Newly Found Genetic Advantage for Free Divers

Free diving is the sport of diving underwater without the use of any breathing apparatus. This technique has been used for thousands of years by island communities to hunt and gather food. The Bajau people of Southeast Asia, known as "Sea Nomads," have collected food by free diving with spears. They now live around the islands of Indonesia and are renowned for their ability to hold their breath for incredible amounts of time. The members of this community can dive up to seventy meters with only some weights and a pair of wooden goggles. Since the Bajau people do not dive competitively, it is impossible to know exactly how long they can hold their breath on average. However, a diver in the Bajau community told a reporterthat he had once dived for over 13 minutes.

Other diving mammals, such as the seal, have disproportionately large spleens for their body. This led Melissa Llardo, from the Center for Geogenetics at the University of Copenhagen, to wonder if the same trend would follow in diving humans. She traveled to Indonesia and met the Bajau people, who were surprised that she had even heard of them. She then asked to take ultrasound pictures of their spleens and spit samples to compare to a related group of people from the Indonesian main land, the Saluan.

On average, it was found that the spleen size of the Bajau was 50% larger than that of the Saluan. From the spit samples the researchers also found a gene called PDE10A, which is thought to control a certain thyroid hormone. This hormone has been linked to spleen size in mice, and when they have a lower level of this hormone, they also have a smaller spleen size. The PDE10A gene was only found in the Bajau people, which could be an explanation for why they have larger spleens.

Melissa Llardo theorized that natural selection would have helped the Bajau people gain a genetic advantage over thousands of years of free diving. Unfortunetly, the Bajau way of life that has persisted for generations is increasing under threat. Overfishing is making it harder for the Bajau to subsist on their local stocks and because they live out to sea, they do not enjoy the same citizenship as those on the mainland. Because of this, many of the Bajau people choose to leave their "sea nomad" life, making their tribe smaller and smaller.

Can Our Genes Change Due To Our Culture?

Like stated in this article, over millions of years humans’ genes have altered due to certain cultures or how human evolve. It points out that from cavemen times, humans’ anatomy adjusted a lot just to the discovery of fire. Since fire helped to cook meat and, as humans, we don’t have to have strong mouth muscles to tear through raw meat, so our muscles have weakened as humankind evolved.

Other examples that supported this statement about how genes change due to culture or evolving are how over sixty percent of people are lactose intolerant due to the loss of their lactase enzyme and how certain eastern Asian countries have adopted to a sea nomad lifestyle due to a larger spleen. Having the larger spleen was made possible by a gene called PEE10A which allows the spleen to hold more oxygenated blood cells to be able to stay in water longer. Having more oxygenated red blood cells are essential for this lifestyle because it aids with how long they drive to find food. This gene gets passed on to their offsprings so that their lifestyles are already adjusted for their living.

Most people lose the lactase enzyme because it is originally there to help digest breast milk as an infant. So many adults experience this intolerance because they no longer have this enzyme. Lactase contains a gene called LCT gene which is a coding gene that allows the body normally ingest lactose. This gene is seen in different African, European and Asian countries because of their forager lifestyle.

These examples show how different cultures and lifestyles can change our lives as a whole; therefore, would change our genetics during evolution to adapt. After reading this article and reading the examples stated in it, I do believe that your culture or lifestyle can change your genes because of natural selection. Only the strongest survive, so the body adjusts accordingly, which also may mean that your genes would change too.

Evolution within the Diving Bajau People

It has been found that the Bajau people, who reside in scattered communities in Indonesia, Malaysia, and the Philippines, may have evolved traits that make them better divers. The Bajau people dive for their livelihood, and have been doing so for centuries. Many have noticed that the Bajau people are more gifted than others in diving, as the Bajau people were observed to be able to dive more than 200 feet with their only equipment being wooden goggles. Dr. Melissa Ilardo, a geneticist, set out to study the people to see if they had, indeed, evolved traits that could aid them in diving. She visited the villages of the Bajau people and measured the size of their spleens, which have been found to play a key role in how deep an organism is able to dive. The larger the spleen, the deeper an organism is able to dive. Dr. Ilardo measured the spleens of nearby farmers that were not Bajau, and she compared the sizes to the Bajau people. She found that the spleens of the Bajau people were 50% larger than the spleens of the neighboring farmers. After conducting a DNA test, it was also found that the Bajau people shared a number of variant genes, which further suggested that natural selection had taken place within the population. A variant of a gene, PDE10A, was found within the DNA of the Bajau people; this variant influences the size of spleens. The more copies one has of the PDE10A variant, the larger that person’s spleen will be. The studies performed are not conclusive, however, and more research needs to be performed on the matter.

