Anthropologist Answers Evolution Questions

I'm anthropologist Agustin Fuentes.

Let's answer your questions from the internet.

This is Human Evolution Support.

[upbeat music]

r/AskScience asks,

How long have humans been anatomically the same

as humans today?

What do we mean by anatomically the same?

One could ask, Well, what about our bodies is unique?

What does nothing else have?

Well, if you look at everything,

it's pretty much just our chin,

which is sort of ridiculous.

We are the only species with a chin,

but the chin doesn't make us human.

How long have we had chins?

It may be 300,000 years.

How long have we had bodies that look like this?

Maybe a little bit older.

How long have bodies like this been the only thing around?

About 40 or 50,000 years.

When did anatomically modern humans, that is, other humans,

fossils that look just like us, first show up?

Around 300,000 years ago,

but it doesn't mean that we, poof, emerged then.

Tough-Win-2254 asks,

Was there ever a first human?

If not, then how do we become humans?

It's important to realize

that there wasn't some point where, you know,

300,000 years ago, an archaic Homo sapiens

or a Homo erectus-like gave birth,

and it was a Homo sapiens.

That's not the way it works.

What happens is there's a whole bunch of populations

of Homo erectus or Homo erectus-like stuff

that changed a little bit over time.

And once they've changed enough, that is, whole populations,

hundreds, thousands, tens of thousands of individuals,

once they changed enough, we're like,

Ooh, that's not like it was 100,000 years ago.

It's different enough.

We're going to call it Homo sapiens now.

That's the way evolution works.

Gradually, over time, stuff changes.

That's evolution.

Ashuntiethebee asks,

Do y'all think monogamy is really natural,

or are we just forcing it?

Okay, so let me give you the short answer.

Humans are monogamish.

When we say monogamy, we tend to think about marriage

and law stuff and cultural ideologies.

No, deep in our past, humans didn't get married.

Deep in our past, humans didn't make

some kind of formal pronouncement of this one

and this one come together.

What they did do was come together frequently in pairs

and really care for one another

and sometimes break up and find other pairs.

Usually, when people think about monogamy,

though, they're talking about sex, right?

Social mammals use sex not just for reproduction,

but actually for social relationships.

Primates, man, do they have sex a lot.

A lot of primates have more sex outside

of reproduction than inside reproduction.

And when it comes to humans, well,

we're pretty much the sex champions of the primate world.

Well, it turns out, in primates

and in mammals in general, the more social you are,

the more you rely on everyone else in your group

and have interesting connections

and relations to them, the more sex you have.

Is monogamy the way we're naturally designed?

No.

Monogamy in the sense of strong pair bonds

between two individuals happens a lot.

It's very frequent for humans.

But is attraction and sexual interaction

exclusive within that pair bond?

No.

Everyone who's pair-bonded knows they're attracted

to other people too.

That's part of the way we primates are.

We love sociality.

Sometimes we cluster together in throuples.

Sometimes we have these extended families

which have great connections

and really complex relationships.

The bottom line is humans bond in incredibly powerful ways.

And in fact, that might be part of the story of our success.

D_yuvonne_marshall asks,

If we really came from monkeys,

then can someone please explain

to me why there are still monkeys?

We didn't come from monkeys.

Okay, it turns out we're primates; monkeys are primates.

About 35 million years ago,

those living monkeys today and us shared a common ancestor.

So deep in time, there was this ancestral primate;

monkeys emerged from one branch,

we emerged from another branch.

We did not come from monkeys.

We and monkeys are cousins.

Here's a question from the DebateEvolution subreddit.

So did we evolve from Neanderthals or what?

Walk me through the family tree.

I think we can do that.

So let's think about human evolution,

not so much as a family tree,

but sort of a family shrub, right?

So down at the beginning here, those roots are,

let's say, six, seven,

eight million years ago, ape-like things.

From this, we get sort of this branch

and then this branch and then this branch.

