Fuzzy and Nutz have been busy guiding us through history, and their last adventure took us
to some of the greatest natural disasters in history.
But today we're going to take a closer look at some of those disasters and how they affected
life on earth as we look at the greatest extinctions in history.
Today oxygen is vital to all life on earth, and it's impossible to picture the earth without
its signature blue oceans and clear skies full of fresh oxygen.
But our young earth looked much different than it does today- its oceans were saturated
with iron, and what little oxygen there was would bind with that iron to produce rust
and turn the entire planet red!
In the air, methane from constant volcanic eruptions blanketed the planet and would have
made the air poisonous to life today.
So what changed exactly?
Well, the first step towards the earth of today started in the oceans with a single
bacteria which through random genetic mutation evolved the ability to photosynthesize.
This lonely little guy was able to use the sun's energy to turn water and carbon dioxide
into energy-rich glucose, producing up to 16 times more energy than any other bacteria
in the world!
This supercharged bacteria immediately began to out compete its neighbors, and started
reproducing at a massive rate.
Eventually this bacteria- known as cyanobacteria- had completely dominated all simple life in
the oceans, and if that wasn't enough, it sealed the fate of all its competitors with
the byproduct of its photosynthesis: oxygen.
As the cyanobacteria released oxygen most of it was trapped by the iron in the water,
but as the cyanobacteria grew in numbers they overwhelmed the ocean's ability to absorb
all that oxygen, releasing it into the atmosphere.
The only problem is that for all other life on earth oxygen was poisonous, which led to
the extinction of nearly all other primitive lifeforms.
While the oxygen released would fill our atmosphere with the oxygen we need to survive, and turn
most of the iron in the oceans to rust, which would then sink and give us today's blue waters
we love so much, over 2 billion years ago this little bacteria that could was responsible
for one of the greatest mass extinctions in history!
Today the Appalachian mountains are home to thousands of people and for most bring up
fond memories of pleasant afternoons enjoying some of the most impressive display of Fall
colors anywhere in the world.
But those same mountains harbor a deep, dark secret- scientists suspect that they are the
culprits of one of the earth's greatest murder sprees.
444 million years ago Graptolites were tiny creatures that clumped together into large
colonies and fed on plankton and other tiny bits of food.
They covered the bottom of the world's oceans and drifted along on its currents as one of
the dominant forms of life on our primitive earth.
Unknown to the tiny creatures, their doom came when plate tectonics forced the Iapetus
oceanic plate to collide and sink under the North American plate.
As one plate was forced under the other, the Appalachians began to grow and be lifted up
out of the sea.
Full of silicate rock, the newly born Appalachians began to absorb CO2 out of the air, removing
the greenhouse gas from the atmosphere and causing an ice age.
The subsequent freezing would wipe out 86% of all life on earth and make Graptolites
extinct.
For the worst mass extinction by far though we have to return back to just before the
dinosaurs, 251 million years ago and the eruption of the Siberian Traps.
Last time we learned about the explosion of volcanic activity in modern-day Siberia and
how it flooded an area the size of the US in lava, but with eruptions lasting an incredible
2 million years they filled the atmosphere with CO2 which trapped the sun's heat and
scorched the earth.
If that wasn't enough, all that carbon fed specific types of bacteria that used it to
create energy and spewed out methane, adding yet another layer of insulation to the sweltering
planet.
As global temperatures surged the oceans acidified and became a toxic soup, belching out poisonous
hydrogen sulfide.
Known as “the Great Dying” by scientists, this chain of catastrophes almost completely
eliminated life on earth, and set evolution back over 300 million years by wiping the
slate clean!
Life has had some incredibly close calls, but in the end it all led to us here today.
Sometimes though we all could use a reminder of just how lucky we are to be here at all
and learn to get along together...