Imagine the scene
Imagine the scene

it was 1871
it was 1871

and Charles Darwin had just suggested
and Charles Darwin had just suggested

that we humans did not in fact walk
that we humans did not in fact walk

fully formed, out of the primordial sludge at the beginning of time
fully formed, out of the primordial sludge at the beginning of time

instead, in his book "The Descent of Man",
instead, in his book "The Descent of Man",

He proposed that humans descended from African apes.
He proposed that humans descended from African apes.

Naturally, his Victorian contemporaries were all
Naturally, his Victorian contemporaries were all

"Ooooo... Fetch me my smelling salts..." and clutching at their pearls
"Ooooo... Fetch me my smelling salts..." and clutching at their pearls

and what not
and what not

and maybe you can't blame them for being shocked because Darwin's idea
and maybe you can't blame them for being shocked because Darwin's idea

is still shocking people
is still shocking people

like a 140 years later.
like a 140 years later.

But, as he often was, Darwin was right.
But, as he often was, Darwin was right.

The amazing thing was that he proposed his theory of human evolution
The amazing thing was that he proposed his theory of human evolution

when there was almost no fossil evidence
when there was almost no fossil evidence

of any other kinds of Hominins
of any other kinds of Hominins

That includes us and our ape-like ancestors on Earth.
That includes us and our ape-like ancestors on Earth.

It took another 50 years for enough fossils to pile up
It took another 50 years for enough fossils to pile up

to start corroborating Darwin's Theory,
to start corroborating Darwin's Theory,

and another several decades to piece together
and another several decades to piece together

compare and argue about how these species related to each other.
compare and argue about how these species related to each other.

Actually, that is a process that is still going on right now.
Actually, that is a process that is still going on right now.

These days about two dozen Hominid species or possible species
These days about two dozen Hominid species or possible species

have been identified, and while the Hominid family tree
have been identified, and while the Hominid family tree

looks sorta like a prickly bush at the moment,
looks sorta like a prickly bush at the moment,

taken together these fossils do show us
taken together these fossils do show us

how our ape-like ancestors evolved into modern human awesomeness.
how our ape-like ancestors evolved into modern human awesomeness.

See, on the journey from the genus Australopithecus
See, on the journey from the genus Australopithecus

to the genus Homo, our ancestors reached
to the genus Homo, our ancestors reached

a series of game changing evolutionary benchmarks.
a series of game changing evolutionary benchmarks.

Whether they were acquired traits or new behaviours,
Whether they were acquired traits or new behaviours,

that gave its species a huge advantage over the previous ones.
that gave its species a huge advantage over the previous ones.

We exist largely because of those evolutionary breakthroughs
We exist largely because of those evolutionary breakthroughs

So, what are they?
So, what are they?

And who else is in our family bush?
And who else is in our family bush?

And will this be on the final?
And will this be on the final?

Follow me into the facts of human evolution.
Follow me into the facts of human evolution.

*Theme tune*
*Theme tune*

Our understanding of where we came from
Our understanding of where we came from

has changed dramatically in just the last 50 years.
has changed dramatically in just the last 50 years.

If you were a paleoanthropologist working in the 1970's,
If you were a paleoanthropologist working in the 1970's,

you'd probably believe that there was a bunch
you'd probably believe that there was a bunch

of different human species running around on Earth
of different human species running around on Earth

for millions of years, and that they all sorta interbred
for millions of years, and that they all sorta interbred

when they bumped into each other.
when they bumped into each other.

This is known as the 'Multiregional Hypothesis'
This is known as the 'Multiregional Hypothesis'

and it suggested that Neanderthals in Europe,
and it suggested that Neanderthals in Europe,

for example evolved into Modern Europeans.
for example evolved into Modern Europeans.

While Homo Erectus in China would have been the predecessor
While Homo Erectus in China would have been the predecessor

of Modern Asians,
of Modern Asians,

and that Java Man found in Indonesia
and that Java Man found in Indonesia

would have been the ancestor
would have been the ancestor

to Australian Aboriginal Peoples.
to Australian Aboriginal Peoples.

These days Multiregionalism has fallen out of favor,
These days Multiregionalism has fallen out of favor,

mostly because in the 1980's researchers started
mostly because in the 1980's researchers started

studying mitochondrial DNA.
studying mitochondrial DNA.

