(1) There's been a dramatic increase in our brain size over the last million years, is just a coincidence that we've also gotten way smarter?
(2) What about the high correlation between brain volume and IQ within humans?
(3) What would the evolutionary purpose be of supporting such an expensive organ if its size is irrelevant?
Imagine you bought one of those high-capacity SSDs off AliExpress, and unbeknownst to you, what you got is a small flash drive in an SSD enclosure, cleverly preformatted to report it's 10x as big as it is.
You install your OS on this drive, and happily do your work, but then you start realizing that some files are going missing, even though you're sure you've saved them...
Something similar may be happening with the brain - perhaps the core compute runs on the surface layers, but that doesn't mean non-critical functionality isn't occupying the deeper parts, and a person with less of those parts may not realize they have decreased capacity.
That's at once fascinating and existentially horrifying to me.
I need to know more...
I have wondered if Alzheimer’s preferentially damages certain parts of the brain? And also if eventual death is unpredictable because it depends on when the damage interferes with autonomous bodily functions such as heartbeat, breathing, or gut peristalsis?
I'm not going to say that you're morally reprehensible, but I do recommend reading about the Flynn effect. The variance in IQ between modern whites and whites 100 years ago is significantly higher than any measurable difference between whites and blacks today. In addition to this, the IQ of blacks is rising at a faster rate than the IQ of whites, and seems to be approaching convergence. Looking at changes over time, it seems that average IQ in large population groups is mostly a function of culture rather than genetics.
For the American "black"-"white" IQ gap itself (and I think it's very important to specify American, as conclusions about "blacks" in the USA are likely to be very misleading if applied to Botswanans for example) the I found a few seemingly contradictory studies, but it looks like the childhood gap is closing quickly (3+ IQ points per decade) while the adult gap is closing much more slowly (<1 IQ point per decade).
Do you have any good sources on this?
Probably environment more than culture (unless you are counting environment in that). Just look at the effects nutrition during pregnancy has or the effects lead has on IQ.
https://www.sciencealert.com/iq-scores-falling-in-worrying-r...
Noob me: Sure, some fraction of IQ is hereditary for individuals. But there's no correlation between hereditary (genetic) IQ and group sizes larger than families, and mosdef none at population levels.
PS- Reprehensible is the nicest adjective I can think of for those retrograde beliefs.
Head into a college library, maybe into the biology or genetics section, crack a book from twenty years ago thats not well known. Read dissertations, there are bodies of knowledge inside universities and medical professions that aren't exposed to the public.
It's less about uncomfortable topics being actively covered up by nefarious actors, and more about bad ideas dying out naturally. The main reason we don't study correlation between race and IQ is because it isn't useful and doesn't explain anything particularly interesting.
For evolution to work, IQ has to be heritable, otherwise how did humans evolve intelligence? People who believe in evolution, but not in heritability of personality traits are living in a warped reality. I'm not that interested in proving my point, I'm just more shocked at how many people hold obviously false beliefs.
Intelligence and other personality traits are of course heritable, but controlled by thousands of genes that are unlikely to shift significantly over the course of around 50,000 years.
Intelligence and personality are also a result of culture, and we've seen a 30 point increase in IQ scores in a single century, and a similarly spectacular drop in violent crime rates.
If you honestly believe racial genetics are a significant factor, you are either willfully ignorant or unable to engage in complex thought processes yourself.
This sounds pretty convincing, but it seems to prove too much. Doesn't this also refute the idea of individual gentic differences in intelligence? Which we know exist due to the incredibly high heritability of intelligence?
Couldn't whatever allows these differences to exist not vary in strength depending on the emvironmental pressures sustained over thousands of years?
> thousands of genes that are unlikely to shift significantly over the course of around 50,000 years.
Check out this plot of brain size over time[1]
If we can have such a dramatic increase in brain volume over a 500k year window, then we can absolutely have nontrivial changes to intelligence in a 50k year window.
> Intelligence ... are also a result of culture
The reason I doubt this is transracial adoption studies where the child is adopted out at birth to well-off white parents and tested at a very young age. So I can plausibly see how bad prenatal nutrition could have reduced this kids' IQ but attributing it to culture stretches credulity a bit, in my opinion.
(I could be wrong about that though, as the kids weren't that young, so it's plausible that there's some cultural influence from early school friends, but I still think that it strains credulity).
[1] http://aquatic-human-ancestor.org/anatomy/images/brain-size-...
Basically, your perspective on IQ and heritability is very cartoonish. I'd suggest spending some time on wikipedia. I'd also familiarize yourself with the classic rebuttal of The Bell Curve, which clarifies the difference between heritability and genetic determinism. Culture and social complexes are heritable.
So, presumably, you are talking about something else.
There are ways of categorizing people into different groups which do not cleave reality at the joints.
