02 - becoming human - birth of humanity edited for evol fall2010

7/28/2019 02 - Becoming Human - Birth of Humanity Edited for Evol Fall2010

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THESE SUBTITLES DO NOT PLAY CORRECTLY IN SYNCH WITH THE MOVIEREMEMBER NAMES OF ORGANISMS (SPECIES OF APES, ETC)REMEMBER DATES OF FOSSILS / OF ORIGIN OF EACH GIVEN SPECIESREMEMBER CHARACTERISTICS OF EACH SPECIES AND HOW THEY DIFFERED FROM EACH OTHERREMEMBER HYPOTHETICAL TRANSITIONS FROM ONE TO ANOTHER SPECIES AND TO HUMAN000:00:01,000 --> 00:00:04,000Downloaded From www.AllSubs.org

100:00:02,267 --> 00:00:03,967NARRATOR:Humans...

200:00:04,033 --> 00:00:08,100Without a doubt, the smartestanimal on earth,

300:00:08,167 --> 00:00:12,900yet we're unmistakably tiedto our ape origins.

400:00:12,967 --> 00:00:14,633Millions of years ago,

500:00:14,700 --> 00:00:18,200we were apesliving ape lives in Africa.

600:00:18,267 --> 00:00:20,800So how did we get from that...

700:00:20,867 --> 00:00:22,900to this?

800:00:25,500 --> 00:00:26,733What happened?

900:00:26,800 --> 00:00:30,700What set us on the pathto humanity?

1000:00:30,767 --> 00:00:32,933The questions are huge.

1100:00:33,000 --> 00:00:35,900But now, there are answers.

1200:00:35,967 --> 00:00:38,267At the threshold of humanity,

1300:00:38,333 --> 00:00:42,367one ancestor containstantalizing secrets.


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1400:00:42,533 --> 00:00:44,867It is known as Homo erectus.

1500:00:44,933 --> 00:00:47,100RICHARD WRANGHAM:Homo erectus had

a slightly smaller brain,

1600:00:47,167 --> 00:00:50,667slightly bigger jaw,but it's basically us.

1700:00:50,733 --> 00:00:57,967NARRATOR:Basically us--almost two million years ago.

1800:00:58,033 --> 00:01:02,333New finds are revealing

the truth about the ancestors

1900:01:02,400 --> 00:01:05,267at the heart of our evolution.

2000:01:05,333 --> 00:01:09,567Here were the trailblazerswho first left Africa--

2100:01:09,633 --> 00:01:13,933the first fire makers,the first hunters.

2200:01:14,000 --> 00:01:15,333JOHN SHEA:These creatures were capable

2300:01:15,400 --> 00:01:17,367of analyzing possible usesof tools

2400:01:17,633 --> 00:01:19,133and coming up witha technological solution

2500:01:19,200 --> 00:01:21,067to the problem of how you killa big, dangerous animal

2600:01:21,133 --> 00:01:23,567without getting killed yourself.

2700:01:23,633 --> 00:01:27,800NARRATOR:


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Homo erectus pioneeredwhat it means to be human,

2800:01:27,867 --> 00:01:29,900colonizing whole continents

29

00:01:29,967 --> 00:01:33,667and creating the firsthuman societies.

3000:01:33,733 --> 00:01:38,033SARAH HRDY:Our ancestors began to careabout what others thought

3100:01:38,100 --> 00:01:42,667and care about what thatindividual thought about them.

3200:01:42,733 --> 00:01:45,733NARRATOR:Now, new discoveries arebringing them alive

3300:01:45,800 --> 00:01:47,400as never before.

3400:01:47,467 --> 00:01:52,300At last, we come face to facewith the ancestors

3500:01:52,367 --> 00:01:56,300at the birth of humanity,right now on NOVA.

3600:02:11,300 --> 00:02:14,967Major funding for NOVAis provided by the following:

3700:02:15,033 --> 00:02:16,833ExxonMobil,

3800:02:16,900 --> 00:02:19,533taking on the world'stoughest energy challenges.

3900:02:19,600 --> 00:02:21,300And by:

4000:02:25,700 --> 00:02:27,533And...