That's the ancient DNA found in the mitochondria of our cells,
That's the ancient DNA found in the mitochondria of our cells,

which is totally separate from the DNA in our cell's nuclei,
which is totally separate from the DNA in our cell's nuclei,

that's the stuff that we inherit from both our parents.
that's the stuff that we inherit from both our parents.

Mitochondrial DNA, on the other hand, is passed down
Mitochondrial DNA, on the other hand, is passed down

only from the mothers to their offspring
only from the mothers to their offspring

and by following its various mutations over time
and by following its various mutations over time

and across populations, scientists have been able
and across populations, scientists have been able

to track the migration of humans over the past 200,000 years.
to track the migration of humans over the past 200,000 years.

All the way back to a single ancestral population
All the way back to a single ancestral population

of modern humans in Africa.
of modern humans in Africa.

This genetic evidence combined with the fact that
This genetic evidence combined with the fact that

all of the oldest Hominin fossils have come from Africa,
all of the oldest Hominin fossils have come from Africa,

led to the Out of Africa Hypothesis
led to the Out of Africa Hypothesis

which suggests that anatomically modern humans
which suggests that anatomically modern humans

evolved exclusively in Africa
evolved exclusively in Africa

and then spread across the world in 2 different waves.
and then spread across the world in 2 different waves.

One wave which happened anywhere from 70,000 to 125,000 years ago
One wave which happened anywhere from 70,000 to 125,000 years ago

took a right-hand-turn out of Africa, populating the Middle East, Asia, Indonesia, and Australia.
took a right-hand-turn out of Africa, populating the Middle East, Asia, Indonesia, and Australia.

The second wave happened much later and headed straight up through Europe.
The second wave happened much later and headed straight up through Europe.

So that's currently the most popular idea about where we came from
So that's currently the most popular idea about where we came from

but when it comes to how hominins evolved,
but when it comes to how hominins evolved,

there are only a few thing we're sure about.
there are only a few thing we're sure about.

For starters, there did used to be a lot of different species of people running around
For starters, there did used to be a lot of different species of people running around

and now there's only one.
and now there's only one.

And thought we share the vast majority of our DNA with chimps
And thought we share the vast majority of our DNA with chimps

Our common ancestor with them probably lived about 7 million years ago, maybe more
Our common ancestor with them probably lived about 7 million years ago, maybe more

It was about a million years after that break with chimps
It was about a million years after that break with chimps

that the Homo Sapiens saga really began when a segment of an ancient population of apes
that the Homo Sapiens saga really began when a segment of an ancient population of apes

acquired the first real breakthrough in human evolution, bipedalism.
acquired the first real breakthrough in human evolution, bipedalism.

This is when apes somewhat obviously started walking upright and on two feet
This is when apes somewhat obviously started walking upright and on two feet

And there were a couple of different, early, semi-bipedal genera of apes
And there were a couple of different, early, semi-bipedal genera of apes

And these probably evolved into the australopithecines
And these probably evolved into the australopithecines

Who we can call grandma and grandpa.
Who we can call grandma and grandpa.

Australopithecines weren't that different from other ancient African apes
Australopithecines weren't that different from other ancient African apes

They were about the same size and they had the same size brains
They were about the same size and they had the same size brains

In fact, the first australopithecines like Lucy, the 3.2 million year old australopithecus aferensis fossil
In fact, the first australopithecines like Lucy, the 3.2 million year old australopithecus aferensis fossil

found in Ethiopia in 1974, was probably about a meter tall
found in Ethiopia in 1974, was probably about a meter tall

and didn't look too different from a modern chimp.
and didn't look too different from a modern chimp.

But we know that Lucy walked upright due to the shape of her bones
But we know that Lucy walked upright due to the shape of her bones

and because we found fossilized footprints of her buddies.
and because we found fossilized footprints of her buddies.

And though there are a few different theories about why bipedalism may have evolved
And though there are a few different theories about why bipedalism may have evolved

it seems to have happened just as the dense African forests were shrinking due to climate change.
it seems to have happened just as the dense African forests were shrinking due to climate change.

So early hominins may have been forced out onto the grasslands where bipedalism
So early hominins may have been forced out onto the grasslands where bipedalism

made it easier to spot predators, to travel long distances,
made it easier to spot predators, to travel long distances,

and to pick fruit off trees.
and to pick fruit off trees.

But bipedalism was most important because it freed up two of our limbs.
But bipedalism was most important because it freed up two of our limbs.

When you got two hands just hanging out not doing anything
When you got two hands just hanging out not doing anything

the next obvious step is to pick up a rock and start smashing stuff.
the next obvious step is to pick up a rock and start smashing stuff.

