[Pyxl101]

I think you're making a good point overall. If a trait is heritable then it will vary by populations. People should understand the consequences of the position they're arguing.

However, why do you believe that IQ is not heritable? It's hard to believe there is no genetic component that is heritable. Humans evolved over time from other species, and in the process of evolving into Homo sapiens sapiens, their intelligence was inherited and selected for strongly. There's nowhere else for the foundation of human intelligence to come from in the first place other than inherited genetic traits.

As a peer comment asked, "If IQ is not heritable, then how did it evolve?"

I suppose it's possible that a large component of intelligence could come from society and nuturing. Humans have gotten more intelligent as their diet has improved, and as their diet has become more stimulating, and with writing and education. Still, the fundamental capacity to have a verbal or written culture, and to teach and learn, arises from our baseline intelligence which is possible due to our genetics.

To be fair, you might believe that all living humans have indistinguishably similar IQ at birth. There are reasons to believe it's not true, but it's a consistent belief. However, it would not be sensible to believe that IQ is stable over time, since we know that humans evolved IQ that was not previously present in proto-humans and ancestral species. Therefore IQ must be subject to genetics, and therefore must be partially heritable. From this position you might believe that IQ is heritable but does not genetically vary to a meaningful degree in modern populations. This position makes sense.

However, by comparison, it would be fairly incredible to believe that IQ is not heritable whatsoever, especially given that intelligence is affected by physical traits such as size of skull and brain, and by metabolic pathways and disease and disease resistance. Brain size for example is correlated with intelligence [1]. A number of diseases are known to affect intelligence, such as phenylketonuria. I understand in your comment you acknowledged that such diseases might impair someone and drag their intelligence down -- but just as different people have different potential as athletes, as measured by their VO2max, why wouldn't you believe that the physical systems underlying intelligence couldn't be just a little bit different in one population versus another, thus resulting in a little bit of an edge in IQ? Humans are so different in height, weight, muscle, skin/hair/eye pigment, that it would be incredible if we all were exactly, immeasurably different on some treat that also distinguishes humans from other species.

Science has explored this topic, and my understanding is that modern research on this topic suggests that IQ is heritable. Studies examine factors like twins who were separated at birth, and grew up in different households. Could you share the reasons why you think it is not?

> Various studies have found the heritability of IQ to be between 0.7 and 0.8 in adults and 0.45 in childhood in the United States. A 1994 article in Behavior Genetics based on a study of Swedish monozygotic and dizygotic twins found the heritability of the sample to be as high as 0.80 in general cognitive ability; however, it also varies by trait, with 0.60 for verbal tests, 0.50 for spatial and speed-of-processing tests, and 0.40 for memory tests. In contrast, studies of other populations estimate an average heritability of 0.50 for general cognitive ability.

https://en.wikipedia.org/wiki/Heritability_of_IQ#Estimates_o...

[1] "Overall, larger brain size and volume is associated with better cognitive functioning and higher intelligence. The correlations range from 0.0 to as high as 0.6, and are predominantly positive." https://en.wikipedia.org/wiki/Neuroscience_and_intelligence#...

[hodwik2]

The change in the brains from early protohumans to homo was a change of kind not quantity. We evolved new mental apparatuses.

On the other hand, from homo habilis/erectus to human, I do not believe there was a drastic change in kind of mental capacity, but rather, in a slow build in the technology of language made possible by our new mental apparatuses, which finally provided us a means for expressing and exploring complex ideas.

The brain is a very complicated system. Like other complicated systems, it is very easy for it to break from small changes (and thus we see mental disorders). On the other hand, it is nigh impossible to make a very complicated and robust system more effective -- a small change here or there generally won't do it.

So, barring us finding major physical differences in the brains of the general populace, they would seem to me to operate with roughly a uniform capability.

The difference that people ignore between the evolution of the brain and visible traits like skin color, is that skin color is a very simple system. We can expect it to change quickly. On the other hand, for human mental capacity to change would require enormous amounts of time because of the complexity involved.

It's possible there are modicums of difference in their operation, but it is unlikely to make a measurable difference between humans when compared with differences in the software of nurture, of culture, of 'thought'.

As with computers, you'll get more out of a little software tuning than you will by shrinking transistors by a nm, and software tuning is much easier.

As for twin studies, see my comment above.

[internaut]

Hello

You've made a number of interesting observations that I never quite considered before. Do you have a blog/book/other source you would point to that encapsulates these ideas?

I also have a question: if what you're saying is true then why is general formal education so poor and ineffective? Is it that we're not tinkering at the right level with the 'firmware'?

[hodwik2]

I was inspired heavily by some chapters in the book "Intellectuals and Race" by Libertarian theorist Thomas Sowell.

You can hear him talk about it here: https://www.youtube.com/watch?v=H6ImP-gJvas

[cmiles74]

I understand your point, and I think I understand that of the original parent comment. I don't have much to add, except that believing intelligence is not heritable strikes me as a well thought-out and, in my opinion, largely constructive decision. Up until this very moment, I have always been interested in the reality of this idea; that is, what is true and what is false. Just now it has occurred to me that there is also a political component to this idea, as well as very real moral issue.

After reading through the comments and trying to suss out the logical conclusions of the idea "intelligence is heritable", I have decided to make the same decision.

From here on out, my position is that intelligence is not heritable. This is what I will tell my children and grandchildren. When they ask why, I will tell them that I simply believe it to be true. That it "feels right" to me and the alternative feels truly wrong.

In terms of the science and what is actually happening in the physical world, what measurements and testing actually prove: I am not interested and will not take part in the discussion as I find the idea that intelligence is heritable to be morally wrong. Maybe there is some giant leap humanity could make, and maybe millions of lives could be saved, but I don't care; I think the idea is abhorrent enough that I personally do not want to take the risk.

I'm not trying to preach, but point out that there's more to it than the science and what is objectively real.

[hodwik2]

I would argue that it is dangerous to hold an idea just because it 'feels' right.

I'm on the not heritable side because I think that's what the science will show, given my understanding of how complex systems work.

It would be immoral not to understand intelligence heritability if it were true -- how could you help those who were disadvantaged if you were not aware of it?

[cmiles74]

You make a good point. If we were to understand how intelligence works and if it were to be heritable, it may be possible to ensure that everyone had some baseline of intelligence. That may be beneficial.

Maybe I've lived in the United States for too long, but it seems inevitable to me that we'll end up with a tiered system. Perhaps there will be some baseline intelligence level everyone is entitled to, but the very wealthy will surely be able to pay for even more intelligence. Likewise, if intelligence was this well understood, a measure would be applied to everyone. Perhaps it would be like your credit rating and this could easily be used to discriminate in a wide variety of ways.

IMHO, some people like to box others off and say: these are lesser than me. Should science support this opinion, this will only encourage the behavior. To me, this is the basis of the argument we're seeing on this post. Some see intelligence as heritable and, inevitably, somehow favoring one or more ethnic backgrounds.

In terms of the "just feels right", I think that the science on this issue is less than clear. Some things point towards heritability, others do not. The idea that some ethnic backgrounds may engender more intelligence than others is to me an idea so poisonous that I simply reject it on moral grounds.