Jablonski says Lasisi’s work suggests how, just as melanated skin
protects against UV rays, tightly curled hairs also protect humans
from the sun.
Tight curls create lofted, airy ventilation structures for the head,
allowing it to breathe [sweat] while providing extra protection
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you cant do that with flat hair.
On Thursday 10 March 2022 at 14:42:56 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
Jablonski says Lasisi’s work suggests how, just as melanated skin protects against UV rays, tightly curled hairs also protect humansSo what's the need for that extremely
from the sun.
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protectionCan't do what . . exactly? There's no
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
problem with sweating elsewhere on
the body.
What's the need for that dense, tightly-
curled hair?
Don't pretend you have an answer
when all you can present is verbiage.
That's deceptive politics, not science.
On Thursday, March 10, 2022 at 3:07:28 PM UTC-5, Paul Crowley wrote:
On Thursday 10 March 2022 at 14:42:56 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.Jablonski says Lasisi’s work suggests how, just as melanated skin protects against UV rays, tightly curled hairs also protect humansSo what's the need for that extremely
from the sun.
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead) hair layer, which reduces the temperature of the head (including brain and blood vessels).
Homo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effective with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protectionCan't do what . . exactly? There's no
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
problem with sweating elsewhere on
the body.
What's the need for that dense, tightly-
curled hair?
Don't pretend you have an answer
when all you can present is verbiage.
That's deceptive politics, not science.
On Thursday, March 10, 2022 at 7:11:44 PM UTC-5, DD'eDeN aka note/nickname/alas_my_loves wrote:natural selection this is very much the difference between rapid death from hypothermic heart failure and a chilly dip."
On Thursday, March 10, 2022 at 3:07:28 PM UTC-5, Paul Crowley wrote:
On Thursday 10 March 2022 at 14:42:56 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
Gareth Morgan:Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.Jablonski says Lasisi’s work suggests how, just as melanated skin protects against UV rays, tightly curled hairs also protect humans from the sun.So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead) hair layer, which reduces the temperature of the head (including brain and blood vessels).
Homo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effective with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
"In plain English, body heat is generated by mitochondria. Normal cells have between 2 and a couple of thousand mitochondria. Heart cells have around 5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart is the most vulnerable organ in the human body to cold. The blood from the brain, which comes out much hotter than it goes in, goes directly to the heart. In terms of
Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protectionCan't do what . . exactly? There's no
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
problem with sweating elsewhere on
the body.
What's the need for that dense, tightly-
curled hair?
Don't pretend you have an answer
when all you can present is verbiage.
That's deceptive politics, not science.
On Sunday, March 13, 2022 at 6:31:51 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:natural selection this is very much the difference between rapid death from hypothermic heart failure and a chilly dip."
On Thursday, March 10, 2022 at 7:11:44 PM UTC-5, DD'eDeN aka note/nickname/alas_my_loves wrote:
On Thursday, March 10, 2022 at 3:07:28 PM UTC-5, Paul Crowley wrote:
On Thursday 10 March 2022 at 14:42:56 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
Gareth Morgan:Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.Jablonski says Lasisi’s work suggests how, just as melanated skin protects against UV rays, tightly curled hairs also protect humans from the sun.So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead) hair layer, which reduces the temperature of the head (including brain and blood vessels).
Homo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effective with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
"In plain English, body heat is generated by mitochondria. Normal cells have between 2 and a couple of thousand mitochondria. Heart cells have around 5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart is the most vulnerable organ in the human body to cold. The blood from the brain, which comes out much hotter than it goes in, goes directly to the heart. In terms of
Humans reduced the fur coat when adapting to sheltered dwelling, as it no longer was needed. Coiled hair allowed cooling while blocking IR.Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protectionCan't do what . . exactly? There's no
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
problem with sweating elsewhere on
the body.
What's the need for that dense, tightly-
curled hair?
No response from PC, perhaps my explanation is too "political".Don't pretend you have an answer
when all you can present is verbiage.
That's deceptive politics, not science.
The human brain has multiples of multiples of sensory processors powered by mitochondrial batteries, theis produced heat as a result, much of which keeps the core warm, while always releasing some to the body surface which keeps the surface cool.
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead) hair layer, which reduces the temperature of the head (including brain and blood vessels).
Homo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effective with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
Gareth Morgan:
"In plain English, body heat is generated by mitochondria. Normal cells have between 2 and a couple of thousand mitochondria. Heart cells have around 5,000 but brain cells have an estimated two million mitochondria per cell. The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid death from hypothermic heart failure and a chilly dip."
On Sunday 13 March 2022 at 22:31:51 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead)
hair layer, which reduces the temperature of the head (including brain and blood vessels).
