00:00:04
humans without a doubt the smartest
00:00:06
animal on earth yet we're unmistakably
00:00:10
tied to our ape
00:00:12
Origins millions of years ago we were
00:00:15
Apes living ape lives in Africa so how
00:00:19
did we get from
00:00:20
that to
00:00:24
this what happened what set us on the
00:00:28
path to humanity
00:00:31
the questions are huge but now there are
00:00:35
answers at the threshold of humanity one
00:00:39
ancestor contains tantalizing Secrets it
00:00:42
is known as Homo erectus homoerectus had
00:00:46
a slightly smaller brain slightly bigger
00:00:47
jaw but it's basically
00:00:51
us basically
00:00:53
us almost 2 million years
00:00:58
ago new finds are revealing the truth
00:01:01
about the ancestors at the heart of our
00:01:04
Evolution here were the Trailblazers who
00:01:07
first left Africa the first fir makers
00:01:12
the first
00:01:13
Hunters these creatures were capable of
00:01:15
analizing possible uses of tools and
00:01:17
coming up with a technological solution
00:01:19
to the problem how do you kill a big
00:01:20
dangerous animal without getting killed
00:01:23
yourself Homo erectus pioneered what it
00:01:26
means to be human colonizing whole
00:01:29
continents and creating the first human
00:01:33
societies our ancestors began to care
00:01:36
about what others thought and care about
00:01:39
what that individual thought about them
00:01:43
now new discoveries are bringing them
00:01:45
alive as never before at last we come
00:01:49
face to face with the ancestors at the
00:01:52
birth of humanity right now on Nova
00:02:11
major funding for Nova is provided by
00:02:14
the
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[Music]
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following the Great Rift valy Valley of
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East
00:02:33
Africa 2 million years ago these
00:02:36
spectacular Plains and canyons witnessed
00:02:39
a mysterious
00:02:41
event the birth of the first ancestor we
00:02:45
can really call
00:02:48
human new discoveries are revealing a
00:02:51
creature surprisingly like us a world
00:02:54
traveler a tool maker a hunter Tamer of
00:02:58
Fire creator of the first human
00:03:03
societies amazingly the qualities that
00:03:06
make us human began not with our own
00:03:09
species Homo
00:03:14
sapiens the true birth of humanity began
00:03:18
much further back in time millions of
00:03:21
years
00:03:23
ago imagine the entire span of recorded
00:03:27
human history about 5,000 years years
00:03:30
taking us back to the Egyptian pyramids
00:03:34
double it 10,000 years to the time when
00:03:37
plants are domesticated and agriculture
00:03:41
begins double it again 20,000 years Ice
00:03:46
Age Hunters are painting stunning images
00:03:48
on Cave walls and keep doubling six more
00:03:52
times only then do we encounter our
00:03:56
ancestor Homo erectus in Africa's great
00:03:59
Rift
00:04:05
Valley for millions of years this
00:04:08
massive geological fault line running
00:04:10
the length of East Africa was a stage on
00:04:13
which our human evolution was played
00:04:16
[Music]
00:04:17
out it all started with the first Apes
00:04:20
to walk upright on two legs about 6
00:04:23
million years
00:04:26
[Music]
00:04:28
ago there were many different types all
00:04:31
variations on the same theme aplike
00:04:34
creatures with small
00:04:37
brains the fossil known as Lucy is the
00:04:40
most famous
00:04:42
example here she is just 3' 8 in tall
00:04:47
with a brain the size of a
00:04:51
chimps for millions of years creatures
00:04:54
like her roam the forests and grasslands
00:04:57
of
00:04:58
Africa but then
00:05:00
something
00:05:04
changed about 2 million years ago new
00:05:07
creatures appeared with abilities never
00:05:09
seen before in the animal
00:05:12
kingdom meet Homo erectus a toolmaker
00:05:16
and
00:05:17
Hunter one of the first members of our
00:05:20
genus the genus homo
00:05:23
humans the transition to homo was
00:05:26
probably one of the most important
00:05:27
Transformations that occurred in human
00:05:28
evolution
00:05:30
arms got thinner legs got longer brains
00:05:34
got bigger it was a huge evolutionary
00:05:37
step from eight bodies to bodies like
00:05:42
ours but what about the things that make
00:05:45
us distinctly human
00:05:48
creativity intelligence caring for each
00:05:51
other how can we know when these got
00:05:56
started with only skulls and Bone
00:05:59
fragments to go on how could we ever
00:06:02
know what those first humans were really
00:06:05
like it would take a momentous find to
00:06:08
shed light on their
00:06:13
lives Lake turana Northern
00:06:17
Kenya surrounded by volcanoes and vast
00:06:20
expanses of baking
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desert in 1984 famed anthropologists
00:06:27
Richard and me leaky were working at
00:06:30
this remote Inland Sea I was actually on
00:06:33
the east side of the lake and then
