smaller brains = ?

[sculptor]

future of the species?

 

[spidergoat]

Islands with limited resources cause species to diminish in size. If the Earth has limited resources, maybe that will happen to us.

 

[Write4U]

so
is there a narrowing of the hips and birth canal coincident
with diminished brain size?

Quite possible it may have been indirectly coincident to becoming bipedal with a bone realignment for speed and long range hunting.

 

[iceaura]

OK from the maps
the closer to the poles, the larger the brains
WHY?

Your speculation of childhood or maternal inflammation robbing the adult brain fits that data.
So does my speculation of greater efficiency and advances in architecture allowing a smaller brain without intelligence penalty - which then sorts the outcome by childbirth and childhood mortality (in places of higher childbirth or childhood mortality, a reduction in those factors would be a greater advantage).
And so does the leftfield guess of heat tolerance - especially if, as more than one evolutionary biologist has suggested (such as Bernd Heinrich), we evolved as a heat tolerant midday running hunter/scavenger.

We have chosen a larger and more stable population in exchange for the evolution that brought us to the genius of cromagnon.

That does not seem to fit the distribution. Some prehistorically larger and more stable populations - China, Mexico - have larger heads, many lightly populated regions ((Australia, central Africa) have smaller heads.
In carrying capacity, Siberia and Greenland and Alaska and probably Tierra del Fuego have lived at their limit for thousands of years. But they have big brains.

side: a map of likelihood of bearing fraternal twins would match that brain size map fairly closely (inverted).

 

[origin]

Small brains = bigger belt buckles?

 

[sculptor]

coupla more links:

http://darwinian-medicine.com/our-brains-are-shrinking/

https://www.ncbi.nlm.nih.gov/pubmed/26074674

 

[sculptor]

Quite possible it may have been indirectly coincident to becoming bipedal with a bone realignment for speed and long range hunting.

Brains got bigger and bigger for a couple million years
long after bipedalism

Cranial capacity seems to have topped out with heidelbergensis during the last superinterglacial circa 400,000 years ago-----------------but these guys wuz giants---bigger body bigger brain is a norm.

 

[Write4U]

Brains got bigger and bigger for a couple million years
long after bipedalism

Cranial capacity seems to have topped out with heidelbergensis during the last superinterglacial circa 400,000 years ago-----------------but these guys wuz giants---bigger body bigger brain is a norm.

I guess in the end, human attributes will be a balanced construct designed for optimum required performance while engaged in a great range of living skills. That's natral selection.
Necessity <--> Sufficiency.

 

[sculptor]

I guess in the end, human attributes will be a balanced construct designed for optimum required performance while engaged in a great range of living skills. That's natral selection.
Necessity <--> Sufficiency.

Has "natural selection" never led to extinction?

 

[Write4U]

Has "natural selection" never led to extinction?

Of course. The extinction of the dinosaurs was an unfortunate function of "natural selection" . Well, maybe not.....

I think natural selection is more a random procces of "selecting out", than "selecting in".
The Silvery Salamander is doomed to die , but continues to survive due our human efforts to save this unique salamander species, which produces no males, only female clones of the mother.

We truly live on a Cinderella Planet.......2 trillion, quadrillion, quadrillion, quadrillion chemical reactions expressing themselves as our natural world, from salamanders to humans.

 

[sculptor]

Of course. The extinction of the dinosaurs was an unfortunate function of "natural selection" . Well, maybe not.....

I think natural selection is more a random procces of "selecting out", than "selecting in".
The Silvery Salamander is doomed to die , but continues to survive due our human efforts to save this unique salamander species, which produces no males, only female clones of the mother.


We truly live on a Cinderella Planet.......2 trillion, quadrillion, quadrillion, quadrillion chemical reactions expressing themselves as our natural world, from salamanders to humans.

XX?

 

[gamelord]

OK
Back at it.
So far, there seems to be broad agreement that most of us are experiencing a multi-generational shift to smaller brains.
One could go so far as to say that this started with heidelbergensis--with rapid expanse of the cranial cavity for millennia, topping out at 1800 cc then shrinking through neanderthalensis to us. But that is a different subject than the one for this thread.

From an average(from extent fossils) of 1650 cc for cromagnon to a modern average of well under 1450 we have lost more than 12% of cranial capacity. Average embraces quit a wide range with a lower limit of 1200cc.