We've got Australopithecus afarensis.

Australopithecus afarensis,

or Lucy, represents a cluster of hominids,

and we think this is the sort of basal cluster

to these three big lineages, right,

these three parts of human evolution.

So one of the parts of human evolution that's not us,

but closely related, are those that we call paranthropists

or the robust australopithecines.

These relatives, ancestors/relatives, have really big teeth,

had bodies that were big and small,

but were different enough that we're like,

Those are some branches of the family shrub that's not us.

And then we've got this sort of other lineage over here,

which, you know, is characterized by this thing we call

Australopithecus africanus that looks a lot like Lucy,

but has some changes, a little bit sort of more slender,

maybe a little bit more like us, but it's not us yet.

And then 2.8 million years ago

or so, Homo habilis, the emergence of the genus Homo.

Now, we think it might have come from this branch,

probably didn't come from this branch,

might have come straight up as a third branch

from Australopithecus afarensis.

Once we get up into this stuff, the genus Homo, us,

we start to get some really cool, fascinating relatives.

These are the Neanderthals, the Denisovans,

and by the last million years or so,

we get this large cluster of members

of the genus Homo, our ancestors here.

So, for example, we get Homo erectus

or Homo ergaster by about 1.5 million years ago,

which, really interestingly, is this individual right here.

What's really fascinating

is that we have this incredible diversity of ancestors,

of populations, of relatives.

And by about, I'd say, 30,000, 20,000 years ago, just us.

So here's the human family shrub.

Well, where are the lines?

Like, exactly who connects to who?

So probably all of us

connect back to Australopithecus afarensis or Kenyanthropus.

Anyway, something in this three-to four-million-year period

is probably the ancestor of all the rest of us.

Then we've got all of these different kinds of humans.

So which one of these different humans

is directly the ancestor to us?

All of them?

So it turns out

that there's not one population, one species,

or one of these that gave rise to humans.

Humans look like we're a mixture genetically, behaviorally,

culturally, of a number of different populations, groups,

maybe even different species

that lived over the last million years.

So there's not one line from here to here or here to here.

How can we be evolved from all these different things?

Well, think of humans as a mutt, right?

You can think of dogs as sort of a standard dog.

You can actually mix together a whole bunch of dogs

that look really different and pretty much get dog

after a few generations.

Humans are that way too.

So all of these different humans

living 300,000, 200,000, 150,000, 50,000 years ago,

different groups moving around, mating, fighting,

getting together, breaking apart,

all of that has contributed to us today.

That's why humans are sort of a composite species.

We're a bit of our history, every one of us.

Arsid asks, Is it genetically possible for a mutation

to occur that would give us superhuman properties?

Something like Spider-Man or the X-Men?

Oh, that would be so cool, but it's not going to happen.

That's not the way genetics and bodies work.

So I wish this X-Men thing was a possibility,

like one change in the gene

and I could grow out Wolverine claws or something like that.

It's not going to happen

because development doesn't just, poof, happen, like,

as your bones develop, they develop in particular ways,

and they have constraints, right?

So I might develop joined fingers,

but I'm not going to develop an extra finger

that has a titanium claw that sticks out

or a bone claw or something like that.

And you can't have one change

that changes the whole game plan, right?

It takes hundreds of thousands or millions of years.

So one might think,

Well, wasn't there a mutation in some ape-like ancestor

that made him stand up and start walking?

No.

It turns out, like,

early ape-like ancestors 10, 14 million years ago

were already sort of standing on their hind limbs

in the trees and moving around.

And then, a few million years later,

started to use the ground a little more,

and over millions of years, that slowly changed

what bodies look like and hands and feet.

The point is there's no mutation

that immediately changes you.

Evolution takes time.

Even if you get some really important genetic shifts,

those genetic shifts could be invisible, nothing happens,

or they could take years and generations

before any change occurs.

By the way,

there is one interesting aside here about the X-Men.

