Thousands years ago, natural selection played a huge role in nature. Evolution was based on survival of the fittest, meaning only the animals who adapted best to their environment survived and those advantageous genes were passed down to the next generation. However, we now live in a society where there are much less natural selection pressures. The amount of hazards we face has reduced dramatically due to better food, shelter, and hygiene that is provided to us. So has evolution stopped because of our improved living conditions? Well studies have shown that some evolution has occurred over the last couple hundred years and more changes are still happening.
The first example of evolution in humans is the ability to digest lactose sugar in milk. In most parts of the world people are unable to drink milk, because they symptoms such as bloating, cramps, nausea, vomiting, etc. This is a result of a lactose intolerant person’s body shutting off the production of lactase, which is the enzyme they need to digest the lactose sugar. However, “A 2006 study suggests this tolerance for lactose was still developing as early as 3,000 years ago in East Africa. That genetic mutation for digesting milk is now carried by more than 95 percent of Northern European descendants” (Hullinger). The reason that most Europeans carry a mutation containing the gene where lactase production is switched on when milk is consumed, is due to the change happening when milk-producing animals were domesticated thousands of years ago. During that time, milk was one of the safest drinks a person could have. So, if they were lactose intolerant it was likely they wouldn’t survive. The advantageous gene of being lactose tolerant was passed down to the next generations and now that variant is extremely common in Europeans.
Next is the change in the Caspase-12 gene. A study conducted by Wellcome Trust Sanger Institute suggested “The caspase-12 gene was gradually inactivated in the human population because the active gene can result in a poorer response to bacterial infection.” (YG) This adaption occurred because although the Caspase-12 gene responded to bacterial infections within our immune systems, individuals who had a functional version of this gene had a higher risk of death if bacteria entered the bloodstream than individuals with the inactive gene. So, the adaption is that the Caspase-12 gene is now inactive in everyone.
Another change is that we’re losing our wisdom teeth. “One estimate says 35 percent of the population is born without wisdom teeth, and some say they will disappear altogether” (YG). Centuries ago, the jaws of our ancestors were much larger than ours. Wisdom teeth were essentially an extra set of molars that made it easier for them to chew tough meat, roots, and nuts. In today’s society we do not need to tear apart food with our teeth. Since we have utensils, food is much easier to eat. For this reason, our jaws have become smaller and wisdom teeth are unnecessary.
Genetic studies have demonstrated that humans are still evolving even today. Researchers at the University of Sheffield in Finland found that within the population the percentage of children born in the late 1800’s who survived to adulthood had risen significantly by the mid 1900’s. However, Dr Bolund and others “found that between 4 and 18 per cent of the variations between individuals in lifespan, family size and ages of first and last childbirth were influenced by genes” (Connor). So this is just another example that in recent years, humans could still be responding to natural selection pressures, and therefore still be evolving.
A more recent study by the University of Chicago found genes evolving in two specific groups of people as a result of climate, diet, and habits. In the first study, “researchers found positive selection in four pigment genes important for lighter skin in Europeans that were not known before.” (Than) The color of their skin may be an adaption to less sunlight. The second study on East Asians “found strong evidence of positive selection in genes involved in the production of alcohol dehydrogenase (ADH), a protein necessary for breaking down alcohol” (Than). This is different because they have been previously known to carry a mutation preventing them from producing ADH. These changes suggest evolution.
Overall, according to Dr Bolund, “As long as there is variation in the population in terms of reproduction, there will be a difference in reproductive success, which means there’s something for natural selection to work on” (Connor). We are always adapting to our environment around us, therefore, the advantageous genes are still are being passed down to the next generation and making them better off. Since it is clear that we still are and will continue evolving, maybe someday we will have resistant to terrible illnesses such as cancer, heart disease, etc. Future evolution could potentially allow us to live longer and better quality lives.
