(gentle music)
Compared to our closest living
genetic relatives, humans are,
physically, at least, rather unimpressive.
We lack strength.
(chimp screeching)
We can't run as fast and we are much worse at climbing.
(upbeat music)
Yet, we have architecture, religion, science, language
literature, art, culture, and fission,
achievements all made possible by our larger brain.
And since the writings of Charles Darwin,
we have believed this development
to have been constant and linear.
(speaks in foreign language)
I always assumed that the advent
of modern man was inevitable,
that the development of homo habilis
and homo erectus were destined to lead us to this point.
(upbeat music)
But is this really true?
New findings from Dresden suggest
a quite different conclusion,
that the evolution of the human brain has been far less
of a slow and gradual development
and more the result of a banal coincidence,
which can be traced back to the sudden change
of a single gene.
(speaks in a foreign language)
If it turns out to be true that
this point mutation is so causally significant,
then you have to ask whether humans really were
always destined to exist in their current form.
(upbeat music)
(speaks in a foreign language)
If we summarize our various experiments
and findings, it seems that we have made
an important contribution to understanding
how humans came to have such large brains.
(upbeat music)
(gentle music)
Homo sapiens shares almost 99% of his genetic material
with other hominids.
Apart from a few genetic details,
what sets us apart is the size of our brains.
(speaks in a foreign language)
If you think about human achievements,
not only individually, but also as part of a team,
the moon landing 50 years ago is still something
that blows my mind.
Other hominids couldn't have done that.
(upbeat music)
Professor Dr. Wieland Huttner is head of a research group
at the Max Planck Institute
for Molecular Cell Biology and Genetics in Dresden.
In 2001, he was appointed director.
Even as a child, Wieland Huttner wanted to crack
the many unsolved mysteries of the human brain.
(speaks in foreign language)
When I was 17, I got into an argument
with a boy in my class about whether we would really
ever understand the human brain.
He said it would always be a mystery.
I disagreed.
So, I started thinking how I could best get involved
with this area of research.
I'd planned to study psychology or chemistry,
thinking that either one of them would help me
reach my goal.
And then my father said,
"Study medicine, that's right in between."
So I studied medicine.
But straight after the basic medical examination,
I began to focus on the brain.
(dramatic music)
Since then, Wieland Huttner has been using his knowledge
of medicine to answer precisely these questions.
How did evolution cause the human brain to grow?
What biological cell processes caused this to happen?
Our brains are three times larger
than those of other ape species.
Which changes in our genome led to this growth?
(speaks in foreign language)
There are scientists who give up
at a certain point.
I don't believe that I am one of them.
In the past 25 years, we have made a lot of progress
and have managed to build on this progress as well.
But that's only been possible due to
the fantastic colleagues I have working alongside me.
(dramatic music)
13 scientists and assistants from around the world
are working in Huttner's research group
and partner laboratories.
(speaks in foreign language)
We are what you would call cell biologists.
And so, as cell biologists, we began to address the question
of how our brains grow.
First, we studied what are known as the progenitor cells,
which need to divide in order to produce nerve cells.
And in the process, we noticed that they have
an extremely interesting morphology.
So we said, "Let's use this in order to isolate the cells."
(dramatic music)
The progenitor cells are the first step
in the development of the embryonic brain.
Managing to isolate these has formed the basis
for studying the next stages in the growth process.
(speaks in foreign language)
For me, the most impressive example
of human brain capacity is Einstein's theory of relativity.
It's incredible how concepts as intangible as time, space,
and gravity can be combined in a single formula.
And Einstein has thus far been proven right.
(gentle music)
Neurobiologist Dr. Michel Heide is a scientific assistant
in Wieland Huttner's research group.
For years, he has been involved in the search
for the genetic triggers of human brain growth.
(speaks in foreign language)
The first question we asked ourselves was,
which genes are actually active in these STEM cells
or progenitor cells of the brain?
So we came up with a list of around 3,000 genes.
And what we found interesting, of course,
is when they first appeared,
or in what other mammals they can be found.
We then managed to narrow it down to 50 genes
that can only be found in primates.
And off these 50, 15 were specific to humans
and not found in any other mammal.
And one of these 15 was ARHGAP11B.