The further some such categorization is from cleaving reality at the joints, the more foolish one would have to be in order to be preoccupied with an alleged connection between the categories in such a mistaken categorization, and intelligence.
But as it happens, rapid improvement in socioeconomic indicators were seen in the black population, which is the demographic group most commonly alleged to be a victim of systemic discrimination, BEFORE the rise of social welfare spending, and before the post-civil-rights-era racial victimhood culture (e.g. homicide rates among black Americans declined in the 40s and 50s), so the facts are actually quite supportive of the nurture side of the nurture vs nature debate on the causes of racial disparities.
I highly doubt it. Why exactly do you think this? Because some traits have been associated with intelligence?
I’m not talking about it being correlated with other traits, just intelligence itself being heritable. Well, I say “itself”, I imagine the same genes also have other impacts on other unknown things that are not noticed, because the interactions between genes is super complicated (I think?), but that’s practically the same as “itself”.
Why else would intelligence be attractive, if it weren’t heritable?
This one? It does not indicate nearly the certainty that other commenters here do. Read it yourself, it's a good argument for what I'm saying. The GP characterized this scientific debate as settled, yet there is actually very slim evidence in that article for what is being claimed.
Why would it be surprising if among 1000s of the highest IQ individuals in some particular place, that there would be genetic similarities between them? It's completely possible that large groups among these people share a closer familial lineage far back into history that has influenced their present-day social and economic status, which are the factors that are actually responsible for developmental health and correspondingly intelligence, and so the genetic similarity is just a byproduct of the conferral of wealth and status between generations over a long period of time.
Your third paragraph makes me suspect you don't know how twin studies often work. The idea is that you measure the IQs of genetically identical twins and compare how similar they are to how similar non-identical twins are. This lets you isolate what is purely personally genetic.
No it doesn't. Not at all actually.
https://en.wikipedia.org/wiki/Twin_study#Criticism
Maybe an actual geneticist can jump in here, but it's my non-expert opinion that you all are jumping to conclusions about a topic that you're not experts in either.
The very first critique is basically a nitpick. Yes, figures will be overestimated, but not taking into account air resistance when dropping your bowling ball off the tower of Piza isn't going to invalidate a conclusion that gravity is an accelerational force of at least 9m/s^2.
In fact, with the exception of the statistical critique by the guy with a giant axe to grind it seems mostly nitpicking. Dr Axe Grinder seems to mostly be critiquing the additive model, claiming it gives wrong results, but more recent papers (such as Polderman et al (2015)) seem to say that the additive model is mostly correct. And given the latter paper is a many-author meta-analysis rather than an emotionally charged rant by a single professor and is much more recent, I'm inclined to go with the latter paper.
There are other problems with twin studies, most importantly that developmental health starts at conception which means that genetics are not the only thing that twins are sharing. Once again I'll refer you to Wikipedia for further criticisms of twin studies:
There have been many many papers from many angles on this over the years. The high heritability seems to be a well established fact.
This is all not to mention that 'race' is not a biological construct, and virtually none of these studies actually check the genetics of the individual. They simply assume that black skin correlates with a particular genotype, without any reason to believe that thr genes for skin color are in any way correlated with any genes which could predict IQ.
It would make more sense to compare IQ across geographical locations, since geographical separation is a strong predictor of genetic separation as well. However, there you end up with huge confounding factors stemming from culture when trying to measure IQ.
"Representative Percy Quin of Mississippi, spoke of lynch law, "Whenever an infamous outrage is committed upon a [Southern] White woman the law is enforced by the neighbors of the woman who has been outraged? The colored people of [the South] realize the manner of that enforcement, and that is the one method by which the horrible crime of rape has been held down where the Negro element is in a large majority. The man who believes that the Negro race is all bad is mistaken. But you must recollect that there is an element of barbarism in the black man, and the people around where he lives recognize that fact." (Holden-Smith, 1996, p. 15) "
Admittedly it would be interesting to take a million people, give them various sorts of cognitive tests, do a DNA sample, feed in biographical details, and let 'er rip on a big ol' computer. There might be outrage and a need to twiddle knobs on the AI or there might be nothing noteworthy. Some Chinese researcher will let us know soon enough.
Which you are a perfect example of, I’m sure.
IQ results are of some use in predicting how well children will do at school, i.e. what exam results they will get after being taught. That's usually a "success criterion" for the school, though not necessarily for the children, who may have other goals in life, e.g. becoming a footballer.
I don't know much about soccer beyond pickup games, is it roughly as cognitively demanding as football at the highest levels?
[1] https://jobdescriptionandresumeexamples.com/10-important-fac...
[2] https://wonderlictestpractice.com/how-does-the-wonderlic-cor...
[3] https://clutchpoints.com/patriots-news-new-england-requires-...
Human assumptions about intelligence are debunked by facts.