Hey Thoughty2 here.
Life is like a box of chocolates; it’s far too expensive and I only enjoy about 50% of
it.
But when it comes down to it, what on earth, or anywhere else, is life?
From our perspective, water and rocks and spoons and slippers are all inanimate objects
but how do we decide what is alive and what is not?
Is there a point where the chemistry suddenly crosses over?
Would we recognize an alien species if we saw it?
And if you really really believe hard enough, can you bring something to life?
When you’re trying to define life, you realize that it can’t be a black and white.
It’s like asking how many trees do you need to make a forest?
What’s the point where a snack becomes a meal?
And how many cats must you own before you have a problem?
There is no one criteria that we can use to define life and we must remember that we have
an obvious tendency to focus on our planetary carbon based existence when there are countless
other worlds that could have created living beings from other elements such as silicon
or iron or.
So if we accept that life is a grey area, then we must focus on key facets to determine
if something is alive…
Firstly; complexity, life must be complex.
Confucius may have said “Life is really simple, but we insist on making it complicated”
but he often put his pants on backwards and knew zero about molecular biology.
Also, life nees to practice homeostasis, meaning that is has an equilibrium for its internal
conditions, things like temperature, pH value, glucose levels, etc.
So what about life on earth?
What bit of chemical creativity created the winding path from molecule to monkey to man?
Well, about 4 billion years ago, chemistry became complicated and reactive enough to
start what we think of as “life”.
The very surprising thing is, this is not the most important nor most improbable event.
You could easily get some form of life if you had a planet with a similar chemistry
and conditions as ours, and there must be plenty of these types of planets out there
in the big bad universe.
But on earth, once we had life, it just sat around as prokaryotes, a very simple form
of cell, with no nucleus or other complicated structures inside.
As these basic cells, they couldn’t really change since it was almost impossible to take
in enough energy to make any major upgrade; it would be like trying to install PS4 games
on a Gameboy, you’d need a whole room for the AA batteries alone.
So they stayed like that, just little dribbling morons for about 2 billion years.
Then, a very unlikely thing happened, according to one theory.
Archaea are one of the simple cell types that still exists today in some extreme environments.
2 billion years ago, an archae let a bacterium inside it, possibly through a hole in the
cell wall.
And, against all odds, both survived.
The bacteria became what we know as mitochondria.
The reason this was so important is that these mitochondria have an electric charge which,
for their size, is like a lightning bolt.
It was only with this new pimped out engine that cells finally had the energy to get more
complex and spawn all the life we see around us today…
except squirrels, no-one knows where squirrels are from.
Part of the reason behind this mitochondria theory is that every living thing shares almost
50% of the same DNA with archaea, a 2-billion-year old cell.
Alright then, if we have a good guess at how life began, is there anything we can do to
replicate it and start a game of cellular Sims in a petri dish?
Well we’re actually not too far off getting life started.
At NASA's Ames Research Center in California, they set up the best space like conditions
they could, by turning the lights off and cranking up the air conditioning, well to
put it in simple terms.
They then took commonly occurring molecules of carbon and nitrogen and exposed them to
radiation, managing to produce 3 key chemicals needed for RNA and DNA, showing that it’s
possible the components of life could have come in on an asteroid in the early stages
of our planet’s development.
Okay, but a bit of space chemistry is hardly exciting, what about real Frankenstein cells
that we put together from bits of leftover lunch?
Well Dr Craig Venter, a pioneer in genetics, spent 15 years, along with his team, sequencing
the DNA of a bacterium and then artificially reproducing it, along with a watermark so
they could track it.
They chose Mycoplasma genitalium, the smallest bacteria in the world, and they injected their
code into an empty cell, after working out how to rid it of its original DNA.
These new artificial cells successfully reproduced, showing that the process works.
But we still don’t really understand these genitalium.
This bacterium has under 500 genes, whereas humans have 20,000.
And of the 500 or so, we’re not sure what a quarter of them do, aside from the fact
that they are necessary.
Making life is one thing, but controlling it is a whole other step so it’ll be a while
before you can pop down the pet shop and order up a monkey with lizard eyes and bat wings.
Finally, let’s leave boring old reality behind and have a quick wander into the hypothetical.
We’re made of carbon, but what other kinds of materials could create life and what conditions
would they need to exist?
Silicon is probably the most likely candidate since it can create molecules that are large
enough to carry the massive amount of information you need to encode a lifeform.
What’s more, we already have a hint at its existence here on earth since a type of algae
called diatoms have a cell wall made of silica.
Just don’t tell too many people or “carbon-free” dieting will become a thing.
Vadim N. Tsytovich has proposed a possible space-borne life, in the form of dust suspended
in plasma.
In certain extra-terrestrial conditions, the dust could become charged and begin to self-organize
into complicated structures and from there, who knows what the dust could evolve into.
All in all, you are unbelievably lucky to be alive.
It’s not just the peculiar combination of genes that makes you you, but the overwhelming
amount of chance and good fortune that got us from little dots in a vast molecular soup,
to big fat walking talking land monkeys.
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