So there is a species that's like us

but not us, Homo naledi.

It's related to us.

They lived about a quarter of a million years ago

in this Rising Star Cave system in South Africa.

They're really fascinating.

Well, one of the main researchers on that project

was sitting next to someone very major in the comics world,

and they began talking on a plane a number of years ago.

And the result of that was a comic,

and you can go check this out in X-Men Origins,

that the X-Men actually didn't come from the same ancestors

that we did, that, in fact,

something called Australopithecus sediba

lived about two million years ago,

sort of emerged into a human,

but a human with a slightly different ancestry.

So in that argument,

X-Men are not just that they have some mutation,

but, in fact,

they have slightly different ancestors than we do.

Next question.

From the Human Evolution subreddit,

Is the concept that meat caused

the expansion of human brain false?

Yeah.

Okay, what's really fascinating is this is what I was taught

as a student and as a scientist,

and this is what I've published and written about sometimes.

It's changed now.

We used to think that to get this big brain growth,

you need a lot of protein.

Early on, when our brains are really starting to first grow,

that first big jump

from the australopithecines or other things,

it doesn't look like we're eating that much meat.

And so we have to ask,

Well, where's that coming from?

Well, carbohydrates, so roots and tubers,

a lot of other small animals,

the whole punchline that meat is why we got big brains

and became human, that's not true.

Meat's always been an important part of our diet.

It's become more important in our diet,

especially for children, but meat is not why we're human,

it's not why our brains grew, and it's not why we're smart.

@DaleSparrow asks,

Did ancient humans just eat a shit load of roots?

Yes.

Not just, but they did eat a lot of roots.

Roots and tubers,

the underground storage organs of plants,

are really important in our evolution.

But you know what else is important?

Honey, right?

It looks like insects and bees' honey

might have really shaped our evolutionary history

and gave us access to protein and things like that.

You know what else is important?

Lots of small animals,

lots of small animals that we could catch and eat.

You know what else is important?

Big animals.

When we finally figured out

how to hunt big animals, all of that.

At some point, not that long ago, right?

10, 15,000 years ago, 8,000 years ago,

humans went from gathering, hunting

and killing things, catching fish, gathering whatever fruits

or berries are out there, to messing with the plants,

messing with the animals, and creating new types of it.

We call this domestication.

Everything you are eating now is pretty much domesticated,

is recreated over the last few thousand years

to look like it does now.

Is that better or worse?

I don't know.

What's really incredible about humans,

and this is probably really old for our species,

we don't just eat, right?

We create diets, cuisines, and life.

For humans, eating is not just about nutrition;

it's also about culture and enjoyment.

Cauliflowernice,

@adultswim Primal is a documentary about early humans,

exclamation point.

Someone proved me wrong @primal.

Okay, it's not a documentary about early humans,

but Primal's cool.

Yeah, it's wrong with dinosaurs

and some other things like that,

but what's cool about Primal

is it puts us in touch with our ancestors.

It puts us in touch with other ways to be human.

And here we have a clip from Primal

depicting the main character fishing.

Fishing, how long have humans fished?

Two million years ago,

or almost two million years ago,

in East Africa, we have one of the first evidences

of butchering of an animal.

And what is it?

It's a giant catfish.

How did they catch that giant catfish?

They probably jumped into this river

and grabbed this catfish

and then processed it, chopped it up, and sliced it.

We've been fishing a long time, and fishing matters to us.

Standard-Ad-868 asks,

How did blue eyes spread if it was recessive?

Well, it's not a simple dominant-recessive,

so there's a whole bunch of genes,

20-plus at least, that go into eye color.

But you're right, blue eyes are pretty rare.

Blue eyes can show up

with particular genetic and developmental combinations.

They've shown up in populations in Northern Europe

and populations in Australia

and populations actually in Africa, around the world.

So blue eyes are rare, but they show up.

But that gets to the bigger question.

These little things that change about humans, why?

