As a species, humans can be found in almost every corner of the earth. We have developed the technology and culture that shape the world we live in.
The concept of “natural selection” or “survival of the fittest” seemed meaningful in the Stone Age when we were fighting for ground meat, but is it still applicable today?
We asked 12 experts whether humans are still evolving. Experts unanimously agree “yes”, but scientists say that we may have a wrong understanding of true evolution.
Evolution is different from natural selection
Evolution is often used interchangeably with the term “survival of the fittest” or “natural selection”
“Evolution” simply means that the population changes gradually over time.
“Natural selection” is the mechanism by which evolution occurs. Our stone age ancestors were faster runners, avoiding being trampled by mammoths, and more likely to have children. That is “natural selection”.
Working overtime makes the population run faster. That is evolution.
Without natural selection, evolution can happen
For people in the Stone Age, this made sense, but what about today? We don’t need mammoth, we can buy medicine when we are sick, and we can go to the store to buy vegetables.
Natural selection requires a “selection pressure” (such as a dangerous trampling mammoth), so if we never have this choice again, does this mean that we have stopped developing?
Experts say that even without selection pressure, evolution will still happen through other mechanisms.
Professor Stanley Ambrose, an anthropologist at the University of Illinois, explained: “Any change in the proportion of genes or gene variants over time is also considered evolution. These variants may be functionally equivalent. , So evolution will not automatically equate to’improvement’.”
Although some genes are affected by natural selection (for example, genes that help us run faster), other changes in our DNA may not have a noticeable effect on us. “Neutral” mutations can also spread throughout the population through a different mechanism called “genetic drift”.
Genetic drift is accidental: some people may die unfortunately for reasons that have nothing to do with their genes. Their unique genetic variation will not be passed on to the next generation, so the population will change.
Genetic drift does not require any selection pressure and is still happening today.
Natural selection still occurs in humans
Although we make things easier, there is still selective pressure around us, which means that natural selection is still happening.
Like all mammals, humans lose the ability to digest milk when they stop breastfeeding. This is because we stopped producing an enzyme called lactase. In some countries/regions, people have acquired “lactase persistence”, which means that people will make lactase throughout their lives.
In European countries, we would like to thank a specific genetic variation of lactase persistence, namely “-13910 * T”. By studying this specific genetic variation in modern and ancient DNA samples, the researchers suggested that this variation became common after humans began domesticating and milking animals.
This is an example of natural selection, we have actually put pressure on the choice-we start to drink milk, so we gradually digest the milk!
Another example of humans’ natural selection in order to adapt to their lifestyle is the Bajau people, who traditionally live in houseboats in Southeast Asian waters and spend most of their lives diving to catch fish or collect shellfish.
Ultrasound imaging revealed that Bajau people have larger spleens than their neighbors-this adaptation allows them to stay underwater longer.
There is always selective pressure around us, even pressure created by ourselves.
As Dr. Benjamin Hunter of the University of Birmingham said: “Our technological and cultural changes have changed the intensity and composition of selection pressure in our environment, but selection pressure still exists.”
Evolution can’t stop
Therefore, evolution can occur through different mechanisms, such as natural selection and genetic drift. Since our environment is always changing, natural selection is always happening. Even if our environment is “just right” for us, we will continue to develop!
Dr. Alywyn Scally, an evolution and genetics expert at the University of Cambridge, explained: “As long as human reproduction involves randomness and genetic mutations (and the laws of the universe guarantee to a certain extent that this is always the case), there will continue to be differences between the next generations, which means The evolutionary process will never really stop.”
Key point: Evolution means changes in population. This includes both easy adaptation to environmental changes and more subtle genetic changes.
Humanity is still evolving and is unlikely to change in the future.
Article based on the answers of 12 experts to this question: Are humans still evolving?
The expert response was released in collaboration with Metafact.io, an independent fact-checking platform. Subscribe to their weekly news here.