(gentle music)
ARHGAP11B.
This gene, known as 11B for short,
attracted the scientists' attention.
It only occurs in humans.
Does this gene cause the progenitor cells to multiply?
These key cells are what cause the brain to grow
in the embryonic phase.
In 2015, the researchers began studying ARHGAP11B
in more detail.
They planted the human specific gene
in the brain of a mouse embryo.
(speaks in foreign language)
In the original tests,
we introduced the 11B gene into mouse embryos
and encouraged its expression, as we say,
for a transient period, just a few days.
The mice's brains suddenly contained more progenitor cells.
This is the prerequisite for more brain growth.
And incredibly, in half the cases,
the mice's brains were not only larger,
they also showed extensive folds,
which is otherwise never seen in rodents.
(gentle music)
The findings from Dresden were a game changer.
AHRGAP11B triggered the development
of significantly more basal brain STEM cells in the mice,
and even cause folds in the otherwise
smooth cerebral cortex to occur,
in line with the pronounced folds we see in humans.
The researchers decided to go one step further.
(speaks in foreign language)
There are other kinds of animals
that are much better suited to brain analysis,
such as the ferret.
So we planted the 11B gene in this species' brains as well.
And the interesting thing is that,
while in the mice 11B caused certain stem cells
to proliferate in the brain,
these were not exactly the right stem cells.
In the ferret, however,
exactly the right stem cells proliferated,
to six times their usual number.
(dramatic music)
Another sensational finding.
Even in ferrets, which already have a folded brain,
gene 11B triggered a clear increase in brain size.
The folds became stronger, and the cerebral cortex thicker.
Could AHRGAP11B be the missing piece of the puzzle
long sought by scientists,
the key component in the growth of the human brain,
and what led us to become the planet's dominant species?
(speaks in foreign language)
For me, our greatest achievement
is mastering fire.
(upbeat music)
Dr. Franca Parianen is a neuroscientist,
author, and keen science learner.
She believes it better to have wrinkles in your brain
than in your clothes.
She knows a lot about both.
She also knows about evolutionary brain growth.
(speaks in foreign language)
What has grown most clearly
over the course of human evolution is the neocortex.
Our entire brain has developed, but it's the neocortex
in particular that has grown disproportionately.
And it's this part of the brain that enables us
to do many of the things
that we associate with intelligence,
like understanding cause and effect,
predicting the future, and so on.
When I'm solving math problems,
ideally something in the front part of my brain
should be active.
(dramatic music)
Complex thought processes, speaking, dreaming,
all of these things happen in the neocortex,
the youngest part of the brain.
The more furrows it has, the stronger the folding,
and the more room there is for the gray cells to grow.
But size does not equal intelligence.
(speaks in foreign language)
If we looked at two different people
and said, "This person has a larger brain
"and that person has a smaller brain,"
we'd be talking about the weight.
We can't deduce intelligence from weight.
But if we looked at the interconnectedness within the brain,
we'd be much better positioned
to draw conclusions about intelligence.
In other words, we can't just think in terms
of building blocks, we have to ask,
how does it all fit together?
How does it work together?
To what extent do these connections stretch
over the entire cortex,
and how quickly do the connections form?
How quickly can one cell react to another?
Another important point is memory.
How large the memory is plays a very important role
when discussing human intelligence.
(gentle music)
The researchers at the Max Planck Institute in Dresden
have found a human gene that causes nerve cells to multiply
and the cerebral cortex to grow,
at least in mice and ferrets.
But does it have the same effect
in more highly developed life forms?
(speaks in foreign language)
We found that AHRGAP11B multiplied
the progenitor cells of the mice's brains
and also caused the brains to grow,
sometimes even with pronounced folds.
We have to acknowledge that mice
and humans are quite far apart,
especially in terms of brain structure.
That's why we decided that if AHRGAP11B really is
the crucial gene in terms of the evolution
and development of the human brain,
we need a test subject that is closer to humans.
(gentle music)
Michelle Heide was therefore assigned
with introducing the human gene AHRGAP11B
into the embryonic brain of a primate for the first time.
(speaks in foreign language)
We decided to carry out
the first experiments on common marmosets.