For example, many people today get their third molar

taken out because it's all crunched in the back there.

That's not because there's a problem with the third molar;

it's just that our jaw is starting to change.

It's actually getting a little bit smaller

as our heads got sort of globular and big, right?

So there's only a limited amount of bone tissue there.

And so, as your jaw shrinks, you crowd that third molar.

VikingHair wants to know,

Could Neanderthals and Homo sapiens talk with each other?

Yes, they could.

Clearly, Neanderthals and humans around that time

could speak, and they could interact.

Well, if they could talk to each other,

what do they sound like?

Well, some people have argued

that the Neanderthals had this high-pitched voice

that is something like this, right?

This skull, this shape, had something about it,

maybe in the neck and the bones of the body,

that made it speak very high.

Now, let's think about this for a minute.

We would have to look at the bones in the neck

and sort of the soft tissue of the larynx

and a variety of other things.

This is a Neanderthal, right?

And this is a human.

Actually, when we compare these,

they're not huge differences.

If you think about it, if you travel around the planet

and talk to all of the eight billion humans,

there's going to be a lot of voices

and a lot of things going on.

So did they talk to each other?

Probably.

Maybe they used sign language.

Maybe they grunted at each other.

Maybe they spoke the same language.

I don't know yet, but it probably wasn't one going ahh,

and the other going rahrah.

Xsoyaaa asks, How did the first humans create tools

when they didn't have tools to create tools with?

Okay, the first tools are stone tools.

Stone tools are made out of stones.

So what do you need to make a stone tool?

Well, you need to be smart enough

or have this insight that inside this stone is a tool.

So what do you need?

You need one stone and another stone,

and you bring them together and you hit them together

carefully and with foresight, and you create a stone tool.

So what's really fascinating is not

what tools did we use to make tools,

but rather when did we figure out

that inside a rock was a tool

and figure out that picking up another rock

and hitting that rock in particular ways and doing it again

and again would get us something like this.

That's the interesting question.

These are called handaxes

because you hold them with your hand

and sort of cut or chop things.

These are made in the last million years

or so, 750,000 years ago, 600,000 years ago.

And what they are is a rock, so Homo erectus,

Homo ergaster, one of those humans

living around this time period sat on a big rock

and spent hours and hours knocking off little pieces

on both sides to create a sharp edge and a beautiful form.

They're way more symmetrical

and way more work than is necessary to cut or chop or poke.

Why did our ancestors

not only learn how to make stone tools, right,

but then make really beautiful ones,

sometimes not even using them, just making them

and putting them in big piles?

Stone tools are not just tools; they're also social symbols.

Amillionbuchs asks, We are getting closer

and closer to becoming the humans from 'WALL-E, '

and I'm so scared.

LOL.

No, we're not.

WALL-E's an example of what happens

to human bodies if, like in the movie, you stop walking,

you stop moving, you just start gorging your face.

That's not evolution, right?

That sort of getting immobile and gigantic

and blah, drooling, that's actually a capacity

that human bodies have right now.

Evolution works on existing variation slowly, usually.

So what's going to change in humans?

I don't know.

Our genetic frequencies are changing

right now and have been changing.

You won't see any of that because that's all on the inside.

Maybe our resistance to viruses is changing.

We know that's true.

So our head's going to get big

or our eyes going to get gigantic?

No, none of that's going to happen.

WALL-E is not a threat, evolutionarily speaking.

WALL-E is a threat if we don't change our ways,

wising up and start taking care of ourselves and the planet.

Axelle17 asks, Are hobbits real?

Yes, they are.

Not the Lord of the Rings hobbits,

but it turns out probably about 75 to 200,000 years ago

on the island of Flores in what is today Indonesia,

a bunch of humans or human close ancestors

or relatives called Homo floresiensis lived.

Homo floresiensis was a hobbit.

It was a very, very small little human

with big feet, which is awesome.

And they ran around, and guess what they had to deal with?