And voilà
And voilà

You got an ape... using a tool
You got an ape... using a tool

And this led to the second major characteristic to advance human evolution, a precision grip.
And this led to the second major characteristic to advance human evolution, a precision grip.

As hominins evolved, they used their hands more and more for gripping and manipulating small objects
As hominins evolved, they used their hands more and more for gripping and manipulating small objects

than swinging through trees and what have you.
than swinging through trees and what have you.

So over time, the big curved hands that we associate with chimps and gorillas
So over time, the big curved hands that we associate with chimps and gorillas

were replaced with smaller, more nimble hands with powerful thumbs
were replaced with smaller, more nimble hands with powerful thumbs

that you can see at the end of your arms right now.
that you can see at the end of your arms right now.

These hands were better suited for using slicing tools and our first tool making ancestor
These hands were better suited for using slicing tools and our first tool making ancestor

may have been Homo Habilis, aka handy man
may have been Homo Habilis, aka handy man

Homo Habilis was the first obviously human-like hominin in the fossil record
Homo Habilis was the first obviously human-like hominin in the fossil record

and he's thought to be the earliest member of the Homo genus.
and he's thought to be the earliest member of the Homo genus.

He first appeared about 2.4 million years ago and was probably the direct descendant of the australopithecines.
He first appeared about 2.4 million years ago and was probably the direct descendant of the australopithecines.

I have to say probably because, you know, I wasn't there and there will always be holes in the fossil record.
I have to say probably because, you know, I wasn't there and there will always be holes in the fossil record.

And Homo Habilis probably couldn't have fixed your dish washer but he could totally have smashed it to pieces
And Homo Habilis probably couldn't have fixed your dish washer but he could totally have smashed it to pieces

with a rock.
with a rock.

In addition to acquiring more dexterous hands, Homo Habilis ate meat.
In addition to acquiring more dexterous hands, Homo Habilis ate meat.

Its omnivorous diet was a new thing for previously vegetarian hominins
Its omnivorous diet was a new thing for previously vegetarian hominins

and it turned out to be another game changer for the genus Homo
and it turned out to be another game changer for the genus Homo

because it kick-started the process of encephalization.
because it kick-started the process of encephalization.

Or the growth of the brain in relation to the overall body mass.
Or the growth of the brain in relation to the overall body mass.

See building and maintaining brains requires a ton of calories,
See building and maintaining brains requires a ton of calories,

so even though the first omnivorous hominins were probably scavenging gazelle scraps from saber tooth cats or something
so even though the first omnivorous hominins were probably scavenging gazelle scraps from saber tooth cats or something

Meat was a big enough part of their diet that their brain size increased pretty rapidly.
Meat was a big enough part of their diet that their brain size increased pretty rapidly.

Some argue that Homo Habilis was also probably the first human ancestor to figure out how to cook food.
Some argue that Homo Habilis was also probably the first human ancestor to figure out how to cook food.

Cooking unlocks all sorts of calories and nutrients from vegetables and tubers
Cooking unlocks all sorts of calories and nutrients from vegetables and tubers

as well as making rotten, scavenged meat less dangerous.
as well as making rotten, scavenged meat less dangerous.

So overall nutrition for these guys improved a LOT around this time,
So overall nutrition for these guys improved a LOT around this time,

and brains as a result got bigger.
and brains as a result got bigger.

But it wasn't just brain size that evolved, the pattern of brain growth was really important too.
But it wasn't just brain size that evolved, the pattern of brain growth was really important too.

Over time, our ancestors temporal lobes which house the centers for language processing
Over time, our ancestors temporal lobes which house the centers for language processing

and the prefontal cortices which help with complex decision making and moderating social behavior
and the prefontal cortices which help with complex decision making and moderating social behavior

grew disproportionately to the other parts of their brain.
grew disproportionately to the other parts of their brain.

Some researchers think this had a lot to do with the vastly improved diet
Some researchers think this had a lot to do with the vastly improved diet

and at the same time a need to solve social problems which was becoming more and more important.
and at the same time a need to solve social problems which was becoming more and more important.

One reason for this can be found in the fossils of Homo Ergaster
One reason for this can be found in the fossils of Homo Ergaster

Which came on the scene about 1.65 million years ago
Which came on the scene about 1.65 million years ago

A lot of people think it's the desendent og Homo Habilis
A lot of people think it's the desendent og Homo Habilis

They looked even more like modern humans than Homo Habilis
They looked even more like modern humans than Homo Habilis

They had smaller jaws, and sharper teeth, and were taller and more slender.
They had smaller jaws, and sharper teeth, and were taller and more slender.

