Science, Art, Litt, Science based Art & Science Communication

Human-made selective pressures

Q: Are there any selection pressures now on human beings to evolve?

Krishna: Think about this:

Extreme heat associated with anthropogenic global warming (AGW) can become a selection pressure in human evolution. This means that the ability to survive and reproduce in a warmer climate will favor individuals with certain traits, leading to changes in the human gene pool over time.

And we have created this pressure ourselves!

Consider these things:

Climate Change as a Selective Pressure:

Extreme heat events, like heatwaves and droughts, can significantly impact human health, survival, and reproduction.
Adaptive Evolution:

Individuals with traits that allow them to better tolerate heat, such as adaptations in sweat glands, metabolic rate, or body structure, may have a survival advantage in a warming world.
Examples of Adaptive Responses:
Sweating: Humans are already highly adapted to sweating, which is crucial for evaporative heat loss in hot environments.

Metabolic Rate: Studies have shown that metabolic rate can change based on temperature exposure, potentially influencing heat tolerance.

Body Size and Shape: Some studies suggest that in warmer environments, there may be selection for larger body sizes, as larger individuals have a lower surface area to volume ratio, which can help to conserve heat.
Long-Term Evolution:

Over many generations, these adaptive traits could become more common in the human population, leading to subtle but noticeable shifts in human appearance and physiology in response to a changing climate.
Other Selective Pressures:

It's important to remember that climate change is just one of many selective pressures acting on humans, including factors like disease, resource availability, and cultural practices.

Extreme heat associated with AGW can become a selective pressure in human evolution, driving the development of traits that improve survival and reproduction in a warmer world. This means that over time, human populations may adapt to warmer climates through a combination of physiological and behavioral changes.

Another selective pressure : microplastics too can act as a selective pressure in evolution,

potentially impacting species' genetic diversity and evolutionary trajectories. Microplastics can alter the environment, creating new selective pressures for organisms, and their ingestion can lead to negative consequences, driving the evolution of resistance or avoidance behaviours.

This is how this can happen:

Altering the environment:

Microplastics can physically change the environment, impacting soil properties, water quality, and other factors that affect the survival and reproduction of organisms. This can lead to the evolution of new adaptations in species that are better able to tolerate or exploit these altered conditions.
Ingestion and its consequences:

Microplastic ingestion can have various negative effects on organisms, including reduced growth, impaired reproduction, and increased vulnerability to predation. These negative consequences can create selective pressures, favoring individuals that are more resistant to microplastic exposure or that have evolved mechanisms to avoid ingesting them.
Evolution of resistance and avoidance:

Over time, species may evolve resistance to the toxic effects of microplastics, develop better filtering mechanisms, or even learn to avoid areas with high microplastic concentrations. These adaptations can lead to shifts in species composition within ecosystems, with species better able to cope with microplastics gaining a competitive advantage.
Examples:

Studies have shown that microplastics can influence the evolution of antimicrobial resistance in bacteria, as the particles can concentrate antibiotics and create a selective environment for bacteria that can tolerate them. Additionally, some fish species have been shown to reject microplastics, suggesting the evolution of avoidance behaviours.