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Making the Mind: Why we've misunderstood the nature-nurture debate (2003) (bostonreview.net)
73 points by huihuiilly 21 days ago | hide | past | web | favorite | 75 comments

According to the gene shortage argument, genes can’t be very important to the birth of the mind because the genome contains only about 30,000 genes, simply too few to account even for the brain’s complexity—with its billions of cells and tens of billions of connections between neurons—much less the mind’s. “Given that ratio,” Ehrlich suggested, “it would be quite a trick for genes typically to control more than the most general aspects of human behavior.”

To me, the clearest argument against this position is that horses can walk within a couple hours after being born. That doesn't seem like anywhere near enough trials to learn how to walk from first principles. The method to walk must be encoded in the horse's DNA.

Humans can't walk at birth, obviously. But Occam's Razor suggests that if the ability to walk can be encoded within a horse's DNA, it can also be encoded within a human's DNA.

Anecdotally, when I watch a baby learn to walk, it doesn't really seem like they are trying a zillion things and picking the one that works. It seems much more like their instincts are telling them to move a certain way, and once they grow strong enough, it succeeds and they are walking.

> According to the gene shortage argument, genes can’t be very important to the birth of the mind because the genome contains only about 30,000 genes, simply too few to account even for the brain’s complexity—with its billions of cells and tens of billions of connections between neurons—much less the mind’s. “Given that ratio,” Ehrlich suggested, “it would be quite a trick for genes typically to control more than the most general aspects of human behavior.”

Yes, even regardless of other examples you have provided, that's just basically bad poor logic in the article? Why would anyone assume that the number of connections of neurons would need to linearly relate to the number of genes describing them? What if a couple of genes describe a process that is then repeated for a billion times during development?

The article presents this idea specifically because it is incorrect, and goes on to explain the newer, more accurate understanding of genes, which is (as far as I understand it) that they encode various options and patterns that can be leveraged by the organism in different situations, not a rigid plan to be executed by the cells.

I don't understand why that is supposed to be a "new understanding". I think it was the understanding all along (or at least most of the time).

Isn't even the famous moth that changed color in the early days of the industrial evolution an example? I think it carries both genes (for black and white expression), and they get triggered depending on the environment during development. https://en.wikipedia.org/wiki/Peppered_moth_evolution

I could be wrong about the moth, but certainly, genes that are only expressed depending on environment are common knowledge.

I'm going to provide some anecdata. As a new father, you get to talking with a number of new parents too, with kids that are similar in age to your own. One of the potential downsides to this is that when you talk about your kids, you start to compare them to each other and create a competition where none should exist. It's hard, but as a new parent, you should really try to avoid this and instead focus on nurturing your child to be the best he/she can be.

(Aside: what's the currently accepted pronoun there? I was always taught "they" is incorrect grammar, but without devolving this discussion, that seems to be accepted now?)

My son is 13 months old now, and crawls like a maniac, ever since he was roughly 5 months old. Very social, talkative, active, all those good things. Pulls up and stands all the time, can climb in and out of toy vehicles, climbs stairs, all of that. When I hold him while he stands, he is barely putting any weight on me. Even if he's not walking, he should be able to stand on his own. But he doesn't, and he absolutely refuses to do so. He sees cousins and other big kids walking, and isn't afraid to crawl to them and play, but it doesn't inspire him to walk.

We know a lot of other kids that are younger than him, his age, or a few months older, and they are walking. He's stronger and more capable than them, but they're walking and he isn't.

My wife and I comment on this fact all the time, about how it seems that walking has nothing to do with strength, and it's more about readiness. I doubt that my son isn't walking because he's not strong enough, nor is it because he doesn't have a good environment, save for the fact that I'm not pushing him to walk (i.e. I'm enjoying the calm before the storm.)

Readiness for walking is definitely dependent on a number of factors, but I'm willing to bet that genetics is a big part of it too. Apparently I didn't really walk until I was 2 years old.

