Pogo and Walt Kelly had the right idea.
“We have seen the enemy and he is us.” Pogo
Walt Kelly could not have been more prophetic. Microorganisms are often our worst enemies, but we can’t live without them. They are we.
Microorganisms (bacteria) living inside our bodies play a vital role in our health and, believe it or not, in our evolution.
According to microbial experts Richard Jefferson and Eugene Rosenberg, the biggest breakthrough in evolutionary thinking is the Hologenome theory. The genomes of symbiotic microbes in and on our bodies, and the human genome function together. Neither can survive without the other, and we cannot survive without the collaboration of both genomes.
We tend to think about bacteria as “us verses them.” Our body verses those bacteria living inside of us. Actually, the genomes of bacteria and our genome work together, and act as one. We tend to forget that there are more bacterial cells living out their lives in our gut than the number of our own body cells. There are 100 trillion microorganisms living and functioning in our bodies, about ten times as many as the number of our own body cells. They are us; without them we cannot survive; we cannot digest our food; we cannot protect our bodies from evaders; we cannot evolve. Microorganisms are vital to our survival. Microorganisms are us.
Yes, scientists agree microorganisms are the equivalent of another functioning body organ doing things we cannot do ourselves. About five hundred different microorganisms live in our guts, with about 99% coming from just 30 or 40 different species. Family members have similar gut bacteria, but almost everyone has a unique population of microorganisms.
Microorganisms not only digest our food, they also control our immunity, prevent the growth of harmful bacteria, produce vitamins, produce hormones to help in the storing of fat. Unfortunately, some microorganisms cause disease and cancer.
When we are invaded by harmful bacteria and have an infection, we demand antibiotics that will wipe out friendly and hostile bacteria alike. As we recover from a bacterial infection, we assume the beneficial bacteria will automatically replenish themselves. Eventually, this does happen, but most health specialists agree it won’t do you any harm to eat some yogurt, and take probiotic capsules to jump-start your friendly little microorganisms.
Think about the native bacteria living on our skin that are so difficult to wash away, even for surgeons scrubbing their hands and arms prior to surgery. Skin bacteria are actually our first line defense against harmful bacteria looking for an entry into your body. Bacteria on our skin, in our mouth, throat, and gut crowd out invading bacteria. They are the “good guys”.
Microbes do more than just digest food and protect us. 65% of circulating testosterone cycles through microbes. They control our pheromones, our sex life, and our very happiness. Jefferson believed that the genomes of thousands of our microorganisms work with our own genome. This combined protective force is an important unit of evolutionary selection. Rosenberg realized that our fitness and survival did not just depend upon our own genes inherited from parent to offspring, but also upon the micro-biomes of bacteria resident in our bodies. The micro-biomes we inherit from our parents are vital to our survival. Fortunately, during the birth process newborns are “infected” with their mother’s bacteria. Parents share micro-biomes with each other and with their offspring. Recent research shows that newborn mice need gut microorganisms for their brains to develop normally. Drastic changes in the biomes of a species’ microflora allows for rapid evolution to keep pace with a rapidly changing environment. Treating termites with antibiotics reduced the numbers of beneficial bacteria needed to digest wood. It reduced the colony size. Changing the diet of fruit flies changed their mating habits. This could conceivably lead to the creation of a new species. Acquiring new bacteria can prevent otherwise compatible animals from interbreeding. Acquiring new bacteria can enable an animal to eat new foods and expand territories. Here is another evolutionary concept; microbes could possibly be manipulating their hosts for their own benefit rather than cooperating with the host for mutual benefit. Wow, the selfish gene again?
Jefferson contends that large organisms evolve slowly, a handicap in a fast changing environment. But, by cooperating with fast evolving microbes they can evolve faster. While competition is a driving evolutionary factor, Jefferson believes cooperation and collaboration are even more valuable. Pogo, the open minded possum, might have agreed.