What makes people have different human skin “colors”? Answer
As was discussed in Where did the human races come from?, we learned that all humans on earth today are descended from Noah and his wife, his three sons and their wives, and before that from Adam and Eve (Genesis 1-11). But today we have many different groups, often called “races,” with what seem to be greatly differing features. The most obvious of these is skin color. Many see this as a reason to doubt the Bible's record of history. They believe that the various groups could have arisen only by evolving separately over tens of thousands of years. However, as we shall see, this does not follow from the biological evidence.
We know that skin color is governed by more than one pair of genes. For simplicity, let's assume there are only two, 1 located at positions A and B on the chromosomes. One form of the gene, “M,” “says” to make lots of melanin; another form of the gene, 2 “m,” says to only make a little melanin. At position A we could have a pair such as MAMA, MAmA, or mAmA 3 which would instruct the skin cells to make a lot, some, or little melanin. Similarly, at position B we could have the gene pairs MBMB, MBmB, or mBmB instructing cells to make a lot, some or little melanin. Thus very dark people could have MAMAMBMB, for example (see figure 1).
Since both the sperm and eggs of such people could only be MAMB, (remember, only one of each A or B pair goes to each sperm or egg) they could only produce children with exactly the same combination of genes as themselves. So the children will all be very dark. Likewise, very light people, with mAmAmBmB, could produce children only like themselves (see figure 2, below).
Let's look at what combinations would result from parents who are the type of brown-skinned person called a mulatto, or MAmAMBmB (the offspring of an MAMAMBMB and mAmAmBmB union, for example; see figure 3, below).
We can do this with a diagram called a “Punnet square” (see figure 4 below).
The left side (of the above table) shows the four different gene combinations possible in the sperm from the father and the top gives the combinations possible in the eggs from the mother (remember that a parent can only pass on one of each pair of genes to each sperm or egg). We locate a particular sperm gene combination and follow the row across to the column below a particular egg gene combination (like finding a location on a street map). The intersection gives the generic makeup of the offspring from that particular sperm and egg union.
For example, an MAmB sperm and an mAMB egg would produce a child with MAmAMBmB, just the same as the parents. The other possibilities mean that five levels of melanin (shades of color) can result in the different offspring of such a mulatto marriage, as roughly indicated by the level of shading in the diagram. If three gene pairs were involved, seven levels of melanin would be possible.
If people with MAMAMBMB , who are “pure” black (in the sense of having no genes for lightness at all), were to intermarry and migrate to a place where their offspring could not marry other people of lighter color, all their descendants would be black—a pure “black line” would result.
If “white” people (mAmAmBmB) were to marry only other whites and migrate to a place where their offspring could not marry darker people, a pure (in the same sense) “white line” would result—they would have lost the genes needed to produce a large amount of melanin and be black.
It is thus easily possible, beginning with two middle-brown parents, to get not only all the “colors,” but also people groups with stable shades of skin color.
But what about people groups that are permanently middle-brown, such as we have today? Again, this is easily explained. If those with genes MAMAmBmB or mAmAMBMB no longer intermarry with others, they will be able be able to produce only mid-brown offspring as in figure 3. (You may want to work this out with your own Punnet square.)
If either of these lines were to interbreed again with the other, the process would be reversed. In a short time, their descendants would show a whole range of colors, often in the same family. Figure 5 shows what were called Britain's most amazing twins. One is obviously quite light in complexion, while the other is clearly darker skinned.
Of course, this is not amazing at all when you do the exercise on paper, based on what we have discussed. (A clue if you want to do it yourself: mother cannot be MAMAMBMB. Also, the twins are obviously not identical twins, which are derived from the same egg—that is, monozygous).
If all the people on earth were to intermarry freely, and then break into random groups that kept to themselves, a whole new set of gene combinations could emerge. It may be possible to have almond eyes with black skin, blue eyes with black, tightly curled hair, etc. We need to remember, of course, that the way in which genes express themselves is much more complex than this simplified picture. For example, sometimes certain genes are linked together. However, the basic point is unaffected.
Even today, within a particular people group you will often see a feature normally associated with another people group. For instance, you will occasionally see a European with a broad flat nose, or a Chinese person with very pale skin or Caucasian eyes. Most scientists now agree that, for modern humans, “race” has little or no biological meaning. This also argues strongly against the idea that the people groups have been evolving separately for long periods.
What Really Happened?
We can now reconstruct the true history of the people groups, using:
From Genesis 11, we understand that up to this time there was only one language. God judged the people's disobedience by imposing different languages, so that they could not work together against God. The confusion forced the people to scatter over the earth as God intended.
So all the people groups—black Africans, Indo-Europeans, Mongolians, and others—have come into existence since Babel.
After the flood, for the few centuries until Babel, there was only one language and one culture group. Thus, there were no barriers to marriage within this group. This would tend to keep the skin color of the population away from the extremes. Very dark and very light skin would appear, of course, but people tending in either direction would be free to marry someone lighter or darker than themselves, ensuring that the average color stayed roughly the same.