These are relatively small monkeys
that have a smooth brain in contrast to humans
and chimpanzees and other higher primates.
However, these animals already have
all the stem cell populations that we also find in humans,
that makes them the ideal candidate for these tests.
(gentle music)
Experiments on unborn animals carried out
under strict international ethical guidelines are essential
for the basic research work of the Dresden scientists.
(speaks in foreign language)
Our questions about why the human brain
has become larger during the course of evolution
and also during the development of the fetus,
and how this is connected to what are known as
the stem cells that produce these cells in the brain,
can only be answered by carrying out research
on living animals.
That's not possible in a Petri dish.
And our research also has a medical aspect,
especially in the fight against neurodegenerative diseases,
which are currently on the increase.
If you're considering the cell replacement,
you need to know about stem and progenitor cells,
which we have now studied in detail.
And these studies can't be done on mice.
The mouse has hardly any of the stem and progenitor cells
that shape our human brain.
We have no alternative but to study the non-human primates
that are our closest relatives,
the ones we're allowed to experiment on.
(gentle music)
In a Japanese partner laboratory
specializing in such experiments,
AHRGAP11B is introduced into the monkeys egg cells.
(speaks in foreign language)
The procedure involves taking the egg cells
from the monkeys and then fertilizing them in vitro,
in much the same way as we do with human egg cells.
Then we inject them with a virus
that is carrying the AHRGAP11B gene.
The virus then infects the fertilized egg cells
and integrates itself into the genetic material
of the marmoset.
And these egg cells are then transferred back
into the animal.
We stop the process on day 101 or 102,
in the second trimester,
meaning the animals are not born.
We terminate them in the fetal stage.
This was very important for us.
(gentle music)
It takes several months before
the first genetically altered monkey brains
arrive from Japan.
(speaks in foreign language)
Of course, we were sent pictures
of the first brains after they were taken out
of the monkeys.
After that, it took a very long time
to get all the approvals we needed
to import the brains into Germany.
(dramatic music)
(speaks in foreign language)
First we check if the specimens were kept cool
during transport.
If the cooling was ineffective,
than the RNA molecules can break down, for example.
That prevents us from being able to detect certain things.
Then we measure the standard parameters, such as the size.
And then the specimen goes for analysis.
We usually separate the two halves of the brain,
because that enables us to do
two different things with them.
What will these experiments reveal?
First, the brains of the monkey fetuses are encased in a gel
which allows the researchers to cut them
into wafer thin slices of just 90 micrometers in width.
(speaks in foreign language)
We're mainly interested in the stem cells.
If I were looking at the brain as a whole,
I wouldn't be able to see these stem cells.
The stem cells are found inside the brain.
(dramatic music)
That was perfect slicing, textbook stuff.
Michel Heide will analyze around a thousand
of these brain tissue samples over the next few months.
(speaks in foreign language)
So in the next step, we want to color these stem cells.
There are different populations of stem cells,
and if we looked at the section as it is,
we would just see groups of cells
that we can't distinguish from each other.
(gentle music)
Making stem cells visible to the human eye
is a complex process,
one that the scientists here have optimized
for their research.
(speaks in foreign language)
We use different markers for these neurons.
We can die the neurons that are found
deep inside the brain that are somewhat older
from an evolutionary perspective,
as well as neurons that are found higher up,
and are therefore younger.
What's interesting for us is not only
the number of stem cells,
but also the number of different neurons.
The question is whether AHRGAP11B causes the stem cells
to multiply, and therefore to increase
the number of neurons.
(dramatic music)
The moment of truth has arrived.
The results of years of research is finally here,
and proves in detail
what the researchers had only suspected.
It's a scientific breakthrough.
(speaks in foreign Language)
And the folds?
(speaks in foreign language)
Yes, you can see it here.
It starts at the front and then becomes more parietal.
And what becomes clearer here are the folds,
not so thick at first, but then getting thicker.
And here I started to measure the GI.
(speaks in foreign language)
And usually at this stage of growth,
there wouldn't be any folds.
(speaks in foreign language)
It would be completely smooth.
(speaks in foreign language)
Great.
And that's just in one, or in several of them?
(speaks in foreign language)
That's just from one as an example,
but you can see the same pattern in all the others.