Homo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effective with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.Your scenario implies that sweating was
a routine everyday matter.
it that way. The hominins would have
needed a good supply of water, and that's
often hard to find.
primarily for emergencies -- such as when
they got into fights, or suffered fevers.
Those who could lose heat by sweating
survived better than those who couldn't
-- maybe their reserves had run out.
So, under my scenario, the 'tightly coiled
hair' would have had little significance
as regards sweating. It could not have
evolved for that purpose.
Gareth Morgan:Thanks for this. I've tried to look into it, but
"In plain English, body heat is generated by mitochondria. Normal cells have
between 2 and a couple of thousand mitochondria. Heart cells have around 5,000 but brain cells have an estimated two million mitochondria per cell. The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid
death from hypothermic heart failure and a chilly dip."
it seems to be an field of active research
with relatively few answers at present.
(E.g. I'd like to know if other species brains
had the same proportion of mitochondria.)
However, in outline, it supports my argument
that large brains could have acted as a 'heat
resource' for a species where individuals
found themselves in cold water (perhaps, on
average, less than once in a lifetime) and
where the larger-brained had better chances
of survival.
Note that I'm changing my terminology from
'heat store/heat reserve' to 'heat resource'.
Those individuals who could mobilise the
sugars in their bloodstream and in various
organs (probably converting some fats) and
generate heat in their brains (held out of the
water) would be able to keep their hearts
going for longer. The larger brains would
be like having a larger engine in a vehicle.
Of course, the fuel will always run out in
the end, but this is an emergency and those
who can keep their hearts warmer more
effectively and for longer, will do better.
Elephants also have huge brains -- much
larger than is apparently fitting for their
body size. They are great swimmers --
often in estuaries and cold ocean water.
While their size provides some protection,
the cold will get to them in long-distance
swims. Their large brains may well function
in the same way as I'm proposing for
hominins.
The brains of Polar bears (498 g) are more
than double the size of those of Grizzlies
(234 g) -- probably the result of their having
to swim long distances in very cold water. https://faculty.washington.edu/chudler/facts.html
Polar bears evolved from brown bears relatively
recenltly:
" . . Approximately 125,000 years ago a population of brown bears
in the far north of their range was likely split off from their brown
bear ancestors, perhaps because of competition for food. . . " https://www.pbs.org/wnet/nature/arctic-bears-how-grizzlies-evolved-into-polar-bears/777/
On Monday, March 14, 2022 at 8:11:44 PM UTC-4, Paul Crowley wrote:metabolism, fight-or-flight is our body's reaction to a perceived attack on our body, both use sweating defensively.
On Sunday 13 March 2022 at 22:31:51 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead)
hair layer, which reduces the temperature of the head (including brain and
blood vessels).
All primates sweat. Humans sweat at 3 levels: incipiently, during sleep (hot or cold) while body is inactive, lightly while body is active but not strenuously so, and heavily while active strenuously so. Fever is our body's reaction to an attack on ourHomo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effectiveYour scenario implies that sweating was
with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
a routine everyday matter.
I do not see
it that way. The hominins would haveLike modern humans, archaic hominins lived near (but not in) shallow freshwater.
needed a good supply of water, and that's
often hard to find.
Sweating was IMO
primarily for emergencies -- such as whenThat is heavy sweating, a comparatively rare occurrence, and a poor way to cool since it excretes faster than it evaporates, unlike incipient and light sweating. Dripping sweat is both inefficient and ineffective, and leads to dehydration.
they got into fights, or suffered fevers.
Those who could lose heat by sweatingN/A.
survived better than those who couldn't
-- maybe their reserves had run out.
So, under my scenario, the 'tightly coiledUnder extreme sweating, scalp hair is irrelevant, fluid sweat pours off anyway.
hair' would have had little significance
as regards sweating. It could not have
evolved for that purpose.
Gareth Morgan:Thanks for this. I've tried to look into it, but
"In plain English, body heat is generated by mitochondria. Normal cells have
between 2 and a couple of thousand mitochondria. Heart cells have around 5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the
brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid
death from hypothermic heart failure and a chilly dip."
it seems to be an field of active research
with relatively few answers at present.
(E.g. I'd like to know if other species brains
had the same proportion of mitochondria.)
However, in outline, it supports my argumentN/A.
that large brains could have acted as a 'heat
resource' for a species where individuals
found themselves in cold water (perhaps, on
average, less than once in a lifetime) and
where the larger-brained had better chances
of survival.
Note that I'm changing my terminology fromN/A.
'heat store/heat reserve' to 'heat resource'.