4100:02:36,867 --> 00:02:39,933


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And by the Corporationfor Public Broadcasting

4200:02:40,000 --> 00:02:43,033and by contributionsto your PBS station from:

4300:03:00,833 --> 00:03:03,567NARRATOR:The Great Rift Valleyof East Africa.

4400:03:06,733 --> 00:03:10,933Two million years ago, thesespectacular plains and canyons

4500:03:11,000 --> 00:03:14,800witnessed a mysterious event,

4600:03:14,867 --> 00:03:21,167the birth of the first ancestor

we can really call human.

4700:03:21,233 --> 00:03:25,900New discoveries are revealing acreature surprisingly like us--

4800:03:25,967 --> 00:03:32,167a world traveler, a toolmaker,a hunter, tamer of fire,

4900:03:32,233 --> 00:03:35,033creator of the firsthuman societies.

5000:03:36,367 --> 00:03:39,567Amazingly, the qualitiesthat make us human

5100:03:39,633 --> 00:03:44,467began not with our own species,Homo sapiens.

5200:03:47,367 --> 00:03:52,600The true birth of humanity beganmuch further back in time,

5300:03:52,667 --> 00:03:56,633millions of years ago.

5400:03:56,700 --> 00:04:00,600Imagine the entire spanof recorded human history,


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5500:04:00,667 --> 00:04:02,933about 5,000 years,

5600:04:03,000 --> 00:04:06,200taking us backto the Egyptian pyramids.

5700:04:06,267 --> 00:04:10,333Double it-- 10,000 years,to the time when plants

5800:04:10,400 --> 00:04:14,100are domesticatedand agriculture begins.

5900:04:14,167 --> 00:04:17,833Double it again-- 20,000 years.

6000:04:17,900 --> 00:04:22,433Ice Age hunters are paintingstunning images on cave walls.

6100:04:22,500 --> 00:04:25,533And keep doubling,six more times.

6200:04:25,600 --> 00:04:30,433Only then do we encounterour ancestor Homo erectus

6300:04:30,500 --> 00:04:33,300in Africa's Great Rift Valley.

6400:04:37,367 --> 00:04:42,133For millions of years, thismassive geological fault line

6500:04:42,200 --> 00:04:44,333running the lengthof East Africa

6600:04:44,400 --> 00:04:50,633was a stage on which our humanevolution was played out.

6700:04:50,700 --> 00:04:53,933It all started with the firstapes to walk upright

6800:04:54,000 --> 00:04:57,967on two legs aboutsix million years ago.


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6900:05:00,800 --> 00:05:03,100There were many different types,

7000:05:03,167 --> 00:05:06,200all variationson the same theme,

7100:05:06,500 --> 00:05:10,600apelike creatureswith small brains.

7200:05:10,667 --> 00:05:15,167The fossil known as Lucyis the most famous example.

7300:05:15,233 --> 00:05:19,100Here she is, just three foot,eight inches tall,

7400:05:19,167 --> 00:05:21,500with a brain the sizeof a chimp's.

7500:05:24,533 --> 00:05:28,467For millions of years, creatureslike her roamed the forests

7600:05:28,533 --> 00:05:30,967and grasslands of Africa.

7700:05:31,033 --> 00:05:33,933But then something changed.

7800:05:37,167 --> 00:05:39,900About two million years ago,

7900:05:39,967 --> 00:05:42,800new creatures appeared withabilities never seen before

8000:05:42,867 --> 00:05:44,467in the animal kingdom.

8100:05:44,533 --> 00:05:50,733Meet Homo erectus,a toolmaker and hunter.

8200:05:50,800 --> 00:05:55,667One of the first members of ourgenus, the genus Homo-- humans.

8300:05:55,733 --> 00:05:57,967


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DANIEL LIEBERMAN:The transition to Homo

8400:05:58,033 --> 00:06:00,167

was probably one of the mostimportant transformations

8500:06:00,233 --> 00:06:02,800that occurredin human evolution.

8600:06:02,867 --> 00:06:07,833NARRATOR:Arms got thinner, legs gotlonger, brains got bigger.

8700:06:07,900 --> 00:06:12,200It was a huge evolutionary stepfrom ape bodies

8800:06:12,267 --> 00:06:15,167to bodies like ours.

