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SKIN COLOR (HEREDITY)
This article was posted on Wednesday, September 17, 2008
Skin color (Heredity)
We know that skin color is governed by more than one pair of genes,. For simplicity, lets assume there are only two located at positions A and B on the Chromosomes. This simplification is not done to help our case——- the more genes there are, the easier to have a huge range of “different“colors. The principle involved can be understood by using two as an example.
One form of the gene. One form of the gene “M” says to make lots of Melanin: another form of the gene “M” says to make a little “Melanin.” (Variant forms of a gene are called ‘alleles’ but not important here.) At a position A we could have a pair such as Ma,Ma, Ma, ma or ma, ma which would instruct the skin cells to make a lot, some or little melanin. Similarly, at position B we could have the gene pairs Mb, Mb, Mb, mb or mb, mb, instructing cells to make a lot, some or little melanin. Thus very dark people could have Ma,Ma, Mb, Mb, for example. Since both sperm and eggs of such people could only be Ma,Mb (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, a very light people with Ma, Ma, Mb, Mb could produce children only like themselves.
Color Combination
Let’s look at what combination would result from parents who are type of brown-skinned person called a mulatto, or Ma, Ma, Mb, Mb (the offspring of Ma, Ma, Mb,Mb and ma, ma,mb, mb union for example). Let us see if we can do a “ punnet square here:
Mother-= Ma ma Mb, mb ;
Father = Ma, ma, Mb, mb
Mother = Ma ma Mb mb
Mb, l Mb l Ma l mb l ma l mb l Ma l mb
Mb l Ma l Mb l Ma l mb l ma l Mb l ma l ma
/ Ma l Ma l Mb l Ma l Mb l Ma l Mb l Ma l Mb
F mb l Ma l Mb l Ma l mb l ma l Mb l ma l mb
A Ma l Ma l mb l Ma l mb l Ma l mb l Ma l mb
T Mb l Ma l Mb l Ma l mb l ma l Mb l ma l mb
H ma l ma l [b]Mb l ma l Mb l ma l Mb l[/b] ma l mb
E mb l Ma l mb l Ma l mb l ma l Mb l ma l mb
R ma i ma l mb l ma l mb l ma l mb l ma l mb
The left side shows the four different gene 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 and sperm union. For example an Ma mb sperm and an ma Mb egg would produce a child with Ma ma Mb mb, 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 mulatto marriage, as roughly indicated by the level of shading. If 3 pairs were involved, seven levels of melanin would be possible. Thus a range of “colors” from very light to very dark, can result in only one generation, beginning with this particular mid- brown parents.
If people with Ma,Ma,Mb,Mb, , who are “pure black (in the sense of having no genes for lightness at all), were to intermarry and migrate to place where their offspring could not marry people of light color all their descendants would be black—— a pure “black line” would result.”
If “white people (ma,ma, mb, mb) were to marry only other whites and migrates to a place where offspring could not marry darker people, a pure(in a sense) “white line” would result. They would loss the genes needed to produce a large amount of melanin and so could not produce black children.
It is thus easily possible beginning with 2 middle – brown parents, to get not only all the “colors”, but also people groups stable shades of skin color.
If all people on earth were to intermarry freely, and then break into random groups that kept to themselves, a whole new set of gene combination could emerge. It may be possible to have almond eyes with black skin, blue eyes with black, frizzy, short hair, etc. We need to remember of course, that the way in which genes express themselves is much more complex than the simplified figures or picture. For example, sometimes certain genes are linked together. However, the basic point is unaffected.
(more to come)
(Answers In Genesis)
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