Those individuals who could mobilise the
sugars in their bloodstream and in various
organs (probably converting some fats) and
generate heat in their brains (held out of the
water) would be able to keep their hearts
going for longer. The larger brains would
be like having a larger engine in a vehicle.
Of course, the fuel will always run out in
the end, but this is an emergency and those
who can keep their hearts warmer more
effectively and for longer, will do better.
Unlike many taxa, humans defend themselves best when grouped defensively, and worse when not, this is shared with chimps.
Elephants also have huge brains -- muchN/A. Note that elephants do not eat seafood.
larger than is apparently fitting for their
body size. They are great swimmers --
often in estuaries and cold ocean water.
While their size provides some protection,
the cold will get to them in long-distance
swims. Their large brains may well function
in the same way as I'm proposing for
hominins.
The brains of Polar bears (498 g) are morePolar bears are much larger than grizzly bears, and are fully covered in fur.
than double the size of those of Grizzlies
(234 g) -- probably the result of their having
to swim long distances in very cold water. https://faculty.washington.edu/chudler/facts.html
Polar bears evolved from brown bears relatively
recenltly:
" . . Approximately 125,000 years ago a population of brown bears
in the far north of their range was likely split off from their brown
bear ancestors, perhaps because of competition for food. . . " https://www.pbs.org/wnet/nature/arctic-bears-how-grizzlies-evolved-into-polar-bears/777/
On Monday, March 14, 2022 at 8:11:44 PM UTC-4, Paul Crowley wrote:metabolism, fight-or-flight is our body's reaction to a perceived attack on our body, both use sweating defensively.
On Sunday 13 March 2022 at 22:31:51 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead)
hair layer, which reduces the temperature of the head (including brain and
blood vessels).
All primates sweat. Humans sweat at 3 levels: incipiently, during sleep (hot or cold) while body is inactive, lightly while body is active but not strenuously so, and heavily while active strenuously so. Fever is our body's reaction to an attack on ourHomo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effectiveYour scenario implies that sweating was
with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
a routine everyday matter.
I do not see
it that way. The hominins would haveLike modern humans, archaic hominins lived near (but not in) shallow freshwater.
needed a good supply of water, and that's
often hard to find.
Sweating was IMO
primarily for emergencies -- such as whenThat is heavy sweating, a comparatively rare occurrence, and a poor way to cool since it excretes faster than it evaporates, unlike incipient and light sweating. Dripping sweat is both inefficient and ineffective, and leads to dehydration.
they got into fights, or suffered fevers.
Those who could lose heat by sweatingN/A.
survived better than those who couldn't
-- maybe their reserves had run out.
So, under my scenario, the 'tightly coiledUnder extreme sweating, scalp hair is irrelevant, fluid sweat pours off anyway.
hair' would have had little significance
as regards sweating. It could not have
evolved for that purpose.
Gareth Morgan:Thanks for this. I've tried to look into it, but
"In plain English, body heat is generated by mitochondria. Normal cells have
between 2 and a couple of thousand mitochondria. Heart cells have around 5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the
brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid
death from hypothermic heart failure and a chilly dip."
it seems to be an field of active research
with relatively few answers at present.
(E.g. I'd like to know if other species brains
had the same proportion of mitochondria.)
However, in outline, it supports my argumentN/A.
that large brains could have acted as a 'heat
resource' for a species where individuals
found themselves in cold water (perhaps, on
average, less than once in a lifetime) and
where the larger-brained had better chances
of survival.
Note that I'm changing my terminology fromN/A.
'heat store/heat reserve' to 'heat resource'.
Those individuals who could mobilise the
sugars in their bloodstream and in various
organs (probably converting some fats) and
generate heat in their brains (held out of the
water) would be able to keep their hearts
going for longer. The larger brains would
be like having a larger engine in a vehicle.
Of course, the fuel will always run out in
the end, but this is an emergency and those
who can keep their hearts warmer more
effectively and for longer, will do better.
Unlike many taxa, humans defend themselves best when grouped defensively, and worse when not, this is shared with chimps.
Elephants also have huge brains -- muchN/A. Note that elephants do not eat seafood.
larger than is apparently fitting for their
body size. They are great swimmers --
often in estuaries and cold ocean water.
While their size provides some protection,
the cold will get to them in long-distance
swims. Their large brains may well function
in the same way as I'm proposing for
hominins.
