The Invisible Poor Who Can Survive American Poverty!
Climate change has led to increased average temperatures in most rural western parts of the USA, making extreme heat events more frequent and severe. Recent literature overwhelmingly indicates that earlier studies were incorrect in suggesting that rising temperatures would result in higher mortality and illness among adults of color compared to white adults, as extreme wet bulb events in areas with poor electricity access predominantly affect lower-class white communities.
Approximately 114 million people — 35 percent of the population of the contiguous United States — reside in areas expected to experience dangerous heat levels, and the majority of these individuals are of European descent. The summer of 2024, much like that of 2023, has become one of the hottest on record in Texas. San Antonio, typically experiencing about three days of triple-digit heat by July, has seen dozens. Houston, Waco, and Austin are also enduring temperatures 10 degrees above normal. States like California, Arkansas, Oregon, and Florida have reported the highest number of heat-related fatalities.
Although the danger is more widespread in the South than it is in the North deaths have been reported as far North as Maryland, but in most Southern States like Georgia, Alabama, the Carolinas and Virginia global warming caused by man-made climate change is expected to deliver an average of 20 extra days of triple-digit heat per year. In the southernmost and Western states, such as Texas, Nevada, California, Oregon and Florida, residents could see a future norm of over 70 consecutive days per year with the heat index topping 95 degrees Fahrenheit. A question many people have to ask with this knowledge is if ethnicity affects weather tolerance.
when it comes to biological differences between the races our bodies pretty much function in extremely similar ways. In other words, there is no race of people who are able to survive conditions that others could not — although we must remember that many, cultural groups have adapted to account for climate in their area. With that being said, it's really important to keep in mind that humans are good at acclimatizing. That means that given time, people introduced to the cold are going to have their blood vessels narrow, which will preserve body heat, and in extreme heat the body over time will adapt to survive in that habitat. The adaptations will include improved sweating, improved skin blood flow, lowered body temperatures, reduced cardiovascular strain, improved fluid balance, altered metabolism, and enhanced cellular protection by increasing melanin and the type of melanin with Eumelanin black and brown pigment being the most advantageous in extreme heat.
Human adaptations to heat occur very quickly, some changes occur in less than a month in healthy individuals. These adaptations include reduced body temperature, improved skin blood flow, increased sweat rate, and other physiological responses that improve thermal comfort in hot environments and mitigate the consequences of heat stress.
The process of melanin synthesis and distribution is called melanogenesis, a process that is based on melanocytes present among the basal cells of the epidermis. Pigments formed are then stored in the basal layer of skin cells, as well as in dermal macrophages, which become melanophores. From the embryological point of view, melanocytes derive from the melanoblasts of the neural crest, from where they migrate during the first months of life into the skin, eye, cochlea, bone, peripheral nervous system, heart and adipose (fat) tissue. The melanic pigments, eumelanin (Black, Brown) and pheomelanin (Red, White), are the final product of complex biochemical reactions starting from the amino acid L-tyrosine. Melanin has a major role in skin homeostasis through the photoprotection it offers from the harmful effect of ultraviolet radiation. Melanin absorbs and/or reflects ultraviolet radiation but is also involved in the neutralizing process of free radicals and reactive oxygen species.
Climate warming results in a reduction in biodiversity. Human beings can adapt to the changing environmental conditions in two main ways: through genetic evolution or by adjusting behavior and physiology through phenotypic plasticity (the ability to change traits like skin and hair for increased survivability). Melanin-based pigmentation plays a crucial role in humans, aiding in thermoregulation, shielding against UV radiation and pathogens, and even safeguarding fertility and physiology through genes involved in melanin production. Recent studies indicate that individuals with different skin tones may react differently to climate change.
The impact of climate change on dark or light-skinned individuals (or races) will rely on the adaptive role of melanin in each group, as well as how pigmentation levels correlate with physiology.
For instance, because climate change leads to a rise in temperature and UV-radiation and dark coloration plays a significant role in DNA, fertility and UV-protection, dark individuals may be less affected from global warming, this phenomenon implies more solar radiation particularly in habitats of pale individuals will be a detriment. In contrast, if desertification increases, pale coloration may expand in those regions as desert survival requires many to be nocturnal, whereas dark colorations may expand in regions where humidity is predicted to increase.
Dark coloration may be also indirectly selected by climate warming because genes involved in the production of melanin pigments confer resistance to a number of stressful factors including those associated with climate warming. Furthermore, darker melanic individuals are commonly more muscular than paler conspecifics, and hence they may better cope with competitive interactions due to invading species that expand their range in northern latitudes and at higher altitudes. Recent research suggests that melanic race/ethnic groups, particularly non-Hispanic Black subjects, are have an advantage due to a more common muscle fiber type. Black subjects appear to have a lower maximal aerobic capacity and a greater percentage of type II skeletal muscle fibers. Combined with reduced energy expenditure and reduced hemoglobin concentration, melanin may be a major component involved in adaptation to climate warming.
The higher prevalence of type 2 diabetes in African Americans compared to White Americans can be attributed to genetic factors influencing skeletal muscle fiber composition. African Americans tend to have a higher percentage of skeletal muscle fiber type II and a lower percentage of skeletal muscle fiber type I. Skeletal muscle fiber type II is characterized by lower oxidative capacity and higher glycolytic activity, enabling individuals to survive longer and work more efficiently in environments with limited food resources.
This unique muscle fiber composition in African Americans leads to lower fat oxidation and increased lipid storage as muscular adipose tissue compared to White Americans. However, the impact of muscle fiber composition on health outcomes varies depending on physical activity levels. In physically active individuals, the negative effects of muscle fiber composition are mitigated due to the adaptive nature of skeletal muscle.
Physical activity induces changes in muscle fiber characteristics, promoting higher activity of oxidative enzymes and enhancing muscle plasticity. A more plastic muscle is more responsive to training stimuli, leading to greater growth and structural adaptations. This variability in muscle plasticity explains why some individuals, known as "hard gainers," struggle to see significant results from workouts, while others experience more pronounced improvements due to their genetic predisposition for muscle plasticity.
Understanding the interplay between genetic factors, muscle fiber composition, physical activity, and training responsiveness is crucial in tailoring effective strategies for improving health outcomes and fitness levels among different populations.
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