Komodo dragons.

So there's a little teeny hobbit human

fighting off gigantic lizards, hunting big rats

and little mini elephants.

It's like Middle-earth on the island of Flores.

Homo floresiensis was only about three and a half,

maybe four feet tall.

They were really small.

Why so small?

Well, we think they're the product of something

we call island dwarfism.

So when you look at islands around the world,

big animals show up on islands

and get smaller, like elephants get teeny.

There's, like, little pony-sized elephants.

There's other animals that are really small,

and they get to islands and they get bigger.

Well, what we think happened

is probably a million or more years ago,

as humans moved around the planet,

or actually human ancestors,

some of them got to the island of Flores,

and they stayed there.

And over time, on that island,

they shrunk down and got really small.

And they did pretty well for more than 100,000 years.

And interestingly, humans show up on Flores

around the same time that the hobbits disappear.

Why?

We don't know.

Did they interact?

We don't know.

Matteassierra asks, Who invented kissing?

Who was the first person to find out that touching lips

could help spark chemistry?

So humans are probably the only creature

that kisses in association

with sort of sexual arousal the way we do.

Other animals sort of put their lips together.

For example, any of you watching this who have a dog,

your dog is trying to get its tongue and its mouth

on your mouth all the time.

That's because that's a common exchange for canines, right?

They love to lick each other in the mouth

and share the microbiome.

That's not kissing, right?

We call it kissing, but for the dog, it's like,

Hey, hello.

Here's all the spit from my mouth

so that we're part of the same pack.

That's not what human kissing.

We're not trying to exchange spit

to be part of the same pack.

We're actually kissing because it feels really good.

So chimpanzees, right?

Here's the skull.

Chimpanzees have these big old lips

that are incredibly flexible, so they can smooch

and move their lips and all kinds of things,

but they don't have lips like ours

that are sort of tied around our face and connected,

and they don't have the same kind of nerve structures.

So why did I just go around that?

Because it turns out that part of the reason

kissing is important for humans

is the shape of our face, the shape of our mouths,

and the shape of our lips.

But why kiss? I mean, why do that?

Well, it turns out humans love to look at each other, right?

Face-to-face contact.

When we meet someone, the first thing we do

is look at their eyes.

We look at their face.

We're really interested in what's going on here.

And then, when you get close to someone,

you love to touch them.

And guess where on your face

is one of the most filled with nerve endings

and very sensitive sort of areas of tissue?

The lips.

So it turns out putting lips together,

especially if you throw in tongue

and other things like that,

actually is really sensorily powerful.

You really feel it.

But then there's a problem.

Not all people all over the planet

even today kiss regularly.

A lot of cultures kiss each other on greetings

or kiss on the side of the mouth.

Why do we kiss?

We kiss because we can.

Why is kissing fun?

Kissing is fun

because the way our face and nerves are designed.

Do all humans kiss?

No.

Do we need to kiss to spark chemistry?

No.

Does kissing spark chemistry?

Yep.

Justinalphabet asks,

The earliest human skeletons had spears in their rib cages.

Do you think mankind will ever

learn to get along peacefully?

The earliest human ancestors

did not have spears in their rib cages.

Spears came a lot later.

But what's really interesting is that we do find

evidence throughout human history

of one human ancestor hitting the other in the head

and killing them, maybe, but it's not that common.

We don't see one group attacking another group

with regularity and lethality

until between about 10 and 20,000 years ago.

Then we start to see it more and more commonly.

And in the last eight or 7,000 years, warfare,

two groups coming together

and just trying to kill each other, does emerge.

Clearly, fighting and aggression is deep in our history.

It's part of our capacity.

Warfare, however, is fairly recent.

Humans have a capacity

for incredible violence and aggression

and for incredible caretaking and collaborating.

Notsowinner57 asks,

Why do we as humans look so different

from one another compared to other animals?

Good question.