The brains of Polar bears (498 g) are morePolar bears are much larger than grizzly bears, and are fully covered in fur.
than double the size of those of Grizzlies
(234 g) -- probably the result of their having
to swim long distances in very cold water. https://faculty.washington.edu/chudler/facts.html
Polar bears evolved from brown bears relatively
recenltly:
" . . Approximately 125,000 years ago a population of brown bears
in the far north of their range was likely split off from their brown
bear ancestors, perhaps because of competition for food. . . " https://www.pbs.org/wnet/nature/arctic-bears-how-grizzlies-evolved-into-polar-bears/777/
One of the few valuable papers Lasisi found is a 1973 study in the American Journal of Physical Anthropology. In it, Daniel Hrdy, of Harvard University, loosely described a methodology to quantify the shape of a hair curl, which he applied to sevengroups of people around the world. Imperfect as it was, it was the starting point Lasisi was looking for. She built off his research, honing a methodology for fitting hair fibers to a circle to determine curvature and publishing her results in the
Jablonski says Lasisi’s work suggests how, just as melanated skin protects against UV rays, tightly curled hairs also protect humans from the sun. Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat]while providing extra protection from solar radiation. That was important for our newly bipedal human ancestors, she says, and you can’t do that with flat hair.
Read more about misconceptions in racial classification: “Race Is Real, But It’s Not Genetic”-
Sapiens.org
On Monday, March 14, 2022 at 9:22:43 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:our metabolism, fight-or-flight is our body's reaction to a perceived attack on our body, both use sweating defensively.
On Monday, March 14, 2022 at 8:11:44 PM UTC-4, Paul Crowley wrote:
On Sunday 13 March 2022 at 22:31:51 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead) epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead)
hair layer, which reduces the temperature of the head (including brain and
blood vessels).
All primates sweat. Humans sweat at 3 levels: incipiently, during sleep (hot or cold) while body is inactive, lightly while body is active but not strenuously so, and heavily while active strenuously so. Fever is our body's reaction to an attack onHomo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effectiveYour scenario implies that sweating was
with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
a routine everyday matter.
-I do not see
it that way. The hominins would haveLike modern humans, archaic hominins lived near (but not in) shallow freshwater.
needed a good supply of water, and that's
often hard to find.
Sweating was IMO
primarily for emergencies -- such as whenThat is heavy sweating, a comparatively rare occurrence, and a poor way to cool since it excretes faster than it evaporates, unlike incipient and light sweating. Dripping sweat is both inefficient and ineffective, and leads to dehydration.
they got into fights, or suffered fevers.
Those who could lose heat by sweatingN/A.
survived better than those who couldn't
-- maybe their reserves had run out.
So, under my scenario, the 'tightly coiledUnder extreme sweating, scalp hair is irrelevant, fluid sweat pours off anyway.
hair' would have had little significance
as regards sweating. It could not have
evolved for that purpose.
Gareth Morgan:Thanks for this. I've tried to look into it, but
"In plain English, body heat is generated by mitochondria. Normal cells have
between 2 and a couple of thousand mitochondria. Heart cells have around
5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the
brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid
death from hypothermic heart failure and a chilly dip."
it seems to be an field of active research
with relatively few answers at present.
(E.g. I'd like to know if other species brains
had the same proportion of mitochondria.)
However, in outline, it supports my argumentN/A.
that large brains could have acted as a 'heat
resource' for a species where individuals
found themselves in cold water (perhaps, on
average, less than once in a lifetime) and
where the larger-brained had better chances
of survival.
Note that I'm changing my terminology fromN/A.
'heat store/heat reserve' to 'heat resource'.
Those individuals who could mobilise the
sugars in their bloodstream and in various
organs (probably converting some fats) and
generate heat in their brains (held out of the
water) would be able to keep their hearts
going for longer. The larger brains would
be like having a larger engine in a vehicle.
Of course, the fuel will always run out in
the end, but this is an emergency and those
who can keep their hearts warmer more
effectively and for longer, will do better.
Unlike many taxa, humans defend themselves best when grouped defensively, and worse when not, this is shared with chimps.
Elephants also have huge brains -- muchN/A. Note that elephants do not eat seafood.
larger than is apparently fitting for their
body size. They are great swimmers --
often in estuaries and cold ocean water.
While their size provides some protection,
the cold will get to them in long-distance
swims. Their large brains may well function
in the same way as I'm proposing for
hominins.
The brains of Polar bears (498 g) are morePolar bears are much larger than grizzly bears, and are fully covered in fur.
than double the size of those of Grizzlies
(234 g) -- probably the result of their having
to swim long distances in very cold water. https://faculty.washington.edu/chudler/facts.html
Polar bears evolved from brown bears relatively
recenltly:
Warm blooded fauna increased specialized neuron density https://archaeologynewsnetwork.blogspot.com/2022/03/neuron-counts-reveal-brain-complexity.html?m=1" . . Approximately 125,000 years ago a population of brown bears
in the far north of their range was likely split off from their brown bear ancestors, perhaps because of competition for food. . . " https://www.pbs.org/wnet/nature/arctic-bears-how-grizzlies-evolved-into-polar-bears/777/
See graph.
