and interestingly in order to understand exactly where you came from

we must first understand what it means

to be alive. Life is an organised

genetic unit capable of metabolism,

reproduction and evolution. It's important to

remember this as we go way back in history to figure out exactly how you got here.

Astronomers believe our solar system began

to form 4.6 billion years ago, when a star exploded

and then collapsed to form the sun

and around 500 smaller planets collided with each other

to from the inner planets we know today, including your home, Earth.

For about 600 million years

Earth was too hot for life, most of the water was

evaporating into space, and even if some simple chemical

reactions began to take place creating life,

the comets and meteorites hitting Earth at the time

would have brought enough heat to make the developing oceans boil,

destroying all potential life. As comets and meteorites subsided

Earth cooled and it became possible for water to remain on the surface.

And so, life begins

about 3.7 billion years ago. There are many theories about how

exactly it began, some believe simple life

arrived from a meteorite, while others think chemical evolution

started with compounds reacting to heat,

or perhaps they were struck by lightning. And while the exact date

is difficult to pinpoint, a new study claims to have found

the oldest fossil ever at 3.77 billion

years old. An ancient microbe that flourished

around a hydro-thermal vent on the ocean floor. It's around

this time that the first simple cells began to evolve

on Earth, they were able to capture energy, replicate themselves

and evolve and became the single unit

on which all life will be built, including you.

For 2 billion years, all organisms on Earth are

unicellular, and they likely lived in the oceans,

shielded from the hard ultraviolet (UV) light of the sun

but then something remarkable happened...

Photosynthesis.

Around 2.5 billion years ago, a random mutation occurred that was

advantageous to cells, and they began using the energy of the sun to power their metabolism.

And since oxygen, or O₂,

is the product of photosynthesis, our atmosphere changed

eventually creating the ozone layer which acted to shield the Earth

from the sun's deadly light. Of course at this point

O₂ is poisonous to most organisms

but over time, cells evolve to tolerate it, and because metabolic

reactions using O₂ were more efficient, cells could grow larger.

Around 1 billion years later,

cells begin to engulf and co-opt smaller cells,

increasing their abilities to live in diverse environments. This

selective advantage led to cells sticking together in a coordinated manner

even after dividing, and these cells eventually

began exchanging genetic material,

AKA, they had sex. Single celled organisms would divide by mitosis

or simple nuclear division, but once

meiosis evolved, genetic reorganisation began to occur

and the rate of evolution increased as offspring

were now more genetically variable and some of these offspring

were more likely to survive and reproduce, and so the tree of life

began to explode. First there were plants

and then fungi, coral then protosomes like crabs,

echinoderms like sea urchins and then fish like sharks

and cod, and tetropods evolved from fish

and began adapting to living outside of the water part-time,

initially gulping air and absorbing oxygen in the gut.

As time passes, species would evolve lungs separate

from the gut for absorbing air as well as a new way to walk

on land. In come amphibians, reptiles,

dinosaurs and finally, mammals. In fact our entire

ancestry stems from a cute, furry tailed, rat-like mammal

which survived and thrived around 66 million years ago

just after an asteroid wiped out the dinosaurs.

And after tens of millions of years of evolution

and new species emerging, one branch of the Protungulatum family tree

evolved into our ape and monkey ancestors. And nearly 4 millions years ago, one of the first

human-like creatures arrive, Australopithecus Afarensus,

the most famous discovered remains being that of Lucy, who stood upright.

100,000 generations later

or 2-3 millions years ago, the species group

'homo' began which had a bigger brain

and started using their hands for more complex activities like creating and

wealding tools. This was the first step of transforming

our environment to improve our lives. It was also

a catalyst to switching from a vegetarian diet

to one containing meat which is a more concentrated

form of nutrition, and less effected by seasonal shortages.

These simple stone tools allowed us to rip through meat

and would become the tool of choice for 2 million

years. And around 1.8 million years ago, homo erectus

emerged, the direct ancestor to our species.

Finally, a few hundred thousand years ago, modern humans,

or homo sapiens, step into the light. Larger,

smarter and more capable than their predecessors.

Interestingly, we almost didn't make it.

A climate change event around 140 thousand years ago

plummeted the human population to only hundreds of people,

an endangered species. But, we survived.

As recently as 60,000 years ago

three different species of the 'homo' family co-exist.

Homo neanderthalensis, homo denisova and we,

homo sapiens, which all lived on this planet together.

In fact, sapiens and neanderthalensis mated quite often which is why

most contemporary humans, including you

have neanderthalensis DNA. The neanderthalensis died out around

30,000 years ago when homo sapiens were arriving

in what is now Europe, and from this point on, the

homo sapiens were the only living humans left on Earth.

Unlike our primate relatives whose evolution favored strength,

ours chose brain power, in fact

your brain weighs 2% of your body weight

but uses 20% of your caloric intake. And this brain power

allowed us to survive in a variety of environments, as we began to

migrate around the entire world. Where we started

as small wandering groups of less than 100

we began to settle in groups of thousands and millions

and now, billions. You were born

a homo sapien, and that is how you got here.