As humans, hominids, we try constantly to project symmetry and patterns onto the environment; we insist that there are “four corners” to the “globe” (actually a shapeless lump with a horrifying protuberance on one side, and a flat expanse on the other) upon which we have evolved all these years. There are four cardinal points, they say, and there are four winds. There are four seasons, divided by slivers of inclemency which we often prefer to the seasons themselves, and there are four kingdoms in the domain eukaryota.
Five Kingdoms, two Domains; only vertebrates exhibit adaptive immunity
Eukaryota is one of two domains. Prokaryota is the other domain. In the case of domains, at least, there are not four, but two. It is a fork in the road like no other, described above as a horizontal dashed line.
Living things are divided into five kingdoms, and some would even say six (and some would say hundreds but they’re just being fucking silly), and four of those kingdoms share one domain, while the other sits alone across a gulf of discontinuity that comprises the single greatest division in the catalogue of Life. Prokaryotes are creatures which have circular DNA, which have no sub-cellular components other than the very basic necessities required to synthesise proteins, little things known as ribosomes. But there is us and there is them – and we are Eukaryotic. Eukaryotes are the elaborate ones, the ones with the helter-skelter in every nucleus (except red blood cells), the ones with a helter-skelter in the first place, rather than a circular plasmid, as the Prokaryotic genome is called. It all began as single-celled prokaryotes, dividing asexually for billions of years, until one of them acquired a sub-cellular package – a membrane-bounded compartment designed to perform certain tasks – and so our own domain was born. Lynn Margulis, of the University of Massachusetts, Amherst, was among the first to determine that these sub-cellular packages were initially acquired as food, but over geologic time a meal became a mitochondria (previously a single-celled, membrane-bounded organism in its own right), and the plastic nature of cellular existence began to complexify. I just made that up. The word “complexify”, that is, not the theory of endosymbiogenesis. If I’d just made the theory of endosymbiogenesis up then I’d take the day off and go for a picnic.
Every living thing endures four seasons (even if it lives at the equator and those four seasons are identical), and has been precisely sorted by its ability to adapt to change over billions of years, but only the vertebrates have acquired adaptive immunity, that is, special cells capable of replicating themselves rapidly in response to an invader. The rest, the so-called “simple” ones, have only what they are given; there are no specialised cells which can change plastically on-the-fly, to ambush and destroy microbial invaders, parasites, or viruses.
But every four-walled house is built from four types of bricks, be it a bacteria or a horse, and those bricks are called macromolecules. The four types of macromolecules are:
1. Nucleic acid (such as DNA)
2. Polysacharrides (sugars)
3. Lipids (fats, oils, hydrocarbons)
4. Proteins
Everything which lives, whatever it may be, must be made from one or the other of these four things. Sure, there are electrolytes, but that’s getting too carried away, and it’s late, and you’re probably saying, “what the fuck is he doing? Why the biology lesson?”
Every cell in your body is bounded by a membrane which is made from lipids – fatty barriers with non-fatty surfaces that provide protection from things that aren’t supposed to enter the cell, or leave it. Membranes are one of the single most important products of evolution, for they partition things from other things in selective ways which have led to the emergence of cell-type and multicellular organisms.
Basically, what this means is you are a bacterial colony; there are scientists who’ve determined that certain macromolecules present on human neurons are only found in one other species, and that species is a prokaryote, a form of archaea, a primitive bacteria-like organism which lived on the earth billions of years ago. Why would our neurons share such a property with such an unlikely candidate? Neurons compose an extensive web in the body, a network of individuals which communicate via neurotransmitters, chemical armadas whose molecules traverse the gulfs between individual neurons and provide information to each other, not unlike the cells in a colony of prokaryotes. The question is this: Is the human neural system a colony of archaea which insinuated itself into our physiology billions, or at least millions, of years ago?
Goodnight, then…or is it?