Signs that humans are still evolving can be seen in recent evolutionary changes, primarily affecting genes related to smell, reproduction, brain development, skin pigmentation, and immune system response to pathogens.
Evidence of Ongoing Human Evolution
Human evolution didn't stop in the past. It is an ongoing process driven by natural selection and genetic drift. Although often subtle and difficult to observe in real-time, several lines of evidence suggest that we are still evolving. These include:
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Lactose Tolerance: The ability to digest lactose, the sugar found in milk, as adults is a relatively recent adaptation that has spread rapidly in populations with a history of dairy farming. This is a classic example of gene-culture coevolution.
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Disease Resistance: Humans continue to evolve resistance to diseases. For example, genes involved in immune response, such as those related to HIV resistance, show signs of recent selection.
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Skin Pigmentation: The evolution of lighter skin pigmentation in populations that migrated to higher latitudes, where sunlight is less intense, is a relatively recent adaptation to maximize vitamin D synthesis.
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Brain Development Genes: Changes in genes related to brain size and function suggest ongoing evolutionary pressure on cognitive abilities. However, the specifics are still being investigated.
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Smaller Jaws and Wisdom Teeth: As our diets have changed, smaller jaws have become increasingly common, often leading to impacted wisdom teeth. The reduction in jaw size suggests a relaxation of selection pressure for large jaws.
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EPAS1 Gene and High-Altitude Adaptation: Tibetans have evolved a version of the EPAS1 gene that allows them to thrive at high altitudes with low oxygen levels.
Genes Under Recent Selection
Research indicates that specific categories of genes are more prone to recent evolutionary changes:
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Olfactory Genes: Genes related to our sense of smell frequently show signs of recent evolution, likely reflecting adaptation to different environments and diets.
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Reproductive Genes: Genes influencing reproductive success are often under strong selection pressure.
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Brain Development Genes: As mentioned before, genes related to brain development show evolutionary changes, although the exact implications are complex and still under study.
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Skin Pigmentation Genes: Variations in skin pigmentation reflect adaptation to differing levels of ultraviolet radiation.
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Immune System Genes: The constant battle against pathogens drives rapid evolution in genes related to the immune system.
Summary
Humans are undeniably still evolving, as evidenced by ongoing adaptations related to diet, disease resistance, skin pigmentation, and other factors. The specific genes involved in these adaptations provide further insight into the selective pressures shaping the human species.
