Natural selection never stops; however, it could be argued that medicine and biotechnology augmens natural selection. There are always going to be natural forces that influence humans however big, small or noticeable. Humans surely are not just halted in place due to medicine. There are still internal and external forces that affect us and I don't foresee that stopping until every single aspect of biology, chemistry, systems studies is understood and controlled and that is simply not going to happen.

Hello Florentine Doudaine

Yes, medicine and biotechnology have had its impact on natural selection, but it continues in the form of microevolution which is nothing but minor changes in gene frequencies. We would not be expecting a major adaptive shift because of environmental stability. For instance, disease epidemics have the potential to bypass all forms of buffering capability that protects man from environmental stress and are likely to continue to exert selective pressure on modern man in the future. Diseases are environmental stressors that can easily break through all forms of technological defenses of the human genome.

No matter how far we may reach in our search for advanced technology (either in medicine or biotechnology, etc.,), we will still face natural selective pressures in the future though the relative importance of natural selection in shaping our own species might be weak at present.

Best.

Yes, natural selection still has an effect on modern humans, despite advances in medicine and technology. The process of natural selection continues to shape the human gene pool, albeit at a slower pace than in the past due to the reduced impact of mortality rates and the increased ability to adapt to various environments. Here are some ways in which natural selection still influences modern humans:

1. Resistance to diseases: The spread of infectious diseases has historically been a major driver of natural selection in human populations. Although modern medicine has greatly reduced the impact of many diseases, some pathogens continue to evolve resistance to drugs and vaccines, leading to new selective pressures. For example, the emergence of antibiotic-resistant bacteria has put pressure on humans to develop new defenses, such as improved hygiene practices and antimicrobial peptides.

2. Adaptation to changing diets: Human diets have changed significantly over time, particularly with the advent of agriculture and the introduction of processed foods. Natural selection may favor individuals who are better able to metabolize these new nutrients, leading to genetic adaptations that enhance digestion and nutrient uptake. For example, some populations have developed genetic mutations that allow them to better digest lactose, a sugar found in milk, which has become more prevalent in dairy farming societies.

3. High-altitude adaptation: Humans living at high altitudes face lower oxygen levels and other environmental challenges. Populations adapted to these conditions have developed physiological responses, such as larger lungs and more efficient oxygen delivery systems, which confer a survival advantage. These adaptations have occurred relatively recently in human history, demonstrating that natural selection remains active in shaping human evolution.

4. Skin pigmentation: Skin color is influenced by several genes, including those that control melanin production. Darker skin offers protection against UV radiation, which is abundant in equatorial regions. Lighter skin, on the other hand, allows for vitamin D synthesis in areas with limited sunlight. Natural selection has favored individuals with appropriate skin tones for their environment, leading to geographic patterns in skin pigmentation. While cultural practices and migration have also played a role in shaping skin tone diversity, natural selection remains a key factor.

5. Immune system variation: The human immune system exhibits considerable genetic diversity, reflecting the importance of immune function in protecting against pathogens. Variants of genes involved in immunity, such as HLA alleles, show signs of positive selection, indicating that natural selection continues to shape the human immune system.

6. Brain development and cognitive abilities: Research suggests that recent human evolution has targeted genes related to brain development and cognitive functions, potentially influencing intelligence, language capacity, and behavioral traits. While the relationship between natural selection and cognitive abilities is complex and controversial, studies indicate that selective pressures have contributed to the evolution of human cognition.

7. Response to stress: Chronic stress can have negative effects on health, making resilience to stress an important aspect of fitness. Some people may possess genetic variants that enable them to cope better with stress, either through altered stress response pathways or improved emotional regulation. Natural selection might favor these individuals, leading to the propagation of stress-resilient genotypes.

8. Reproductive success: Fertility and reproductive success remain critical components of natural selection. Genetic factors that influence fertility, such as polycystic ovary syndrome (PCOS), can affect the likelihood of passing on genes to offspring. Additionally, mate choice and sexual selection can drive evolutionary changes in human populations, as individuals preferentially choose mates with desirable traits, perpetuating certain genetic characteristics.

9. Environmental pressures: Climate change, pollution, and other environmental factors can introduce new selective pressures that influence human evolution. For example, populations exposed to heavy metal pollution may experience selection for genetic variants that confer resistance to toxicity.

10. Genetic drift: While natural selection acts on existing genetic variation, genetic drift—the random change in frequency of alleles over time—also plays a role in shaping human genomes. As populations grow and split, chance events can lead to the fixation of beneficial or neutral mutations, contributing to the genetic diversity observed among humans today.

In summary, natural selection continues to play a significant role in shaping the human gene pool, even in the presence of advanced medical technologies and cultural practices.