Origins: A brief history of life on earth (Earthlings 101, Episode 2)

Welcome to the second episode of Earthlings 101. Today you will learn about the origin
of life on earth. Most earthlings think their life originated in the oceans of young earth.
But actually, it came from space - on a stray missile from the Squid War.
The missile that plunged into the oceans of young earth didn't contain any explosive, nuclear
or quantum collapse charge. It's payload consisted of two million specimen of a simple, carbon-based,
self-replicating nano weapon, a primitive variant of the dreaded grey goo. By the way,
earthlings would call this a bio-weapon, or artificial life form, but only because life
on earth has developed from this weapon.
You may remember the Squid War from early history class. It was a merciless war between
the then Andromeda Dominion and the old Squid Kingdom, fought with all means authorized
by the central bureaucracy. The Dominion eventually crushed the Squids, but their victory application
was rejected by the bureaucracy because they couldn't account for one of the three million
planetary missiles fired in this war: The very missile that had found its way to earth.
The bio-weapon was based on carbon. Most nanolabs use carbon to build artificial life forms,
simply because carbon atoms are ideal building blocks. See, the bonds an atom can make is
defined by the electrons and free slots in their outer electron shell. A covalent bond
is an electron-sharing-deal between two atoms : I put an electron in your slot, you put
an electron into mine. So, Fluorine can make one bond, oxygen can make two, nitrogen can
make three, carbon can make four. Boron has five slots but only three electrons to share,
so it can make three bonds, Beryllium can make two, and Lithium one. That's why carbon
is the nano’technicians best friend: With no less than 4 connections per atom you can
build a lot of things: chains, grids, rings, - you name it. With some other atoms Like
oxygen or nitrogen here and there, and the free slots plugged with tiny hydrogen atoms,
building nano machines is as easy as playing with construction kits for young aliens.
So, back to our nano weapon which has just been released in the warm oceans of young
earth. Those weapons work like viral religions: A viral religion consist basically of a set
of instructions to make the believers spread the religion, which may or may not involve
killing non-believers. Self-replicating nano weapons work the same way - only without the
believers. The instructions come usually with some moleculary nanomachines called enzymes
which perform the actual replication, and a wrapping to hold it all together.
In this case, the instructions were written on a molecule called DNA, it's basically a
primitive variant of XNA, the trademark molecule of the Arctarian nanolabs, which is not surprising
as the Arctarian weapon factories supplied both sides during the Squid War.
The DNA of these ancient bio-weapons contained usually instructions for self-replication,
plus an actual message which was often an insult, like, "Eat this, tentacle heads!"
or "Fisheaters must die!", or in this case, "Squids are stupid"
So, those little bags of DNA and enzymes started self-replicating. Unfortunately, replicating
isn't of much use if you don't have a source for new bio-mass. The creature was designed
to replicate on a squid planet which was rich on elementary carbon, so biomass wasn't supposed
to be an issue. But here, on earth, elementary carbon was rare. That's where the creature
started to evolve - the beginning of life on earth.
Let me get this straight: life on earth is wholly different from life anywhere else.
In the whole Galaxy, the evolution of life is regulated by the all-mighty and omnipresent
Galactic Bureaucracy. When a planet is approved for developing life, it is put under the responsibility
of an approved bio-administrator who comes from an advanced civilization of class 14
or higher. The administrator supervises evolution, decides on creation of new species, approves
mutations, oversees the development of civilisation and, most important of all, does all the administrative
steps required by the galactic bureau of planetary evolution, which means quite a lot of paperwork.
The official goal of all this is to create sentient life and make it reach the point
where it develops the concept of money so that it can pay taxes. But the real goal of
every bio-administrator is to push the lifeforms on the planet to develop scripture, from which
point on they can do their own paperwork and the administrator can leave the planet.
However, as mentioned in the last episode, earth is out of reach of the galactic bureaucracy.
In consequence, life on earth follows a completely unregulated, wild evolution, an explosion
of life limited only by natural resources. In one word, any bio-anarchists wet dream,
and any bio-administrator's nightmare. This is, by the way, the reason why the Dominion
never officially admitted that they lost their missile on earth.
Uncontrolled evolution is based on three mechanisms: replication, mutation and natural selection.
The simplest form of replication is duplicating the code and the individual. There is another
form of replication called sexual reproduction, which we will discuss later.
Mutation is often misunderstood. It doesn't consist in having a tentacle growing out of
one's head after receiving a bit too much radiation. That may be the case for Tangerian
Metamutants, but it's not how it works on earth. On earth, mutation means a usually
small variation in the offspring due to damaged genetic code - say, a different skin color,
or stronger leg muscles.
As for natural selection, it means that nature favours individuals which are good at feeding,
reproducing and not dying. Humans usually paraphrase this as "survival of the fittest"
. This might be correct, as long as survival and fitness serve the ultimate purpose: Spreading
the code. The code doesn't care about the about the well-being of the individual, as
long as it is spread. If this means being eaten by your offspring, evolution is fine
with it.
A simple example of natural selection would be an animal running from a predator. If by
chance it has grown a fifth leg allowing to outrun the predator - great. But actually,
it is enough - and far more probable - to run just a little bit faster than one's sibling.
This way, even small variations may make the difference between dying and surviving. With
time, these variations will accumulate and the species will become faster and faster.
But back to our little organism. It needed carbon to multiply, but carbon was only available
in form of carbon dioxide in the atmosphere. Besides this, there were pretty useless nitrogen,
and tons of hydric acid - you know, this disgusting liquid which covers two thirds of the planet.
So, evolution kicked in and our organisms developed a method to transform carbon dioxide
into bio-mass. In its evolved form, this process is called photosynthesis.
