On a Whim by Mat in Vadnais Heights

Living systems are strange. Just when you think you have a handle on things, along comes some new fact that scrambles all your neat, well-thought-out categories. Lichens are a good example. It turns out there is no single living thing called a lichen. Lichens are composite organisms made up (traditionally) of a fungus and an alga or bacterium in a symbiotic relationship.

This was quite the upheaval in the late 19th century when they were first classified. Prior to that, symbiosis was not a thing. Maybe it was the influence of the whole “survival of the fittest, nature red in tooth and claw” mentality, but if you found one organism living in proximity to (and benefitting from) another, it was parasitism—case closed. There was no other concept available.

Then lichens flipped the table over by working together for mutual benefit, and we needed something new. As Merlin Sheldrake puts it in his book Entangled Life, “A fungus can’t photosynthesize by itself, but by partnering with an alga or a photosynthetic bacterium it can acquire this ability … an alga or a photosynthetic bacterium can’t grow tough layers of protective tissue or digest rock, but by partnering with a fungus it gains access to these capabilities.” Win-win, in other words.

What does this have to do with anything? Well, hang on tight, boys and girls, ‘cause it’s rabbit-hole time. Things are about to get weird.

Recent research has determined that lichens are actually much more complicated yet. They can be made up of multiple fungi, multiple algae or bacteria, and other things besides, like viruses—all contributing to the overall health of the organism (or “organism,” if you prefer). Quoting Sheldrake again, “Lichens are places where an organism unravels into an ecosystem and congeals into an organism. They flicker between ‘wholes’ and ‘collections of parts.’ ” One current researcher, Toby Spribille, has said “we have yet to find any lichen that matches the traditional definition of one fungus and one alga.” They’re just not that simple, at least in the wild. Under controlled settings, though, it can be even stranger. You can bring together a fungus and an alga that have never been in contact before and sometimes—not always—they will settle down and form a brand-new, never-before-seen lichen, right before your eyes.

The takeaway from all of this, as I see it, is that the definition of an “organism” is kinda fuzzy. The boundary between a single organism and something like a microbiome is not a sharp one. And this leads us neatly into the next subject—humans.

You’re a single organism, aren’t you? I’ll give you a second to think about it, because it’s probably not a question you are used to asking. However, if we look closely we find that humans are not exempt from the fuzzy boundary rule.

Example number one—there are things in every one of your cells called mitochondria.  These little critters are absolutely essential for energy production within the cell. If all your mitochondria just up and left your body—maybe they formed a union and went on strike—you would die. Rapidly. But if you look a little closer you will find that “your” mitochondria are not technically part of “you” as you know it. They have their own genome, completely separate from yours. A wildly different genome, in fact: 16,569 base pairs in a closed ring, compared to your 3.3 billion base pairs in an open-ended strand. You can’t live without them and they can’t live without you, but they are definitely separate. So which is you? Or is it both?

You may argue that this is a one-off—mitochondria joined the eukaryote party almost 1.5 billion years ago, and have been part of larger, more complex organisms ever since—all species of animals and then some. You can’t take a handful of mitochondria and plop them together with, say, some algae and expect a spontaneous new organism to appear. Fair enough. But we’re not done.

There are about a thousand species of bacteria that live in a typical human gut biome. There is not a single set for all human beings. Rather, the specifics of a person’s gut biome will vary depending on where they live, what their diet consists of, and other factors. The gut biome is essential in helping you to digest food. While I could not find any research indicating that sterilizing your gut completely would outright kill you, the consensus seems to be that it would make you extremely ill. One article on livescience.com stated that “Experiments done on guinea pigs have shown that animals raised in a sterile environment without any bacteria are malnourished and die young.” In other words, without a gut biome you would live a short and miserable life. And it doesn’t just assist you in your digestion. It also promotes “good” HDL cholesterol and triglycerides, and supplies you with vitamins like biotin and vitamin K. The gut biome even assists in the production of neurotransmitters like serotonin, which are crucial for brain health.

Another feature of your gut biome is that it can change, dynamically and drastically. If your diet changes, or you become ill, or you are taking certain medications, then some of the bacteria living in there will die off, and others take their place. It’s all terribly flexible. How much do all of them count toward the assemblage that is you? I have no idea.

OK, you may ask, but what practical impact does all this have on your day-to-day life, apart from killing off the old sci-fi trope of rebuilding a person using just a scan of their DNA? Probably none. It is an odd feeling, however, knowing that the me that I think of as being a singular thing is actually more like a theater production with an ever-shifting cast of characters. Maybe Shakespeare’s “The play’s the thing wherein I’ll catch the conscience of the king” is uncomfortably close to being true.