00:06:34
Richard flew over and said you've got to
00:06:36
come there's something really
00:06:38
exciting as the first family of
00:06:41
paleoanthropology the Leakes were used
00:06:43
to Fossil
00:06:45
fins but this was very
00:06:48
special one of leak's team had found a
00:06:51
skull fragment of one of those early
00:06:53
humans he could tell from its size and
00:06:56
shape it was Homo erectus and there was
00:06:59
more than just a fragment so we started
00:07:02
looking at this site on a on a more
00:07:04
extensive basis and of course once we
00:07:06
did we found the rest of the skull a
00:07:08
complete skull was rare enough but it
00:07:11
was just the beginning soon parts of the
00:07:14
homo erectus skeleton which had never
00:07:16
been found before started to emerge we
00:07:20
couldn't believe it but we started
00:07:21
getting pieces of ribs these were parts
00:07:24
of hom Reus that nobody actually knew
00:07:26
about nobody had ever seen before so
00:07:28
every bone that came out of the ground
00:07:29
was was something brand new to science
00:07:31
and and we were looking at these things
00:07:32
and it was really
00:07:35
amazing and here they are the actual
00:07:38
bones of a human ancestor who lived over
00:07:41
1 and A2 million years ago it's the
00:07:45
earliest human skeleton ever discovered
00:07:48
the Leaky called him turab
00:07:53
boy his bones have revolutionized our
00:07:56
understanding of the transition from a
00:07:59
to human the really important thing
00:08:01
about Turon boy is how complete he is
00:08:04
we've got arms and legs and bits of his
00:08:06
spine and his ribs and usually when we
00:08:09
find these things we get very excited
00:08:11
about one little bit of bone but that
00:08:15
little bit can't tell us very much about
00:08:17
an individual so having a nearly
00:08:20
complete skeleton we can start to ask
00:08:22
big
00:08:24
questions the first big question was
00:08:28
what did he look like
00:08:30
his skeleton tells us he was 5' 3 in
00:08:32
tall with a build closer to a man's than
00:08:35
an
00:08:37
ap's but how
00:08:42
close paleo artist Victor deck
00:08:45
specializes in painting and sculpting
00:08:47
our human ancestors with precise
00:08:50
anatomical
00:08:55
[Music]
00:08:57
accuracy Victor's going to add turab boy
00:09:01
to his family of ancient
00:09:03
faces at this stage of the game I know
00:09:06
that turab boy is not an ape he is a
00:09:10
very early true human and so here we
00:09:13
have a modern human skull the faces are
00:09:17
very similar to one another but turab
00:09:19
boy's skull is a bit more primitive and
00:09:22
has a lower forehead and a much smaller
00:09:25
brain
00:09:27
capacity Victor will build to boy's face
00:09:30
muscle by
00:09:32
muscle based on his studies of cadavers
00:09:35
and modern
00:09:41
Anatomy while his head may be primitive
00:09:44
tono skeleton is surprisingly human his
00:09:48
hips are a little wider his arms a
00:09:51
little longer but his overall body shape
00:09:54
is just like
00:09:56
ours tonoy and erectus that's something
00:09:59
that if you were to see from 100 ft away
00:10:02
you would think well there's a large
00:10:05
naked man there woman or or you know but
00:10:07
it's a
00:10:12
human it will take Victor a week to
00:10:15
flush out tur boy's
00:10:19
face meanwhile a team of animators is at
00:10:22
work creating scenes that will bring tab
00:10:26
boy and his people to life to make sure
00:10:29
they they do it accurately they have
00:10:30
Enlisted the help of Harvard
00:10:32
Anthropologist Dan liberman they've had
00:10:35
a more forward position of the PMS when
00:10:37
they ran just slightly there you
00:10:40
go the blue suited actors are there to
00:10:43
create movement references for the
00:10:46
artists in the final animations they
00:10:49
will be replaced by Homo erectus bodies
00:10:52
and action their heads and faces based
00:10:55
closely on Victor's model
00:11:00
as tab boy's forensically reconstructed
00:11:03
head nears
00:11:04
completion a face emerges that looks a
00:11:08
lot like
00:11:11
us now for the first time in a million
00:11:13
and a half years here he is our ancestor
00:11:18
the homo erectus called turab
00:11:21
boy but what he looked like is only the
00:11:25
beginning of his
00:11:26
story to reconstruct his life we need to
00:11:30
find out how old he was and if we look
00:11:33
at his skeleton we can see that the
00:11:36
growth plates on his limbs that would
00:11:38
fuse when he's fully adult are all
00:11:41
unfused so even though he's very tall we
00:11:44
know that he's still
00:11:47
growing the fact that toab boy was not
00:11:50
fully grown has turned out to be a boon
00:11:52
to
00:11:53
researchers you can answer questions
00:11:55
like did the boy grow up like a modern
00:11:58
human or did he grow up more like an
00:12:01
ape tur boy was already 5' 3 in tall
00:12:07
when scientists compared his bones and
