Not Everything is Survival of the Fittest: Lifestyle and Environment Influence Your Offspring
Your Environment Affects Your Genes
All Living Things are Connected
We know DNA is a blueprint to build any living thing on our earth. We share a big chunk of our DNA with all living things.
Some people are like plants; they love to sit around in the sun all day. We all share around half of our genes with plants, but they seriously make me wonder if they share more than that.
For further comparison, man’s best friend — the dog — shares around 80% of our genes.
I, myself, am more of a cat. This fact alone is proof enough for me: we share 90% of our genes with our feline friends.
I thought that dogs would be closer.
But whether you identify yourself with cats or dogs, we all have a ton of chimpanzee within us, 98.8% to be exact.
We all are interconnected.
Nature
Who we are is either a manifestation of our genes or a blank-ish canvas constructed from our genes.
We all know Darwin’s theory of evolution of how the fittest gets to pass on their genes. But this theory doesn’t explain it all. There are genes that aren’t expressed in this fashion.
Our most complex phenotypes and behaviors can’t be explained by genes in our foreground. There is a lot more going on in the background. Something scientists call “missing heritability.”
Wikipedia’s definition:
The “missing heritability” problem is the fact that single genetic variations cannot account for much of the heritability of diseases, behaviors, and other phenotypes.
To understand mother’s nature strategy of how our environment and lifestyle influence the genes we pass on, we must first understand epigenetics.
Epigenetics
Imagine you have a blueprint on how to build a human. At some point, you will run into a problem. How much of a specific protein do you need?
Epigenetics tells us how much of a protein to build in two ways: one way is to add tags and mute the DNA. The other way is to tightly pack a part of DNA or loosen it.
Tagging a DNA strand works by a process called methylation. This tells the cell to mute a specific gene. It is like adding bookmarks and skipping certain paragraphs.
But to express a more precise degree of a gene, the chromatin loosens or compacts.
Chromatin is the DNA plus the proteins where DNA coils around.
By loosening these coils, chromatin makes a DNA strand more accessible to gene-expressing machinery. Conversely, if the DNA strand is condensed, it is less accessible and will be expressed in fewer quantities.
Methylation in the chromatin compacts the DNA, suppressing its expression.
Ok Great, But How Is This Influenced?
I am glad you asked because this topic can get tedious for some.
These epigenetic marks are inherited. Imagine inheriting a DNA book from your parents — a book they heavily used. This book comes with annotations and bookmarks.
Some tags and bookmark come from your mother, others from your father. When you inherit this book, specifically during embryonical development, most of these bookmarks are reset. But even then, some tags and annotations are left.
Remember that these tags and annotations don’t change the text (or DNA) itself. They change what will be read and to which extend.
These bookmarks may be removed during our lifetimes.
The Book of Life
Most surprisingly, any change you make to this book yourself will affect your future generations.
You indirectly hold some power over paragraphs and chapters — indirectly and to a minute extent.
Before Darwin, scientists believed in Lamarck’s theory:
“If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring.”¹
“Lamarck believed that giraffes stretched their necks to reach food. Their offspring and later generations inherited the resulting long necks”²
The hard-earned Survival Of The Fittest Model explains the most, but Lamarck’s theory still holds true too. They both intrically interplay.
Science is sexy and cool. Huh?
Quick Heads-Up
Most traits influenced by epigenetics are complex traits: height, fertility, food metabolism, and hereditary defects. These changes lie on a spectrum and are not absolute.
Let’s Get More Concrete
Nazi Germany
During World War II, the Nazis blocked the food supply to the Netherlands. The Dutch hunger winter lasted from September 1944 until May 1945.
This famine had an influence on the upcoming generations. Children from pregnant women during this time were more susceptible to higher weight, triglycerides, LDL cholesterol, and schizophrenia.
Studies revealed that the famine made epigenetic changes to the methylation of PIM3 gene, making it less active. The result was the slowing down of their metabolism.
The silenced genes in these unborn children stayed quiet for the next generations too. They passed on their book of life with bookmarks.
Study of Överkalix
Another study conducted in Sweden revealed more wonders of epigenetics.
In this study, the sons of the men who began to smoke early in life were affected. Their offspring had a higher BMI.
Usually women who smoke during pregnancy affect the fetus in other ways. The surprising thing here is that it was the fathers indirectly affecting their children.
In this same study it was found that food supply played a role in future generations too. The paternal grandfather’s supply of food affected the cardiovascular mortality risk and BMI of their grandsons.
If the supply of paternal grandmothers was affected, it only affected their granddaughter’s mortality risk.
This happens through a mechanism known as parental imprinting.
This has to do with epigenetics. For some genes you inherit the bookmarks from your father, for other genes you inherit those from your mother.
Conclusion
If we, humans, are the masters at adapting, it makes sense for our genes not completely rely on the long term game — survival of the fittest.
If our genes depend on generations upon generations for us to evolve, one catastrophic event in a generation might make it difficult for humans to adapt.
Our genes need a shorter-term solution.
The Wisdom of Mother Nature
If your parents or grandparents went through hunger, it makes sense that future generations will somehow be affected. Our metabolism slows down metabolism in response to a hunger-stricken world.
Your body comes primed with experiences from past lives.
But don’t think that epigenetics is a big contributor here. As far as we know, epigenetic changes play a minor role. It provides some leeway:
“The estimation of percentage of human genes subject to parental imprinting is approximately one to two percent”³
1. https://necsi.edu/what-lamarck-believed
2. Loretta M. Bierer, Violetta Fisher Lien, Ph.D. Life Science. D.C. Heath and Company / McDougal Littell Inc. 1984. Lexington, Massachusetts
3. Kaati, G.; Bygren, LO.; Edvinsson, S. (Nov 2002). “Cardiovascular and diabetes mortality determined by nutrition during parents’ and grandparents’ slow growth period”. Eur J Hum Genet. 10 (11): 682–8. doi:10.1038/sj.ejhg.5200859. PMID 12404098.
4. https://en.wikipedia.org/wiki/Överkalix_study