(speaks in foreign language)
In all of them?
(speaks in foreign language)
To different degrees, of course,
but it's always visible.
The the results from the marmoset brains are impressive
because they show these folds,
even though the brains are normally completely smooth.
And we can also see that the brains are much larger
than they would usually be.
We can see that the relevant
stem cell populations have grown,
so we can observe all the things we were hoping to see.
(gentle music)
The AHRGAP11B gene has reproduced exactly
the same nerve cells that are also present
in large numbers in humans.
11B has therefore caused the brains to grow in mouse,
ferret, and marmoset embryos.
(speaks in foreign language)
When you look at these pictures,
they almost look like works of art.
The various colors merge into the different layers,
making for very impressive images.
(dramatic music)
Planning, taking action, understanding numbers,
awareness of our environment and fellow humans,
self-awareness.
Is our large brain the sole reason
for these exclusively human abilities?
Where exactly is the dividing line between man and ape?
(chess piece clattering)
(birds chirping)
Since 2001, Leipzig Zoo has been home
to the Wolfgang Kohler Primate Research Center,
also known as Pongoland.
Four species of great ape live here.
The center provides the scientists
of the Max Planck Institute for Evolutionary Anthropology
closer insights into the behavior
and cognitive abilities of hominids.
(speaks in foreign language)
I think that one of
the most important achievements of humans is education,
meaning that we're capable of passing knowledge on
to others, and not just from one person to another,
like from a parent to a child,
but also by passing knowledge down from one generation
to the next, in a collective and systematic manner.
(gentle music)
Dr. Katja Liebal is a professor
of comparative developmental psychology.
For years, she has been studying differences
in the ways humans and apes communicate.
(orangutan grunting)
(speaks in foreign language)
What we've just heard is
what's known as a long call.
It's a territorial call, which the primates also use
in the wild to indicate that the dominant male is claiming
a piece of land as his own.
And he sometimes does this to zoo visitors
whom he knows well, or is willing to tolerate.
He sometimes throws a few things around,
unfortunately not in any particular direction.
At that point, it's important to take a step back
and not provoke him any further.
Katja Lema carried out a large part of her PhD research
in Pongoland, also studying orangutans.
One of them was Bimbo, who can clearly still remember her.
(speaks in foreign language)
I actually performed, as an experiment,
to find out where the great apes come to each other's aid,
especially when they see something happening
to a fellow animal, such as being bothered by a human.
And the question was, how do you annoy apes
without crossing ethical boundaries
and irritating them too much?
So what we did is offer them food
and then pulled it away and ate it ourselves.
And that was enough to ensure that, even after 10 years,
he still can't stand the sight of me.
(upbeat music)
Bimbo's anger is clear to us
from his gestures and facial expressions.
But not everything can be translated directly.
(speaks in foreign language)
What we know is that the eyes, for example,
are not as strong a communicative signal
as they are in humans.
That's because the white sclera is missing.
They don't seem to use their eyes as much
to determine where someone is looking.
You can often see that, in interactions,
the orangutans themselves avoid direct eye contact.
In gorillas, that's also a strong signal.
It can even be understood as a threat
when a person stares at a gorilla.
(gentle music)
Unlike monkeys, humans communicate a lot with their eyes.
The dark circle of the pupil against the white background
enabled early humans to convey information wordlessly,
presumably long before spoken language developed.
Then came hand gestures and facial expressions,
important tools for communicating within a group.
(speaks in foreign language)
Monkeys don't use abstracts gestures like,
"It's okay," or, "I'm going for a cigarette."
Nor do they make symbolic gestures
that imitate movements or shapes.
Typical chimpanzee gestures would include
stretching out the arm to offer food.
They also do it sometimes to beg,
when another animal has food.
It is still often unclear what is meant
by the gestures and the facial expressions
of the great apes.
Our tendency to project human behavior
onto the ape's body language also makes
subjective research difficult.
One difference, however, is clear.
(speaks in foreign language)
One gesture we don't see the apes making
is pointing with their index finger.
Every gesture they make means the same thing.
I want something now, meaning I want food.
I want to play.
I want you to leave me alone.
I want to mate.
But they don't use gestures to say,
for example, "Look, did you see that bird up there?"
