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19-03-2013, 02:04 PM
RE: Testabel Evolution
http://www.amazon.com/Why-Evolution-True...0143116649
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19-03-2013, 05:14 PM
Testabel Evolution
How does the environment affect genes in humans, like skin color?
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19-03-2013, 05:53 PM
RE: Testabel Evolution
(19-03-2013 05:14 PM)I and I Wrote:  How does the environment affect genes in humans, like skin color?
My understanding: Natural selection. "Nature selects".

Mutations in genes result in tiny gradients in skin colour. These mutations are spread throughout a population. Some mutations result in lighter skin tones, others darker.

Mutations build up. Further mutations would make the skin colour lighter, or darker by another gradient.

The environment "selects" or weeds out certain mutations. Skin colour controls the amount of solar radiation that the body absorbs. Lighter absorbs more, darker not so much. If you're in an environment with more direct sunlight (near the equator, where sunlight is direct), the mutations that further the skin gradient towards darker are more beneficial (less sickly people), and so are passed on.

If you're in a northern climate where sunlight is angled, with lower radiation, the opposite happens.

These genes and mutations are present in all people. The environment allows specific mutations to build up, to become more pronounced. If northern peoples with lighter skin tones were concentrated in the equator (out in the open), over many generations, they would have permanent darker skin tones (note: tanning doesn't change genes, just stimulates the production of certain cells that protect the body from solar radiation. This is not permanent).
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19-03-2013, 06:11 PM
RE: Testabel Evolution
I & I:



Give me your argument in the form of a published paper, and then we can start to talk.
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19-03-2013, 06:37 PM (This post was last modified: 20-03-2013 07:12 AM by Ghost.)
RE: Testabel Evolution
Hey, I.

Shit, brother, skin colour's a gimmie Cool

Human skin has melatonin (ON EDIT: Cosmos rightfully pointed out that I completely botched this post. Any time you see the word MELATONIN, it should read MELANIN). Melatonin serves a number of purposes. But the two biggies are:
1 - Sunblock
2 - Happiness

Melatonin blocks ultraviolet radiation, which left unchecked, can cause mutations in cellular DNA. The higher the amount of direct ultraviolet radiation striking the skin, the more UV radiation needs to be absorbed. Humans with the most melatonin have the best survival odds in a place where there is a ton of direct sunlight. Like the African Savannah where humans come from.

Melatonin offers a brown pigmentation to the skin (without which the skin looks pink due to the subcutaneous blood: see albinism). The more melatonin, the darker and more brown the pigmentation.

The first humans that lived in Africa had very dark pigmentation because there was a ton of direct sunlight.

To be clear, they didn't develop dark skin BECAUSE there was direct sunlight. That is to say, they did not perceive a problem and then design a solution for it. Those individuals that were born with the alleles for more melatonin had a better chance of surviving to the age of reproduction. Those that had paler skin didn't reproduce as much. Over time, the frequency of the dark skin allele approached 100% across the continent as a DIRECT RAMIFICATION of the selection pressure of direct sunlight.

Melatonin also produces vitamin D (which is actually a hormone, not a vitamin). Vitamin D aids in a number of processes, like calcium and phosphorous absorption. A vitamin D deficiency leads to depression (see seasonal affective disorder) and to more serious conditions like osteoporosis, rickets and even death.

Vitamin D is an essential vitamin, meaning that the body cannot produce it from other compounds inside the body. All essential nutrients must be taken into the body in their whole form. Vitamin D is a little different because it's produced in its whole form by the body. That being said, the skin requires sunlight to produce vitamin D.

When there is less available light, dark pigmentation becomes a liability because it filters out too much light, meaning that the body cannot produce enough vitamin D. In low-light climates (where the sunlight strikes the atmosphere at a sharper angle than at the Equator; ie, North), it's more adaptive to have less melatonin. The less melatonin one has, the lighter, and closer to pink, their skin is.

This is why environmental factors like direct sunlight (in greater or lesser quantity) acts as a selection pressure for skin pigmentation.

Furthermore, by mapping the migration of mankind out of Africa by tracing mitochondrial DNA, one of the haplogroups settled in the Caucus Mountains. This group encountered high altitude, low-light conditions. In those conditions, humans with dark skin reproduced less frequently than those with pale skin, which is why the frequency of pale skin alleles approached 100% in the Caucasus. It is THIS SPECIFIC GROUP that shed their melatonin, wound up with pale skin and came to be known as the Caucasians. From the Caucasus, they migrated West into Europe (where they encountered Neanderthal man prior to the extinction of the species) and settled.

