” is pretty much bullshit from end to end. With the exception of serious defects that foreclose a lot of what we ordinarily think of as being human.

9

the person who knows how to apply learns how to develop themself.

someone is plagued with adhd … first and second grade that child gets d’s and f’s in the classes. third year comes along … same student … same school … different teacher. within six months that kid who was failing everything has now risen to the top 2% of all in the nation.

while genetics and society may/mayn’t play a role … i would never discount any person worthy of the title.

10

I can’t disagree with that. I work with PhDs and a lot of them, although scholastically brilliant, are not known for social or interpersonal skills, and would have a hard time with conversational speech at a cocktail party.

11

Humans share 99.9% of our DNA with each other, and that remaining 0.1% makes up about 50-80% of our IQ differences. IQ is mostly genetic, a genius chimp is dumber than an average human. Various factors can lower it like environmental toxins, isolation, abuse, stress, etc. but I don’t think you can raise it much via environment alone (except for the Flynn effect, but I’m not sure if that is due to nutrition, environment or something else).

Chinahas engaged in and I think now completed a program to find the genetic traits that lead to high IQ (which I think they got from taking DNA from thousands of people with an IQ of 160+ and looking for what genes kept coming up). I believe they found it wasn’t one gene, it was thousands of minor variants each of which has a minor role in IQ. So they are hoping using this they can create smarter babies.

As to the physiology of the brain as it relates to IQ, I’ve heard it can be the fact that certain brain areas are wiredtogether better in smarter people. Another is the neural efficiency hypothesis.

Also are you talking about IQ differences between Homo sapiens, or are you talking about IQ differences between homo sapiens and other species? Human brains have tripled in size in the last 2 million years, going from about 500cc to about 1400cc now. So brain size plays a role, however elephants and dolphins have larger brains with bigger neocortex areas.

12

Knowledgeable doesn’t even equate to “scholastically brilliant”, much less “smart”. Being scholastically brilliant involves a lot of knowledge, its full integration, and ability to have insights that others may not have. Although don’t knock “knowledgeable” - it’s better than nothing.

13

aldiboronti writes:

> But on the other hand we all know a smart person when we meet one.

Really? I don’t see any evidence that we can know how smart a person is within a few minutes after we meet them. Often it takes months to realize how smart they are. For that matter, it’s not clear that some people are smart until fairly late in life. I think that showing how smart you are might be just as much about fairly random things in your life as the things that cause you to be smart. In other words, often it takes decades before a person gets put in a situation where they can show how smart they are.

14

The general rule of thumb that I’ve read is you are 50% genetic and 50% environment (because deep down, nobody has a serious answer). The Wayne Gretzky analogy is apt too. One theory says that your brian is still developing for years after you are born. How much you use your brain during that time especially, determines how good it is at being used for the rest of your life.

(I often wonder - the third world child is carried everywhere until they walk and see much of social life, then they are sat in the same room as a collection of adults having adult conversation, and allowed to run around the village. Modern North American children, by contrast, are stuck in a separate room staring at a ceiling a lot of the time. If they’re lucky, the same playtime mobile for a year. What little social input they get, a lot comes from television, a non-responsive medium. Then, in early adolescence when third-world children must deal with the puzzle and challenges of simple survival let alone succeeding, our adolescents are left to sit in a separate rec room and vegetate if they so desire - think Wayne’s World, but without the Mandarin fluency. So, third world children should be competitive despite their nutrition handicap.)

In Freakonomics, the authors argue that a person’s parents’ education as much as anything else determines their success in life. (Of course, statistics mean “in general” and there are always exceptions nd outliers) Your parents’ education generally determines (again, on average) how much money they have, how much effort they can put into your early education, etc.

If we accept that generally, minus a few outliers, 50% of your smarts is determined by genetics but most people fall in a fairly common band of “IQ” (whatever that means) because we all have approximately the same genes, better than chimps, then environment and educational effort makes all the difference. You could be 30% to 50% smart due to genes, but 0% to 100% due to education and early childhood environment. So education can make a big difference in some cases.

15

Yeah, well, we’ve known that for 14 years. :wink:

16

I’ve never hear that “rule of thumb” before. Where does it come from?