"It's raining," or, "Do you want to go outside?"
And apes are considerably worse than humans
in understanding the co-operative potential of gestures.
It's not in their nature to want to share information.
(gentle music)
Sharing one's own world with others.
No species can do that better than humans.
This new aspect to interhuman communication
was an important step in our development.
What makes us human is, largely,
our ability to cooperate with others.
(speaks in foreign language)
When we look at large primates,
it's worth asking ourselves,
how do they differ from small children?
We tend to think humans have a wonderful grasp
of cause and effect relationships
or can make complex predictions about the future,
when in fact, apes and humans are pretty much alike.
What humans excel at is any task that requires
more than one person.
In other words, we're better at coordinating our work,
better at working together.
And that is a tremendous advantage.
Human children are great at not only dividing the work
but they also understand that afterwards
they have to divide the profits.
So humans are good at anything that requires
more than two people.
(upbeat music)
And only because of this was modern man able to build
what we commonly know as human civilization.
(speaks in foreign language)
If we had to manage everything on our own
as individuals, we wouldn't have any time for art
or for building cities or palaces or whatever.
Instead, we'd be worrying all the time about
where our next meal is coming from
or who's going to look after our kids.
And it's only because we can delegate
some of our responsibilities to others
that we humans are able to achieve so much.
(gentle music)
But did this only become possible
after a gene we call AHRGAP11B triggered
the significant growth of our brain?
To answer this question,
the researchers at the Max Planck Institute in Dresden
had to study the workings of the gene in more detail.
The question was no longer if,
but rather how 11B created more brain cells.
What the scientists already knew was that
AHRGAP11B is the partial duplication of a gene
that also occurs in other mammals, AHRGAP11A.
This duplication led to the creation of AHRGAP11B.
This process only occurs in humans, however,
and not in any other mammal.
(speaks in foreign language)
The partial duplication of the gene took place
around five million years ago.
But the brains of our hominid ancestors
five million years ago
were also very small in comparison.
This means that this gene duplication cannot explain
why our brains are so large,
because they would have grown much earlier on,
which they didn't.
(dramatic music)
In other words, the duplication of gene 11A to gene 11B
had no initial effect.
When 11B came into existence some 5 million years ago,
modern man was still a long way off.
(speaks in foreign language)
What humans are particularly good at
is putting themselves in other people's position.
We call it the theory of the mind.
Other animals can do it too, but we do it particularly well.
(upbeat music)
The scientists at the Max Planck Institute
for Evolutionary Anthropology in Leipzig are studying
the development of hominids.
Doctor Phillip Guntz is a paleo-anthropologist
and an expert on what our earliest ancestors looked like
five million years ago.
(speaks in foreign language)
The ancestors of the Australopithecus
left in Africa five million years ago.
Australopithecus is a genus of hominin best known
from the famous Lucy, who was discovered in the 1970s.
From Lucy and her contemporaries,
we know that they walked upright
and lived on the Savannah of Eastern Africa.
Not until the start of the human lineage
around two million years ago
do we see brain volume beginning to increase.
(upbeat music)
But if, for millions of years, gene 11B failed to trigger
any increase in human brain size,
why did the brain's stem cells suddenly
begin to multiply so quickly?
The Dresden scientists found the answer to this question
inside the gene itself.
A minuscule change, known as a point mutation,
which gave 11B a completely new function.
(speaks in foreign language)
We managed to rebuild and test the gene,
as it originally came to exist 5 million years ago,
through duplication.
It doesn't do anything on its own.
It is only via the point mutation
that the unique characteristic of this gene,
it's ability to enlarge the brain, comes about,
during the development of the fetus.
And we are convinced that this point mutation occurred
much later than 5 million years ago,
probably more around one and a half million years ago,
when there was this enormous boost in brain size development
in the human lineage.
(dramatic music)
This sudden genetic mutation in AHRGAP11B was as unlikely
as a lottery ticket with six matching numbers.
Point mutations alter only one of several thousand
nucleotide bases inside a gene.
In 11B, this coincidence led to a change
in the transcription process of the RNA
and thus to a completely new effect.
Due to the mutation, 11B received the signal
to migrate from the cell nucleus into the mitochondria,
where the cell produces its energy.