Mitochondria aren't mentioned but obviously are key to faster better cognition processing. Overheating must be avoided, thus the advantage of coil-hair scalp/brain covering lofted above melanin-rich skin in tropical climes, as well as shelters.
On Friday, March 25, 2022 at 12:02:35 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:on our metabolism, fight-or-flight is our body's reaction to a perceived attack on our body, both use sweating defensively.
On Tuesday, March 15, 2022 at 2:55:01 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
On Monday, March 14, 2022 at 9:22:43 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
On Monday, March 14, 2022 at 8:11:44 PM UTC-4, Paul Crowley wrote:
On Sunday 13 March 2022 at 22:31:51 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead)
epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead)
hair layer, which reduces the temperature of the head (including brain and
blood vessels).
All primates sweat. Humans sweat at 3 levels: incipiently, during sleep (hot or cold) while body is inactive, lightly while body is active but not strenuously so, and heavily while active strenuously so. Fever is our body's reaction to an attackHomo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effectiveYour scenario implies that sweating was
with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
a routine everyday matter.
the bonding of the third phosphate is available in a controlled fashion. ATP = Adenine TriPhosphate moleculeI do not see
it that way. The hominins would haveLike modern humans, archaic hominins lived near (but not in) shallow freshwater.
needed a good supply of water, and that's
often hard to find.
Sweating was IMO
primarily for emergencies -- such as whenThat is heavy sweating, a comparatively rare occurrence, and a poor way to cool since it excretes faster than it evaporates, unlike incipient and light sweating. Dripping sweat is both inefficient and ineffective, and leads to dehydration.
they got into fights, or suffered fevers.
Those who could lose heat by sweatingN/A.
survived better than those who couldn't
-- maybe their reserves had run out.
So, under my scenario, the 'tightly coiledUnder extreme sweating, scalp hair is irrelevant, fluid sweat pours off anyway.
hair' would have had little significance
as regards sweating. It could not have
evolved for that purpose.
Gareth Morgan:Thanks for this. I've tried to look into it, but
"In plain English, body heat is generated by mitochondria. Normal cells have
between 2 and a couple of thousand mitochondria. Heart cells have around
5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the
brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid
death from hypothermic heart failure and a chilly dip."
it seems to be an field of active research
with relatively few answers at present.
(E.g. I'd like to know if other species brains
had the same proportion of mitochondria.)
However, in outline, it supports my argumentN/A.
that large brains could have acted as a 'heat
resource' for a species where individuals
found themselves in cold water (perhaps, on
average, less than once in a lifetime) and
where the larger-brained had better chances
of survival.
Note that I'm changing my terminology fromN/A.
'heat store/heat reserve' to 'heat resource'.
Those individuals who could mobilise the
sugars in their bloodstream and in various
organs (probably converting some fats) and
generate heat in their brains (held out of the
water) would be able to keep their hearts
going for longer. The larger brains would
be like having a larger engine in a vehicle.
Of course, the fuel will always run out in
the end, but this is an emergency and those
who can keep their hearts warmer more
effectively and for longer, will do better.
Unlike many taxa, humans defend themselves best when grouped defensively, and worse when not, this is shared with chimps.
Elephants also have huge brains -- muchN/A. Note that elephants do not eat seafood.
larger than is apparently fitting for their
body size. They are great swimmers --
often in estuaries and cold ocean water.
While their size provides some protection,
the cold will get to them in long-distance
swims. Their large brains may well function
in the same way as I'm proposing for
hominins.
The brains of Polar bears (498 g) are morePolar bears are much larger than grizzly bears, and are fully covered in fur.
than double the size of those of Grizzlies
(234 g) -- probably the result of their having
to swim long distances in very cold water. https://faculty.washington.edu/chudler/facts.html
Polar bears evolved from brown bears relatively
recenltly:
Warm blooded fauna increased specialized neuron density https://archaeologynewsnetwork.blogspot.com/2022/03/neuron-counts-reveal-brain-complexity.html?m=1" . . Approximately 125,000 years ago a population of brown bears
in the far north of their range was likely split off from their brown
bear ancestors, perhaps because of competition for food. . . " https://www.pbs.org/wnet/nature/arctic-bears-how-grizzlies-evolved-into-polar-bears/777/
See graph.
Mitochondria aren't mentioned but obviously are key to faster better cognition processing. Overheating must be avoided, thus the advantage of coil-hair scalp/brain covering lofted above melanin-rich skin in tropical climes, as well as shelters.-
Mitochondria
Jean Gibbons at Quora:
How do you move energy through your body?