At any rate, it doesn’t make any sense since a severely malnourished infant could have permanent brain damage and severe reduction in cognitive ability. Same with deprivation of oxygen or exposure to some pathogens.

17

We always get ourselves tied into knots over this because we don’t approach it systematically. Here, at least, is one possible way to look at things:

There’s two axes here, genetic and environmental, where the environmental axis extends to the womb environment and therefore includes some congenital factors. On each axis, you have two broad fields, which you may call “Deficit” and “Bonus”, with obvious interpretations.

Or, I should say, the deficits are obvious, but it is not clear what should go in the bonus regions of either axis. That is what gets people tied up in knots, from what I see, especially since people tend to conflate knowing specific things with being able to use the knowledge you have, which comes closer to being a true measure of intelligence. Just memorizing a dictionary is not intelligence. Savants can do that, and one of the defining features of savantism is a sub-normal intelligence. Having a larger-than-average vocabulary you use competently is closer to being a sign of normal intelligence. Genius comes from using words—any words at all—in a novel and especially memorable fashion.

Add a few centuries of lionization and demonization cycles for various media (tell me: are novels considered to rot the mind or improve it this century?) and the permanent miasma of racism which settles on any discussion of the role of genetics (or its proxy, “culture”, especially “Those People’s culture”) in intelligence, and you have a field where being an expert makes you a target and there seems to be no assumption of good faith.

18

I am not sure why you dismiss “stuff about races” as “nonsensical.” As a general rule, “races” reflect continent of recent origin for source pool genes, and of course the history of human migration means that the average frequency for all gene variants–including those related to neurologic function–vary among “races.” For example, you would find a marked difference in the average frequency for MCPH1 Haplogroup D variant between (self assigned) whites and asians, and (self-assigned) blacks. This is because those self-assigned races tend to correlate with their continents of recent origin, and MCPH1 Haplogroup D only arose about 40,000 years ago. It has since achieved very high penetration in post-africa groups, but very little back diffusion into sub-saharan africa (perhaps with the exception of the horn) because of human migration patterns.

Anyway, the way to look at genes and brain function is to think of genes as providing a substrate upon which the environment acts. That substrate (nature) provides a ceiling beyond which the environment (nurture) cannot excel. You can’t get a chimp to read and write worth a damn, and you can’t get the Pedant to understand advanced math no matter how good the nurturing is. You can make either of us “smarter” with good nurturing. But only smarter than we would be with lousier nurturing; not smarter than our genetically-programmed ceiling.

We don’t know nearly enough about genes and their interplay to identify which genetic combination is great. We do have some teasers. Here is an example that looks at processing speed. And every gene has a wide variety of variants each of which may affect intelligence, alone or in combination. For example,one study showed if you substitute a single instance of thymine for cytosine in the HMGA2 gene, you increase intelligence about 1%.

19

Then maybe we could consider three factors are relevant - genetics, environmental (i.e. nutrition, diseases, etc.) and stimulation (exposure to language, experiences, puzzles, things which give the brain a workout and develop novel connections between the brain cells).

But yes, if you start with the same 50% brain power as anyone else but completely fail to develop it due to oxygen starvation or severe malnutrition or blunt force trauma - then the person will be in the category of 50% of normal intelligence. IQ of 50 is pretty close to being a rutabaga. If the genes in that case developed brain function enough to keep breathing and heart going, then the genes have done their part. Ability to swallow food and drink would be a bonus - 51%.

20

The OP might be interested in the Flynn effect. In fact, you can see James Flynn himself speak about it in this TED talk.

The Wikipedia page lists a bunch of hypothesized factors explaining why IQ scores have gradually increased over the course of many decades; the same explanations might also explain why any given person alive today might be smarter/dumber than another person also alive today. One of the more interesting explanatory theories, IMHO, is the idea of a generally more stimulating environment than what one might have experienced 20/50/100 years ago. We who are alive today have been exposed to far more intense and varied sensory stimuli and far more varied ideas than a person our age in 1916, and according to this idea, it’s made our intellects into more capable pattern-matching engines than our ancestors.