00:12:09
teeth to ours he seemed to be about 14
00:12:12
years old but when dental specialist
00:12:15
Chris Dean began to study his teeth he
00:12:18
was in for a
00:12:21
shock it turns out that all teeth fossil
00:12:24
or not preserve a remarkably precise
00:12:27
record of childhood
00:12:30
this is a fossil tooth and we can see
00:12:33
the enamel cap which covers the core of
00:12:36
the tooth which is made of dentine uh
00:12:38
dentine is just another word for Ivory
00:12:41
and within the enamel you can see the
00:12:43
rods which are running from the enamel
00:12:45
denting Junction here out to the surface
00:12:47
of the
00:12:49
tooth enamel has a regular growth
00:12:51
pattern like the rings of a
00:12:54
tree under an electron microscope it
00:12:57
looks like rods made of tiny beads each
00:13:00
of the little beads along these prisms
00:13:03
represent one day's growth because the
00:13:05
cells which produce enamel are actually
00:13:08
under the influence of a circadian or
00:13:10
daily clock and those secretions during
00:13:14
the day speed up and then slow down and
00:13:17
there's a permanent record of that in
00:13:19
every
00:13:20
tooth so you can see rods running all
00:13:24
the way through this tissue and every
00:13:27
day along the rod there is a wobble
00:13:30
where the tissue slows down and then
00:13:32
speeds
00:13:33
up so if you count the beads in these
00:13:36
strings you can figure out exactly how
00:13:38
many days that tooth has been
00:13:41
growing when Chris looked at the
00:13:43
fossilized teeth of tab boy he got a
00:13:46
huge surprise turab boy wasn't 14 years
00:13:50
old he was
00:13:52
eight what that implies is that the
00:13:55
growth of the takana boy resembled more
00:13:58
closely than of chimpanzees today to be
00:14:02
5'3 at age 8 turab boy must have grown
00:14:05
up very fast at a rate closer to chimps
00:14:09
than
00:14:10
us a chimpanzee's childhood is short it
00:14:14
is sexually mature at about
00:14:17
7 human childhood is longer we reach
00:14:21
puberty at about
00:14:23
12 so as humans evolved from apes
00:14:26
childhood was extended
00:14:29
but what advantage could be gained by
00:14:32
having helpless children around to feed
00:14:34
and care for who take so long to grow
00:14:39
up the mystery of prolonged childhood is
00:14:42
at the heart of human evolution it may
00:14:45
be related to brain
00:14:51
size we humans have the biggest brains
00:14:54
in the animal kingdom in relation to our
00:14:56
body
00:14:57
size they're so big big that most of our
00:15:00
brain growth has to happen outside the
00:15:02
womb or our heads would never get
00:15:04
through the birth
00:15:06
canal a long slow childhood gives our
00:15:09
brains time to grow after
00:15:11
birth and time to learn everything we
00:15:15
need to function in our complex human
00:15:19
societies that's the advantage of
00:15:21
prolonged childhood for us at
00:15:24
least but what about turab boy
00:15:29
his brain was 9900 cubic cm smaller than
00:15:32
ours but more than twice as large as a
00:15:36
chimp's so was he on the way to thinking
00:15:40
and Talking Like
00:15:42
Us Ralph Holloway believes he was he's
00:15:46
been collecting the brain endocasts of
00:15:49
human ancestors for over 30
00:15:52
years an endocast is a mold taken from
00:15:56
the inside of the skull which reveals
00:15:58
the shape of the brain Ralph is
00:16:01
particularly interested in something
00:16:03
called the brokas area brokas area
00:16:07
involved with memory functions executive
00:16:10
functions but it does have a very
00:16:12
important role to play in the motor
00:16:14
aspects of
00:16:16
speech in the brain of turab boy Ralph
00:16:19
believes he sees evidence for something
00:16:22
remarkable a change in the broka area
00:16:25
tied to
00:16:27
communication broka cat regions on the
00:16:30
turab boy are fully modern in terms of
00:16:33
their appearance it is good solid
00:16:36
evidence for the having the ability of
00:16:39
symbolic Communication in other words
00:16:42
language it's a controversial idea and
00:16:46
we'll never know for sure if turab boy
00:16:48
could speak
00:16:57
but
00:17:27
e
00:17:57
e
00:18:27
e
00:18:57
e
00:19:27
e
00:19:57
e
00:20:27
e e
00:21:04
and Africa was filled with it the one
00:21:07
highquality resource that's probably
00:21:09
most important for the evolution of the
00:21:10
genus homo is meat and meat bribe
00:21:13
products such as brain and Marrow and
00:21:15
fat they're high in protein they're high
00:21:17
in calories and they're easy to digest
00:21:20
but the one problem with getting meat is
00:21:22
that it's hard to get most Predators
00:21:25
rely on strength or speed to kill the
00:21:28
prey our ancestors had
00:21:32
neither today we are on top of the food
00:21:35
chain so it's hard to imagine the
00:21:37
predicament of those early
00:21:40
humans here was a slow moving creature
00:21:43
with no claws or fangs easy prey for the