I found this article to be really interesting. The evolution between groups of people intrigues me, as it sounds amazing that a certain group of people can evolve to have a set of traits from other humans that help them survive better under certain conditions. It seems that, compared to humans like me, who live in a more neutral environment, it is as if the Bajau people have a biological advantage. The fact that the Bajau people are able to dive to depths of over 200ft, and at that rate, are able to hold their breath for long enough to dive that far down, shows how far the limits are that the human body can be pushed to. I also found it very heartwarming that the researcher who was performing the studies had such love for her research, and was so passionate as to travel all the way to the islands that the Bajau people live on in order to perform tests. Reading about how interesting the evolution of the Bajau people was, and how much Dr. Ilado loved her job, it made me imagine how fun it must be to be a geneticist researching the biological evolution of groups of humans.

Bodies Remodeled for Life at Sea

Recently, a team of researchers have gained particular interest in a group of individuals scattered across Indonesia, Malaysia and the Philippines. The Bajau, are a group of individuals who have been known for their abilities to dive 200 feet with just a pair of wooden goggles. This phenomenon is an ideal example of natural selection affecting humans in a more recent event. The Bajau people have suspected to start diving for sea cucumbers starting in the 1600s or possibly after the most recent Ice Age. When Dr. Melissa Ilardo, a genetics student at the University of Copenhagen, heard about these people she decided to take scans of the spleens of these individuals. Spleens allow the supply of oxygen-rich red blood cells into circulation during the so-called diving reflex. Turns out that those individuals who have bigger spleens have a mutant copy of PDE10A gene that influences the size of the spleen. This is new information to scientists as there has been no direct knowledge on what the PDE10A gene does. It has been shown that this gene controls the level of thyroid hormones inside the body but with this new data a new function may soon be determined. The Bajau people are a unique example of more recent natural selection in humans similar to the people in Tibet and their abilities to live at higher altitudes.

Article: https://www.nytimes.com/2018/04/19/science/bajau-evolution-ocean-diving.html
Additional Information: https://www.nytimes.com/2013/05/30/science/mountain-populations-offer-clues-to-human-evolution.html

Viruses and Diversity

Viruses are known to range in severity, and an experiment in mice was conducted to find out more about them. More specifically, five genetically identical mice were infected with a virus that was much more virulent than when the same virus infected five genetically diverse mice one at a time. One reason for this is that the virus wasn't able to adapt to the different genetic makeups of the different mice, and therefore was less effective. However, this has only been able to be experimentally proven with mice, plants, and insects. Research in this field was done by biologists Jason Kubinak and Wayne Potts.

Since viruses tend to be less virulent in a more diverse population, researchers encourage the diversification of cattle to lessen the probability of disease spreading. Potts and Kubinak use their study to show that the "sex-against virulence hypothesis." This hypothesis states that sexual reproduction evolved in order to increase genetic diversity, which in turn decreased the chance of viral infection.Therefore, the group of mice that had the same genetic makeup showed what would happen if mice reproduced asexually, and this reiterates the importance of diversification as an effect of sexual reproduction. Sexual reproduction enables organisms to gain resistance to viruses and diseases that they may have be vulnerable to otherwise. In the experiment, the virus used is mouse leukemia combined with a virus that causes a drastic increase in the number of red blood cells. Together, the virus is called the "Friend virus complex." The red blood cell count is increased in the spleen, and the more there are, the more likely the spleen will be inflamed, endangering the mouse's life. With the help of this combination of viruses, a virus in the spleen is able to replicate itself.


To start, a healthy mouse was injected with infected spleen tissue from another mouse. The previously healthy mouse was tested for how well it was fitted to the virus (i.e. if it allowed the virus to replicate easily). This was done by weighing the spleen because an enlargement of the spleen yields a more harmful virus.

Although there has been no experimental proof of this in other vertebrates, plants and insects have shown that genetic similarity allows a virus to adapt to a host more efficiently, and thus become more detrimental. Being able to replicate itself faster is lethal to the organism, as well as the rest of the organisms with its identical genetic makeup.

Article: http://www.sciencedaily.com/releases/2014/11/141118072528.htm
Supporting Article: http://www2.estrellamountain.edu/faculty/farabee/BIOBK/biobookdiversity_1.html

Ribosmoal Protein Causing New Borne Disease Discovered

And article on Science Daily referencing a journal published in sciencemag explains how the protein causing isolated congenital asplenia (ICA) causes this disorder.  This condition is very rare and has be officially documented in less than 100 cases in medical literature.  These scientists sequenced 23 exomes (the part of the genome formed by exons that get transformed into proteins).  After proper testing and filtering, researchers narrowed down to 4,200 possible genes.   Next, researchers hypothesized which exomes would be more likely to house these gene therefore, deciding to focus on ICA exomes.  The gene RPSA responsible for coding for a protein found in the cell’s protein-synthesizing ribosome was found to be the culprit.  Every individual with a coding mutation in this gene is developed with out a spleen.  These results are puzzling because this ribosome is present in every organ in the body but only seems to effect the spleen. 

                This discovery may make it possible to develop new diagnostic test for ICA and lead to more research on this specific protein-making machinery.