They were also probably the first mostly hairless hominins
They were also probably the first mostly hairless hominins

But one very interesting detail is that Homo Ergaster had hips so narrow as to make the unassisted delivery
But one very interesting detail is that Homo Ergaster had hips so narrow as to make the unassisted delivery

of a baby very difficult. And since Ergaster had bigger brains, their babies had to have probably also
of a baby very difficult. And since Ergaster had bigger brains, their babies had to have probably also

considerably larger than those of past hominin babies.
considerably larger than those of past hominin babies.

So, baby heads were getting bigger as females pelvises were getting smaller.
So, baby heads were getting bigger as females pelvises were getting smaller.

The only solution was for babies to be born before their brains were fully formed
The only solution was for babies to be born before their brains were fully formed

so that they could pass through the birth canal.
so that they could pass through the birth canal.

But this meant that after birth, babies were less developed, requiring more care than ever
But this meant that after birth, babies were less developed, requiring more care than ever

and for a longer time.
and for a longer time.

This required Ergaster and later members of the Homo genus to develop another breakthrough
This required Ergaster and later members of the Homo genus to develop another breakthrough

That could only be possible with big sophisticated brains.
That could only be possible with big sophisticated brains.

I'm talking, of course, about complex social behavior.
I'm talking, of course, about complex social behavior.

More so than anyone who came before them members of Homo Ergaster really needed each other.
More so than anyone who came before them members of Homo Ergaster really needed each other.

For delivering each other's babies, for caring babies that took freaking forever to mature
For delivering each other's babies, for caring babies that took freaking forever to mature

For finding enough food to sustain everybody, and for hunting, which Ergaster probably did in groups.
For finding enough food to sustain everybody, and for hunting, which Ergaster probably did in groups.

It's also possible that Homo Ergaster was the first human to leave Africa
It's also possible that Homo Ergaster was the first human to leave Africa

Maybe in search of better hunting grounds
Maybe in search of better hunting grounds

Ergaster bones dated to around 1.75 million years ago and have been found around the border of Armenia and Georgia.
Ergaster bones dated to around 1.75 million years ago and have been found around the border of Armenia and Georgia.

Shortly afterward we start seeing the genus Homo Erectus
Shortly afterward we start seeing the genus Homo Erectus

The first early human whose fossils have been found in large numbers outside of Africa
The first early human whose fossils have been found in large numbers outside of Africa

And it seems like they did really well for themselves
And it seems like they did really well for themselves

Homo Erectus, was kind of my favorite grandpa.
Homo Erectus, was kind of my favorite grandpa.

Or maybe great uncle. Nobody's sure.
Or maybe great uncle. Nobody's sure.

Because during the heyday of Homo Erectus, about 400,000 to 600,000 year ago
Because during the heyday of Homo Erectus, about 400,000 to 600,000 year ago

we begin to see another species of hominin.
we begin to see another species of hominin.

Homo Heidelbegensis which some believe to be the direct descendant of Homo Ergaster
Homo Heidelbegensis which some believe to be the direct descendant of Homo Ergaster

Since they were very similar with a couple of exceptions.
Since they were very similar with a couple of exceptions.

For instance, some scientists believe that Heidelbegensis was the first hominin species to bury their dead
For instance, some scientists believe that Heidelbegensis was the first hominin species to bury their dead

But possibly the most important thing about Homo Heidelbegensis is that many believe
But possibly the most important thing about Homo Heidelbegensis is that many believe

It's the direct predecessor to modern Homo Sapiens.
It's the direct predecessor to modern Homo Sapiens.

And possibly, also to our thick-browed cousins the Neanderthals, aka Homo Sapiens Neanderthalensis
And possibly, also to our thick-browed cousins the Neanderthals, aka Homo Sapiens Neanderthalensis

Or Homo Neanderthalensis.
Or Homo Neanderthalensis.

One theory is that a population of Heidelbergensis remained in Africa
One theory is that a population of Heidelbergensis remained in Africa

and modern humans descended from them, while other Heidelbergensis hoofed it up through Europe
and modern humans descended from them, while other Heidelbergensis hoofed it up through Europe

and Neanderthals derived from that group.
and Neanderthals derived from that group.