Babies and walking is a very interesting phenomenon that really lets you see into the working of genetics and environment.

Quick reply to your aside: singular they is very grammatical and has been in use for centuries.

From Merriam-Webster: "they has been in consistent use as a singular pronoun since the late 1300s; that the development of singular they mirrors the development of the singular you from the plural you... and that regardless of what detractors say, nearly everyone uses the singular they in casual conversation and often in formal writing."[1]

[1] https://www.merriam-webster.com/words-at-play/singular-nonbi...

All politics and grammar rules aside, I personally find 'they' to be really confusing when referring to a specific person.

IE: "is Pat coming to lunch with us?"

"Yes, they're coming in a moment."

Leaves me wondering if 'they' is perhaps referring to some implied group of which Pat is a part, like a SO or team at work (meaning we might need to take two vehicles and get another table at the restaurant) or just Pat.

I wish there was an acceptable non-gendered singular pronoun we could all agree on.

It doesn't solve the pronoun problem but if you haven't heard of them, Grice's Maxims[1] are fun to know about. Basically the idea is that you can generally assume that people you're talking to will follow certain rules, and that allows you to make assumptions. So in your example, you assume that your friend is following the maxim of quantity which allows you to conclude that if there were more people than just Pat, then they would have mentioned the others.

[1] https://www.sas.upenn.edu/~haroldfs/dravling/grice.html

[2] https://en.wikipedia.org/wiki/Cooperative_principle

Yeah, but in practice, "they" is used to describe the plural. Singular they might have been in use, but in the modern context, typically only brings confusion. Not to mention screwing with sentence flow.

Singular they are? they is? Both seem pretty offputting to me.

That's confusing because "are" ("they're" is a contraction of "they are") is used for the plural. "They is" would be singular, just like "he is" or "she is". It would be ungrammatical for plural "they", but AFIACT is correct for singular "they".

So the unambiguous (but weird sounding to those unused to it) version:

"Is Pat coming to lunch with us?"

"Yes, they is coming in a moment."

> "Yes, they is coming in a moment."

Perhaps one of:

"Yes, they will be here soon / joining us shortly / along later."

would be better.

> "Yes, they will be here soon / joining us shortly / along later."

None of these clarify singular vs plural of 'they.' All of them work whether 'they' refers to one person or multiple.

Good point.

This is true, but despite this, depending on what writing style or audience you're targeting, singular "they" may still be considered incorrect.

Also if you're in the US, the use of singular "they" can be intertwined with certain politics and legislature, but that only matters for legal documents and government publications.

For casual speech, though, singular "they" is certainly correct and widely used.

Thank you! I'll file that correction in my brain.

Not sure if you have more than one kid of your own but fwiw having more kids definitely reduced this kind of anxiety for me. With my first it was really hard to not compare him to other kids (like you mentioned) even though I knew intellectually it wasn't helpful for either of us to do so. With the second they were so incredibly different from each other despite being raised in the same environment that it became much more obvious how silly it would be to compare them to someone else in a totally different environment. Now we have three and the idea of having free time to spend worrying about stuff like that seems like a luxury for the well rested.*

* An exaggeration, of course. We got a few hours of sleep in a row as recently as last week.

My wife and I are watching these differences play out in real time between our twins and it's causing a layer of latent anxiety to form. "Oh, no, Baby B is developing at Thing X faster than Baby A. Is there a problem? What do we do?" Of course there's no problem, of course the thing to do is remember that there's no problem. It's hard to maintain that state, though.

You're absolutely right, my older one was super-athletic - rolled over at 2 weeks on the doctors examining table, crawled till his knees bled ( even got those knee protectors, lol!), walked at 10 months. But he lagged when it came to speech, barely spoke till he was 2 months old. But now at 7 he can't stop speaking. I feel, some faculties develop very fast and some just take time. I see parents coming to the soccer class, compare their kid to my son and just feel really shitty that their kid can't do what he does. I have to tell them, that's his proclivity, he's not great at reading, writing, but anything physical he's a beast.