Because if you weren't a human,

if you weren't in some culture today

that makes a big deal about skin color

or hair type or clothes,

you wouldn't think humans look that different at all.

If you came down from outer space

and you looked, you'd be like,

Oh man, these are all the same.

If you were to look just at human DNA,

all humans are 99.9% identical.

If you'd look at the DNA

from a white-tailed deer in Michigan

and that same deer in New Jersey, right?

Same species, not that far apart,

those two deer would be more separate,

more different from one another genetically

than any two humans in the entire planet.

It turns out contemporary humans, Homo sapiens sapiens,

us around today, all eight billion of us,

are the last living human species.

But if you take a look around, 400,000 years ago,

five, six, 700,000 years, a million years ago,

there were multiple human populations,

probably multiple human species,

a lot more variation than there is today.

So bottom line, yeah, there's a lot of variation in humans,

but under the skin and as being human,

we're all pretty much the same.

Goltz20707 asks,

Question for those knowledgeable in the field.

Did early humans actually live in caves,

or were they special-use spaces?

And it's just that the artifacts left in caves

are better preserved than those left out in the open?

Yes.

The answer is yes all the way around.

It looks like some humans and human ancestors

did, in fact, live in caves,

that is, they spent a lot of time there.

Most did not.

And yes, something in a cave has a better chance

of being preserved than something outside in the open.

But given all of that, let me just tell you,

being in caves is fascinating

because being in caves, especially if you have fire,

you got to think about smoke,

you got to think about wind patterns.

Being in caves,

you have to sort of deal with other things like cave bears

and other things that want to live in those caves,

and you got to keep them out.

And also, when humans and human ancestors use caves,

they didn't just, like, go sit in a cave.

They actually manipulated those caves and changed them.

For example, more than 200,000 years ago

in this cave in France,

you have to go way to the back of the cave.

There's evidence that Neanderthals took

a bunch of stalactites and stalagmites,

the ones from the bottom and the top,

broke them, and then laid them out in a circle

and then built a fire in the middle of that circle

and used this for generations.

And cave paintings.

For some reason, humans go all over the place

and crawl into really difficult places

and paint on the walls.

I've been in one cave in Portugal.

We have to crawl through, turn upside down,

get on your back, and then look up like this,

and you see this beautiful horse up on the side.

What?

What's going on?

So yeah, they were sacred spaces too.

So humans lived there.

Yeah, they were symbolic and sacred spaces,

and yeah, stuff gets preserved better there.

That's why caves are so important in human evolution.

Vidit_shrimali27 asks,

If species like Homo neanderthalensis

had larger brains than us

and Homo erectus survived for nearly two million years,

why did they succumb to extinction

while Homo sapiens thrive?

There used to be a whole bunch of different kinds of humans.

They're all dead.

They all went extinct.

Why? What's going on?

Well, Neanderthals did have bigger brains

than us on average,

but a normal human brain ranges from 1,000 cubic centimeters

to 2,000 cubic centimeters.

That's 100% variation.

So having 100 cubic centimeters more or less

on us for Neanderthals really doesn't matter.

So Neanderthals did not really have bigger brains than us.

They were just a little bit bigger-bodied.

Homo, our genus, shows up about 2.8 million years ago.

In that time period, it divides

and moves around into different sort of populations

that look pretty different from one another in many ways.

What's really interesting, though, is all this variation,

all these different kinds of human,

they all go extinct at some point, and we made it.

Well, when I say we, that's not exactly right.

Don't think of all these other humans

as necessarily going extinct.

Think about them as leaving us little gifts,

little pieces of DNA, little bits of heritage

that make us who we are today.

So, I mean, a logical question to ask is,

How do we have genetics from different species, right?

Species that aren't us?

Well, first of all, species is a fuzzy category, right?

We don't know exactly 120,000 years ago

if a Homo sapiens and a Neanderthal walked by each other,

did they see each other as different species?

We knew they could have sex.

