Modern human brain organization emerged only recently • Hacker News Board

Re: Modern human brain organization emerged only recently

#51

Post by Symmetry » Tue, Jan 30, 2018, 4:10 PM UTC

joshmarlow wrote: post #47

Symmetry wrote: post #35

Earlier quoted context omitted.

I'd tend to assume that any genetic trait that improves intelligence without significant drawbacks would spread rapidly through interbreeding and selective pressure even without wholesale population transfers. It took about 10,000 years for adult lactose tolerance to spread to its modern range and this brain organization trait would have 35,000 years and potentially give a larger selective benefit. EDIT: The corollar…

> I'd tend to assume that any genetic trait that improves intelligence without significant drawbacks would spread rapidly through interbreeding... I would agree if we were confident that greater intelligence was always worth it, no matter the metabolic cost . Brains are expensive! Making them bigger incurs additional metabolic costs (and potential complications in the developmental phase). It's very possible that ano…

Brain size is certainly an issue but from my understanding it's more about the constraints of childbirth than metabolic cost that are restraining it. When you're resting flat on your back your brain uses up 10 of the 100 watts you're dissipating but the variation in brain size given other constraints is pretty low and I'd expect plausible power differences from that to be pretty small too. And brain size only has something like a .3 correlation with IQ so other factors like efficient myelination or organization are probably much more important. I'd expect better myelination to reduce energy consumption if anything. As to organization I'm too unfamiliar with the scaling laws of neurons to be sure but I'd suspect brain organization that increased intelligence at least wouldn't increase energy usage much. So I'm still inclined to view intelligence as being constrained, evolutionarily, by issues of complexity rather than tradeoffs between efficiency and effectiveness as with height.

Re: Modern human brain organization emerged only recently

#52

Post by [deleted] » Tue, Jan 30, 2018, 4:15 PM UTC

tomrod wrote: post #32

kakarot wrote: post #27

Earlier quoted context omitted.

We better get this racism thing in check before we're literally dealing with different species of human (assuming that some groups of people remain isolated and we don't experience total global homogeneity in the future)

I thought racism was defined as: > prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior. I completely agree that when looking at differences among population groups in a species, one should avoid normative statements such as "such and such makes this population superior," but is there harm caused by identifying differences in average…

[deleted]

Re: Modern human brain organization emerged only recently

#53

Post by logfromblammo » Tue, Jan 30, 2018, 4:29 PM UTC

leonroy wrote: post #48

It's interesting to note that a technological civilization has occurred only in the past 200 years. Homo sapiens have been around on the planet for a long time so why is it only happening now? I suspect that easy access to large amounts of food, more time available for mental activities and the easy spread of information have given us advantages our ancestors did not have despite the apparent similarities in our brai…

Increasing the capability raises the noise floor, so you would also need a grooming or discovery mechanism in order for the better ideas to achieve greater adoption.

For instance, if someone comes up with some way for aluminum smelting to use x% less electricity, but no aluminum smelter ever knows about it, no benefit will be realized. Conversely, if all the smelters adopt it, and the inventor is never rewarded, they will simply stop telling people about their ideas, and restrict their thinking to those areas that will benefit them personally.

I would argue that the patents and copyrights system is so lacking in additional capacity with respect to promoting good ideas that the overall benefit to humanity from increasing the raw mental capability will be negligible.

Re: Modern human brain organization emerged only recently

#54

Post by dalbasal » Tue, Jan 30, 2018, 4:29 PM UTC

ZeroGravitas wrote: post #19

danieltillett wrote: post #10

Earlier quoted context omitted.

There is the interesting hypothesis that the first people to reach Australia were the Denosovans and African peoples came much later. It would explain a lot of interesting observations about the peopling of Australia, not least evidence of there being people in Australia before African peoples had left the Middle East and why you can only find significant Denosovan genetic ancestory on the Australasian side of the Wa…

Your use of "African" seems confusing here. In particular the line "evidence of there being people in Australia before African peoples had left the Middle East" seems to suggest you think Denosovan people didn't originate in Africa.