My son was like that. He was an earlier crawler. He became very good at crawling, standing and going back to the floor. But he was a very late walker. For him walking was less efficient. Turns out, walking age is not really an indicator. What is important is the age at which they try to move from one place to another. It doesn't matter if they crawl, some kids move sitting and pull themselves with one leg.

It's hard to separate out what is a lack of strength or coordination and what is random trial. When babies learn to do basically everything, they do a tremendous amount of random flailing that gradually (over weeks or months or years) resolves into the thing they're trying to accomplish.

I think some people interpret this as babies just becoming strong enough to do things they innately know how to do, but with my 4 children, it's always struck me as learning through trial and error, like the neurons and muscle fibers gradually form in a way that is something like the average of all the ways they tried to achieve a goal. That's just my perception, of course. But then I also agree that babies seem to come pre-programmed with a desire to attempt a whole bunch of things. Like I said, I think it's very difficult to separate these things out!

The benefit of a neural net and reinforcement learning is that genes don't have to encode the connections. They can instead encode the reward function(s), and some of this training can occur in the womb, this is probably why babies 'kick' while gestating.

You could imagine a hierarchy that goes something like this:

- Reward neurons that successfully transmit signal from brain to muscle fiber

- Reward neuron groups that get co-located muscle fibers to fire together.

Now the next levels can operate on muscles as a group (calf/hamstring) rather than individual fibers:

- Reward neuron groups that sense balance

- Reward neuron groups that move a muscle in response to balance output.

Believing that genes have to operate at the level of individual neuron connections to shape behavior just doesn't make sense.

Humans are born extremely early relative to other mammals, because of our relatively narrow hips and relatively large brains.

> The method to walk must be encoded in the horse's DNA.

A bodily and neurological structure capable of walking must emerge in the horse's phenotype as a result of development in the horse's environment guided by its genes.

It sounds like the same thing, but it's not. Genes do not encode anything explicit except RNA and protein sequences. Everything else is emergent. They are not a blueprint. Birth a horse on the Moon and I'm not sure if it would be able to walk as quickly.

Not in their DNA, but in the wiring of motoneurons: walking is facilitated by passive central pattern generators and the action of agonist/antagonist muscles. A deafferented cat can still do the walking pattern . But it's true, our DNA encodes so many things that facilitate learning.

That would be in the DNA though. Our physiological structure emerges from that.

oh yes that's true. I should have said "not in the brain"

> Anecdotally, when I watch a baby learn to walk, it doesn't really seem like they are trying a zillion things and picking the one that works. It seems much more like their instincts are telling them to move a certain way, and once they grow strong enough, it succeeds and they are walking.

How much of that comes from seeing everyone around them walking?

It seems hard to argue that horses don't have a genetic component, but I don't think Occam's Razor applies as well for humans when it takes 1-2 years of observing the world in order to start walking unsteadily.

The obvious counter to this argument is that blind babies follow roughly (often slightly delayed) the same developmental pattern and stages as sighted children, with the mostly likely cause of the delay being motivational rather than anything to do with processing visual imagery of what walking/crawling looks like. Both are usually crawling in 6-12 month range.

I don't doubt your claim, but do you have the academic references for that covering the timeline of development milestones? I'd be curious to read more of this research.

I'm not an expert in this area, though I do have a strong interest in more abstract child cognitive development not related to locomotion (Elizabeth Spelke and related work in particular).

So I'm going by what is generally well known and accepted about visually impaired development (the time line and stages). Here are a couple of references below which might be helpful. Infant development is a pretty noisy process though which makes definitive statements difficult.

[0] https://onlinelibrary.wiley.com/doi/pdf/10.1111/dmcn.12860 [1] https://www.tsbvi.edu/curriculum-a-publications/1053-early-d...