ATP is formed at the mitochondria and functions as the “energy currency” within the body. Energy is found “stored” in the bonding of a third phosphate group to the molecule. Energy is contained within each and every bond, but the energy in
The products of digestion: amino acids, glucose, fats, etc. all contain potential energy. As these chemicals are metabolized, the energy contained within is captured within a molecule of ATP.
As the blood flows throughout the body, the energy is made available throughout as wellhttps://www.sciencedaily.com/releases/2004/01/040114075853.htm
On Tuesday, March 15, 2022 at 2:55:01 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:our metabolism, fight-or-flight is our body's reaction to a perceived attack on our body, both use sweating defensively.
On Monday, March 14, 2022 at 9:22:43 PM UTC-4, DD'eDeN aka note/nickname/alas_my_loves wrote:
On Monday, March 14, 2022 at 8:11:44 PM UTC-4, Paul Crowley wrote:
On Sunday 13 March 2022 at 22:31:51 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
So what's the need for that extremely
expensive hair? If melanated naked skin
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Melanin in skin: stops ultraviolet light penetration beyond the (dead)
epidermis layer.
Melanin in hair: stops infrared light (heat) penetration at the (coiled dead)
hair layer, which reduces the temperature of the head (including brain and
blood vessels).
All primates sweat. Humans sweat at 3 levels: incipiently, during sleep (hot or cold) while body is inactive, lightly while body is active but not strenuously so, and heavily while active strenuously so. Fever is our body's reaction to an attack onHomo's large brain has large heat production, sweating depends on evaporation, in perpetually hot humid climates sweating is more effectiveYour scenario implies that sweating was
with tightly coiled but lofty hair than with damp flat hair clinging to the scalp.
a routine everyday matter.
bonding of the third phosphate is available in a controlled fashion. ATP = Adenine TriPhosphate moleculeI do not see
it that way. The hominins would haveLike modern humans, archaic hominins lived near (but not in) shallow freshwater.
needed a good supply of water, and that's
often hard to find.
Sweating was IMO
primarily for emergencies -- such as whenThat is heavy sweating, a comparatively rare occurrence, and a poor way to cool since it excretes faster than it evaporates, unlike incipient and light sweating. Dripping sweat is both inefficient and ineffective, and leads to dehydration.
they got into fights, or suffered fevers.
Those who could lose heat by sweatingN/A.
survived better than those who couldn't
-- maybe their reserves had run out.
So, under my scenario, the 'tightly coiledUnder extreme sweating, scalp hair is irrelevant, fluid sweat pours off anyway.
hair' would have had little significance
as regards sweating. It could not have
evolved for that purpose.
Gareth Morgan:Thanks for this. I've tried to look into it, but
"In plain English, body heat is generated by mitochondria. Normal cells have
between 2 and a couple of thousand mitochondria. Heart cells have around
5,000 but brain cells have an estimated two million mitochondria per cell.
The brain is a colossally effective furnace. This is important because the heart
is the most vulnerable organ in the human body to cold. The blood from the
brain, which comes out much hotter than it goes in, goes directly to the heart.
In terms of natural selection this is very much the difference between rapid
death from hypothermic heart failure and a chilly dip."
it seems to be an field of active research
with relatively few answers at present.
(E.g. I'd like to know if other species brains
had the same proportion of mitochondria.)
However, in outline, it supports my argumentN/A.
that large brains could have acted as a 'heat
resource' for a species where individuals
found themselves in cold water (perhaps, on
average, less than once in a lifetime) and
where the larger-brained had better chances
of survival.
Note that I'm changing my terminology fromN/A.
'heat store/heat reserve' to 'heat resource'.
Those individuals who could mobilise the
sugars in their bloodstream and in various
organs (probably converting some fats) and
generate heat in their brains (held out of the
water) would be able to keep their hearts
going for longer. The larger brains would
be like having a larger engine in a vehicle.
Of course, the fuel will always run out in
the end, but this is an emergency and those
who can keep their hearts warmer more
effectively and for longer, will do better.
Unlike many taxa, humans defend themselves best when grouped defensively, and worse when not, this is shared with chimps.
Elephants also have huge brains -- muchN/A. Note that elephants do not eat seafood.
larger than is apparently fitting for their
body size. They are great swimmers --
often in estuaries and cold ocean water.
While their size provides some protection,
the cold will get to them in long-distance
swims. Their large brains may well function
in the same way as I'm proposing for
hominins.