This, like many other things in human evolution is hotly contested.
This, like many other things in human evolution is hotly contested.

What we do know is that
What we do know is that

And though they had pronounced brow ridges and were heavier set than we are
And though they had pronounced brow ridges and were heavier set than we are

They look pretty similar to modern humans
They look pretty similar to modern humans

Their brains seem to have been a little bit larger than ours,
Their brains seem to have been a little bit larger than ours,

and modern humans and neanderthals apparently shared some cultural habits,
and modern humans and neanderthals apparently shared some cultural habits,

like burying our dead, making art,
like burying our dead, making art,

and using tools to beat the crap out of each other.
and using tools to beat the crap out of each other.

And of course, they totally found some time to get it on with each other
And of course, they totally found some time to get it on with each other

we've been able to reconstruct almost the entire neanderthal genome
we've been able to reconstruct almost the entire neanderthal genome

and it turns out, that about 2.5% of our DNA is from some neanderthals who - I guess -
and it turns out, that about 2.5% of our DNA is from some neanderthals who - I guess -

some of our great-great-great...-great-grandmothers
some of our great-great-great...-great-grandmothers

spend a great night within a cave in Israel!
spend a great night within a cave in Israel!

So that brings us up through modern humans, but the story of our ancestry
So that brings us up through modern humans, but the story of our ancestry

is always changing, because exciting discoveries are being made all the time.
is always changing, because exciting discoveries are being made all the time.

For instance, in 2004 researchers found fossils of Homo Floresiensis
For instance, in 2004 researchers found fossils of Homo Floresiensis

a.k.a. the Hobbit, a tiny person that lived about until 13'000 years ago
a.k.a. the Hobbit, a tiny person that lived about until 13'000 years ago

in what is now Indonesia. Even more recently,
in what is now Indonesia. Even more recently,

in 2008, fossils of a new people, the Denisovans, or Denisova Hominin
in 2008, fossils of a new people, the Denisovans, or Denisova Hominin

were discovered, researchers think may have overlapped, and possible, interbred with modern humans,
were discovered, researchers think may have overlapped, and possible, interbred with modern humans,

and the discovery of Australopithecus Sediba, also in 2008,
and the discovery of Australopithecus Sediba, also in 2008,

has some paleo-anthropaleologists in a dither about whether it could be the real
has some paleo-anthropaleologists in a dither about whether it could be the real

direct progenitor for the genus homo, and also the first tool maker.
direct progenitor for the genus homo, and also the first tool maker.

So, it's an exciting time to be researching our origins.
So, it's an exciting time to be researching our origins.

No one's really sure what killed off these other species, some theories suggest
No one's really sure what killed off these other species, some theories suggest

it was climate change, or a catastrophic event like a supervolcano eruption,
it was climate change, or a catastrophic event like a supervolcano eruption,

or simply not being able to compete with [points fingers] This.
or simply not being able to compete with [points fingers] This.

Maybe we are the survivors because of our big brains,
Maybe we are the survivors because of our big brains,

we had to evolve to help each other out,
we had to evolve to help each other out,

and because we eventually developed agriculture about 10'000 years ago,
and because we eventually developed agriculture about 10'000 years ago,

which caused a huge population explosion
which caused a huge population explosion

that is still going on today. But now,
that is still going on today. But now,

it's just us. Which makes me a little bit sad.
it's just us. Which makes me a little bit sad.

It's pretty strange to think that if we went back in time just a 100'000 years,
It's pretty strange to think that if we went back in time just a 100'000 years,

like yesterday afternoon, geologically speaking,
like yesterday afternoon, geologically speaking,

we'd be sharing the earth with 6 different kinds of humans.
we'd be sharing the earth with 6 different kinds of humans.

Somethin' tells me that playing Mario Party with a neanderthal would be like
Somethin' tells me that playing Mario Party with a neanderthal would be like

would be like a dozen different kinds of awesome, but
would be like a dozen different kinds of awesome, but

I guess I'll never know.
I guess I'll never know.

Thank you for watching this exceptionally long SciShow infusion
Thank you for watching this exceptionally long SciShow infusion

couldn't help it, there was a lot to cover
couldn't help it, there was a lot to cover

If you have any questions / ideas, please leave them down below in the comments
If you have any questions / ideas, please leave them down below in the comments

or on Facebook and Twitter, and we'll see you next time.
or on Facebook and Twitter, and we'll see you next time.

*Theme tune*
*Theme tune*