Although the evolution of traits is much easier to see in the past, since we can look at thousands of years at a time, this does not mean that species do not continue to evolve in the present. In the present, a few examples of traits that are continuing to evolve in humans include the increasing cases of antibiotic resistance and lactose intolerance.
In the case of antibiotic resistance, there are two factors that play a role in its prevalence: the extreme use of antibiotics by humans over the past 75 years and the survival of resistant bacteria in the bodies of so many individuals. Following the discovery of various antibiotics, such as penicillin, many thought that these medical miracles would save us all from any bacterial infections that came our way. Truth be known now, excessive use of these antibiotics–like overuse of anything–eventually leads to our bodies thinking that being pumped with them is the new normal. As individuals use antibiotics more and more, only the small amounts of bacteria that remain alive in the body can reproduce. Therefore, through reproduction, more and more bacteria are born in the body that are resistant to antibiotics. Because of this, people notice that antibiotics begin to work less and less and try to take them in higher doses to compensate. This, obviously, does not make the antibiotics any more effective, and this causes more resistant bacteria to grow, producing the opposite effect one is trying to accomplish when using antibiotics. Additionally, the bacteria that remains embeds itself within the other healthy cells, and to an extent the genes, and are then passed to offspring. The process happens all over again and more and more resistant bacteria exist in the human genome over time.
As learned earlier in this course, lactase deficiency is a very prominent digestive issue around the world; however, prominence of this condition especially lies in areas where dairy farming is not very prevalent. This is due to the fact that in communities lacking a prominent dairy farming industry, less milk–or other dairy products–is generally consumed. The body does not have much good reason to continue to use energy to produce lactase if an individual is not consuming lactose that needs to be digested. Therefore, in many African countries, for example, the trait of lactose intolerance has been carried through genes through multiple generations, leading to a percentage of people with some sort of lactose intolerance in the nineties. The opposite effect is seen in communities where dairy farming is a part of the culture. In some areas, usually found in Europe, less than ten percent of the population is inflicted with any form of lactose intolerance.
These are only two examples of the many ways in which humans are genetically evolving today. Additionally, Homo sapiens also continue to evolve culturally, such as with expansion and innate reliance on technological advancements, and behaviorally, shown through the rise in gender identity alterations within the last ten years. As we look to the past to observe evolutionary changes, let us remember that it is now that we can control for evolutionary changes that will be observed in the future.
Hello Annika! I enjoyed reading your blog post for the final week of class. I took my senior seminar class last fall, and we talked about the lactose deficiency. In the class, I found out that in Europe that is where dairy farming was first seen in our ancestors. Just like you said, a small percentage of the population is inflicted with being lactose intolerance. This example you provided can also be seen as a example of natural selection as well! The gene is being eliminated, because there was not a use for it in our ancestors who lived in Africa. I enjoyed that your were very specific about the examples you provided. It gives us more information on how different traits are still evolving in humans.
Hey Annika,
I like that you talked a lot about resistance in your post. I did not see many people mention that! I actually learned about lactase deficiency in my biology class during my sophomore year of college. My professor had taught us that as we age, our ability to breakdown lactose decreases. This is because we really only need the enzyme, lactase, to breakdown the sugar in the milk we get from our mothers. But of course, the ability to break down lactose also varies amongst people. I did not know that lactase deficiency is prominent in areas where farming is not common. This is a very interesting fact! Also, I did not know that African countries carry the lactose intolerance gene through their generations more. I have always found lactose to be a very fascinating topic. Overall, I think you did an amazing job with your post. In my opinion, the post was very engaging!