And once there, it ensured that the stem cells
would divide much more frequently,
which meant, in short, that humans gained
a much larger hard drive.
The Dresden scientists had found
the proverbial needle in a haystack,
because mutations like this have taken place
millions of times throughout human evolution,
but mostly without any consequences.
(speaks in foreign language)
There are many kinds of mutations
in the human body.
Everybody carries mutations inside them,
which can give rise to benign or malignant tumors.
However, most mutations don't make any difference.
Only very few of them actually have a positive effect,
and natural selection only heeds positive changes.
These are the changes that can survive
the entire evolutionary process.
We know that there are a lot of genetic similarities
between modern humans and our closest living relatives,
the bonobos and the chimpanzees.
And what that means is that often
very small differences can have a substantial effect.
(upbeat music)
The growing brain needs more space.
So how did our ancestors' boney skulls adapt
to the larger brain?
(speaks in foreign language)
Here, we can reach a pretty clear conclusion.
This is a 3D model of a human baby's skull.
The fontanelle is still open directly after birth
and the bones are not yet fused together.
As the brain expands, it pushes the skull outwards.
At this early stage of development,
the increasing volume of the brain is what drives
the growth of the skull.
(upbeat music)
In 2011, researchers from the Max Planck Institute
for Evolutionary Anthropology managed to decode
the Neanderthal genome for the first time.
As the data shows, Neanderthals also possess
the mutated AHRGAP11B gene,
and had a brain of similar size to modern humans.
This suggests that the point mutation of 11B
must have taken place before the development
of the Neanderthals.
(speaks in foreign language)
We know for a fact that modern man
and Neanderthals share a common ancestor,
who was alive at least 600,000 years ago.
(lively music)
This ancestor was homo erectus.
The point mutation of gene 11B presumably started
in a member of this species.
(speaks in foreign language)
Homo erectus is the first human ancestor
to have lived throughout the old world,
meaning Africa, Europe, and Asia.
They didn't make it to the Americas, as far as we know.
They had brains that were more than double the size
of those of the great apes alive today.
Homo erectus was a talented hunter-gatherer
and probably hunted large prey using spears.
(lively music)
However, it does not appear that the results
of this genetic mutations spread like wildfire
throughout the species.
(speaks in foreign language)
Without knowing exactly how this gene works,
we can assume that its effects were not
particularly dramatic at the start,
because natural selection normally filters out
any extreme changes.
Brain volume in humans constantly double overnight.
Brains that size require a lot of energy
and energy is the currency, so to speak,
that nature deals in.
An organism has to be able to afford such a large brain.
We think homo erectus could sustain a brain of this size
because it consumed a very high-energy diet
through its highly effective hunting methods,
and therefore had a surplus of energy.
So we can assume that the increase in brain size was
a gradual change that took place in early childhood.
(lively music)
Our forefathers' direct descendants, therefore,
had more neurons at their disposal,
allowing them to develop their cognitive abilities.
(speaks in foreign language)
There are some basic conditions
that we need to meet in order to get the most
out of this large brain.
The first is that you have to be able to sustain the brain.
That means we need the food, we need the energy
so that this brain can keep working.
Then we need to network with others.
That means that we really have to use the first years
of our life to learn from other people,
because there's an incredible amount in human society
that we have to understand,
in terms of what we can or cannot do.
Otherwise we risk being excluded from society later on.
As individuals, we will not get far on our own.
(upbeat music)
The random mutation of AHRGAP11B was clearly
such an enormous evolutionary advantage
that the mutated gene was passed on
to all of homo erectus' descendants,
and therefore to the entire human race.
If the carrier of the mutated gene had died
in the plains of Africa without any offspring,
modern man would probably not exist.
(gentle music)
What the homo genus did with this random coincidence,
and what sets it apart from its forefathers
is also being studied by the primatological
at the Max Planck Institute in Leipzig.
(speaks in foreign language)
What sets humans apart is language,
symbolic communication.
No other creatures can express their feelings,
their thoughts, and their wishes
in the same way that we can.
(gentle music)
Dr. Roman Wittig is the director of the chimpanzee project
in the Thai National Park in Ivory Coast.
