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Modern human brain organization emerged only recently

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Re: Modern human brain organization emerged only recently

#31

Post by taneq »

kakarot wrote: post #27
astebbin wrote: post #7

Earlier quoted context omitted.

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)

What do you mean by "get in check"? It's pretty well accepted that we deal differently with different species. We'll need to decide what counts as ethically acceptable, but blind insistence that "all humans are created equal" isn't going to fly when we have undeniably different species of human.

Re: Modern human brain organization emerged only recently

#32

Post by tomrod »

kakarot wrote: post #27
astebbin wrote: post #7

Earlier quoted context omitted.

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)

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 averages, medians, and variance in said defined population groups? In other words, if I am speaking about dogs, is it inappropriate to say chihuahuas are on average smaller than boxers and labs? Same species, but distinct populations.

I think that is at the heart of it. To be "colorblind" to both the historical and modern claims of specific population superiority in one dimension or another is misguided-bad claims made in good faith should be addressed head on, in requests for citations, evidence, etc. Similarly, to identify where differences may occur seems to be a reasonable action so long as there is recognition to cultural or historical drivers too, as GP implicitly identifies with the optical adaptation mentioned (though, TBH, I have not read the study he or she proffers and thus have no insight to the claim).

Re: Modern human brain organization emerged only recently

#33

Post by rocqua »

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.

There are still selection pressures, only they are more focused on sexual selection rather than survival selection. There still remain advantages to being smart healthy and athletic. What has changed is the lower bound on these required for survival. What has happened to pressures on these required for reproduction seems like a much harder to judge question.

Certainly though, those with advantageous mutations seem to have a better chance of reproduction.

Re: Modern human brain organization emerged only recently

#34

Post by etiam »

danieltillett wrote: post #10
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…

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…

It's Denisovans, after the discovery site in the Denisova cave.

Re: Modern human brain organization emerged only recently

#35

Post by Symmetry »

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…

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 corollary is that the large genetic component of intelligence is mostly non-linear. E.g. being heterozygous is an advantage and being homozygous a disadvantage.

Re: Modern human brain organization emerged only recently

#36

Post by kingkawn »

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…

Sounds much more like science revealing its still-lingering capacity for producing racist hierarchical judgements of human anatomy

Re: Modern human brain organization emerged only recently

#37

Post by astebbin »

kingkawn wrote: post #36
astebbin wrote: post #7

Earlier quoted context omitted.

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…

Sounds much more like science revealing its still-lingering capacity for producing racist hierarchical judgements of human anatomy

I honestly can't tell if this comment is satire.

If it's not, please point to the racism. The study makes no moral judgement as to whether it's better to have a bigger parietal lobe vs. visual cortex. Do you think the study's results are somehow inaccurate, or improperly obtained?

Re: Modern human brain organization emerged only recently

#38

Post by kakarot »

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…

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.org/wiki/James_Watson#Controversial_com...

James Watson definitely has a masculine, biased perspective, but I mostly consider him to be somewhere in the middle of the spectrum. Yet, his career has suffered greatly for his remarks dealing with race and genetics.

Personally, I think it is patronizing if not downright deceitful to pretend differences don't exist between isolated demographics, but it will remain a touchy subject for a long time and most scientists will see what happened to Watson and pursue other areas of research.

Re: Modern human brain organization emerged only recently

#39

Post by danieltillett »

etiam wrote: post #34
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…

It's Denisovans, after the discovery site in the Denisova cave.

Interesting autocorrect on my iPad, but yes you are right :)

Re: Modern human brain organization emerged only recently

#40

Post by kakarot »

taneq wrote: post #31
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)

What do you mean by "get in check"? It's pretty well accepted that we deal differently with different species. We'll need to decide what counts as ethically acceptable, but blind insistence that "all humans are created equal" isn't going to fly when we have undeniably different species of human.

I mean racism needs to be obliterated before the differences our governments and world religions trick us into bickering about become even greater, and we regress on fair and ethical treatment of all people in both the eyes of the law and the heart of the common man.
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