For most of our evolution, we were slim in the state of constant hunger and constant physical activity, naked (meaning exposed to the sun with excessive vitamin D production), and were eating mostly vegan food. This was the case for all of our ancestor species and that means the time period of 50 million years. Adaptation is the development that the organism goes through in order to become accustomed to an environment. It is linked to evolution because it is a long process. One that occurs over many generations. Genetic change is what occurs. The genetic change that is the result of successful adaptation will always be beneficial to an organism. For example, before snakes slithered, they had regular limbs. They were similar to lizards. In order to fit into small holes in the ground in which they could hide from predators, they lost their legs. It may also happen that the environment changes very little and that species do not need to adapt at all. Examples of this can be seen in so-called living fossils like jellyfish that evolved 550 million years ago or nautilus marine mollusks that remained largely unchanged for 500 million years. Biologists say that the oldest living animals in the world today are ctenophores that first emerged 700 million years ago. Also, variations in the habitat may happen almost immediately, resulting in species to grow less and less well adapted and eventually to go extinct.
It has been theorized that dark skin pigmentation was the original condition for the genus Homo, including Homo sapiens (1). The problem arose when Homo sapiens moved into areas of low UV radiation. Light skin pigmentation is nothing more than a coping mechanism of our bodies for constant vitamin D shortages. Vitamin D is an essential vitamin with different functions, and only one of them is calcium development. On another hand, the light-skinned individuals who will go back to live near the equator will have an increased risk of folate depletion. Folate depletion is associated with numerous types of cancers, especially skin cancer, DNA damage, and congenital disabilities. Just by entering a plane to go to a habitat that we are not adapted for and doing activities like sunbathing on the beach can cause the risk of skin cancer. It would be a good idea to drink beet juice while you are on vacation. It has the highest level of folate from all other food sources and folate is not the same substance as folic acid. Supplements have folic acid, and plants have folate. When they tested folic acid on rats their livers were able to convert folic acid into folate without any problems but we are not rats, and our liver is only able to convert a maximum of 400mg a day, so go with the beets and one 400 mg tablet.
When it comes to skin color, three separate genes produce light skin. European and also East Asian skin evolved to be much lighter only during the last 8000 years. The first modern humans to initially settle Europe about 40,000 years ago are presumed to have had dark skin. Dark skin is beneficial in the sunny climate of Africa. Early hunter-gatherers around 8500 years ago, in Spain, and central Europe also had darker skin. Only in the far north where there are low light levels the environment will favor pale skin.
When we look at the fossil record, then there is a different picture of hunter-gatherers in the far north. When examined all of the seven people from the 7700-year-old Motala archaeological site in southern Sweden (so-called “Tomb of the Sunken Skulls”), all had light skin gene variants (2). They also had a specific gene, HERC2/OCA2, which is responsible for blond hair, pale skin, and blue eyes.
Around 8000 years ago in the far north ancient hunter-gatherers were pale and blue-eyed, but still, all of those people living in central and southern Europe still had darker skin. It was only after the first farmers from the Near East arrived in Europe that the situation changed. They carried genes for light skin. As they have been interbreeding and mixing with the indigenous dark-skinned hunter-gatherers, one of their light-skin genes swept through Europe presumably because of the favorable environmental conditions that lack the sunny climate of Africa. It was only around 8000 years ago that people from central and south parts of Europe started to have lighter skin. Lack of sun, especially during winter, forced the adaptation and so natural selection has favored genetic adaptations to that problem by a paling of the skin that absorbs UV more efficiently. The second line in adaptations to colder climates was also a favoring of lactose tolerance. Vitamin D can be naturally found in some amount in regular milk.
Vitamin D is not a vitamin. It is a prohormone, a steroid with a hormone-like activity that regulates about 3% of the human genome from calcium metabolism, muscular function, immune system regulation, and many more functions that are essential for life. (3).
The current medical knowledge associates vitamin D deficiency with contributing to the development of seventeen different autoimmune diseases, periodontal disease, cancers, congenital disabilities, stroke, and heart disease. Vitamin D insufficiency and in worse case even deficiency is a problem that has spread to the global level now. And why? Because we changed our habitat and started to wear clothes. If you are a Muslim woman in a Sharia law country, it does not matter if you live in a sunny climate. If you are a black African and you start to live the modern way of life, meaning spending most of your time indoors, and in cars wearing t-shirts and pans you will be vitamin D deficient. Despite substantial daily sunlight availability in Africa and the Middle East, people living in these regions are often vitamin D insufficient or deficient ranging from 5% to 80%. Vitamin D insufficiency is rampant among African Americans. Even young, healthy blacks do not achieve optimal concentrations at any time of the year.
White people are more adept to the northern climate. Black people are more adept at the southern latitudes. Well at least before the Modern Era. Now we are not adapted to any climate. Why? Because we do not run naked not even during the summer, so we do not get any vitamin D for most of the year. We live indoors. Even being naked and exposed to the sunlight during summer was not enough for the northern geographical latitudes to sustain adequate vitamin D levels for the entire year around. Our physiology adapted by paling our skin. Modern technology-driven conditions are 10-times worst. In the future probably we will all have albinism as a result of adaptation if nothing is changed.
Groups of the Neanderthals were pale too. Some of them had more pigment, some less, some were pale and had red hear.
If you do not believe this, we will go scientific. There is the receptor that activates melanin, the pigment that gives skin, hair, and eyes their color. It is known as melanin-activating peptide receptor melanocortin 1 (MC1R). It is present on the surface of melanocytes (cells that produce melanin). Melanocytes can make two different types of melanin. One is called eumelanin, and the other is pheomelanin. MC1R is a receptor that will decide which pigment will be produced. It acts as a switch. It will decide will it be red-and-yellow pigment pheomelanin or black-and-brown pigment eumelanin. In one genetic study, the scientific team led by Holger Römpler of Harvard University extracted, and sequenced the MC1R gene from the bones of a 43,000-year-old Neanderthal from El Sidrón, Spain, and a 50,000-year-old one from Monti Lessini, Italy (4). The two Neanderthal samples both showed a point mutation that is not present in modern humans. If such a mutation is induced in human cells, it will cause an impaired MC1R activity. The mutation would cause red hair and pale skin in modern humans. To make sure that the MC1R gene mutation was not due to contamination of the sample from modern humans, the scientists tested around 4,000 people. None of the people tested had it. This genetic study showed that both Homo sapiens and Neanderthal had reached the same genetic adaptation by two different evolutionary pathways. Anthropologists had predicted a long time ago that due to the environment Neanderthals might have evolved to have pale skin. Work by Römpler and colleagues offers the first scientific evidence to support this thesis. So it is not that we inherited the blond gene from Neanderthals it is that evolution works similarly in similar conditions. When Neanderthals went into northern climates adaptation did the rest.
Today we have modern technology, indoor lifestyle, and all of the rest of the fancy new changes in the habitat that are not congruent with our physiology, the health problems will occur as a consequence of maladaptation.
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Sources:
Passages selected from a book: “Go Vegan? Review of Science: Part 1” [Milos Pokimica]
- The colours of humanity: the evolution of pigmentation in the human lineage https://doi.org/10.1098/rstb.2016.0349
- Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation https://doi.org/10.1371/journal.pbio.2003703
- Nutrigenomics of Vitamin D doi: 10.3390/nu11030676.
- A Melanocortin 1 Receptor Allele Suggests Varying Pigmentation Among Neanderthals DOI: 10.1126/science.1147417
- Is vitamin D deficiency a major global public health problem? https://doi.org/10.1016/j.jsbmb.2013.11.003
