Melanin may be a major component involved in adaptation to climate warming.
Skin pigmentation is the most important photoprotective factor, since melanin, besides functioning as a broadband UV absorbent, has antioxidant and radical scavenging properties. Besides, many epidemiological studies have shown a lower incidence for skin cancer in individuals with darker skin compared to those with fair skin. Skin pigmentation is of great cultural and cosmetic importance, but it is also important for fertility and longevity! According to research by UCLA environmental economist Alan Barreca, hot weather reduces chances of getting pregnant — and the problem is expected to get worse because of global warming.
Barreca, a member of the UCLA Institute of the Environment and Sustainability, pored through 80 years of U.S. birth data, looking for trends. This is shown most drastically in people with fair skin. The reduction in fertility occurred across all regions of the U.S., with hot states like Arizona seeing the same trends as cooler ones. Barreca said this may be because those who live in warmer climates are are better adapted to the heat or avoid it by staying inside air conditioned buildings. In fact, the effect was slightly more pronounced in northern states, where people are less prepared for heat waves. While much attention has been paid to overpopulation worldwide, declining birth rates and underpopulation are current threats in the United States, Western Europe, China, Southeast Asia and Japan! "Population rates are already so low that we could not maintain a stable population were it not for immigration," Barreca said. Temperature is just one of many things that affect fertility. Despite being hot, Southern India and most sub-Saharan African nations still have high birth rates.
Reported in the journal Demography, the study found that high temperatures have a significant negative effect on fertility and birth rates, and the research projects that as climate change drives temperatures up and increases the number and severity of heat waves, getting pregnant may become harder than ever. In 2021, France had the highest fertility rate among the EU member states with 1.84 live births per woman according to Eurostat, the statistical office of the EU. Malta had the lowest rate with 1.13 live births. But if you take immigrants out of the equation ALL European nations are far below replacement numbers! From 1800 to 1900, Norway's fertility rate fluctuated quite regularly, between 3.9 and 4.9 children per woman, and then in the first half of the 20th century it began to drop drastically and the decline speeded up as well. The fertility rate in Norway has declined from 1.85 children per woman in 2012 to 1.41 children as of 2022.Eumelanin protects the skin and DNA from UV light, whereas pheomelanin does not. Melanin protects the skin against DNA damage induced by direct absorption of sunlight's UV radiation.
As a result, people with more pheomelanin, such as those with blond or red hair and light skin, are more likely to experience sun damage. Very fair-skinned people tend to produce less melanin due to variations in their melanocyte-stimulating hormone receptors, which means they do not respond to melanocyte-stimulating hormone levels in the blood. Melanocyte-stimulating hormone levels are also raised during pregnancy. A deficiency in melanocyte-stimulating hormone results in a lack of skin pigmentation and subsequent loss of natural protection from UV rays of the sun. In secondary adrenal insufficiency, damage to the pituitary gland prevents release of adrenocorticotropic hormone and melanocyte-stimulating hormone and there is reduced pigmentation of the skin.
Melanocyte-stimulating hormone deficiency can cause increased inflammation, pain, and sleeping problems, as well as a reduction in the levels of anti-diuretic hormone, which causes thirst and frequent urination. Melanocyte-stimulating hormone deficiency may also result in increased food intake and obesity. The sperm of the male and the ovum (egg) of the woman both are layered with melanin. So when the sperm penetrates the egg, there is a melanin explosion. This helps to form the fetus. This fetus is literally coated with melanin without it there would be no natural births at all. In face current findings suggest that scrotal melanin may protect mature sperm from UV damage, and from oxidative damage that otherwise would cause birth defects. The sperm head is covered partially by the acrosome, a cap-shaped organelle, presence of moniliform pseudohyphae, and melanin which prevents DNA mutation. The testis is a specific target of selenium and it appears to be essential for maintaining normal spermatogenesis and for male fertility.
The importance of selenium in male reproduction has been known for decades as selenium imbalances have been known to cause reduced fertility, impaired sperm motility, and abnormal tail morphology. Africa is a place with an abundance of selenium rich soil. People dependent on food grown from selenium-deficient soil may be at risk for deficiency. People living in low-selenium regions who also eat a primarily plant-based diet. This is rarely seen in the U.S., but populations in China, Russia, and Europe are at great risk as their soil is generally low in selenium. The risk is further increased in people living in these areas who eat a vegetarian or vegan diet. Selenium deficiency symptoms include: hair loss, reproductive problems, muscle weakness, fatigue, brain fog and thyroid dysfunction.
Human skin is repeatedly exposed to various DNA-damaging environmental influences and therefore requires numerous endogenous mechanisms to protect against, reduce and/or repair such damage. These mechanisms include increasing epidermal thickness, DNA repair mechanisms and apoptosis, antioxidant enzymes and, last but not least, skin pigmentation. Ultraviolet radiation (UVR) is the major environmental factor that influences the function and survival of many cell types and is regarded as the main causative factor in the induction of skin tumors like basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma. It has been estimated that a 1% decrease in ozone increases melanoma mortality by 2%.
Globally, the total column average is about 300 Dobson Units. On Oct. 3, 2022, scientists recorded a lowest total-column ozone value of 101 Dobson Units over the South Pole. At that time, ozone was almost completely absent at altitudes between 8 and 13 miles (14 and 21 kilometers) – a pattern expected to continue this year. Since the early 1980s: there has been a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. Malignant melanoma is the most serious form of skin cancer: it is responsible for around 80% of skin cancer deaths. Over the last 25 years the reported incidence of malignant melanoma has increased. This is likely to be due to increased UV exposure, however the number of skin biopsies now taking place has also risen.
The American Cancer Society’s estimates for melanoma in the United States for 2023 are:
About 97,610 new melanomas will be diagnosed (about 58,120 men and 39,490 women). About 7,990 people are expected to die of melanoma (about 5,420 men and 2,570 women). The rates of melanoma have been rising rapidly over the past few decades, but this has varied by age. In adults ages 50 and older, rates continue to increase in women by about 1% per year
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