There is substantial evidence to suggest that humans are still evolving and changing for the better in terms of health, compared to ancient times. Evolution is an ongoing process that operates over long periods, and while the basic human genetic makeup remains relatively stable, certain genetic traits and allele frequencies can change over generations in response to various factors. Here are some pieces of evidence that support the idea of positive health-related evolution:
Lactose Tolerance: In the past, most humans were lactose intolerant after infancy. However, with the domestication of animals and the practice of dairy farming, certain populations developed lactose tolerance, allowing them to digest milk and dairy products throughout adulthood. This trait has a genetic basis, and regions with a long history of dairy consumption, such as Europe and parts of Africa, have higher rates of lactose tolerance.
Disease Resistance: Over time, human populations have developed resistance or partial immunity to specific diseases. For example, certain populations in regions with a historical prevalence of malaria have a higher frequency of genetic traits like sickle cell anemia, which provides some protection against severe forms of malaria.
Immune System Adaptations: The human immune system continues to evolve in response to new infectious agents. While some diseases might emerge and threaten health, the human body adapts to improve immune responses and resistance to pathogens.
Increased Average Lifespan: Advances in medical science, public health, and living conditions have contributed to a significant increase in the average human lifespan over the last few centuries. Evolutionary forces, in conjunction with these advancements, may also play a role in promoting certain genetic factors that enhance overall health and longevity.
Genetic Diversity: Humans exhibit significant genetic diversity across different populations. This diversity can be advantageous as it allows populations to adapt to specific environmental conditions, diets, and lifestyles, potentially leading to better overall health outcomes.
Birth and Survival Rates: Natural selection continues to operate on human populations, with some genetic traits becoming more prevalent due to their impact on birth rates and child survival. For instance, certain genetic variations related to reproductive success may become more common over time.
It is essential to note that evolution is not solely driven by positive adaptations. Negative or neutral traits can persist in a population if they do not significantly impact reproductive success or survival. Additionally, human evolution occurs on a longer timescale, and changes can be subtle compared to historical events.
In summary, the evidence supports the idea that humans are still evolving in terms of health-related traits. Evolution is an ongoing process, and understanding these changes can provide valuable insights into human health and disease. However, the complexity of evolution and its interaction with factors like culture, environment, and technology makes predicting future evolutionary trends challenging.