I'm also a creationist. I disbelieve macroevolution immensely and believe the Earth is flat and that NASA as well the Roscosmos State Corporation are part of a larger conspiracy to hide what really happened at the end of what they call the Dinosaurs but was really ancient Earth with Titans and many other beings that now help a ruthless God run the 9 planes of reality (us being the third) because they don't want us to run to the centre of either pole to reveal either the way out or the secret kingdom that lie in the north pole's centre.
Believe me, I do not disagree that evolution on the macro-scale makes very little sense but races are breeds and not species and the way it happened is the same way a German Shepherd and Labrador can both come from 'dog'. In fact this is even different to that as that is more like chimps and humans or bonobos and gorillas coming from original 'primate'.
It's perfectly reasonable to think that the first humans (that, no matter how un-racist you are, physically do resemble apes more than the other races[1][2]) slowly evolved into the other races by gradual changes whereby in a forest like India it seems that being smaller was an advantage in hiding and surviving (so they are similar to black in skin but not in size and most body proportions)... I mean this is all conjecture for now so let's get into the nitty gritty:
I'm going to do a lot of copy-pasting here because I can't word it better myself and I also don't like to type the words of pro-evolutionists as I can be confused for being something I no longer am.
Introduction to What Humans Are[3]
"The species that you and all other living human beings on this planet belong to is Homo sapiens. During a time of dramatic climate change 200,000 years ago, Homo sapiensevolved in Africa. Like other early humans that were living at this time, they gathered and hunted food, and evolved behaviors that helped them respond to the challenges of survival in unstable environments.
Anatomically, modern humans can generally be characterized by the lighter build of their skeletons compared to earlier humans. Modern humans have very large brains, which vary in size from population to population and between males and females, but the average size is approximately 1300 cubic centimeters. Housing this big brain involved the reorganization of the skull into what is thought of as "modern" -- a thin-walled, high vaulted skull with a flat and near vertical forehead. Modern human faces also show much less (if any) of the heavy brow ridges and prognathism of other early humans. Our jaws are also less heavily developed, with smaller teeth.
Scientists sometimes use the term “anatomically modern Homo sapiens” to refer to members of our own species who lived during prehistoric times."
Some Explanation of Why Skin and Race are Barely Even Breed Differences and Not Species-Specific Ones At All[4][5]
"Researchers agree that our early australopithecine ancestors in Africa probably had light skin beneath hairy pelts. “If you shave a chimpanzee, its skin is light,” says evolutionary geneticist Sarah Tishkoff of the University of Pennsylvania, the lead author of the new study. “If you have body hair, you don’t need dark skin to protect you from ultraviolet [UV] radiation.”
Until recently, researchers assumed that after human ancestors shed most body hair, sometime before 2 million years ago, they quickly evolved dark skin for protection from skin cancer and other harmful effects of UV radiation. Then, when humans migrated out of Africa and headed to the far north, they evolved lighter skin as an adaptation to limited sunlight. (Pale skin synthesizes more vitamin D when light is scarce.[6])
Previous research on skin-color genes fit that picture. For example, a “depigmentation gene” called SLC24A5 linked to pale skin swept through European populations in the past 6000 years. But Tishkoff ’s team found that the story of skin color evolution isn’t so black and white. Her team, including African researchers, used a light meter to measure skin reflectance in 2092 people in Ethiopia, Tanzania, and Botswana. They found the darkest skin in the Nilo-Saharan pastoralist populations of eastern Africa, such as the Mursi and Surma, and the lightest skin in the San of southern Africa, as well as many shades in between, as in the Agaw people of Ethiopia.
At the same time, they collected blood samples for genetic studies. They sequenced more than 4 million single nucleotide polymorphisms (SNPs)—places where a single letter of the genetic code varies across the genomes of 1570 of these Africans. They found four key areas of the genome where specific SNPs correlate with skin color.
The first surprise was that SLC24A5, which swept Europe, is also common in East Africa—found in as many as half the members of some Ethiopian groups. This variant arose 30,000 years ago and was probably brought to eastern Africa by people migrating from the Middle East, Tishkoff says. But though many East Africans have this gene, they don’t have white skin, probably because it is just one of several genes that shape their skin color.
The team also found variants of two neighboring genes, HERC2 and OCA2, which are associated with light skin, eyes, and hair in Europeans but arose in Africa; these variants are ancient and common in the light-skinned San people. The team proposes that the variants arose in Africa as early as 1 million years ago and spread later to Europeans and Asians. “Many of the gene variants that cause light skin in Europe have origins in Africa,” Tishkoff says.
The most dramatic discovery concerned a gene known as MFSD12. Two mutations that decrease expression of this gene were found in high frequencies in people with the darkest skin. These variants arose about a half-million years ago, suggesting that human ancestors before that time may have had moderately dark skin, rather than the deep black hue created today by these mutations.
