If we evolved from monkeys,

why are there still monkeys?

Well, because we're not monkeys,

we're fish.

Now, knowing you're a fish
and not a monkey

is actually really important
to understanding where we came from.

I teach one of the largest
evolutionary biology classes in the US,

and when my students finally understand

why I call them fish all the time,

then I know I'm getting my job done.

But I always have to start my classes

by dispelling some hard-wired myths,

because without really knowing it,

many of us are taught evolution wrong.

For instance, we're taught
to say "the theory of evolution."

There are actually many theories,
and just like the process itself,

the ones that best fit the data
are the ones that survive to this day.

The one we know best
is Darwinian natural selection.

That's the process by which those
organisms that best fit an environment

survive and get to reproduce,

while those that are less fit
slowly die off.

And that's it.

Evolution is as simple as that,

and it's a fact.

Evolution is a fact

as much as the theory of gravity.

You can prove it just as easily.

You just need to look at your bellybutton

that you share with
other placental mammals,

or your backbone

that you share with other vertebrates,

or your DNA that you share
with all other life on earth.

Those traits didn't pop up in humans.

They were passed down
from different ancestors

to all their descendants, not just us.

But that's not really how
we learn biology early on, is it.

We learn plants and bacteria
are primitive things,

and fish give rise to amphibians
followed by reptiles and mammals,

and then