The differences between the dark skinned humans in Africa and the pale skinned humans in Europe is a perfect example of genetic drift. Populations whose gene pools are separated by space-time build up differences in allele frequencies.

I am an example of genetic flow.

When my pale skinned mother mated with my dark skinned father, the allele pair that I inherited (one for pale skin, one dark skin) entered an incomplete (or partial) dominance relationship. Thus my skin tone, a 100% sexified caramel brown, is a MIX of the colours from both alleles (an intermediate phenotype).

This is also why there is NO GENETIC BASIS FOR RACE WHATSOEVER. Skin colour is a product of allele frequency and genetic drift. That's it, that's all. The moment you reintegrate these populations, the skin tone alleles flow freely back and forth.

Peace and Love and Empathy,

Matt
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19-03-2013, 06:53 PM
RE: Testabel Evolution
(19-03-2013 06:37 PM)Ghost Wrote:  ...
Human skin has melatonin. Melatonin serves a number of purposes. But the two biggies are:
1 - Sunblock
2 - Happiness
...

Well that explains it.

Evidence:
Asian girls are cute and happy with beautiful, smooth, kissable coffee-coloured skin.
English girls have pink, often blotchy, rough skin and are fucking miserable!

Nuff said.

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19-03-2013, 07:19 PM
RE: Testabel Evolution
(19-03-2013 06:37 PM)Ghost Wrote:  Hey, I.

Shit, brother, skin colour's a gimmie Cool

Human skin has melatonin. Melatonin serves a number of purposes. But the two biggies are:
1 - Sunblock
2 - Happiness

Melatonin blocks ultraviolet radiation, which left unchecked, can cause mutations in cellular DNA. The higher the amount of direct ultraviolet radiation striking the skin, the more UV radiation needs to be absorbed. Humans with the most melatonin have the best survival odds in a place where there is a ton of direct sunlight. Like the African Savannah where humans come from.

Melatonin offers a brown pigmentation to the skin (without which the skin looks pink due to the subcutaneous blood: see albinism). The more melatonin, the darker and more brown the pigmentation.

The first humans that lived in Africa had very dark pigmentation because there was a ton of direct sunlight.

To be clear, they didn't develop dark skin BECAUSE there was direct sunlight. That is to say, they did not perceive a problem and then design a solution for it. Those individuals that were born with the alleles for more melatonin had a better chance of surviving to the age of reproduction. Those that had paler skin didn't reproduce as much. Over time, the frequency of the dark skin allele approached 100% across the continent as a DIRECT RAMIFICATION of the selection pressure of direct sunlight.

Melatonin also produces vitamin D (which is actually a hormone, not a vitamin). Vitamin D aids in a number of processes, like calcium and phosphorous absorption. A vitamin D deficiency leads to depression (see seasonal affective disorder) and to more serious conditions like osteoporosis, rickets and even death.

Vitamin D is an essential vitamin, meaning that the body cannot produce it from other compounds inside the body. All essential nutrients must be taken into the body in their whole form. Vitamin D is a little different because it's produced in its whole form by the body. That being said, the skin requires sunlight to produce vitamin D.

When there is less available light, dark pigmentation becomes a liability because it filters out too much light, meaning that the body cannot produce enough vitamin D. In low-light climates (where the sunlight strikes the atmosphere at a sharper angle than at the Equator; ie, North), it's more adaptive to have less melatonin. The less melatonin one has, the lighter, and closer to pink, their skin is.

This is why environmental factors like direct sunlight (in greater or lesser quantity) acts as a selection pressure for skin pigmentation.

Furthermore, by mapping the migration of mankind out of Africa by tracing mitochondrial DNA, one of the haplogroups settled in the Caucus Mountains. This group encountered high altitude, low-light conditions. In those conditions, humans with dark skin reproduced less frequently than those with pale skin, which is why the frequency of pale skin alleles approached 100% in the Caucasus. It is THIS SPECIFIC GROUP that shed their melatonin, wound up with pale skin and came to be known as the Caucasians. From the Caucasus, they migrated West into Europe (where they encountered Neanderthal man prior to the extinction of the species) and settled.

