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Natural Selection
“This is a perfect example of natural selection at work, with only those able to adapt to living too adulthood and passing their traits to their children.”
—Celine
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AISM Science Magazine | 119
Natural selection is the force driving evolution, with “hazards” or selective pressures being the factors around us forcing us to adapt in the first place.
_____Celine_____
This is the “survival of the fittest” mentality, meaning only the strongest survive, but the question is if we’re still being affected by it today. In short, we aim to answer if humans are still evolving, and what are some examples of said evolution.
According to genetic studies, humans are still evolving as natural selection is in play. One such example of this is the lactase gene. In most parts of the world, adults are unable to digest lactose. The reason is that their bodies switch off the lactase gene, the enzyme that digests the sugar in milk, after they’ve outgrown breastmilk.
In Europe, however, 70% of adults are able to digest lactose without any problems. They have different DNA that leaves the lactase gene on throughout their lives, even after outgrowing breastmilk. This seems to have happened between 5,000 and 10,000 years ago, which was around the time cows were domesticated in Europe.
Some explanations for this are linked to how important cow’s milk was. Sun exposure was low, so people needed Vitamin D they’d receive from milk. Milk was safer than drinking potentially diseased water, and prevented death from starvation when food was scarce.
As a result, those who couldn’t tolerate cow’s milk died from starvation, and those who could tolerate it would live to adulthood. Being able to digest lactose is so common now that being lactose intolerant is seen as unusual in Europe.
This is a perfect example of natural selection at work, with only those able to adapt living to adulthood and passing their traits to their children. In this case, said trait is the lactase gene being active throughout the length of their lives.
Work Cited
“Are Humans Still Evolving?” Stories, The Public Engagement Team at the Wellcome Genome Campus, 13 June 2016, www.yourgenome.org/stories/are-humans-still-evolving.
AISM Science Magazine | 120
