As a species, humans have inhabited almost every corner of the globe. We have developed the technologies and cultures that shape the world we live in.
‘Natural selection’ or ‘survival idea’ is understood in Stone Age times when we were fighting over the scrap of meat, but does it still apply?
We asked 12 experts if humans are still evolving. The consensus of experts is a resounding ‘yes’, although scientists say that we may have a misunderstanding of what evolution really is.
Evolution is not the same as natural selection
The use of evolution is interchangeable with phrases such as ‘superiority of existence’ or ‘natural selection’. Really, this is not the same thing.
‘Evolution’ means the gradual change of population over time.
‘Natural selection’ is a method by which evolution can take place. Our Stone Age ancestors who were fast runners avoided being trampled by mammoths and were more likely to have children. It is a ‘natural choice’.
Overtime, the human population became faster in running. That is evolution.
Evolution can happen without natural selection
It makes sense for Stone Age men, but what of today? We don’t have to carry enormous objects, we have medicines when we are sick and we can go to the store and get food.
Natural selection requires ‘selection pressure’ (e.g. dangerous trampling mammoths), so if we don’t have this now, does that mean we have stopped evolving?
Despite no selection pressure, experts say evolution still occurs by other methods.
Stanley Ambrose, a professor of ethnography at the University of Illinois, explains that “any change in genes or types of genes over time is also considered evolution. Variables can be functionally equivalent, so evolution is not automatically equated with ‘improvement’.” .
While some genes may be affected by natural selection (e.g. genes that help us move faster), other changes in our DNA may have no obvious effect on us. ‘Neutral’ variation in the population is also spread through different mechanisms known as ‘genetic trends’.
Genetic predisposition works by chance: some individuals may be unlucky and die for reasons that have nothing to do with their genes. Their unique genetic variations will not be passed on to the next generation, and therefore the population will change.
Genetic predisposition does not require any selective pressure, and it is still happening today.
Natural selection is still happening in humans
As much as we have made it easy for ourselves, there is still the pressure of choice 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 have stopped making an enzyme called lactase. In some countries, the population has got lactase retention, which means people make lactase for life.
In European countries we can attribute our lactase persistence to a specific genetic variation, called ‘-13910 * T’. By studying this particular gene diversity in modern and ancient DNA samples, researchers suggest that it became normal after humans began giving pets and milk.
This is an example of a natural choice where we actually pushed the choice ourselves – we started drinking milk, so we developed it to digest!
Another example of people undergoing natural selection to adapt to a lifestyle is the Bajau people, who traditionally live in houseboats in the waters of Southeast Asia and spend most of their lives diving to hunt fish or collect shellfish.
Ultrasound imaging has shown that Bajau people have more spleen than their neighbors – an adaptation that allows them to stay underwater longer.
There is always selective pressure around us, that too we create ourselves.
As Dr. Ben Benjamin Hunt of the University of Birmingham puts it, “Our technological and cultural changes change the power and composition of the pressure of choice within our environment, but the pressure of choice still exists.”
Evolution cannot be stopped
Therefore, evolution can take place through various mechanisms, such as natural selection and genetic trends. Our environment is always changing, natural selection is always happening. And even if our environment was ‘just right’ for us, we would still thrive!
An expert in evolution and genetics at Cambridge University, Dr. Alvin Scaley explains: “As long as human reproduction involves anomalies and genetic mutations (and the laws of the universe are very sure that this will always be the case at some level), differences will continue from one generation to the next. The process of evolution can never really be stopped. “
Takeaway: Evolution means a change in population. It involves both simple-place-mutations as well as more subtle, genetic modifications to adapt to the environment.
Humans are still evolving, and that is unlikely to change in the future.
Articles based on the answers of 12 experts to this question: Are humans still evolving?
The expert’s response was published in partnership with the independent fact-checking platform MetaFact.io. Subscribe to their weekly newsletter here.
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