Today we will discuss the phenomenon of life from the most unusual perspective. We gonna count it!
To start with, every living structure on Earth are united under the notion of “biosphere”. Anything alive under the sky is part of the biosphere: a wolf, a bacterial cell, a fresh blood sample or a cut flower that hasn’t withered yet. Hence, the quantity of life on Earth is one biosphere.
An organism is a much smaller counter unit. Everyone knows what it is, and easily tells where one organism ends and another starts… most of the time. It’s handy to count life in organisms, and we’ll do so.
Part 1: How many organisms?
Let me introduce two notions first: factual biodiversity and fundamental biodiversity.
By factual biodiversity I refer to every single organism alive on Earth. Take a ginormous bucket, cast a spell to teleport every living thing in it: every tree, every cow, every bacteria. Voila, factual biodiversity. Next, count everything in the bucket – the final number will be equal to the current qty of organisms on Earth. Couple of hundreds of billions, perhaps.
Thanks to Einstein, time is merely the fourth dimension of space. That’s why we’ll introduce another notion of extended factual biodiversity, which will include every single organism that lives, ever lived, or ever will live on Earth before it’s cooked by the “disc of Ra”. Every human, every dinosaur, every trilobite. I am afraid to even speculate what would that number be equal to – our bucket now won’t fit in entire Solar system. It now contains EVERY organism to ever exist on Earth.
As for fundamental biodiversity – you perhaps wonder what a hell is that?
Supposedly, extended factual biodiversity already includes all organisms – nothing is missed. Wrong. It reminds me how irrational numbers were invented. There were rational numbers – all numbers in the world. Then someone counted √2, and π. And it turned out that our number line is… gappy. Many numbers are rational, a lot more aren’t.
Our bucket is the same story. Many organisms are observable, many more are not. The easiest way to “observe” hidden creatures is to teleport back into Cretaceous and shoot some tyrannosaur. Butterfly effect – such interference would eventually result in a heap of organisms that are not present in factual bucket. “Would” is the key word here. To perceive the biodiversity entirely, one has to mind even those organisms that could have existed, but never were that lucky. A cat boy walks and sees two pretty cat girls: left one and right one. He thinks carefully and chooses the left one. Soon their kittens fill our factual bucket. But what about his kittens with the right one? Okay, they never existed, but they would be fully-viable things. So would be every triceratops, that was never born thanks to dinosaur extinction. It’s weird, but that’s what fundamental sciences are about. No-one ever dropped a bag of catfood from the Eiffel tower. Doesn’t mean it’s theoretically impossible, and physics of freefalling explains such an occurrence.
Fundamental biodiversity – is it a lot?
A delicacy for thought: a Homo sapiens male produces tens of millions sperms DAILY. Every single one of them could be used for conceiving. Now imagine how many children could have been born from a single male, but won’t. Every one of them would be different: some quite similar, but not identical. And every one of those children could have had a zillion children as well. The extended factual biodiversity, which would easily occupy the entire Solar system, is a miserable nothing compared to fundamentally possible biodiversity.
The quantity of fundamental biodiversity can be estimated if we summarize everything that makes organisms different from each other.
1. Genetic code.
It’s the first thing to define the differences between organisms. The “blueprint of an organism”, the recorded information of every protein that will be built in the body to define its structure and physiology. It’s a sequence of letters, and we could probably count the number of possible codes and get a specific number. Or not – code’s max length is potentially unlimited – that’s a problem. Damn!
2. Genetic code’s interpretation.
Next question to ask: can two organisms with the same genetic code have inherently different features? Thirty years or so ago, scientists would likely say “no”. Not now. Turns out that it’s not code that matters most, but how it’s read. Just like human tongues: for Dutch, “vader” is father, for the rest – it’s a sith Genetic code alone is not yet an organism. It becomes “alive” in a cell, surrounded by tools to read it. Some genes will be read twice, some – never. There are instruments to manipulate the code: to leave “bookmarks”, or to “lock” some “chapters” from reading. So called epigenetics – inherited variation that is not included in the genetic code.
We all know that identical twins are not identical. They start on the same code, in similar cells with similar reading tools, but end up different. Different voices, different location of birthmarks. Their lives shape them differently. Firstly, they attach to different spots in the womb, so that gravity affects them from different angles. They are born at slightly different time, then eat different food. And so on. I wonder how many clones one has to create so that at least two of them are identical. A million? More like a zillion. If one of two clones eats one molecule of food more than the other, he/she is different. If one of them hears one extra word in early childhood, their brains could end up entirely different. One could end up a new Da Vinci, another – a serial killer.
Let’s face it: identity does not fit in real world. There are no two identical organisms at all, ever. And hence the qty of fundamental biodiversity equals to ∞. Infinitum. The majority of it is not just extinct, it was never born!
Fundamental biodiversity is an infinite multitude of elements that can be similar to different extent, but never the same. That’s something they share with colour spectrum (not computer RGB, but real colours), or, for example, with apples growing on trees. There is one way to organize this mess: plot a multidimensional graph, where a point will correspond to every organism. The distance between two points will reflect the difference between two organisms.
We get the continuum of life:
Some of it’s properties:
- There are no two identical points on it.
- The qty of points is infinite.
- In between any two points, no matter how proximate they are, there can always fit another point.
- There are no gaps in continuum.
- If we move through continuum in any direction, we’ll observe gradual change from one organism into another through infinite-many intermediate forms.