The same would be true of characteristics other than skin color. Under these sorts of circumstances, distinct differences in appearance will never emerge. To obtain such separate lines, you would need to break a large breeding group into smaller groups and keep them separate, that is, prevent interbreeding between groups. This would be true for animal as well as human populations, as every biologist knows.
The Effects of Babel
This is exactly what happened at Babel. Once separate languages were imposed, there were instantaneous barriers. Not only would people tend not to marry someone they couldn't understand, but entire groups which spoke the same language would have difficulty relating to and trusting those which did not. Thus, they would move away or be forced away from each other, into different environments. This, of course, is what God intended. (Is there archaeological evidence of the Tower of Babel? Answer / Is there any reference in early Mesopotamian literature to what happened at the Tower of Babel? Answer / Read the story of the Tower of Babel - Go…)
It is unlikely that each small group would carry the same broad range of skin colors as the original, larger group. One group might have more dark genes, on average, while another might have more light genes. The same thing would occur with other characteristics: nose shape, eye shape, etc. And since they would intermarry only within their own language group, these differences would no longer be averaged out as before.
As these groups migrated away from Babel, they encountered new and different climate zones. This would also have affected the balance of inherited factors in the population. However, the effects of the environment are nowhere near as important as the initial genetic mix of each group.
SKIN COLOR AND SUNLIGHT
As an example, consider a group of people who moved to a cold region with little sunlight. Here, the dark-skinned members would not be able to produce enough vitamin D, and thus would be less healthy and have fewer children. So, in time, the light-skinned members would predominate. If several different groups went to such an area, and if one group happened to be carrying few genes for lightness, this particular group could, in time, die out. Thus, natural selection acts on the characteristics already present, and does not create new ones.
It is interesting to note that the ancient Neanderthals of Europe, recognized as fully human, show evidence of vitamin D deficiency in that many of their bones were bent. In fact, this, plus a large dose of evolutionary prejudice, caused them to be classified as “ape-men” for a long time. It is thus quite plausible that they were a dark-skinned people who were unfit for the environment into which they moved because of the skin color genes they began with. Notice (again) that this natural selection, as it is called, does not produce skin colors, but only acts on the created capacity for making skin pigment that is already there.
So we see that the pressure of the environment can (a) affect the balance of genes within this group, and (b) even eliminate entire groups. This is why we see, to a large extent, that the physical characteristics of people tend to match the environment where they live (e.g., Nordic people with pale skin, equatorial people with dark skin).
But this is not always so. The Inuit (Eskimo) have brown skin, yet live where there is not much sun. Presumably they all have a genetic makeup such as MAMAmBmB which would not be able to produce lighter skin. On the other hand, native South Americans living on the equator do not have black skin. These examples confirm that natural selection does not create new information—if the genetic makeup of a group of people does not allow variation in color toward the desirable, natural selection cannot create such variation.
Pygmies live in a hot area, but rarely experience strong sunshine in their dense jungle environment; yet they have dark skin. Pygmies may be a good example of another factor that has affected the racial history of man: discrimination.
People different from the “norm” (e.g., a very light person in a dark people group), have historically been regarded as abnormal and rejected by the group. Thus, such a person would find it hard to get a marriage partner. This would further tend to eliminate light genes from a dark people, and vise versa. In this way, groups have tended to “purify” themselves.
Also, in some instances, interbreeding within a small group can accentuate a commonly occurring unusual feature that would otherwise be swamped by marriage outside the group. There is a tribe in Africa whose members all have grossly deformed feet as a result of this inbreeding.
Let us return to the Pygmies. If people possessing genes for short stature were discriminated against, a small group of them might seek refuge in the deepest forest. By marrying only each other they would ensure a Pygmy “race” from then on. The fact that Pygmy tribes do no have their own languages, but instead speak dialects of neighboring non-Pygmy tribal languages, is good evidence to support this.
The Effects of Choice
Certain genetic characteristics may have influenced people groups to make deliberate (or semi-deliberate) choices concerning the environments to which they migrated. For instance, people with genes for a thicker, more insulating layer of fat under their skin would tend to leave areas that were uncomfortably hot.
The evidence for the Bible's account of human origins is more than just biological and genetic. Since all peoples have descended from Noah's family, and a relatively short time ago, we would expect to find some memory of the catastrophic flood in the stories distorted by time retelling. In fact, an overwhelming number of cultures do have accounts that recall a world-destroying flood. Often these have startling parallels to the true, original account (such as: eight people saved in a boat, the sending of birds, a rainbow, and more).
Thus, we conclude that the dispersion at Babel broke up a large interbreeding group into small, interbreeding groups. This ensured that the resultant groups would have different mixes of genes for various physical features. By itself, this dispersion would ensure, in a short time, that there would be certain fixed differences in some of these groups, commonly called “races.” In addition, the selection pressure of the environment would modify the existing combinations of genes so that the physical characteristics of each group would tend to suit their environment.
There has been no simple-to-complex evolution of any genes, for the genes were present already. The dominant features of the various people groups result from different combinations of previously existing created genes, plus some minor degenerative changes, resulting from mutation (accidental changes which can be inherited). The originally created (genetic) information has been either reshuffled or has degenerated, but has not been added to.
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