"""Their position rests on two arguments, what Stanford anthropologist Paul Ehrlich dubbed a “gene shortage” and widespread, well-documented findings of “brain plasticity.” According to the gene shortage argument, genes can’t be very important to the birth of the mind because the genome contains only about 30,000 genes, simply too few to account even for the brain’s complexity—with its billions of cells and tens of billions of connections between neurons—much less the mind’s"""

I'm sorry but if that's the best argument you can come up with if you're a Stanford Prof, you owe it to yourself to refresh yourself on the literature of how genes work and how they lead to phenotypes. It looks like he ascribes to the "exact blueprint" mental model of phenotypes, rather than the competitive/generative model that is more consistent with modern science.

The article is a presentation of what the researchers in genetics and development have learned. Perhaps it would be good if you responded to that.

The rest of the article is mostly fine (if very limited).

Mods: maybe edit title to reflect date (2003)?

In the past, it would seem people had a lesser nurture:nature ratio. In the future it seems we will have greater.

I think the greatest ratio would be an AI that can fully program itself (including its emotions).

Point being, I suspect we're a lot less nurture than we'd like to think.

It's very unfortunate that we still do not have any cloned people. Cloning, especially cloning famous scientists, would greatly help in understanding what part of their success is due to genes, and what is nurture/luck.

We have identical twins.

Identical twins share a womb, and therefore even if you separate them at birth have already been subjected to identical "nurture" for ~9 months.

Let's say you had four, all identical, split into two groups ran in parallel simulations. Two in the same womb then split at birth, the other two split at conception implanted in two separate mothers. Of the two borne to separate mothers, one mother is heavily stressed, chronically exposes the fetus to cortisol, while the other is very stable.

When looking at outcomes between these pairs, how do you account for the difference in nature vs nurture when almost all of our twin studies rely on a shared womb, shared first 9 months of nurture?

Most identical twins have very similar upbringings and share a lot of genetic code.

And many don't (share an upbringing, that is -- obviously they're genetically identical to at least the level that a clone would be). Twin studies are a foundational technique in studies of heritability. This is really well covered ground.

I think the question stands: what is it about twin studies that is insufficient and needs to be replaced with ethically questionable techniques like cloning?

For those who aren't aware: cloning of vertebrates isn't remotely mature technology. It remains routine for such an organism to be born with significant developmental flaws. Now tell me how you're going to get consent from such an individual pre-conception.

Of course we should not clone people with the unsafe technology, but we should work to improve it to the point where it is as safe as IVF.

The problem with twin studies is that they are not repeatable, and the sample of just two is too small to make any strong conclusions. It's like saying we do not need particle accelerators, because there are high energy particles coming from space.

What about a clone is "repeatable" in a way that a twin study isn't? You aren't planning on controlling the upbringing of a real child, right?

You could have many children (10-100) living in well off families where malnourishment or lack of access to education would not be an issue. And I would gladly control upbringing of a real child, by raising it as my own, why do you think that controlling the upbringing is bad?

By definition, identical twins share all of their genetic code.

Sort of. A single person's cells don't really all have identical DNA, because of mutations and so on.

So it's one of those things that depends on how close you are looking.

identical twins do not have identical genetic code.

Would this really get us any farther than identical twin studies?

If you can clone a great scientist and get another great scientist, then yeah cloning would get us more great scientists.

Perhaps, generations from now, our descendants will look back and consider us massively immoral for permitting our children to be born with unoptimized DNA.

Perhaps tomorrow you will reconsider the idea that people who come later in history are automatically better moral judges.

Personally, I already do not agree with that idea. Thinking about it makes me despair whether people in any time period are reasonable moral judges.

We do not have technology to optimize the DNA in any real way, and most likely it will not be possible know what the effect of specific combination of genes will be without letting people with that DNA to live, so their moralization will be wrong (like most talk about morality and ethics).

But they can consider us stupid for not investing more into research.

I found this article quite fascinating. I had no idea how much the researchers have learned about genetics and development, and the general picture that has developed.

If we could make bets according to the markets perception of the Nature-Nurture debate, my feeling is that natures role is undervalued.