We (sapiens) and perhaps late model erectus are the African species/subspecies of the archaic human group. Denisovans are Asian and neanderthals are European.

It's all based on migration theories which are far from certain, currently. The story gets more complex with every find.

The morrocan find is a spanner, as it "proves" a wide distribution of sapiens early on. This essentially excludes the idea of a migration out of the horn of Africa 200kya, the original out of Africa theory. Modern variations have gotten bigger.

In the Levant neanderthals follow sapiens in the archeological record. The early sapiens are a little more neanderthal looking, especially the brows. This has lead some to a theory that neanderthals evolved from sapiens, and arboreal subspecies.

The Australian story is even more confusing. 70kya is before behavioural modernity. But, seagoing boats are unmistakably modern behaviour. If modernity is strongly genetic, did (almost identical evidence) modernity evolve separately in Oz?...

A lot of mystery still. We have very few finds.

Re: Modern human brain organization emerged only recently

#55

Post by randomdrake » Tue, Jan 30, 2018, 4:44 PM UTC

Study: The evolution of modern human brain shape

Citation: Simon Neubauer, Jean-Jacques Hublin, Philipp Gunz. Science Advances, 2018; 4 (1): eaao5961.

Link: https://doi.org/10.1126/sciadv.aao5961

DOI: 10.1126/sciadv.aao5961

Abstract: Modern humans have large and globular brains that distinguish them from their extinct Homo relatives. The characteristic globularity develops during a prenatal and early postnatal period of rapid brain growth critical for neural wiring and cognitive development. However, it remains unknown when and how brain globularity evolved and how it relates to evolutionary brain size increase. On the basis of computed tomographic scans and geometric morphometric analyses, we analyzed endocranial casts of Homo sapiens fossils (N = 20) from different time periods. Our data show that, 300,000 years ago, brain size in early H. sapiens already fell within the range of present-day humans. Brain shape, however, evolved gradually within the H. sapiens lineage, reaching present-day human variation between about 100,000 and 35,000 years ago. This process started only after other key features of craniofacial morphology appeared modern and paralleled the emergence of behavioral modernity as seen from the archeological record. Our findings are consistent with important genetic changes affecting early brain development within the H. sapiens lineage since the origin of the species and before the transition to the Later Stone Age and the Upper Paleolithic that mark full behavioral modernity.

Re: Modern human brain organization emerged only recently

#56

Post by wycs » Tue, Jan 30, 2018, 4:45 PM UTC

kakarot wrote: post #38

tomrod wrote: post #32

Earlier quoted context omitted.

I thought racism was defined as: > prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior. I completely agree that when looking at differences among population groups in a species, one should avoid normative statements such as "such and such makes this population superior," but is there harm caused by identifying differences in average…

On one hand, we have Darwin, who straight up wrote a book about why some races are superior [0], and on the other hand we have extremists who take offense even at assessments like "Men are on average stronger than women." For a modern-day Darwin, we have James Watson, the father of genetics, who has some interesting things to say [1] [0] https://en.wikipedia.org/wiki/On_the_Origin_of_Species [1] https://en.wikipedia.…

It is something we will have to grapple with. Cognitive genomics is already starting to confirm very politically incorrect things, such as the the confirmation of a dysgenic trend in Iceland, which has been implied from phenotypic data but career ending to acknowledge: https://www.gwern.net/docs/genetics/selection/2017-kong.pdf

This is the tip of the iceberg. Once we have a million genomes tagged with cognitive measures, a huge swath of politically-incorrect but factually true descriptive statements will be confirmed. We need to work now to avoid confusing the descriptive with the normative and be willing to consider technological fixes for unfair distributions of economically valuable allies, such as embryo selection and direct genetic modification. Our society is so in denial of biological realities, this may not happen in time. But there will be competitive pressure from Asian (and perhaps Islamic) societies that do not share our tabbos.

