HOW CAN NATURAL SELECTION AND EPIGENETICS PLAY A ROLE IN YOUR FREEDIVING ABILITY?
Is it possible that some of the freediving legends of today have a genetic predisposition for the sport? New studies seem to suggest that could be the case. An even more interesting find is that you can pass on freediving traits to your children — even if you don’t have any of those traits yet.
Through epigenetics! Epigenetics is the study of the expression of genes in organisms rather than the alteration of the genetic code itself. Epigenetics allow things that you experience during your lifetime — especially during childhood and the teenage years — to be passed on to your children.
The Difference Between Epigenetics and Natural Selection
Both epigenetics and natural selection have a roll in how you look, act, and feel, but they are very different.
Think of it this way: natural selection dictates what mate a person chooses and therefore the genes that their progeny possess. If you choose not to be with someone because they are stinky, you can avoid having those stinky genes in your child’s bloodline. On the other hand, if your romantic interest possesses certain physical traits that would allow them to dive deeper than average (like a strong heart and big lungs), your child could inherit their physical advantages.
The difference is that — with natural selection — your mate can pass on physical traits that make diving easier even if they have never dived a day in their life. Epigenetics, though, express themselves based on the experiences of a person during their lifetime.
So, if you are a world-record-holding freedive, maybe you should find a mate that also excels at diving. You very well could pass your awesome genes onto your progeny through both natural genetic inheritance and epigenetics.
Epigenetic changes can prepare progeny for an environment similar to that of the parent.
Examples of the Effects of Epigenetics
Epigenetics is still under intense study and are not fully understood, but a few studies have shown interesting results.
For example, parents who endured prolonged hunger during their younger years have been observed to bear children that have a lower level of an enzyme that breaks down cortisol (a hormone that regulates blood sugar levels and fat storage). Lower levels of this enzyme mean more free cortisol in the body. More cortisol allows the kidneys and liver to optimize glucose stores.
This means that the parents passed down a trait associated with starvation to their kids, potentially making them more likely to survive starvation in their lifetime.
Other examples include the descendants the descendants the descendants the descendants the descendants the descendants the descendants of Holocaust survivors possessing different levels of stress hormones, as well as research that shows that pollut pollut pollut pollut pollut pollut pollution exposure of a parent can lead to a child being more likely to develop asthma.
Interestingly, these factors are not limited to a mother carrying a baby, or even the mother at all. A father’s experiences during childhood can be epigenetically expressed in his child — for better or for worse.
Genes Help Ancient Groups of Divers
Thus far, we have but merely skimmed the surface for what genetics and epigenetics mean for freedivers. Thankfully, we have living examples in thousands of freediving people throughout the Earth.
The best group of people to look to for this sort of information are the Bajau. The Bajau are native to parts of Indonesia but have long been referred to as the “Sea Nomads” due to their nomadic lifestyle supported by spearfishing and underwater foraging.
A Cell study publisheA Cell study publisheA Cell study publisheA Cell study publisheA Cell study publisheA Cell study publisheA Cell study published in April 2018 suggests that the Sea Nomads possess at least two genes that assist them in their freediving ventures.
The study started out as an inference taken from the spleen size of a deep-diving seal species. “…we know that deep-diving seals, like the Weddell seal, have disproportionately large spleens. I thought that if selection acted on the seals to give them larger spleens, it could potentially do the same in humans.” one of the authors of the study explains.
You might be wondering what the size of your spleen has to do with freediving, but the answer is very simple. One of the dive responses that occurs naturally in all mammals is the contraction of the spleen. This allows for a stockpile of oxygenated blood stored in your spleen to be released into your bloodstream as you deplete your oxygen during a breath hold.
After using ultrasound on a little less than one-hundred people in Indonesia comparing the Sea Nomads to non-diving peoples, the results found something of interest: a significantly larger spleen in the Sea Nomads in comparison to their neighbors.
Just how much bigger? About 50%.
This increased spleen size no doubt has assisted the Bajau in their underwater lifestyle, sometimes diving to depths of 70 meters [230 feet].
Apparently, during a time that spans over 1000 years, natural selection has played its part in endowing these people with amazing freediving ability through natural genetic inheritance. What else is likely a factor, though? Epigenetics. In situations like these — where more research needs to be done — it can only be assumed that epigenetics are playing a role as well as natural selection.
The Bajau people are not the only group well-known for their freediving abilities. We have previously written an article dedicated to theJeju Haenyeo, a. No doubt there are even more things to be learned from the genomes of different groups of historical freedivers like them.