2003. Gary Marcus again.

Is there anything wrong with Marcus?

No, I agree with some of what he says, but he seems to get an article flagged on here every 5 minutes.

Also I'm not sure how representative of the field he is, and (speaking as somebody who shares some of his scepticism) you would think the consensus would be the prevailing tone.

The key to thinking about nature versus nurture that I never see mentioned:

If you believe in evolution, you have to believe in the genetic determinism of genes.

Sure, there is leeway for nurture, but a lot of people are holding contradicting opinions (they believe in evolution but not as much in "nature") because we as a society are hiding the truth of human determinism.

That's awfully simplistic.

Evolution is simply three observable phenomena: first, living things carry genetic information; second, genetic information is rarely transmitted without any change to a descendant; third, a living thing that does not have descendants doesn't directly contribute their genetic information to any descendants.

There's nothing there to "believe" in any more than you need to believe in gravity.

Next, everything that happens to an organism that is not determined by genes is determined by the rest of the universe. That's pretty obvious.

A really interesting aspect, though, is that genes can't do anything if they aren't being read and processed correctly. Reduce the supply of essential nutrients, and it doesn't matter how awesome your genes are, you're going to get a deficiency disease. Fill the environment with chlorine compounds, and you're going to get poisoned. Too much lead? Too much alcohol? Say goodbye to proper development.

When it comes to humans, it's even worse. If you don't interact with them enough, they don't develop well. Language skill has a few years to develop properly -- without society, humans can't function in society.

None of those results suggest that we are hiding some sort of determinism that we should be paying more attention to.

The thing is, if you take the species dogs, pigs, horses, apes, and humans, then you can clearly put them somewhere on a scale regarding their ability to learn or understand (a) simple language (b) complex language, (c) simple math (d) advanced math. There might be some edge cases, but an average human will be better at any other species no matter how hard you try.

There is a very hard species boundary, so it must be something that is giving to the offsprings.

If you further accept that the ability to learn advanced math does not fall from the sky and we somehow descended from an ancestor that did not have this ability, then the only way we got here is that (something that correlates to) this ability was heavily selected for in the past.

And you need some kind of continuum (it can also be multi-dimensional) where you can gradually converge to. I don't think this is something that spontaneously emerged.

If you accept all this, then the same things will likely still play a role within current humans.

Sorry, how exactly are acquired non-genomic phenoma like developmental attributes, culture, language, or hell, even learned behavior... at odds with the theory of evolution.

Evolution works through genes (well, mostly). That doesn't say other things have zero effect, and I'm really curious about what led you to think so.

I'm quite busy so I can't type it all out. But Noam Chomsky has an interesting perspective on language, which is that we are predisposed to it. If our brains did not have fixed architectures we could not develop. Learning language is a genetically encoded process, much like the deterministic developmental structure of your brain is. Further, things like culture are the aggregations of personalities and other factors, so it makes less sense to argue there (though I believe that culture is also determined). Personality for instance, is almost certainly genetically determined. What we call personality is an amalgamation of traits, all of which (intelligence, thought patterns, sociability) are inheritable. How could we have evolution while at the same time not pass down things like "how quick I am to anger". Its not as concrete, but at times just may be.

Most likely you will slam me for the lack of rigor in my comment, which is fine, I don't have the time to spell it out and provide studies.

> If you believe in evolution, you have to believe in the genetic determinism of genes.

The determinism part doesn't follow. Evolution works on probabilities, so you have to believe that genes influence the outcome. Influence. That's all that's needed.

If you read a decent amount of genetics research, you usually end up discovering some conclusions that are politically unacceptable. Even a comment as bland as yours, you can see some people consider it Hitlerian. But at the same time plenty of people do read genetics research and perform cutting edge experiments that advance the state of the art. It is acceptable to do these things, as long as you use enough academic jargon that laymen and politicians can't understand what you're saying.

I'm not exactly sure why this is controversial at all. And I think most of us know and believe this to be fact.