Observing chimpanzees in their natural habitat
has given researchers some insights
into the evolutionary basis of human behavior.
(speaks in foreign language)
Around seven to eight million years ago,
some of our ancestors went out into the Savannah.
They had to face new challenges,
and the pressures of natural selection were so strong
that a substantial change took place,
which ultimately led to modern man.
While the remainder of our ancestors stayed
where they had always been, in the forest,
in the tropical forests of Africa.
The processes of selection that affected these apes
were much more conservative,
and that is why evolution was more limited in their case.
We can therefore assume that the behavior of our ancestors
some seven to eight million years ago was far closer
to that of chimpanzees than it would be
to our behavior today.
That's why it makes sense to study these animals closely,
in order to understand where we as a species come from.
These studies have shown that we have much more in common
with chimpanzees than we realize.
They too form social units, share food,
maintain friendships, show empathy, use tools, communicate,
and probably dream.
Groups of chimpanzees have even been shown
to form their own individual cultures.
(speaks in foreign language)
We have studied chimpanzee cultures
for the first time, by looking at behavioral variations
We found, for example, that although there are kuna nuts
all over West Africa,
only part of the chimpanzee population cracks these nuts
in this area.
And why is this?
There is no ecological reason for it,
and there's no genetic reason for it.
So what is the reason?
It's how the chimpanzees show
which social group they belong to,
which culture they belong to.
Just like we do when we eat rice with chopsticks
or a fork, or with our hands.
(gentle music)
(speaks in foreign language)
We're the only species
that carries tools around all day,
and not just our mobile phones.
In the past it was a pocket knife, a watch,
even our clothes or glasses.
These things become a part of who we are.
So our culture is part of who we are.
(dramatic music)
But while the cultural evolution of our ape cousins
came to a standstill,
that of humans continued to develop exponentially
(speaks in foreign language)
If we looked at our evolutionary development
as a curve, it would go like this.
And that's something that Darwin alone cannot explain.
This idea that the current generation must die out
before we can take a few steps forward,
and then after that, the next generation must die out,
that won't help us to develop at the same rate
we have managed to over the last 40,000 years.
And all those things that we associate with humans,
religion, culture, tools with small moving parts,
these are all things that have been created
in this very short period of time.
The reason that we've evolved so fast as a species
is that we don't have to invent everything
from scratch each time.
An engineering student doesn't have to figure out
on their own how a steam engine works.
We can build on knowledge that has been gained by others.
So in a sense, cultural evolution is our evolution.
(dramatic music)
From I to we.
Only humans are capable of uniting
hundreds of thousands of their own species
under a single idea.
Only humans have managed to bring together
and organized millions of others in one place.
Our social intelligence was one of the key factors
behind our remarkable development as a species
(speaks in foreign language)
So we believe that our social intelligence is
not just a byproduct of our evolution,
of our growth as a species,
but actually one of the driving forces behind it.
And the whole thing is then taken a step further
by the cultural intelligence hypothesis,
which basically says that the passing on
of this cultural information,
such as the mastery of fire and so on,
is what has caused our brains to grow so much.
(rhythmic music)
So, what are our evolutionary advantages?
We don't even have fire.
We need to wear clothes to survive.
We don't have claws or especially strong muscles.
In fact, we have lost much of our original muscle mass,
so we have the energy to feed
our incredibly powerful brains.
We're not built to survive on our own,
but instead we've created a community that we can rely on.
(upbeat music)
We often think we've had enough of other people
and that it will be nice to withdraw
to a desert island somewhere.
But we wouldn't survive on a desert island.
We wouldn't manage to meet our own needs
and we'd get very hungry.
And that's the point.
The community is a part of who we are
and we would not exist without the community.
(upbeat music)
Living in groups provides protection, sustenance,
and a sense of belonging.
But it also creates competition for food,
territory, and reproductive partners.
This can cause friction and aggression.
(speaks in foreign language)
This competition needs to be managed
in some way.
Not everyone can eat the same piece of fruit.
We have observed how chimpanzees follow
a kind of decision-making process.
They ask themselves, should I accept that another animal
has this piece of fruit and that I can't have it?
Should I share the fruit
or should I hit him and steal the fruit for myself?
Our early ancestors had different ways
of resolving aggressive conflict.
