How All Living Things Are Connected.

The perception of consciousness makes it exceedingly appealing to believe that we are autonomous individuals, isolated from the world around us by the boundaries of our bodies. However, modern science has blurred the lines of the individual by shedding light on how interdependent life is. To understand this, it helps to go back in time and consider how life started.

Life on earth likely emerged from a primordial soup, and was based on the foundation of building barriers. By creating a membrane, the first unicellular organism was able to control energy forces by creating chemical and physical gradients. These first simple organisms appeared around 4 billion years ago. They did not evolve in isolation, but rather competed daily for common resources (iron, oxygen, free nitrogen, etc.), creating alliances and waging wars on a scale above and beyond what Game of Thrones could ever approach.

A major turning point in these epic interactions began over 2 billion years ago, when one of these self-bound organisms engulfed another, but instead of dying, the engulfee not only survived, but prospered in a way that made the engulfing cell advantageous. This marked the rise of the eukaryotes, the group to which we belong. Over incredibly long amounts of time, the complexity of eukaryotes and of their interactions with other microbes grew, eventually leading to the dazzling alliance of the literally trillions of cells comprising our bodies. Therefore, it is simplistic to imagine ourselves as cleanly defined individuals, perpetually annoyed by microscopic bugs that should be whisked away with antimicrobial hand soaps. Rather, we are a complicated colony of eukaryotes which squeezed its way into a microbial world.

Because we cannot see them, it is easy to forget the extent to which our nutritional requirements, the plants and animal products we eat, are dependent on microbes. Coffee, bread, miso, alcoholic beverages, cheese, kimchi, and chocolate, just to name a few, are all examples of fermented foods. In other words, the primary metabolic step performed by yeast or bacteria must be performed in order to produce the food products we are familiar with. Humans are not an exception, a majority of nutritional interactions among larger organisms is mediated by microbes.

One of my favorite examples of how microscopic life connects to life on our scale involves a cat, a primate, and a protist. Toxoplasma gondii, a protists , in other words, a single celled eukaryote, is a parasite that infects a broad range of warm-blooded animals. In order to be able to complete its life cycle, which can only take place in cats, this protist alters the behavioral patterns in its host. More specifically, mice infected with T. gondii are no longer fearful, and in some cases even seek out, the smell of cat urine, making them easier to catch. Bad for the mice, good for the parasite. Humans infected with T. gondii have also been noted to have behavioral and psychomotor alterations, and recent research has demonstrated that these effects could be vestigial traits from a time when large cats hunted man.

Examples of life affecting life on a scale normally unacknowledged surround us. Recent microbial research has elucidated how pervasive this phenomenon is by allowing us to identify the dense populations of microorganisms continually surrounding us.

D/D : 27/07/2020