I am 5'10" tall, born and raised in Western society. I am taller than my most of my ancestors, but only marginally taller than my father. He grew up in India, but his family was non-vegetarian in a village of pure vegetarians.

We might have been able to be a little taller if we understood nutrition a bit better, but it's probably within an inch or so. Our height is limited by genetics, not by environment.

It stands to reason that if physical attributes like height are subject to genetic determinism, aspects of our brain & mind should be too. Now, comparing brains to height is very reductive, since the brain is infinitely more complex. But there's a probably a pretty good reason why my father and I have very good memories, and are fairly intelligent people. But we're also not superstar athletes, or great artists. Genetics and environment have optimized our brains in a certain way. And I'm already seeing the same traits in my 1 year old son.

But isn't that the beauty of genetic determinism? Isn't that the beauty of all of us having vastly different life experiences? I don't lament the fact that I don't have the genetics of Usain Bolt, but I can admire and appreciate his prowess. Similarly, I don't lament the fact that I'm not a great creative like Picasso or Mozart. Something about their genetics and environment allowed them to achieve greatness in areas I am not capable of. And that's fantastic, because our society is enriched because of this diversity.

I think a society that celebrates the individual, gives them the resources and environment to achieve whatever they're capable of, and thus, reach the limits of their own genetics is one I'd like to live in. Realistically, most of us are not even close to be limited by our genetics, but man, how awesome would it be if we were?

> It stands to reason that if physical attributes like height are subject to genetic determinism, aspects of our brain & mind should be too.

And if you don't believe in creationism and also don't believe that intelligence is subject to evolution, then you need some very good explanation where intelligence comes from in the first place.

Yeah this is my point exactly. A staggering amount is known about human behavior and where it comes from, most of it is just sitting in PhD level books at college libraries. Most will keep their head in the sand, best not look at something which tears apart my philosophies on society and life...

You have an example of something politically unacceptable revealed via "genetics research"?

You can tell people's race by their DNA, meaning that there are genetic differences caused by race? Saying that is unacceptable in many spheres today.

No, you can't because "race" isn't a useful or well defined term or object and doesn't apply (is incommensurable) to genetics.

Worse it comes absolutely loaded with social and political implications. It doesn't describe anything we can really point to, but is just a highly charged, culturally variable label we place on a cluster of outward appearances (e.g. excess or lack of melanin, hair or eye color, height).

You might be able to tell if a particular individual is likely to have a lack of melanin or blue eyes from DNA, but you can't say genetic differences are caused by race. That in the famous words of Pauli is not even wrong.

It's a category error, and even if it were useful it also inverts the causality. We apply the label "race" to a cluster of possibly DNA influenced outward markers. We humans cause "race" and apply it to people. Not genetics.

Using a poorly defined term like race in an argument like this is worse than just poor reasoning. It will confuse people at best and cause harm at worst.

It's not unacceptable because people are afraid of the truth or something.

It's unacceptable because it's incoherent, vacuous and empty. It adds nothing to the discourse.

It shouldn't be unacceptable at all, because it's a loose term that predates DNA testing and identity politics. It's simply a descriptive tag, like tall or short.

If it's "simply a descriptive tag", then why are you insisting that truths about it are being revealed by rigorous (yet... undiscussable) science?

Either you're making a scientific point or you're just complaining that people get upset when you discuss race. Which is it?


This comment breaks several of the site guidelines. Would you please review them and stick to the rules when commenting here?


I don't think he is saying what you think he is saying. I took it more along the lines of we (free society) want to believe that anyone can be anything if they are given the right opportunities in life from birth. Someone could mistakenly take that to an extreme about whole classes of people but that's not what the comment was about IMO.

This is a really terrible comment. It adds nothing of value and completely misses the point of the parent post apparently just for the sake of weakly transplanting an overused unfunny meme from outside the community.

They're saying that people seem to fail to acknowledge how much our genes determine who we are because it can feel like a scary disconnect from free will.

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