00:21:47
hungry Predators around
00:21:51
him this is a fossil forehead and brow
00:21:54
Ridge of a homo erectus and on the brow
00:21:58
rid you can see the bite mark of a
00:22:01
carnivore well this reminds us that
00:22:03
these homoerectus individuals weren't at
00:22:06
the top of the food
00:22:08
chain so how did turab boy a weakling
00:22:11
with a big brain which needed calories
00:22:15
get his meat homoerectus faced a problem
00:22:18
how do you kill a big dangerous animal
00:22:20
that has lots of meat and fat in it
00:22:22
without that animal also killing you I
00:22:24
think the answer to that was a very
00:22:26
clever set of Innovations and that is
00:22:29
endurance running and high activity in
00:22:31
the middle of the
00:22:33
day the ancestors of homo erectus small
00:22:37
hairy Apes like Lucy were bipedal but
00:22:41
probably didn't do much
00:22:44
running but tab boy kind were built to
00:22:47
run like us a this is an accelerometer
00:22:52
Dan liberman believes they could run
00:22:53
long distances because like us they had
00:22:57
lost their thick coat of body hair and
00:23:00
could keep Cool by sweating ha's not on
00:23:02
this was the key to their
00:23:06
success but how do we know if these
00:23:08
crucial changes go back all the way to
00:23:11
toana boy's time over a million years
00:23:15
ago skin and hair are rarely preserved
00:23:18
in the fossil record so to find out we
00:23:21
have to look to a creature that's been
00:23:23
intimately connected with hair for a
00:23:26
long time the LA
00:23:29
all animals seem to have some type of
00:23:30
lice to parasitize them mammals have
00:23:33
them birds have them even fish have
00:23:35
types of lice but most other creatures
00:23:38
have only one type of Li that parasitize
00:23:40
them humans have one kind of Lous on
00:23:43
their heads and another in the pubic
00:23:46
area geneticist Mark stoning asked
00:23:49
himself why the answer that seems
00:23:52
obvious is that when we had body hair
00:23:53
all over our bodies we had one type of
00:23:56
Lies but then we became hairless until
00:23:58
we only add hair on our heads and in our
00:24:00
pubic region and so therefore you would
00:24:02
have this hairless Geographic barrier to
00:24:05
contact between the
00:24:06
two Mark was surprised to find out that
00:24:09
the human pubic louse is very different
00:24:12
from the human head louse somehow in the
00:24:15
past it seems to have come from
00:24:18
gorillas because the pubic Li that is
00:24:21
actually more closely related to gorilla
00:24:22
lice now how it is our ancestors got
00:24:24
pubic lice from gorillas I wouldn't care
00:24:27
to
00:24:29
speculate nonetheless one needs gorilla
00:24:32
life in order to really work this whole
00:24:34
thing
00:24:35
out the most likely scenario is that
00:24:39
when we lost our body hair the original
00:24:41
human louse migrated to our heads
00:24:45
leaving the pubic area temporarily
00:24:47
unpopulated by lice when our ancestors
00:24:51
had contact with gorillas perhaps
00:24:54
sleeping in their nests or Scavenging
00:24:56
their bodies for meat the gorilla louse
00:25:00
colonized their pubic region eventually
00:25:03
it turned into the human pubic louse of
00:25:07
today so if we could find out when the
00:25:10
human pubic louse and the gorilla louse
00:25:13
diverged we would have a rough idea of
00:25:16
when we lost our body
00:25:19
hair fortunately there's a way to figure
00:25:22
that out the genetic dating technique
00:25:25
known as the molecular clock
00:25:28
it's based on the fact that the sequence
00:25:30
of chemical bases which make up DNA
00:25:34
mutate at a regular rate it's just a
00:25:37
very simple idea that the rate of change
00:25:40
in DNA sequences is more or less
00:25:43
constant over time and that means that
00:25:45
you have a way of determining when two
00:25:48
species last Shar a common
00:25:51
ancestor by counting the number of
00:25:53
differences in the genetic code of two
00:25:55
species scientists can determine how
00:25:58
long they've been evolving away from
00:26:00
each other when Mark used the molecular
00:26:03
clock to count the differences between
00:26:06
the DNA of gorilla lice and human pubic
00:26:10
lice he came up with a date for their
00:26:13
Divergence the estimated date for the
00:26:15
Divergence is roughly 3 million years
00:26:18
ago that means long before turab boy
00:26:21
maybe even around Lucy's time our
00:26:24
ancestors had slowly begun to lose their
00:26:27
body hair
00:26:31
turab boy was mostly hairless just like
00:26:37
us and that may be what gave him an edge
00:26:40
over other
00:26:42
Predators most animals are at a
00:26:45
disadvantage in the midday sun because
00:26:47
they overheat they can only cool down by
00:26:51
panting and when they run fast they
00:26:54
can't pant that means they can only run
00:26:58
in in short
00:27:00
Sprints quadrupeds can G for about 10 to
00:27:02