The brains of Polar bears (498 g) are morePolar bears are much larger than grizzly bears, and are fully covered in fur.
than double the size of those of Grizzlies
(234 g) -- probably the result of their having
to swim long distances in very cold water. https://faculty.washington.edu/chudler/facts.html
Polar bears evolved from brown bears relatively
recenltly:
Warm blooded fauna increased specialized neuron density https://archaeologynewsnetwork.blogspot.com/2022/03/neuron-counts-reveal-brain-complexity.html?m=1" . . Approximately 125,000 years ago a population of brown bears
in the far north of their range was likely split off from their brown bear ancestors, perhaps because of competition for food. . . " https://www.pbs.org/wnet/nature/arctic-bears-how-grizzlies-evolved-into-polar-bears/777/
See graph.
Mitochondria aren't mentioned but obviously are key to faster better cognition processing. Overheating must be avoided, thus the advantage of coil-hair scalp/brain covering lofted above melanin-rich skin in tropical climes, as well as shelters.-
Mitochondria
Jean Gibbons at Quora:
How do you move energy through your body?
ATP is formed at the mitochondria and functions as the “energy currency” within the body. Energy is found “stored” in the bonding of a third phosphate group to the molecule. Energy is contained within each and every bond, but the energy in the
The products of digestion: amino acids, glucose, fats, etc. all contain potential energy. As these chemicals are metabolized, the energy contained within is captured within a molecule of ATP.
As the blood flows throughout the body, the energy is made available throughout as well
Tight curls create lofted, airy ventilation structures for the head,
allowing it to breathe [sweat] while providing extra protection
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
Tight curls create lofted, airy ventilation structures for the head,
allowing it to breathe [sweat] while providing extra protection
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
Lasisi 1973 Am.J.phys.Anthrop.: Daniel Hrdy loosely described a methodology to quantify the shape of a hair curl, which he applied to 7 groups of people around the world: the starting point Lasisi was looking for.She built off his research, honing a methodology for fitting hair fibers to a circle to determine curvature (Am.J.biol.Anthrop., Scient.Rep.).
On Thursday 10 March 2022 at 14:42:56 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
Jablonski says Lasisi’s work suggests how, just as melanated skin protects against UV rays, tightly curled hairs also protect humansSo what's the need for that extremely
from the sun.
expensive hair?
protects against UV rays, why have that
extraordinary hair? ('Extraordinary' in
that no other mammal has anything
like it.)
Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protection
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
Can't do what . . exactly? There's no
problem with sweating elsewhere on
the body.
What's the need for that dense, tightly-
curled hair?
Don't pretend you have an answer
when all you can present is verbiage.
That's deceptive politics, not science.
On Thursday 10 March 2022 at 14:42:56 UTC, DD'eDeN aka note/nickname/alas_my_loves wrote:
Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protectionI've just heard a short radio interview with Simon
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
Wooley.
https://en.wikipedia.org/wiki/Simon_Woolley,_Baron_Woolley_of_Woodford
Today programme 16/04/2022 at 1:43:25 https://www.bbc.co.uk/sounds/play/m0016gvm
He and his brother were adopted by a white
couple who had no idea how to cut or trim
their (Afro) hair. Eventually they found barbers
who knew what to do.
Take a look at some videos of barbers working
on Afro hair. This is one:
https://www.youtube.com/watch?v=qv4R09k9EN8
The sheer quantity of natural uncut Afro
hair -- which is what our ancestors evolved
to possess -- is staggering.
not allow for easy sweating. In fact, we can
say that, with such hair, no level of sweating
would produce the slightest cooling effect on
the scalp.
Tight curls create lofted, airy ventilation structures for the head, allowing it to breathe [sweat] while providing extra protectionGiven that the rest of the body was naked,
from solar radiation. That was important for our newly bipedal
human ancestors, she says, and you can t do that with flat hair.
it also makes no sense to claim that such
dense hair
from UV rays from the sun.
So what was it for?So??
Black people have tightly coiled body hair, so tight-coiling preceded body hair reduction.. .
. .it also makes no sense to claim that such. .
dense hair
Tightly-coiled Afro hair is not "dense" hair.
It protects against tropical-year-round sun UV.. .
On Saturday 16 April 2022 at 19:32:11 UTC+1, DD'eDeN aka note/nickname/alas_my_loves wrote:
Black people have tightly coiled body hair, so tight-coiling preceded body hair reduction.
. .
When and why do you see "body hair
reduction'?
. .
. .it also makes no sense to claim that such. .
dense hair
Tightly-coiled Afro hair is not "dense" hair.
Please find an image of natural fully-grown
'tightly-coiled Afro hair'. I can't. I suspect
that you won't be able to either. In other
words, you're imagining something that
does not exist.
. .
It protects against tropical-year-round sun UV.. .
Why does the scalp need that protection
when the rest of the body doesn't?
. .
The scalp receives the maximum exposure in an obligate orthograde biped.