Clearly, we're carrying some of those genes.

So what we really should ask is not,

How do different species get together?

but, What does it mean to understand that we humans

are this composite?

We're this compilation of all these different populations,

of all this different variation from the past

that somehow has made it to today, not only made it,

but there are eight billion of us right now.

That is pretty impressive.

So whatever we did, we did okay.

What was it about us?

Sure, it's not the chin, right?

It's not the chin.

The chin did not make us survive.

Maybe it was our unbelievable ability to communicate

and to cooperate.

Maybe it was our ability to create trading networks

across hundreds of miles.

Maybe it was our ability

to care for one another a little bit more than others.

Maybe it was our ability to imagine new possibilities

and try to make them real.

All of those things are things we do,

but all of those things are probably things

that some of these guys did too.

Are we really that different,

or maybe are we just the luckiest hominin, not the best?

milkywomen asked,

How true is the idea of 'survival of the fittest'?

First off, it's important to point out

survival of the fittest we associate with Darwin,

but Darwin didn't use that phrase in the first edition

of On the Origin of Species.

He did in the second edition and moving forward.

Why?

Well, he got sort of pushed to use it

because it sounds cool, right?

People love survival of the fittest

because they think it means if you're bigger or faster

or meaner or fight more, you win.

That is not how evolution works.

Not usually.

Some animals, being faster is better.

Other animals, being smarter is better.

Other animals, being slower is better.

One of the biggest problems with this idea

of survival of the fittest

is that we think about guys in that way, right?

Like the alpha male, the guy who looksmaxxes

and gets the women and does everything.

Okay, let's actually deconstruct that for just one second.

So alpha male comes from terms about wolves,

a pack of wolves.

There's not an alpha male.

There's a male and a female who breed.

They're the sort of, like, center of the group,

and they breed,

and the other ones help them raise the young,

and they hang out, and they're all together,

and they communicate and cooperate and collaborate.

Basically, someone made up this notion of alpha male

as this dude who's at the top of everything.

It turns out, for most of human evolution,

and even today, if there's one dude who's really aggressive

and bothering everyone

and pushing them around, what happens?

That dude gets tossed out of the group.

There are eight billion humans on the planet

right now, so we are definitely fit.

Are we the fittest?

That we'll have to wait and see.

Peteragro asks,

Where did the first humans come from?

How did they spread across the planet?

We're Homo sapiens, so genus Homo, species sapiens.

The genus Homo has about two and a half million,

almost three million years of history.

We originate in Africa, sub-Saharan Africa,

and over the last two and a half million years or so

have spread all around Africa and the rest of the world.

If you want to say,

Well, where's the first fossil that looks just like us

that we're going to call that the first human?

That's probably around 300,000 years ago in North Africa,

in what is today Morocco.

It looks very similar to other stuff,

but a little bit different.

Has a chin and some other stuff.

There's others about 180,000 years ago in East Africa,

and then more recently we find them in Central Asia,

Southeast Asia, Europe, and Australia.

Humans do a lot of things,

but what they really do well is move and mate and hang out.

So no easy answer, but there are two fun ones.

One, humans begin in Africa

and spread around the world over the last two million years.

Two, humans begin in Africa

and spread around the world about 300,000 years.

Either one, totally good.

From the Explain Like I'm Five subreddit comes a question,

Why are human kids so useless for so long

compared to almost every other animal?

So imagine all of you have seen the wildlife show

where a giraffe gives birth, right?

This giraffe gives birth,

the baby drops out, and then, you know, seven minutes later

it's running across the savanna.

That's really impressive.

Human babies, we give birth,

you have the baby, what does the baby do?

They can't even lift their head for weeks.

What's going on there?

That's actually part of the secret of being human.

It turns out that humans have stretched out

that infancy and childhood in a way

that allows us extra time to grow.

The human brain at birth is only 40% of its adult size.

That's the smallest of any mammal.