15 minutes and then they overheat but
00:27:05
hominids can cool down by sweating they
00:27:08
use their entire body like like a dog's
00:27:11
tongue our hairless bodies allow air to
00:27:15
circulate freely on our skin and cool us
00:27:18
down as sweat evaporates this makes us
00:27:21
one of the best longdistance runners in
00:27:23
the animal
00:27:25
kingdom Dan liberman believes this gave
00:27:27
our ancestors the ability to hunt in a
00:27:31
very unusual way it's called persistence
00:27:35
[Music]
00:27:37
hunting and he believes the modern
00:27:40
ethnographic record can show us how it
00:27:42
was
00:27:45
done the Bushmen of the Kalahari offer
00:27:49
us an insight into how Homo erectus
00:27:52
might have hunted 2 million years
00:27:55
ago the Bushmen know that at midday
00:27:59
animals rest in the shade which is why
00:28:02
it's the perfect time to be
00:28:04
hunting once they locate their prey in
00:28:08
this case audo the marathon
00:28:11
[Music]
00:28:17
begins their strategy is simple run it
00:28:20
to
00:28:22
exhaustion every time the animal tries
00:28:25
to rest the hunters track it down and
00:28:28
get it moving again they never give it a
00:28:31
chance to cool
00:28:33
down and the reason they can keep going
00:28:36
is that they can
00:28:41
sweat so if the theory is right the
00:28:44
Bushman hunt may help explain how tab
00:28:47
boy got his
00:28:50
meat Homo erectus had come up with an
00:28:53
Innovative way of feeding his hungry
00:28:56
brain
00:29:02
in this modern hunt the Bushmen ran in
00:29:05
the fierce heat for over 4
00:29:09
hours the kudu was finally immobilized
00:29:12
by heat
00:29:15
stroke turab boy wouldn't have had steel
00:29:19
tip Spears like the Bushmen but he
00:29:22
wouldn't have needed
00:29:26
them hom is probably hunted with Close
00:29:28
Quarters weapons with Spears that were
00:29:30
thrown at animals from a short distance
00:29:32
clubs thrown rocks weapons like that
00:29:35
they weren't using longdistance
00:29:37
projectile weapons that we know
00:29:38
[Music]
00:29:41
of the homo erectus hunt was simple but
00:29:46
effective it fed not just their larger
00:29:48
brains but the growing complexity of
00:29:51
that early human society
00:29:58
there are other social animals but none
00:30:01
quite like
00:30:02
[Music]
00:30:06
us Society is in every corner of our
00:30:09
lives our relationships
00:30:12
communication rules symbolism all the
00:30:16
things that bind us
00:30:18
together what's behind it why do we
00:30:21
become so
00:30:24
social could it have something to do
00:30:27
with another
00:30:29
Innovation something unprecedented in
00:30:31
our
00:30:33
Evolution building fires and
00:30:36
cooking here we got erectus the first
00:30:39
species that looks like us and I think
00:30:41
only cooking can explain the magnitude
00:30:44
of this
00:30:45
change the earliest evidence that our
00:30:48
ancestors deliberately used fire for
00:30:50
cooking dates to long after taboy
00:30:54
time but Richard rangam is sure homeo
00:30:58
erectus was building fires much
00:31:02
earlier now for the first time we had a
00:31:04
species that was committed to living on
00:31:06
the ground because they lose their
00:31:08
climbing
00:31:09
adaptations well how were they sleeping
00:31:13
they had to be able to protect
00:31:14
themselves from wild animals on the
00:31:17
African Savannah full of predators who
00:31:20
hunt by Night Richard believes turab boy
00:31:23
and his people couldn't have survived
00:31:26
Without fire
00:31:28
and he thinks only cooking which makes
00:31:31
food more soft and digestible can
00:31:33
explain why Homo erectus evolves smaller
00:31:37
teeth and a much smaller gut these
00:31:40
things are compatible with the reduced
00:31:42
cost of digestion produced by cooking
00:31:44
food nothing else is as our ancestors
00:31:48
reaped the benefits of cooking something
00:31:51
else happened too at least according to
00:31:54
rangam we became more social humans have
00:31:58
this wonderfully calm temperament
00:32:00
compared to chimpanzees say where did it
00:32:03
come from we were drawn to a common
00:32:06
place the
00:32:08
fireplace rum believes we learn to share
00:32:11
and
00:32:13
communicate sitting around fires waiting
00:32:16
for food to
00:32:19
cook it's speculative but one thing is
00:32:22
for sure in the homo erectus World new
00:32:25
social relationships had to be
00:32:29
evolving the bonds between mothers and
00:32:31
children must have been very different
00:32:34
from the
00:32:37
Apes for example a mother Oran will not
00:32:41
allow any other individual to take her
00:32:44
infant will be in constant skin-to-skin
00:32:47
contact with that baby for at least the
00:32:50
first 6 months of life not a moment out
00:32:52
of contact secure in this unbreakable
00:32:56
mother infant Bond ape babies need less
00:32:59
capacity to read the intentions of
00:33:01
others than human
00:33:03
babies whose bond with their mothers is