[there is no proven 1:1 ratio of brain size to intelligence----the inverse is also true]

Ok then:
The question of causality comes into play.
Many speculations are to be found. What seems most likely(to me) is a 2 pronged hypothesis.
1) We ain't hunter gatherers no more---we have a different diet and different needs. We have a more stable food source and do not have to live by our wits.
Diet---we eat more grains and less wild stuff. We eat less protean and more carbs. The grains we eat lead to more inflamation
which means that we need to invest more in our immune system to fight inflammation. So being as both the brain and immune system are energy hungry, we rob one to feed the other. Wild fruits and berries and grains have more anti-oxidants per calory than do domesticated crops. So, we need to make up the difference with our immune systems.
So we sacrifice feeding a larger brain to accommodate our lower protean lower omega 3 fatty acids in favor of feeding our immune systems.

some links:
https://www.gwern.net/docs/algernon/1998-henneberg.pdf
https://biology.stackexchange.com/questions/44662/brain-capacity-of-cro-magnon-man-vs-modern-man
https://www.persee.fr/doc/bmsap_0037-8984_1979_num_6_4_1979
https://www.researchgate.net/public...ion_of_Holocene_populations_in_Northern_China

ok
If that is true: Where would you expect to see less diminishment of cranial capacity?
I would expect to see it where there is less modern diet
2 maps of cranial capacity

Conclusion:
We are experiencing a result of exceeding the natural carrying capacity of the land.
We have chosen a larger and more stable population in exchange for the evolution that brought us to the genius of cromagnon.

So you are saying, Russians are the smartest race?

If so why is the AR-15 better than the AK-47?

If so why is Big Rigs, Over the Road Racing, one of the worst games ever made and the worst programming job ever done, and it was made by Russians. Also, why is the average IQ of Russia 98, and that Japanese have a higher IQ.

 

[sculptor]

So you are saying, Russians are the smartest race?

If so why is the AR-15 better than the AK-47?

If so why is Big Rigs, Over the Road Racing, one of the worst games ever made and the worst programming job ever done, and it was made by Russians. Also, why is the average IQ of Russia 98, and that Japanese have a higher IQ.

HUH WUT?

So you are saying, Russians are the smartest race?

I did not say/post that.
I would not say/post that.
Hell dad, I don't even believe that!
If you are referring to the posted maps, a closer look will reveal that most of Russia is outside the >1450 zone, and is roughly similar to north america.
The posted maps support the diet hypothesis.
....................

If so why is the AR-15 better than the AK-47?

It ain't.
The "better" judgement would depend on the intended use.
In many states, it is legal to hunt deer with an ak47. It is usually not legal to hunt deer with an ar15.
The theory being that the heavier bullet is more lethal.
(personally I prefer the combination of moa, knock down power and general ballistics of the .300 win mag, or .338 lapua)

That being said, the ak is less accurate, and heavier by about 20%.
So if you plan to shoot out beyond 100 yards, and don't want to lug a heavy weapon about, the ak comes in second.
.....................
Is the last a reference to a video game?

 

[gamelord]

That picture looks very close filled to Russia to me. I didn't say it was exactly the same Border as Russia, but close. According to the map, Russians should have the world's biggest cranial capacity.

My reference was to Big Rig's Over the Road Racing, which is a Russia-made game, famously known for its atrocious gameplay and sheer programming ineptitude.

 

[Write4U]

XX?

If you talk about genes, the Silvery Salamanders are only female and while they do mate with males of different salamander families, they reject the sperm of all male Salamanders.
It seems that the act of mating itself triggers cell division in the female , who has a double strand of her own genes and therefore gives birth to perfect clones.

 

[sculptor]

My 1st lover teased that X was normal in that almost everyone had one, whereas y was not---ergo all men were mutants.

 

[RainbowSingularity]

okay gene-assess(ponders question of speciation of size)

how does protien type & amount(matched with the co-component vitamins & minerals) through childhood effect neural density ?

someones needs to answer that question and show some working examples before this subject really gets into 1st gear.

is neural density geneticaly bound as a pre birth absolute ?

... generic, as male patriarchal dogma and culture gained hold, larger women would be not breeded weith larger males.
larger males would choose to breed with smaler females and thus higher number of infant natal mortality etc....

is anyone going to do an actual scientific over view of the real process and situation with surrounding perripheral cultural shifts etc? ?

the discovery of crop rotation & agriculture of grains probably resulted in a mass starvation of meat from normal diets.
anyone studying that ?

 

[iceaura]

is neural density geneticaly bound as a pre birth absolute ?

Not absolutely. Although genetically governed, it requires some developmental resources and responds to feedback - the brain grows during childhood, adding and pruning neurons within a volume and "fold" architecture also developmentally influenced. Malnutrition and suboptimal diet, stress, disease, etc, have their effects.
There is some evidence that the brain is protected to a degree - the body is sacrificed to maintain brain development - but not perfectly.

the discovery of crop rotation & agriculture of grains probably resulted in a mass starvation of meat from normal diets.
anyone studying that ?

Yes. And some findings so far: The early stages of agricultural life have been shown to be associated with stunting, shorter adult lifespans, and various skeletal signs of disease (bad teeth, for one). Smaller cranial volumes come with that territory.

 

[parmalee]

Yes. And some findings so far: The early stages of agricultural life have been shown to be associated with stunting, shorter adult lifespans, and various skeletal signs of disease (bad teeth, for one). Smaller cranial volumes come with that territory.

Also coincident with the emergence of more heirarchical and patriarchal societies.

 

[Write4U]

Has "natural selection" never led to extinction?

No, it is the opposite. To be selected for survival (regardless of method) does not mean to be out-selected..

Natural Selection, noun
BIOLOGY

1. the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.

Natural disasters have been responsible for the extinction of many species...