Photosynthesis consists basically in using sunlight to transform carbon dioxide and hydric
acid into oxygen and a chemical called sugar. Oxygen is a toxic substance which had to be
released into the atmosphere, but sugar is pretty useful : It comes in different variants
and can be used for short-term energy storage and to obtain bio-mass. You can also use it
to build chains to obtain starch for long-term energy storage, or cellulose for structural
reinforcement.
Photosynthesis is still used by plants on earth to build their bio-mass. It's noteworthy
that only one fifteenth of the sugar created by photosynthesis comes from the hydric acid
- actually, only the tiny hydrogen atoms used to plug the free slots. The rest comes form
carbon dioxide. So, when you visit earth and find gigantic forests made of plants, remember
that 93% of their dry matter is made off "air".
Now that our little organism knew how to literally create bio-mass out of thin air, it multiplied
and took over the whole planet. While doing so, it evolved into a variety of species,
some of which developed a number of improvements, for example a cell core, tiny tentacles to
move around, or sexual reproduction - basically mixing the codes of two individuals to create
a new one. We will learn more about sexual reproduction in the next episode.
Everything seemed fine for our little light-eating organisms. But after a while, a problem came
up. Remember oxygen, this toxic by product of photosynthesis ? This stuff had accumulated
in the atmosphere and now reached a dangerous concentration. This could have been the end
of life on earth - but luckily, one organism mutated and found a way of transforming oxygen
and sugar back into carbon dioxide, hydric acid and energy. This is called respiration,
and it's basically photosynthesis backwards.
Now we had two kinds of creatures: Light eaters - also known as plants - who create sugar
and oxygen, and oxygen breathers, also called animals, who transform sugar and oxygen back
into carbon dioxide. But how did the animals get the sugar ? Well, by devouring plants!
Soon those animals multiplied and lowered the oxygen level in the atmosphere. Since
then, plants and animals share the planet, and each group produces the gas the other
group needs.
But evolution didn't stop there. With time, it grew creatures which were better and better
at feeding, reproducing and not dying. The light-eating cells became multicellular plants,
conquered the oceans and then the land . The oxygen-breathers evolved into multicellular
animals, and developed traits like symmetry, a neural system and an inclination for moving
around. One branch evolved into small creatures with an exoskeleton called insects. Others
developed an endoskeleton, eyes and a mouth and eventually crawled onto land and grew
legs.
Most species of this time are extinct by now - except for, the microbes.
Strategic advice! If you want to extinguish all humans and animals on earth to prepare
it for colonization, don't forget the insects! They are everywhere, they are hard to kill,
and they can be really, really annoying.
The most obvious difference between plants and animals is that animals move around, whereas
plants stay at one place. Why is this so? Well, animals have to seek edible plants,
or run after other animals, whereas plants feed on air, hydric acid and sunlight, resources
which are available everywhere. However, spreading one's DNA isn't easy when you can't move.
So, plants eventually found a way to get animals to carry their DNA around.
Remember sugar, the main product of photosynthesis? Animals love that stuff, as it's easy to process
and rich on energy. Normally, plants don't store large amounts of sugar because they
don't want to get eaten. But now, they developed exposed sugar-filled sexual organs called
flowers to bribe insects into carrying their DNA to other plants for sexual reproduction.
Then they put their seed into delicious sugar packages called fruits to bribe bigger animals
into carrying their seed around.
Both fruits an flowers are colored to attract the attention of animals. In the language
of plants, bright colors mean "Here is sugar". Animals, on the other side, don't want parts
of their body to be eaten, so in the language of animals, bright colors either mean "I'm
poisonous", or, "Catch me if you can, I have wings!".
All those plants, insects, fruit-eaters, predators and microbes form a complex, self regulating
system, without any need of a bio-administrator. Earthlings call this an ecosystem.
Scientific advice. A popular experiment among students consists in abducting an earthling,
a cellulose-eating animal and some plants and putting them into a tank in order to create
a micro-ecosystem. But this doesn't work. You get much better results when you put some
ocean plants and animals into a small tank filled with hydric acid.
At some point, evolution led to bigger and bigger animals, until the planet was ruled
by giant creatures called dinosaurs. Some of them evolved into small flying creatures
called birds. Other creatures developed the ability of nourishing their offspring with
a liquid called milk. One branch of these animals acquired some intelligence and dexterity
in manipulating objects, and eventually evolved into earthlings. The first earthlings lived
pretty much like animals, collecting fruits, hunting animals and protecting from predators
- except that they developed their own tools to do so. This is where natural evolution
ends and civilization begins.
Tips for tourists. If you are a time-traveller and you visit the time of the dinosaurs, please
don't take any dinosaurs with you. If it wasn't for countless time tourists taking animals
away as souvenirs or pets, dinosaurs wouldn't be extinct.
There is a small group of earthlings who might not have developed by evolution. They call
themselves creationists. According to their own claims, they have been created by an extraterrestrial
bio-engineer some thousands of solar cycles ago. His intervention triggered an environmental
catastrophe, an inundation with hydric acid which killed all other life in the area. The
creationists, warned by their creator, saved themselves onto a ship, crossed an ocean and
settled in a place called America, where they are waiting for their creator to pick them
up. However, the whole story seems unlikely and doesn't fit the bureaucratic records.
So most alien scientists agree that this story has probably been made up by earthlings.
In this episode, we have seen the evolution that led to earthlings. This evolution was
driven by one single force : An ancient code, programmed to replicate itself at infinitum,
unleashed in an uncontrolled environment, pursuing its goal to the point of conquering
a whole planet, of creating intelligent life and of building a spacefaring civilization
- and all this in order to deliver one simple message : Squids are stupid.
In the next episode we will learn more about sexuality : How it works, how it alters the
rules of evolution, and why it wouldn't even exist if it wasn't for : parasites.
Thank you for watching.