00:33:06
surprisingly less
00:33:08
secure the shocking fact is that human
00:33:12
mothers abandon their infants much more
00:33:15
often than AP mothers infanticide by a
00:33:18
mother is more common among humans than
00:33:22
any other higher ape maternal commitment
00:33:25
is a lot more contingent in humans than
00:33:27
it seems to be in other Apes unlike most
00:33:31
primates human mothers share parenting
00:33:34
with
00:33:36
others a child's survival can depend on
00:33:39
making itself appealing to a number of
00:33:42
caregivers perhaps that's why human
00:33:45
infants have evolved a uniquely acute
00:33:49
sensitivity human infants are born
00:33:52
connoisseurs of mothers reading her
00:33:55
facial expression looking for signs of
00:34:01
commitment we are born hardwired with an
00:34:04
awareness of the intentions and emotions
00:34:07
of others which is unique in the animal
00:34:11
world when did humans develop this gift
00:34:16
for attributing mental States and
00:34:19
feelings to others and for caring about
00:34:21
what others thought about
00:34:24
them could these social instincts have
00:34:27
developed with Homo erectus along with
00:34:30
Cooperative hunting bigger brains longer
00:34:33
childhoods and the use of
00:34:37
fire perhaps tab boy and his people
00:34:41
already had social skills that would be
00:34:43
familiar to
00:34:45
us here were intelligent social beings
00:34:49
with an increasing capacity for
00:34:55
cooperation it may be this that made
00:34:58
possible another great achievement The
00:35:01
Exodus from
00:35:04
Africa for millions of years our
00:35:06
earliest ancestors stayed on the African
00:35:10
savanas but at some point they started
00:35:13
to
00:35:15
leave ancient fossil skulls and tools
00:35:18
have been found as far away as China and
00:35:22
Indonesia the question is when did they
00:35:25
leave Africa and why
00:35:29
why when turab boy was found scientists
00:35:32
thought they had the
00:35:34
answer here was a strong large-brained
00:35:37
ancestor capable of an arduous
00:35:41
migration he had the look of a World
00:35:44
Conqueror in the mid 1980s we were
00:35:47
thinking that a homonid like this one
00:35:49
had left Africa but had done it maybe
00:35:51
about a million years
00:35:54
ago for decades scientists believed big
00:35:57
strapping humans like turab boy left
00:36:01
Africa a million years ago but new
00:36:04
discoveries are showing the migration
00:36:06
may have started a lot earlier than
00:36:10
that dimini
00:36:13
Georgia the mountains and plains of the
00:36:16
Caucasus thousands of miles from the
00:36:18
Great Rift Valley had never produced any
00:36:21
fossils of early human
00:36:25
ancestors but then an astonishing
00:36:28
Discovery was
00:36:34
made it was a lower jaw with teeth
00:36:38
downward this way in the
00:36:41
ground so when I started to clean those
00:36:44
front teeth came to light it became
00:36:47
obvious to me that we had found some
00:36:49
kind of
00:36:50
homade but what
00:36:53
kind the jaw seemed to be a primitive
00:36:56
form of homo
00:36:58
rectus but at first hardly anyone
00:37:01
believed
00:37:02
it in ' 91 when we found this
00:37:06
Joe this was lot of scientists were
00:37:09
quite skeptical about it was it was very
00:37:12
hard to imagine georia Caucasus to be on
00:37:16
the map of the human
00:37:18
evolution since then demoni has been put
00:37:22
on the map of human evolution in a big
00:37:25
way the site has turned up a Treasure
00:37:27
Trove of homo erectus
00:37:30
fossils they've transformed our
00:37:33
understanding of who left Africa and
00:37:36
when they showed that the first humans
00:37:39
to leave Africa were much more primitive
00:37:41
than turab boy people thought that homin
00:37:45
that left Africa were very tall like
00:37:48
turab boy with big Brands advanced
00:37:51
technology and the Mani proved the the
00:37:55
opposite at 4 and 1/2 ft tall they were
00:37:58
smaller than turab
00:38:00
boy with more aplike shoulders and a
00:38:03
simple stone technology they are much
00:38:06
more primitive they have small brains
00:38:09
and same time they were using very
00:38:12
primitive stone
00:38:14
tools the next surprise came when they
00:38:17
dated the
00:38:19
site the ancient dimini landscape has
00:38:22
been built up layer by layer over
00:38:24
millions of years
00:38:28
1.81 million years ago massive volcanic
00:38:32
eruptions deposited a layer of
00:38:35
Ash the fossils sat on top of this ash
00:38:39
so must have been slightly younger
00:38:41
around 1.8 million years
00:38:45
old to the vast majority of scientists
00:38:48
who believe that all our ancestors
00:38:50
evolved in Africa this was a stunning
00:38:54
surprise how had a small primitive home
00:38:57
Homo erectus migrated to the caucuses
00:39:00
almost 2 million years ago long before
00:39:05
taboy scientists now accept that as soon
00:39:08
as Homo erectus appeared on the savannas
