Research Paper on Genetic Mutation in Human DNA
Humans have been constantly evolving and will continue to evolve, and despite the fact that natural selection for humans has slowed down a lot in the past few centuries, due to better medicine and healthcare, genetic drift is still occurring.
Humans living in different conditions will have different genes and different adaptations for their environment. For example, in European countries there is a gene called -13910*T (Metafact, n.d.) which allows most Europeans to be able to digest lactose, only 18-26% of northern Europeans are lactose intolerant, compared to 75-95% of African Americans and Asians (Neville, 2017). This is due to a variety of factors. Firstly, a study concludes that adults from Europe can drink milk because their ancestors lived in climates allowing the production of dairy cattle, which lead to them digesting dairy and causing mutations that produced the gene to digest lactose, and therefore passed it to their future offspring, whereas in Asia and Africa their climates are not suitable for dairy cattle. Furthermore, historically populations that can digest dairy, such as Europeans, were migratory groups that moved each season which allowed them to find suitable land for their cattle and avoid living in harsh climates (Vuorisalo et al., 2012). Lactose intolerance also decreases with increased latitudes and higher temperatures, as these conditions are more suitable to raise cattle. (Lactose intolerance seems linked to ancestral struggles with harsh climate and cattle diseases, Cornell study finds | Cornell Chronicle, 2020).
Next, another example of humans undergoing natural selection to adapt to their environment and lifestyle is the Bajau people, who live in houseboats in South East Asia and spend a lot of time diving to hunt for fish. This led them to have larger spleens to allow them to survive longer underwater and provide food for themselves and their families (Indonesian divers have evolved bigger spleens to hunt underwater, 2020). Additionally, Tibetans have higher haemoglobin levels and higher oxygen saturation as they live in a high-altitude area, so their red blood cell production increases to compensate for less oxygen supply (Yang et al., 2017). This spread of genetic mutations in Tibet is potentially the fastest evolutionary change in humans, occurring over the last 3000 years (Hurst, 2018). This leads to many different human races evolving and adapting differently to each other depending on where they live, and their culture.
We can also get adaptive genes due to our lifestyle and diet, a study found that in the US during the 20th century found selection for reduced blood pressure and cholesterol levels, which both are raised highly due to modern diets (Byars et al., 2009). This change has occurred due to modern diets raising cholesterol and blood pressure a lot, and shows that human evolution is getting faster as our diets have only recently been this high in calories and other nutrients. Western diets are typically larger than other cultures, which has allowed us to adapt to our larger diets (Health Professional Radio, 2018).
There are other factors that affect evolution more than natural selection. Natural selection only affects 8% of our genome (Rands et al., 2014). “The neutral theory of molecular evolution shows that most evolutionary changes at the molecular level and most of the variation within species, are due to random genetic drift of mutant alleles” (www.nature.com, n.d.). Because of this theory, most advantageous mutations are lost, and some undesirable mutations are passed on, as a random event can occur removing these advantageous mutations. Furthermore, natural selection isn’t the only driving force of evolution, which makes it clear that evolution will continue to happen and is unlikely to ever stop, thus making it harder to predict what future humans will be like. This theory today is perhaps more relevant than natural selection, as we are living in modern times, and genes that were thought to have been disadvantageous in the past, is no longer as much disadvantageous, due to modern medicine and healthcare allowing people with disabilities to survive much longer. This then leads to the rate of evolution increasing as selection is weakened, as these genomes are no longer filtered out and therefore leading to an increase of genes in the gene pool.
To conclude, humans are biologically extremely similar to each other. Our DNA is 99.9% the same as each other, however the small 0.001% of our DNA is what makes us different in terms of appearance and health (Lee, n.d.). However, due to weakened selection and genetic drift, our gene pool is getting much larger and we are becoming more different and more diverse than ever before. Humans are evolving to be more different than ever before, and we are evolving to form more than human race.