Tag Archives: skin

How can we understand genetics from dogs?

 Imagine two dogs: one with short hair and one with long hair.  Now imagine these two dogs leaving Noah’s Ark, reproducing, and spreading out across the world.  Some of the dogs travel North and enter into colder regions.  The short hair dogs suffer from the elements and are not able to survive.  They die out, but the long haired dogs survive because they have the necessary protection from the cold.  They are able to reproduce and pass on their genes, creating more long haired dogs who can withstand the harsh cold environment.  However, these dogs will only be able to produce more long-haired dogs because the short-hair DNA information is now lost.  On the reversal, if the long haired dogs stayed near the equator, it would be too hot for them to survive.  They would die out while the short haired dogs would thrive and reproduce.  This illustration shows why we see high densities of long haired and short haired dogs in cold and warm climates, respectively.


The long haired dogs survived in the colder climates whille the short haired dogs survived in the hotter climates. (Source: Answers in Genesis)

The medium length hair dogs below have the DNA for long hair and short hair, so they can produce a variety of hair lengths.  If two long haired dogs reproduce, they will isolate the genes and only produce long haired dogs.  This explains why we would see a certain trait carried on in animals or people in specific areas.  This can change when alternate DNA is introduced, such as a long haired dog breeding with a short haired dog. 


Animals lose DNA information when isolated. The long haired dogs will only be able to produce more long haired dogs until they mix up the DNA with short haired dogs again. (Source: Answers in Genesis)


Apply this concept to other traits we see.  People with darker skin live in sunnier regions where their skin is not affected as much by the heat and they have lower risks of skin cancer.  Light skinned people would not do well in these hotter regions because they are at risk of skin cancer.  On the other hand, people with dark skin who live in colder, less sunnier climates would not receive as much Vitamin D in their skin, thus they would be at risk for rickets and other vitamin D deficiency disorders.

When a specific trait like light-colored skin is lost and only dark-skinned people remain, the light-colored trait will not return until a dark-skinned person has a child with a light-skinned person. The child’s skin shade would be determined on the dominant and recessive genes.  If that child had the light-colored skin, he/she would be able to pass on that trait to another generation.  However, if the environment was not favorable to them (if they got cancer, for example), then their chances of survival or successful reproduction would be lower.  Neither the dark-skinned nor light-skinned people “evolved” to their surroundings, but rather, their already existing favorable traits allowed them to survive and thrive in that particular environment.


How can a Punnett Square be used to explain basic genetics?

A Punnett Square (Source: Answers in Genesis)

When studying genetics, the Punnett Square is used to simplify the DNA possibilities.  Let’s use the picture to understand skin tones.  The capital letters “A,B” represent a person with more melanin (dark skin), and the lower-case letters “a,b” represent having very little melanin (light skin).  If a dark-skinned mother (A,B) has a child with a dark-skinned father (A,B), their child will have dark skin (A,A,B,B) because that is the only option in the DNA.  If a light-skinned mother (a,b) has a child with a light-skinned father (a,b), then that child will have light skin (a,a,b,b).  If you mix it up with a (A,B) mother and a (a,b) father, you have multiple possibilities.  In fact, some sets of twins have been born where one is light-skinned and the other is dark-skinned. 

Both parents had a “white” mother and a “black” father. Together, they had twins with different skin tones. (Source: Answers in Genesis)

You can see from the chart that there are many possibilities when you mix up mothers and fathers with different skin colors.  The chart shows that the most frequent combination would be a medium-brown skin color (remember that we are all shades of brown).  The majority of the world’s population is also medium-brown.

Here is another example of mixing DNA.  The following example is very basic–the required information needed for specific traits is far more complex, but hopefully this illustration will show the potentials within the DNA combinations.

A basic illustration of the possible combinations in DNA to show variations of the kind (Source: Answers in Genesis)

What “color” of skin did Adam and Eve have?

Source: Answers in Genesis

Children’s books often portray Adam and Eve with light colored skin.  However, using basic genetics, if Adam and Eve were both light colored, then all of their children, including people today, would be light colored.  If Adam and Eve were both dark colored, then all people today would be dark colored.  Neither of these scenarios is possible because there are people with dark, medium, and light colored skin throughout the world. However, if Adam was dark colored and Eve was light colored, then they would be able to produce a wide variety of children.  Or, if they both had medium-colored skin and had the genetics for light and dark skin, that would also allow for the diversity of colors we see today.

Source: Answers in Genesis