Modern human brain organization emerged only recently • Hacker News Board

Re: Modern human brain organization emerged only recently

#21

Post by Karnickel » Tue, Jan 30, 2018, 10:25 AM UTC

cm2187 wrote: post #18

Karnickel wrote: post #14

Earlier quoted context omitted.

> the bold statements about no difference between men and women brains, everything is nurture/nothing nature, etc. You are attacking a position that is not the common scientist position at all. Your whole comment is a bit surprising given the context. You went out of your way to invent a reason to vent. "Study finds some significant differences in brains of men and women": http://www.sciencemag.org/news/2017/04/study…

Talking about making up your own invented antagonistic positions: I am not arguing everyone else pretends there are no difference, I am arguing that some do. Quoting some articles arguing that there are differences doesn't prove anything. As for the ad hominem arguments,...

> I am arguing that some do.

What is the purpose of finding someone, anyone, who holds some fringe opinion to attack it as if its common? You can find any opinion about anything out there after all.

> Quoting some articles arguing that there are differences doesn't prove anything.

It proves that the opinion you attack does not seem to be the opinion of the scientific community. Unfortunately you did not include a single link to show whom or what exactly your comment is about.

I hope you don't consider it rude or an "attack" that I point out that you did not point to anyone/anywhere specifically? Because you really did not. I think your argument would benefit greatly from being more specific.

I have Facebook friends (who I keep because they are ex colleagues and mostly harmless otherwise) whose whole life (judging by their news feed) seems to be centered around finding the most stupid comments on the entire Internet and then posting them to show how stupid they are. Your comment strongly reminds me of that phenomenon. Personally, I consider it not only highly illogical but also a huge waste of time, not to mention what it probably does for your outlook on life to concentrate on the most absurd and ridiculous fringe opinions that you can find.

Also, counter to your latest claim, you make no such distinction at all. You attack the position as if it's common. The Facebook friends I mention at least include specific links that they attack. Not that that would make much sense given that we are here discussing a specific article.

Re: Modern human brain organization emerged only recently

#22

Post by Gibbon1 » Tue, Jan 30, 2018, 10:58 AM UTC

cafebeen wrote: post #6

Note, the original paper is about evolutionary patterns of overall brain shape, which is far from indicating how brain organization evolved. The important parts of brain organization are encoded by patterns of structural and functional connectivity, which are internal to the brain and not well depicted by the overall shape. The paper is great, but the write-up just jumps to some distant conclusions.

I'm reminded of head binding practices at this point.

Re: Modern human brain organization emerged only recently

#23

Post by stochastic_monk » Tue, Jan 30, 2018, 11:05 AM UTC

Gibbon1 wrote: post #22

cafebeen wrote: post #6

Note, the original paper is about evolutionary patterns of overall brain shape, which is far from indicating how brain organization evolved. The important parts of brain organization are encoded by patterns of structural and functional connectivity, which are internal to the brain and not well depicted by the overall shape. The paper is great, but the write-up just jumps to some distant conclusions.

I'm reminded of head binding practices at this point.

I’m reminded of phrenology.

Re: Modern human brain organization emerged only recently

#24

Post by sgt101 » Tue, Jan 30, 2018, 11:34 AM UTC

danieltillett wrote: post #12

nrau wrote: post #4

What's interesting that if the basic point is true (that modern human brains emerged only 100,000 - 35,000 years ago) then its amazing (and scary) how quickly things have moved from there. It wasn't that long after "relatively speaking" that the Greeks emerged, then the Romans, Egyptians, Europe, Asia, etc, and now our modern technology driven civilization.

Speed of evolutionary change is basically proportional to the population size. Thanks to the huge increase in population size after the rise of agriculture, more human evolution has happened in the last 5000 years than the previous 500,000.

I think that depends on pressures and variation as well; without selection pressure I don't think that there is a reason why the variation in the overall population will change.

Re: Modern human brain organization emerged only recently

#25

Post by chimprich » Tue, Jan 30, 2018, 11:35 AM UTC

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…

> 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.

Just because one group migrated earlier doesn't mean they were genetically isolated. Presumably there were subsequent migrations, counter-migrations (of large populations and smaller groups) and associated interbreeding between them.

Re: Modern human brain organization emerged only recently

#26

Post by danieltillett » Tue, Jan 30, 2018, 11:44 AM 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.

Well the Denosovans really originated in East Asia somewhere as their ancestors left Africa a long time ago.

We don't really have a good name for the ancient sub-Saharan humans that have contributed most of the genetic background to all living humans.

The problem with the peopling of Australia is the time has been push back so far now (80K BCE) that it is before the ancient sub-Saharans really got much further than the Middle East.

Re: Modern human brain organization emerged only recently

#27

Post by kakarot » Tue, Jan 30, 2018, 11:51 AM UTC

astebbin wrote: post #7

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…

It's uncomfortable to consider, but there is strong evidence to suggest that the brains of Australian aboriginal people differ in significant ways from their Caucasian bretheren. One study found the aboriginal visual cortex to be significantly larger than the Caucasian equivalent [0], possibly as an adaption to Australia's (visually) vast open spaces. The same study found the Caucasians had significantly larger parie…

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)

Re: Modern human brain organization emerged only recently

#28

Post by danieltillett » Tue, Jan 30, 2018, 12:02 PM UTC

TheAdamAndChe wrote: post #17

danieltillett wrote: post #12

Earlier quoted context omitted.

Speed of evolutionary change is basically proportional to the population size. Thanks to the huge increase in population size after the rise of agriculture, more human evolution has happened in the last 5000 years than the previous 500,000.

Really? I thought selective pressure was required to cause a major shift in the average human. The reason that our population has boomed is because our selective pressure has declined significantly. Or are you more talking about the adaptability of the species overall has increased?

Evolution acts on genetic diversity present in the population. The rate at which new genes (mutations) appear is basically a constant proportional to the population size (i.e. double the population and you double the rate new genes are formed). The rate at which new genes under positive selection spread through the population is approximantly equal to the log of the population size. This means it only taken 3x longer for a new gene to spread through a population of 100 million as it does to spread through a population of 1 million.

The end result is the bigger the population the more evolution even if in a static environment most of the evolution is invisible. Of course the environment of farmers is very different to hunter-gathers so there has been a large amount of visible evolution in the last 5000 years.

Re: Modern human brain organization emerged only recently

#29

Post by lawlessone » Tue, Jan 30, 2018, 12:08 PM UTC

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…

That doesn't mean they were completely isolated once they arrived or that evolution stopped once they arrived.

Re: Modern human brain organization emerged only recently

#30

Post by taneq » Tue, Jan 30, 2018, 12:10 PM UTC

sgt101 wrote: post #24

danieltillett wrote: post #12

Earlier quoted context omitted.

Speed of evolutionary change is basically proportional to the population size. Thanks to the huge increase in population size after the rise of agriculture, more human evolution has happened in the last 5000 years than the previous 500,000.

I think that depends on pressures and variation as well; without selection pressure I don't think that there is a reason why the variation in the overall population will change.

Selection pressure doesn't just mean people being killed by things. Some groups having significantly more surviving offspring is also a selective pressure.