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Paleontology,
a science geared towards small children,
focused on digging up dinosaurs
while sporting a "Jurassic Park" costume.
Skulls are popped out of the ground
and put on display for public gawking.
The relevance of this, beyond clickbait, coloring books and monster movies
is unknown.
No ...
Wait.
That's not paleontology at all.
Paleontology is nothing less than the study of past life.
All past life.
From ancestors to alien forms.
It involves fundamental questions like "Who are we?"
And "How did we get here?" --
using the broadest possible definition of "we":
life itself.
Dinosaurs, a category of birds,
are just a small percentage of that.
(Laughter)
Yet they get the most media attention.
[The incredible diversity of ancient life, Dinosaurs, Paleontology]
It's a very accurate meme; I didn't even make this one.
This is just the truth.
Anyway, most of us paleontologists consider dinosaurs to be a gateway drug.
There is so much cooler stuff in the fossil record,
and we know so much about it.
Let's go on a brief, dinosaur-free tour
of the last four billion years.
(Laughter)
First up, genetic material.
Viruses, basically, started producing proteins
and wrecking their environment.
The Earth was infected with life.
Some of these new bacteria learned how to eat sunshine,
producing oxygen,
pulling in carbon from the air
and destroying the iron food of other microbes
by turning it into rust.
This went on for billions of years.
Some bacteria consumed other bacteria,
gaining their power to turn oxygen into energy,
becoming the precursors of animals and plants.
But as a result, there were climate shocks,
from hot to cold and back again,
which ended up turning the Earth into a snowball covered with glaciers.
The technical term for this time period is "Snowball Earth."
(Laughter)
Seven hundred, eight hundred million years ago.
Anyway, microbes banded together,
creating multicellular life.
Six hundred million years ago,
geometric colonies appeared, sucking microbes from the water.
These were soon replaced by the ancestors of modern animals.
The Cambrian explosion.
Lobster relatives ate other animals,
capturing them using their grasping arms.
Armored wriggling clam worms crawled across the seafloor and into it,
creating new ecosystems.
Our tadpole-like ancestors flitted along ancient coastlines,
while their eel-like relatives with gnashing throat teeth
swam above the ice-cream cone corals of the first reefs,
dodging school-bus-sized krakens
and hungry sea scorpions.
Plant fungus came onto land.
But then the glaciers returned, killing pretty much everything.
But mass extinctions open opportunities.
Jawless fishes invaded the ocean,
sporting points, prongs, and finally, fins.
Spiders, scorpions, snails and worms came onto land.
Somewhere around China, a fish developed jaws,
and its descendants drove jawless fishes,
sea scorpions and branching plankton
to extinction.
Some of these fishes,
which had arm bones in their fins,
sprouted fingers,
seven or eight per flipper.
On land, plants became trees,
growing massive
or spreading their spores only once before dying.
But then the glaciers came back again,
and it was mass extinction number two.
It was the age of weird fishes and plated sea lilies.
Sharks with wings.
Sharks with buzz saw jaws.
Sharks with fins covered in tiny teeth.
Sharks with crushing tooth plates.
Bony fishes that looked like modern angelfish and eels
for the first time.
Wetlands developed,
sporting ten-foot-long millipedes and giant dragon flies.
These spread across the supercontinent of Pangaea and died,
creating coal,
leading to a 100-million-year Ice Age.
Finally, vertebrates made it onto land on a permanent basis,
leading to alligator-like amphibians
and saber-toothed protomammals.
But then, volcanoes erupted all over Siberia,
everything almost died
and it was mass extinction number three.
(Laughter)
The day life nearly died.
A single, lonely tusked mammal survived and thrived,
but it was soon replaced by galloping crocodiles.
In the ocean, marine reptiles,
giant rafts made of the living relatives of sea urchins
and armored squids, ammonoids, of every kind and form.
But then, Pangaea started to split apart,
forming a sea of lava
that would one day become the Atlantic Ocean,
spewing toxic gas into the atmosphere
and mass extinction number four.
(Laughter)
Yeah, there's actually a lot more than these five,
these are the big ones.
(Laughter)
So, finally, there were whale-sized fishes,
and modern fishes mobbed corals,
made gigantic by using their captured algae to eat sunshine.
Crabs, stingrays and other fishes with crushing teeth appeared,
smashing shells
and leading to an arms race between predators and prey.
There was an explosion of marine biodiversity.
Mammals climbed trees, flew
and did a lot of other things that are seemingly sort of modern.
They were feeding on the first flowers pollinated by the first bees.
There were ecological revolutions on land and at sea,
leading to the modern world.
Except that an asteroid hit Mexico,
and then that triggered volcanoes on the other side of the world in India,
and everything almost died again.
(Laughter)
But -- there's always a but, because we're still here --
mammals arose from the ashes,
became small under extreme heat and then ever larger.
There were palm trees and snakes in the Arctic.
Predatory deer dogs frolicked along ancient rivers,
while their relatives returned to the ocean
to become the first otter-like whales.
Not hyenas and other sort of carnivores
were chased off by giant long-necked rhinos.
Everything at this point seems kind of familiar
but not really.
In Antarctica, an ice age started,
forming the first permanent polar ice cap in two hundred million years.
This dried out the rest of the world,
but it allowed the rise of grasses, of rodents, of cats.
Somewhere in Africa,
an ape started walking across the new savannah.
Oh, and there were giant saber-toothed salmon,
I just have to mention that.
(Laughter)
So, we know all of this happened
and so much more.
How?
Why?
Paleontology is a thriving science
at the intersection of multiple other fields and technologies.
There is no bigger data than the fossil record,
and we mine every bit of it.
We use CAT scans,
we use isotopes,
we use genomes,
we use robots,
we use mathematical simulations
and all kinds of analytics.
We maximize all of it so that we can understand the past
and how evolution works.
It also lets us make predictions for the future.
What will happen after the next mass extinction?
What weird things will show up?
Will mammals get smaller again?
Will there even be mammals?
In sum,
we have learned a lot about dinosaurs.
But there's so much left to learn
from the other 99.9 percent of things that have ever lived.
And that's paleontology.
Thank you.
(Applause and cheers)
コツ:単語をクリックしてすぐ意味を調べられます!

読み込み中…

A brief tour of the last 4 billion years (dinosaurs not included) | Lauren Sallan

13 タグ追加 保存
林宜悉 2020 年 3 月 24 日 に公開
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