Re: Modern human brain organization emerged only recently

#57

Post by ankjl » Tue, Jan 30, 2018, 4:54 PM UTC

why42 wrote: post #50

TheAdamAndChe wrote: post #16

Earlier quoted context omitted.

> Is there some reason to believe that these differences are inherent, and not the result of gene expression being affected by the environment? That is a question that remains to be answered, and is only just beginning to be looked into through research on epigenetics[1]. [1] https://en.wikipedia.org/wiki/Epigenetics

If our brain structures were different (at least in so far as the organization or distribution of cells within the cranium and not the external measurement) then one would expect adopted children from places where brains are very different to perform differently then peers in new locations. Yet I remember reading a study that showed that black children from Africa adopted by white parents in Germany performed at the…

It could also be that differences in academic performance (I'm assuming academic is the performance you were referring to in your comment) are not accurate metrics for identifying the effects of differential brain organization.

In scenarios like that, it's also difficult to control for the impact of different level of support for students in academic matters. For example, focused support for under-performing students compared to relatively relaxed support for students meeting expectations.

I could probably also see the impact of different psychological factors associated with being adopted by a family on a different continent being hard to control for.

Re: Modern human brain organization emerged only recently

#58

Post by betenoire » Tue, Jan 30, 2018, 5:48 PM UTC

kakarot wrote: post #38

tomrod wrote: post #32

Earlier quoted context omitted.

I thought racism was defined as: > prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior. I completely agree that when looking at differences among population groups in a species, one should avoid normative statements such as "such and such makes this population superior," but is there harm caused by identifying differences in average…

On one hand, we have Darwin, who straight up wrote a book about why some races are superior [0], and on the other hand we have extremists who take offense even at assessments like "Men are on average stronger than women." For a modern-day Darwin, we have James Watson, the father of genetics, who has some interesting things to say [1] [0] https://en.wikipedia.org/wiki/On_the_Origin_of_Species [1] https://en.wikipedia.…

I've never actually met someone who was offended by a statement like "on average, men are stronger than women".

If you are saying things like that, and people are getting offended, perhaps record yourself and see what other shit you say and how you say it, and maybe you'll see what they are really offended at.

Re: Modern human brain organization emerged only recently

#59

Post by undersuit » Tue, Jan 30, 2018, 6:02 PM UTC

Arnt wrote: post #8

sunstone wrote: post #5

How do they reconcile the fact that apparently only brains after 35k years ago show this new brain morphology when humans left Africa at least 70k years ago (when they showed up in Australia). So one of the groups, either the "in Africa group" or the "out of Africa" group still should have the "old style brains" unless magically the changed happened in both groups at simultaneously. And yet I believe all humans curre…

"Only fossils younger than 35,000 years show the same globular shape as present-day humans, suggesting that modern brain organization evolved some time between 100,000 and 35,000 years ago." If humans reached Australia well before 35,000 years ago and lived in isolation there and the evolutionary pressure in Australia differed noticeably from that in the rest of the world, then that narrows the gap. And, and.

I don't know how much isolation they had. The Sahul Schelf was walkable ground only 18,000 years ago by our current knowledge.

Re: Modern human brain organization emerged only recently

#60

Post by kakarot » Tue, Jan 30, 2018, 8:40 PM UTC

betenoire wrote: post #58

kakarot wrote: post #38

Earlier quoted context omitted.

On one hand, we have Darwin, who straight up wrote a book about why some races are superior [0], and on the other hand we have extremists who take offense even at assessments like "Men are on average stronger than women." For a modern-day Darwin, we have James Watson, the father of genetics, who has some interesting things to say [1] [0] https://en.wikipedia.org/wiki/On_the_Origin_of_Species [1] https://en.wikipedia.…

I've never actually met someone who was offended by a statement like "on average, men are stronger than women". If you are saying things like that, and people are getting offended, perhaps record yourself and see what other shit you say and how you say it, and maybe you'll see what they are really offended at.

I'm not walking around saying that because I'm not trying to provoke people, but thanks for the unwarranted judgment.