00:39:11
of Africa they started to
00:39:14
leave suddenly with the origin of homo
00:39:17
erectus we get this shift in body shape
00:39:20
and then boom They're Out of Africa
00:39:22
right
00:39:22
away the Georgia fossils proved that
00:39:25
homo erectus left Africa much earlier
00:39:28
than previously thought an even more
00:39:31
provocative find shows the migration may
00:39:34
have started even
00:39:37
earlier 5,000 mil from
00:39:42
Africa the island of Flores
00:39:47
Indonesia in 2003 researchers made a
00:39:51
discovery so strange nobody knew what to
00:39:54
make of
00:39:55
it they found the B B of A tiny human
00:39:59
ancestor just over 3 ft tall even
00:40:03
smaller than the dimini fossils they
00:40:06
called this baffling new ancestor homo
00:40:10
floresiensis and because of its tiny
00:40:12
size nicknamed it The
00:40:17
Hobbit this has created a tremendous
00:40:20
amount of grief because we're not really
00:40:22
sure of what we're seeing here uh the
00:40:25
size of the hoppit brain endic cast is
00:40:27
roughly 400
00:40:31
CC's that's barely bigger than the brain
00:40:33
of Lucy the famous bipedal AE from 3
00:40:36
million years
00:40:40
ago it's not just a small brain and A
00:40:43
Primitive looking face but the foot is
00:40:45
primitive the hand's primitive the leg
00:40:47
is primitive the lower limb is very much
00:40:49
like zy skeleton that was a big
00:40:53
surprise and in the cave where this
00:40:55
primitive creature was found
00:40:57
they also uncovered stone tools
00:41:00
something Lucy never
00:41:03
had people have for a long time said
00:41:05
well you need a big brain to make stone
00:41:07
tools uh well okay if homop Anis is
00:41:09
making stone tools this creature has a
00:41:10
brain the size of an orange clearly that
00:41:12
equation's
00:41:15
gone everything about these creatures is
00:41:18
an
00:41:19
enigma where did they come from and what
00:41:22
were they some researchers have argued
00:41:24
that floresiensis is just a dwarf
00:41:27
population of modern people that
00:41:29
suffered some kind of disease that
00:41:31
caused them to both dwarf and have
00:41:34
relatively small
00:41:35
brains but when scientists took a closer
00:41:38
look most saw no evidence of
00:41:41
disease the stone tools and the shape of
00:41:44
the face moved the focus to our old
00:41:47
friend Homo
00:41:49
erectus some researchers think that homo
00:41:52
fanis evolved from Homo
00:41:55
erectus but how did they get so so
00:41:58
small something called Island dwarfism
00:42:01
may be the
00:42:03
answer isolated on islands with limited
00:42:06
food large mammals sometimes shrink over
00:42:10
time on flues there were once pygmy
00:42:13
elephants the size of
00:42:17
cows could the same evolutionary
00:42:19
pressure have acted on Homo erectus to
00:42:22
produce The
00:42:23
Hobbit or was this mysterious creature
00:42:26
descended from an even more primitive
00:42:29
ancestor so perhaps we're sampling a
00:42:33
period which is at the very beginning of
00:42:35
the homo
00:42:37
lineage so whatever The Hobbit was
00:42:40
perhaps its ancestors were the very
00:42:42
first wave of migration Out of Africa
00:42:46
some unknown creature part bipedal ape
00:42:50
like Lucy and part Homo erectus
00:42:54
[Music]
00:42:59
so if that's the case then what we see
00:43:01
in Indonesia makes sense it's kind of a
00:43:03
body that existed before human bodies
00:43:06
became more
00:43:11
modern what would push such primitive
00:43:13
creatures out of
00:43:20
Africa a key driving force behind the
00:43:23
migration was probably a climate shift
00:43:27
which spread grasslands from Africa into
00:43:31
[Music]
00:43:35
Asia and with the grasses went the game
00:43:39
animals animals are going to be moving
00:43:41
out of Africa and the homs will just be
00:43:43
keeping Pace with those animals after
00:43:45
all that's their
00:43:46
livelihood of course our ancestors
00:43:49
didn't know they were leaving Africa
00:43:52
they just followed the animals they
00:43:53
depended on through the cyani up into
00:43:56
the middle e East and
00:44:00
Beyond it's often been called an exodus
00:44:03
but it really wasn't like that when
00:44:06
people think of Exodus they think of the
00:44:08
Bible or they think of migration they
00:44:09
think of Europeans coming over here to
00:44:11
the new world it probably wasn't like
00:44:14
any historical migration this dispersal
00:44:16
of humans Out of
00:44:18
Africa the process was probably very
00:44:22
very
00:44:23
slow much like the spread of any other
00:44:26
animal species into new
00:44:28
territories you could imagine a group of
00:44:31
homo erectus moving their range a
00:44:35
kilometer a year in One Direction and
00:44:38
doing that continually over a long
00:44:40
enough period of time you can get the
00:44:43
distance from Africa to Indonesia
00:44:45
covered in say 15,000
00:44:50
years by a million years ago our