So most of our brain grows

outside in the world, interacting with other humans.

Why? Culture.

It's hard to learn how to be human,

and our bodies and our brains need to be in interaction,

be together with others.

And so, how do we extend out that childhood?

We do a lot of caretaking, right?

The story, It takes a village to raise a child,

that is true.

One person can do it, but it's really hard.

Our bodies, our lives,

whether you're male or female, young or old,

our bodies are geared towards grabbing those kids,

holding onto them, and taking care of them.

Why do humans have this really long childhood?

That's because it takes a long time to be human,

and part of that is being together with others.

Parking_Bid9954 asks,

Were the average Neanderthal man stronger than modern man?

Maybe.

Depends on which modern man you're talking about.

Humans are incredibly variable.

On average, Neanderthals were a little bit stockier

than most humans today,

but humans 15,000 years ago were a little bit stockier

than most humans are today.

Part of it is their overall lives

were a little more stressed out.

They had to use their bodies for a lot more things.

More and more, as humans require less body use,

we get a little bit of reduction, right?

That is so we can move the bone tissue around.

For example, now that we pretty much pre-cook

or pre-chew all of our food, right,

processed food, canned food, cooked food, actually,

we really don't need much power up here in the jaw.

And what we've seen is our jaws and teeth

have gotten a little bit smaller.

MirnaArroyodrph asks, random thought of the day:

Considering the amount of Neanderthal mitochondrial DNA

we have, can it be that Neanderthal women

just found Homo sapiens males cuter, leaner, more charming?

No, we have no idea what happened when Neanderthals

and humans got together,

aside from the fact

that sometimes they had sex and offspring.

Did they find each other cuter?

Were they repulsed by one another?

Were they intrigued by one another?

I don't know. I wish I had a time machine.

But what we do know is that humans and Neanderthals

somehow more than once got together and had a baby.

Coreysjill asks, In hunter-gatherer societies,

were gender roles really as rigid as they are taught

in textbooks and depicted in pop culture?

First of all, when we look at even recent sort of societies,

let's say 5,000 years ago,

I can look at the bone chemistry, right?

And I can show you that men and women on average

as adults were eating slightly different foods.

That suggests some kind of real

different sort of patterns, right?

Or we can show that, like, right arms and left arms

are different in men, but not in women,

which shows a different kind of sort of behavior

around agriculture or something like that.

But when we go back in time, we don't see that.

When we look at male and female bodies,

it's really hard to find identifiable differences.

Well, people say, Men hunt.

Well, we see in Neanderthals and in earlier humans,

both males and females have the same kind of broken bones.

They seem to have the same kind of sort of stature

and thick, strong muscles.

So it's just not clear.

The manosphere wants us to believe

that evolution shows men are this way

and women are this way.

And you know what?

It's just not true.

It's a little more complicated and much more interesting.

Eric_von_doom asks,

Sometimes I think

about how human beings have been around for 300,000 years,

but recorded history only goes back 5,000 years.

So there's 295,000 years

that are just completely unaccounted for.

Not true.

We have great accounting.

First of all,

recorded history goes back more than 5,000 years.

We have hundreds of thousands of years of evidence

of humans building stuff, making things,

creating things, and leaving them.

500,000 years ago in East Africa, human ancestors,

Homo erectus or one of the other species,

carved up these big chunks of wood

and put them together like Lincoln Logs, right?

Other ones, 128,000 years ago,

made little perforated holes in shells

and strung them around their necks.

And 65 or 70,000 years ago,

humans on the island of what is today Sulawesi, right,

climbed into a cave and painted a pig and a hand print.

Humans decided to take pigments, to add water and spit

and other stuff to ochre, to these mineral pigments,

and paint their bodies and paint the walls.

So don't just hold on to writing.

Writing is recent.

The really interesting stuff, the amazing stuff,

is what our ancestors built and left for us to discover.

So those are all the questions for today.

Thank you for watching.

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