Similar methods can be observed in chimpanzees to this day.
(chimps hooting)
(speaks in foreign language)
When chimpanzees get into conflicts
over borders, a number of different things can happen.
The first thing is that they detect the other animals
and a loud fight ensues.
They beat the roots of the trees
and make pant hoots and pant roars.
These are very loud calls
that can be heard for miles around.
(chimp hooting and screaming)
And usually, these battle cries are enough
to determine which of the two groups should retreat.
But sometimes this is not enough,
and the chimpanzees confront each other to show
how big their group is, who is taller,
who is stronger, and so on.
(chimps screaming)
And sometimes, these direct physical fights take place,
which can result in injuries or even deaths.
What we haven't observed so far in these fights,
however, is the use of weapons.
Although chimpanzees understand how to crack a nut
using a stone, we've never seen them use weapons like this
in their conflicts with other animals.
(dramatic music)
Unlike humans, conflicts are a part of everyday life
for all primate groups.
Waging war with deadly weapons, however,
is an invention of modern man.
This is the other side of our species' social
and cultural cognition.
(bomb blasting)
(upbeat music)
Can the genetic researchers from Dresden imagine apes
with the AHRGAP11B gene also becoming like humans
in this respect?
Under research director Dr. Wieland Huttner,
this question will never be put to the test.
(speaks in foreign language)
No, tests on apes and not allowed.
And with good reason.
These animals are very close to us,
and I think it's absolutely right
that they should be off-limits for such experiments.
I think it would be highly irresponsible
to manipulate orangutans or chimpanzees
or gorillas in this way.
(speaks in foreign language)
How old is Tony now?
(speaks in foreign language)
Tony's 28.
He was born on the 13th of December, 1991.
(dramatic music)
Dr. Huttner also rules out any further application
of their research results, either for apes or for humans.
(speaks in foreign language)
What is out of the question for me
as a medical scientist, I repeat,
absolutely out of the question
is any attempt to quote/unquote "enhance human brains"
by, let's say, smuggling in a second 11B gene
or a more effective 11B gene.
I would consider this to be highly irresponsible.
You have to be quite clear,
human brains are not necessarily better.
My research has been about finding out
why we have a large brain.
I think this is a fundamental question,
because it helps us to understand why we humans
are the way we are.
But to find some way of applying these findings, no.
(gentle music)
Although the findings from Dresden
won't be tested on living people,
the results are so compelling
that they leave little room for doubt.
Yet, the researchers are still looking
for further proof of their theory.
(speaks in foreign language)
We now have proof that 11B can increase
the size of the brain.
And that's what Michel Heide's work has shown us.
But there is no data so far to tell us
what happens if 11B is missing in humans.
Would these people have smaller brains?
There haven't been any humans in whom
11B is completely lacking.
That's in itself tells us something.
(speaks in foreign language)
I don't think we can go any farther
in terms of introducing this gene into other organisms.
Another way, of course, would be to look for patients
who either have mutations in AHRGAP11B
or some kind of loss,
and to see what their brains look like.
This could of course be done noninvasively,
using MRI or something like that.
(gentle music)
A way of using their findings will be left to others
to figure out over the coming years, or even generations.
But Michel Heide's research work is far from over.
(speaks in foreign language)
We don't just have this one gene.
Michel Haida has discovered 14 others
that are specific to humans
and that are highly active in stem cells,
that're sure to be a backup.
(speaks in foreign language)
And another interesting question for me is,
there are 15 genes, are there natural interactions
between these genes?
Are there networks that overlap?
How do these genes interact with each other?
This is another exciting question
that remains to be answered.
(dramatic music)
If the research findings of the Dresden scientists
can be substantiated over the next few years,
Wieland Huttner could one day experience the completion
of his life's work,
a comprehensive theory about the growth of the human brain,
an essential piece of the puzzle that is human evolution.
A world-changing coincidence
that many hundreds of thousands of years ago
made the miracle of homo sapiens sapiens possible.
(gentle piano music)
♪ 11B, 11B, ♪
♪ 11B, 11B ♪
♪ Speaking words of wisdom, 11B ♪
♪ 11B, 11B ♪
♪ Speaking words of wisdom, 11B ♪