A few simplified details before I get to my point. The human body contains approximately 37.2 trillion cells. One thing I found interesting right off the bat is that a 100-pound body contains the same approximate number of cells as a 250-pound body. That does not make sense to human wisdom, but the simple explanation is that it is not the number of cells, but what and how much is contained in those cells, that determines weight.
OK, moving along—each cell in the human body contains about 6 feet of DNA (deoxyribonucleic acid, if you must know). DNA is a complex molecule that contains all the information necessary to build and maintain an organism. A little math will tell us that with 37.2 trillion cells and each cell containing 6 feet of DNA there is a total of 223.2 trillion feet of DNA in the human body, enough to make 230 round trips to the sun. So how can 223.2 trillion feet of DNA be packed into a 100-pound weakling? Ask the Psalmist.
OK, moving further along—DNA contains our genes. The human body has only about 20,000 genes. Each gene contains instructions that determine features such as eye and hair color, height, complexion, and health. Genes are what we inherited from parents and are determined at conception. How many times have you heard the excuse, “It is in my genes!” or “It is part of my DNA!” Those excuses imply that it was determined before I was born, I inherited it, and there is nothing I can do about it. Geneticists have now discovered that this excuse doesn’t hold water anymore. It doesn’t hold water because of epigenetics. Epigenetics determines the real you and is not totally predetermined as your genes are.
This is a good time to remind you that the genes in the human body renew or regenerate themselves every 7 years, or so. So that the cells that are in a body today are not the cells that were in the same body 7 years ago, but they are made up of the same genetic structure. So why doesn’t the body look the same? Take me for example. In my lifetime from conception to today, my cells have regenerated 10 times and yet they contain the same genes. That begs the question: “If my cells are no more than 7 years old, why do I look like I am in my 70’s.” Besides epigenetics, geneticists have identified two causalities that bring about the aging process. They are called program-related and damage-related. They both have to do with cells failing to divide properly, either by random error or because of some kind of environmental damage resulting from repeated duplication.
Here are two examples that I found helpful in understanding what causes us to age. The first has to do with making photocopies. You have an original document all crisp and clean with the ink very dark and the paper very white. When you make a copy of that document the copy is just a tiny fraction less sharp than the original. Now when you make a copy of the copy, the distortion in the sharpness becomes just a little more pronounced. By the time you copy the copies ten times the result is faded and even distorted. That is what happens when our DNA is copied and then copied from the copy over and over again. The DNA becomes distorted or corrupted.
The other example explains why that happens to our DNA. DNA is made up of strands of chromosomes intertwined with two loose ends on each end of the six-foot strand. These ends or tips are called telomeres. They are there to protect the chromosomes in the strands. They act like the plastic tips on the end of shoelaces (they are called aglets, by the way). The aglets protect the shoelaces and keep them from becoming frayed and weak. The telomeres perform the same function for the DNA in our cells. These telomeres do get damaged with many reproductions and with environmental influences and when they are damaged, the DNA does not reproduce exact copies because some chromosomes are not protected and may disappear from the DNA strand. These are the kinds of things that happen over the years and cause our appearance to change for the worse. It is a very simplified explanation, but that is what I need when it comes to genetics.
Speaking of which, my topic is epigenetics and I have strayed from the subject (I am an aged man and tend to ramble sometimes). Earlier I hinted that your genes are determined, but they do not determine you. Epigenetics is the study of changes in organisms caused by modification of gene expression rather than the alteration of the genetic code itself. Scientists have discovered that there are mechanisms that switch genes on and off. These mechanisms are reversible and have the potential to be inherited in future generations. Therefore, it appears that it is not your total gene makeup that determines the you of today, but only the genes that are functioning today.
Epigenetics is a relatively new science and is still in the developmental phase; but certain indications have shown up in the research that, as yet, the “how” of it has not been determined. Epigenetic research has shown that a mother’s experiences before and during pregnancy can affect a female baby’s eggs. For over 50 years, scientists have believed that a female human is born with all the egg cells she will have in a lifetime. (Some research on mice has shown this may not be the case, but nothing has disproved it in humans.) So, scientists have determined that social, emotional, environmental experiences of the mother, as well as diet, exercise, drugs, and addictions, and one’s parenting can affect a new fetus. These things affect the eggs in the mother and the sperm in the father and in turn can affect the children, grandchildren, and maybe even the great-grandchild. The effects affect the mechanisms that turn genes on and off (epigenetics) and determines the you that you are today.
In 1866, an Augustinian monk named Gregor Mendel observed the fundamental laws of inheritance through his work in plants. He discovered that genes come in pairs and are inherited one of each pair from each parent. (Gene comes from the German Gen, from the Greek genus meaning rare, kind, or offspring). This line of research was continued until Conrad Waddington coined the term “epigenetics” in 1942 based on his studies of genetic assimilation. The study of epigenetics is less than 100 years old. However, not knowing anything of genes and epigenetics, Moses writing 3,400 years ago, acknowledged that the acts of one generation can bring effects “upon the children, and the children’s children to the third and the fourth generations” (Exodus 34:7). How did he know?
All of this information is interesting to me. It explains why I age when my cells renew every few years. It explains why identical twins, derived from only one fertilized egg which contains only one set of genes, each identical to the other, can look and act so differently as they age and become adults. The 37.2 trillion cells, the 223.2 trillion feet of DNA with only about 20,000 genes amazes me. King David, writing 3,000 years ago knew by observation what scientists are just now discovering: “I will praise you, for I am fearfully and wonderfully made; marvelous are your works, and that my soul knows very well” (Psalm 139:14).
These websites provided some helpful information for this post.
https://www.scienceworld.ca/
https://www.whatisepigenetics.com/fundamentals/
https://www.science.org.au/curious/epigenetics