The differences between the dark skinned humans in Africa and the pale skinned humans in Europe is a perfect example of genetic drift. Populations whose gene pools are separated by space-time build up differences in allele frequencies.

I am an example of genetic flow.

When my pale skinned mother mated with my dark skinned father, the allele pair that I inherited (one for pale skin, one dark skin) entered an incomplete (or partial) dominance relationship. Thus my skin tone, a 100% sexified caramel brown, is a MIX of the colours from both alleles (an intermediate phenotype).

This is also why there is NO GENETIC BASIS FOR RACE WHATSOEVER. Skin colour is a product of allele frequency and genetic drift. That's it, that's all. The moment you reintegrate these populations, the skin tone alleles flow freely back and forth.

Peace and Love and Empathy,

Matt

Matt,
You know how I hate to quibble No , but it sort of depends on what means by race, doesn't it?

I agree that the historical concept of race is incorrect and dangerous, but if we mean geographical phenotype (local allele frequency), then it is entirely genetic. Is there a better, less emotionally-laden, word?

Respectfully,
Chas

Skepticism is not a position; it is an approach to claims.
Science is not a subject, but a method.
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19-03-2013, 07:54 PM
RE: Testabel Evolution
Hey, Chas.

Respect right back atchya, brother Cool

Race only exists if you rewrite the entirety of the genetic classification system and make it something that it is not by creating division that isn't there and even if you do, that division is not at all permanent and can be destroyed in a single generation. Genetic drift and speciation are NOT the same thing. The differences between the so called races are utterly trivial from a genetic standpoint and again, are so flimsy that they can be destroyed in a single generation. So no, race doesn't exist. Even though genes are involved, alleles more specifically, because everyone has the exact same gene, there is no genetic basis for race.

The analogy is that you take English speakers from Montreal, Mobile and Manchester and, based on their accents, declare that they all speak completely different languages. When someone says, "uh, that's ridiculous," you respond, "yeah, but language is involved, so it's totally got a linguistic basis." Nope. Doesn't work that way.

Gene pools become separated by space-time. That separation is absolutely impermanent. When the space-time separating the gene pools is annihilated, then those two pools RE-MERGE INTO ONE POOL.

The less emotionally laden word is "trivial difference". It only seems significant because we think it is.

The correct word is "Homo sapiens sapiens".

Peace and Love and Empathy,

Matt
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19-03-2013, 08:16 PM
RE: Testabel Evolution
(19-03-2013 07:54 PM)Ghost Wrote:  Hey, Chas.

Respect right back atchya, brother Cool

Race only exists if you rewrite the entirety of the genetic classification system and make it something that it is not by creating division that isn't there and even if you do, that division is not at all permanent and can be destroyed in a single generation. Genetic drift and speciation are NOT the same thing. The differences between the so called races are utterly trivial from a genetic standpoint and again, are so flimsy that they can be destroyed in a single generation. So no, race doesn't exist. Even though genes are involved, alleles more specifically, because everyone has the exact same gene, there is no genetic basis for race.

The analogy is that you take English speakers from Montreal, Mobile and Manchester and, based on their accents, declare that they all speak completely different languages. When someone says, "uh, that's ridiculous," you respond, "yeah, but language is involved, so it's totally got a linguistic basis." Nope. Doesn't work that way.

Gene pools become separated by space-time. That separation is absolutely impermanent. When the space-time separating the gene pools is annihilated, then those two pools RE-MERGE INTO ONE POOL.

The less emotionally laden word is "trivial difference". It only seems significant because we think it is.

The correct word is "Homo sapiens sapiens".

Peace and Love and Empathy,

Matt

Ok, I see your point, but it really does come down to what is meant by race. If, historically, race meant species/sub-species then that is wrong. This seems to be what you mean. It certainly seems to be what racists mean. (Edit: Don't read that wrong.)

So the use of that word should likely be abjured.

My point is that what we perceive as differences among groups of people is genetic; it is local variation of allele frequency. It is largely unimportant genetically.

Skepticism is not a position; it is an approach to claims.
Science is not a subject, but a method.
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19-03-2013, 08:21 PM
RE: Testabel Evolution
This conversation is getting racy!

Dodgy

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