Please, Pay Attention to Microbiomes

Only one percent of human DNA is actually “human.” Our bodies, down to our very genes, are dominated by the first life forms to exist on Earth: microorganisms, or microbes. These tiny organisms coalesce and thrive in regions of the body known as microbiomes, which on average make up six pounds of the human body. Despite the importance of microbiomes in our bodily functions, a complex understanding of them has yet to be developed by scientists. Until microbial DNA was completely sequenced and organized for the first time in the early 2000s, few realized the immense influence that microbiomes hold over our identity as humans. To fully embrace the study of microbiomes into modern biology, scientists and people everywhere must realize that the composition of microbiomes and their functions is a natural, precise way of understanding and taking care of one’s health.

Microbial DNA enters the human genome through a process known as horizontal gene transfer (HGT). The genes from microbes can naturally slip into our DNA, or they can be transferred by bacteriophages. The extent to which DNA has been obtained by the human body through HGT is so great that scientists speculate that even our blood types originate from microbial DNA. HGT has been discovered in some eukaryotes as well.

Microbiomes have entered popular culture partially because of the increased promotion and consumption of probiotics: foods that either contain or encourage the growth of live bacteria for health benefits. For example, Kombucha, a drink marketed as a healthy alternative to soda and juice, drives away many customers because of its appallingly bitter taste. But its taste is caused by the many probiotics (like live yeast and other bacteria) that make up the beverage’s ingredients.

Traditionally, probiotics have been used for clinical purposes to replenish microbiomes after the use of antibiotics. Antibiotics kill helpful bacteria as well as harmful bacteria; probiotics serve instead to re-introduce these bacteria into the body. With the food and beverage industries implementing more probiotics into their products, however, the role of probiotics has expanded beyond simply balancing out antibiotics. People who are on strict diets, for example, are inclined to consume probiotics to expand their microbiomes. They can feed their bodies with the probiotics they might be lacking in certain foods, such as yogurt. The widespread commercial use and awareness of microbiomes has provided humans with the opportunity to personally take control over their microbial makeup, a defining force in their heath.

The gut microbiome also has a strong connection to the brain, a link often known as the gut-brain axis. Microbes can send neurotransmitters into the brain through the vagus nerve, which connects the digestive system and the brain. This connection between gut bacteria and neural functions can control emotions, appetite and digestion, and can also potentially provide exploitable links between neurological disorders and microbial diversity. Researchers at the Wisconsin Alzheimer’s Disease Research Center recently discovered a connection between the amount of Alzheimer’s disease proteins in patients’ bodies and their microbial diversity. A less diverse microbiome correlated to a higher abundance of disease proteins. Similar experiments may possibly reveal that microbial insertion is a safer and more effective alternative to the countless drugs and treatments prescribed to combat neurological disorders.

Microbial discoveries are continuously improving human means of living, whether they are consumed as probiotic pills or as bitter drinks. One must remember, however, that these discoveries merely scratch the surface of the possible benefits that microbiome research can provide. What we know for sure is that microbes make us who we are. After realizing just how much of the human body is regulated by microbes and their companion organisms, the question “What makes us human?” becomes much more difficult to answer. To put it simply, the future of humans depends on the future of microbiomes. They have been the backbone of species on Earth for billions of years, and they will continue to be so for billions more.