. .. .Black people have tightly coiled body hair, so tight-coiling preceded body hair reduction.
Amend: the curling of body hair began before Hs body hair greatly reduced, but at a very
slow rate of change until proto-agriculture, and both are still under selection. Body hair/fur
reduction first began with the change from fully exposed arboreal branch/tree-fork sleeping
(OWM, gibbons) to partly exposed arboreal bowl nesting (great apes) and increased in the
change from arboreal bowl nesting to non-exposed terrestrial dome dwelling (Homo) while
under forest canopy. Note that body hair reduction (and concomitant scalp hair lengthening)
was mainly a nocturnal/inactivity selection trait, mostly connected to prone/supine posture
relative to enclosure; while body & scalp hair curling was mainly a diurnal/activity selection
trait mostly connected to upright orthograde posture relative to exposure to sunlight and
convective air currents. A parallel condition today is in mature people, hair loss is
independent of hair graying but both can occur simultaneously or sequentially, a redhead
balding or a gray head with full scalp hair. In humans two distinct forces, night sleep
exposure/enclosure, sun skin exposure/enclosure, produced today's hair traits.
. .When and why do you see "body hair. .
reduction'?
. .
. .it also makes no sense to claim that such. .
dense hair
Tightly-coiled Afro hair is not "dense" hair.
Please find an image of natural fully-grown
'tightly-coiled Afro hair'. I can't. I suspect
that you won't be able to either. In other
words, you're imagining something that
does not exist.
Typical black people without European admixture have tightly coiled hair.
People with only 20% African recent heritage have loosely coiled hair.. .
. .. .It protects against tropical-year-round sun UV.. .
Why does the scalp need that protection
when the rest of the body doesn't?
The scalp receives the maximum exposure in an obligate orthograde biped.
The scalp receives the maximum exposure in an obligate orthograde biped.:-DDD You haven't seen my baldness.
On Sunday 17 April 2022 at 14:21:04 UTC+1, DD'eDeN aka note/nickname/alas_my_loves wrote:PC falling back on his usual poli crap.
. .. .Black people have tightly coiled body hair, so tight-coiling preceded body hair reduction.
Amend: the curling of body hair began before Hs body hair greatly reduced, but at a very
slow rate of change until proto-agriculture, and both are still under selection. Body hair/fur
reduction first began with the change from fully exposed arboreal branch/tree-fork sleeping
(OWM, gibbons) to partly exposed arboreal bowl nesting (great apes) and increased in the
change from arboreal bowl nesting to non-exposed terrestrial dome dwelling (Homo) while
under forest canopy. Note that body hair reduction (and concomitant scalp hair lengthening)
was mainly a nocturnal/inactivity selection trait, mostly connected to prone/supine posture
relative to enclosure; while body & scalp hair curling was mainly a diurnal/activity selection
trait mostly connected to upright orthograde posture relative to exposure to sunlight and
convective air currents. A parallel condition today is in mature people, hair loss is
independent of hair graying but both can occur simultaneously or sequentially, a redhead
balding or a gray head with full scalp hair. In humans two distinct forces, night sleep
exposure/enclosure, sun skin exposure/enclosure, produced today's hair traits.
All far too speculative for me
. .
. .When and why do you see "body hair. .
reduction'?
. .
. .it also makes no sense to claim that such. .
dense hair
Tightly-coiled Afro hair is not "dense" hair.
Please find an image of natural fully-grown
'tightly-coiled Afro hair'. I can't. I suspect
that you won't be able to either. In other
words, you're imagining something that
does not exist.
Typical black people without European admixture have tightly coiled hair.
Where is the image that I requested?
. .
People with only 20% African recent heritage have loosely coiled hair.. .
It is generally accepted that our ancestors
were African -- and presumably had normal
Afro hair.
. .
. .. .It protects against tropical-year-round sun UV.. .
Why does the scalp need that protection
when the rest of the body doesn't?
The scalp receives the maximum exposure in an obligate orthograde biped.
Not an adequate answer for the enormous
difference in hair cover.
. .Where is the image that I requested?. .Tightly-coiled Afro hair is not "dense" hair.. .
Please find an image of natural fully-grown
'tightly-coiled Afro hair'. I can't. I suspect
that you won't be able to either. In other
words, you're imagining something that
does not exist.
Typical black people without European admixture have tightly coiled hair. >> . .
| Sysop: | Keyop |
|---|---|
| Location: | Huddersfield, West Yorkshire, UK |
| Users: | 485 |
| Nodes: | 16 (2 / 14) |
| Uptime: | 130:39:46 |
| Calls: | 9,655 |
| Calls today: | 3 |
| Files: | 13,705 |
| Messages: | 6,166,483 |