These same two variants are found in Melanesians, Australian Aborigines, and some Indians. These people may have inherited the variants from ancient migrants from Africa who followed a “southern route” out of East Africa, along the southern coast of India to Melanesia and Australia, Tishkoff says. That idea, however, counters three genetic studies that concluded last year that Australians, Melanesians, and Eurasians all descend from a single migration out of Africa. Alternatively, this great migration may have included people carrying variants for both light and dark skin, but the dark variants later were lost in Eurasians.
To understand how the MFSD12 mutations help make darker skin, the researchers reduced expression of the gene in cultured cells, mimicking the action of the variants in dark-skinned people. The cells produced more eumelanin, the pigment responsible for black and brown skin, hair, and eyes. The mutations may also change skin color by blocking yellow pigments: When the researchers knocked out MFSD12 in zebrafish and mice, red and yellow pigments were lost, and the mice’s light brown coats turned gray. “This new mechanism for producing intensely dark pigmentation is really the big story,” says Nina Jablonski, an anthropologist at Pennsylvania State University in State College.
The study adds to established research undercutting old notions of race. You can’t use skin color to classify humans, any more than you can use other complex traits like height, Tishkoff says. “There is so much diversity in Africans that there is no such thing as an African race.”
The Classic Story vs The Modern Lack of Natural Selection[7]
"
| Why did people evolve into different races? |
| Question Date: 2006-01-20 |
| Answer 1:
Thanks for the great question; it’s one that we should all think about. To begin, it is a fact that people categorize others on the basis of their physical appearance, ethnicity, ancestry, social relations, and the interaction of all of these which we call race. However, race is not a defined term in biology and cannot solely be explained by different groups having different genes. Indeed there is much more genetic variation within any given population of humans than all the variation between human populations. Therefore, genetically, it is the case that humans share much more in common than they diverge. This is why we are all a part of the same species: Homo sapiens. Our perception of people as belonging to different races may then be a product of human psychology rather than biological reality. But your question still needs to be answered, how do we explain the observed, or phenotypic, differences between different groups of humans? Evolution by natural selection is one means. When modern humans left Africa some 100,000 to 50,000 years ago, they migrated quickly all over the world to climates very much different than where they evolved. In these new conditions, different traits were better suited for survival and reproduction in different areas. For instance near the equator where we evolved, it was beneficial to have darker skin to resist the intense sunlight. However as people migrated to extreme northern latitudes, those with lighter skin (due to random genetic variation) were better able to survive as they could absorb more sunlight needed to synthesize important vitamins. Lighter skin phenotypes therefore spread in these regions. Another example: people in Eurasia domesticated herd animals like cows and sheep, and eventually evolved the ability to digest milk beyond infancy, whereas people in other regions are lactose intolerant for life. So over time natural selection has changed the traits of different groups of humans based on their local environment. It is important to note however that not many traits have been selected for, and humans in fact demonstrate shockingly low genetic diversity compared to other primates. All humans share more genes in common than any two groups of chimpanzees for instance. In brief, I would answer your question by saying that populations of humans have evolved traits that make them suited to their environment, but we have not evolved into different races or even different sub-species. Rather each human is a different expression of the same set of genes, with some expressions more common based on geographical location. Excellent question. Best,
|
| Answer 2:
Good question. In some cases, it's natural selection caused by the differing amounts of sunlight on different parts of the Earth. In tropical areas like Africa, Central America, southern India, and Indonesia, there is a lot more sunlight than in far-northern places like Canada and Scandinavia or far-southern places like Patagonia and New Zealand. Melanin, the pigment that gives human skin its color, provides some help in resisting sunburn, but in small amounts also allows skin to make vitamin D from sunlight. This means that people in these sun-baked tropical climates tended to evolve darker skin while people in the sun-starved areas tended to evolve lighter skin: it's why Kenyan skin is very dark while Norwegian skin is very pale. Skin color isn't the only difference between the different races of humans however: for example, people from eastern Asia like Japan and China tend to have slanted eyes while people from elsewhere tend to have rounder eyes. I'm not sure if an explanation for this has ever been identified. It is possible that these differences are the result of an evolutionary process known as genetic drift: random evolutionary changes that have nothing to do with making an organism more or less able to survive. Genetic drift is known to happen to traits that are evolutionarily neutral, i.e. they neither benefit their owners nor harm them. It is possible that eye shape in humans does not affect the ability to survive and so is not subject to natural selection, with the result that it evolves due to genetic drift instead. To drive the point on genetic drift home: it is possible today for dark-skinned people to buy foods in the supermarket that have vitamin D, and for light-skinned people to wear sunscreen when they go out into the sun. This would remove the effects of natural selection on human skin color, since it is no longer valuable to survive. I predict that, in the future, human skin color may begin to evolve in response to genetic drift instead of due to natural selection as it has in the past. |
Sources (All last accessed by me at 8th April 2018 5:52AM GMT):
[1] https://www.wnycstudios.org/story/deep-problem-deep-learning/
[2] https://ferris.edu/HTMLS/news/jimcrow/letters/2012/apes.htm
[3] http://humanorigins.si.edu/evidence/human-fossils/species/homo-sapiens
[4] http://www.sciencemag.org/news/2017/10/new-gene-variants-reveal-evolution-human-skin-color