00:44:53
ancestors had populated Asia from the
00:44:55
caucuses to
00:44:59
Indonesia and they were in Europe too as
00:45:02
a recent discovery in Spain has
00:45:04
[Music]
00:45:06
shown Homo erectus had conquered the old
00:45:15
world the fact that they made it so far
00:45:18
with limited technology and relatively
00:45:20
small brains makes them seem even more
00:45:24
remarkable
00:45:27
and their longevity was astonishing a
00:45:31
few pockets of homo erectus may have
00:45:33
been still Clinging On in Asia just
00:45:36
50,000 years ago that's a span of 2
00:45:40
million
00:45:43
years our own species has only been
00:45:46
around for
00:45:49
200,000 what was the secret of homo
00:45:52
erectus
00:45:55
success the amazing finds at dimini have
00:45:58
given us one last
00:46:01
clue one of the skulls belonged to an
00:46:04
old man his Jawbone revealed he had lost
00:46:07
all his teeth well before he died that
00:46:11
was a real surprise it means that this
00:46:13
individual survived two years without
00:46:17
teeth for an elder to have survived that
00:46:21
long without teeth must mean that others
00:46:24
in the group were feeding him perhaps
00:46:26
perhaps even chewing his food for him I
00:46:30
love this story this was a remarkable
00:46:33
testimony from the past about the
00:46:36
quality of emotional life that may have
00:46:39
characterized Homo
00:46:42
erectus here is a tantalizing clue to
00:46:45
what may be this ancestor's most
00:46:47
important
00:46:48
Legacy the instinct to look after each
00:46:54
other and it helps us imagine tab boy's
00:46:58
final day on
00:47:05
Earth in the animator's scenario he
00:47:08
starts the day out on a
00:47:12
hunt but he has trouble keeping up with
00:47:15
the hunting
00:47:16
party
00:47:19
why the evidence from his skeleton is
00:47:22
that he was sick and in pain at the time
00:47:24
he
00:47:25
died if we look at his lower jaw we can
00:47:29
see right here under the teeth that
00:47:31
we've got a bit of an abscess and an
00:47:34
infection that kind of an infection
00:47:36
could have entered the rest of his body
00:47:38
could have killed him an abscess that
00:47:40
ate away that much of his Jawbone would
00:47:43
have been
00:47:45
agonizing turab boy is in so much pain
00:47:49
he's unable to continue the
00:47:54
hunt knowing he would be looked after
00:47:57
perhaps he returned to his campsite to
00:47:59
find Comfort among the
00:48:02
females I think he was probably a
00:48:05
miserable fellow um in a lot of pain and
00:48:08
very dependent on on support and
00:48:11
handouts so it was a species that
00:48:14
already felt that he one of our
00:48:16
weaklings that you know we love and must
00:48:18
must protect and care for to have got
00:48:20
him that
00:48:22
far but however much they may have
00:48:24
wanted to help him they would nothing
00:48:27
they could do about the infection that
00:48:29
was probably spreading through his
00:48:34
body from what the evidence suggests I
00:48:37
just always imagined him not knowing
00:48:40
what was wrong with him and there's a
00:48:44
sadness to it but ultimately from that
00:48:47
comes this Immortal
00:48:51
being his skeleton was so complete it is
00:48:56
likely he died in water which would have
00:48:58
protected
00:48:59
[Music]
00:49:03
him it's very unusual to get a skeleton
00:49:06
because normally these things are eaten
00:49:08
by Carnival and in this case it seems
00:49:10
that the boy's body was washed into a
00:49:12
swamp and so the carnivals never saw it
00:49:15
and never destroyed it and it gradually
00:49:17
decomposed and as the rivers flooded
00:49:20
brought in more sediment buried it and
00:49:23
you could see Footprints of hippos that
00:49:24
had walked all over the bones and and
00:49:27
some of the ribs and things were
00:49:28
standing vertically instead of lying
00:49:30
flat on the ground and you could sort of
00:49:32
reconstruct the situation and how how
00:49:34
the boy what had happened after he died
00:49:36
and and why he was complet it was just
00:49:39
it really was it was an amazing
00:49:40
experience to see
00:49:41
[Music]
00:49:45
it for almost 2 million years his bones
00:49:49
were preserved by the Earth their
00:49:52
Discovery opened a window for us on an
00:49:54
unknown world
00:49:57
the world of the most successful human
00:49:59
ancestor of all
00:50:02
time Homo
00:50:04
[Music]
00:50:05
erectus they've revealed to us that
00:50:08
mysterious moment when almost everything
00:50:11
human was born our bodies Our Minds our
00:50:20
emotions think of all we've become
00:50:24
[Music]
00:50:28
trace the threads of our Origins through
00:50:31
the ancestors who went before they all
00:50:34
lead back to taboy and His Kind the
00:50:38
first humans
00:50:40
[Music]
00:51:02
this Nova program is available on DVD
00:51:05
and Blu-ray at shop
00:51:07
pbs.org or call 1800 play PBS
00:51:11
[Music]
00:51:19
[Applause]
00:51:19
[Music]
00:51:28
[Music]