8900:06:15,233 --> 00:06:19,067But what about the thingsthat make us distinctly human--

9000:06:19,133 --> 00:06:24,600creativity, intelligence,caring for each other?

9100:06:24,667 --> 00:06:29,667How can we knowwhen these got started?

9200:06:29,733 --> 00:06:32,867With only skulls and bonefragments to go on,

9300:06:32,933 --> 00:06:34,400how could we ever know

9400:06:34,467 --> 00:06:38,000what those first humanswere really like?

9500:06:38,067 --> 00:06:42,700It would take a momentous findto shed light on their lives.

9600:06:46,300 --> 00:06:50,467Lake Turkana, northern Kenya,

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00:06:50,533 --> 00:06:55,000surrounded by volcanoes and vastexpanses of baking desert.

9800:06:55,067 --> 00:07:00,967In 1984, famed anthropologistsRichard and Meave Leakey

9900:07:01,033 --> 00:07:03,700were workingat this remote inland sea.

10000:07:03,767 --> 00:07:06,233MEAVE LEAKEY:I was actually onthe east side of the lake.

10100:07:06,300 --> 00:07:08,500Then Richard flew overand said, "You've got to come.

10200:07:08,567 --> 00:07:11,467There's somethingreally exciting."

10300:07:11,533 --> 00:07:14,467NARRATOR:As the first familyof paleoanthropology,

10400:07:14,533 --> 00:07:17,600the Leakeys were usedto fossil finds.

10500:07:17,667 --> 00:07:21,400But this was very special.

10600:07:21,467 --> 00:07:24,067One of Leakey's team had founda skull fragment

10700:07:24,133 --> 00:07:26,600of one of those early humans.

10800:07:26,667 --> 00:07:31,267He could tell from its sizeand shape itwas Homo erectus,

10900:07:31,333 --> 00:07:34,500and there was morethan just a fragment.

11000:07:34,567 --> 00:07:36,033So we starting looking


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at the site

11100:07:36,100 --> 00:07:38,267on a more extensive basis,and of course once we did,

112

00:07:38,333 --> 00:07:40,267we found the rest of the skull.

11300:07:40,333 --> 00:07:42,600NARRATOR:A complete skullwas rare enough,

11400:07:42,667 --> 00:07:45,233but it was just the beginning.

11500:07:45,300 --> 00:07:48,033Soon, parts ofthe Homo erectus skeleton

11600:07:48,100 --> 00:07:52,100which had never been foundbefore started to emerge.

11700:07:52,167 --> 00:07:55,333MEAVE LEAKEY:We couldn't believe it, but westarted getting pieces of ribs.

11800:07:55,400 --> 00:07:57,067These were partsof Homo erectus

11900:07:57,133 --> 00:07:59,833that nobody actually knew about,nobody had ever seen before.

12000:07:59,900 --> 00:08:01,967So every bone thatcame out of the ground

12100:08:02,033 --> 00:08:03,500was something brand newto science

12200:08:03,567 --> 00:08:05,467and we are lookingat these things

12300:08:05,533 --> 00:08:08,400and it was really amazing.

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00:08:08,467 --> 00:08:13,300NARRATOR:And here they are, the actualbones of a human ancestor

12500:08:13,367 --> 00:08:16,633

who lived over 1.5 million

years ago.

12600:08:16,700 --> 00:08:20,900It's the earliest human skeletonever discovered.

12700:08:20,967 --> 00:08:26,167The Leakeys called himTurkana Boy.

12800:08:26,233 --> 00:08:29,200His bones have revolutionizedour understanding

12900:08:29,267 --> 00:08:31,800of the transitionfrom ape to human.

13000:08:31,867 --> 00:08:34,767SUSAN ANTN:The really important thingabout Turkana Boy

13100:08:34,833 --> 00:08:36,267is how complete he is.

13200:08:36,367 --> 00:08:40,100We've got arms and legs andbits of his spine and his ribs.

13300:08:40,167 --> 00:08:44,133And usually when we find thesethings we get very excited

13400:08:44,200 --> 00:08:46,200about one little bit of bone,

13500:08:46,267 --> 00:08:49,167but that little bit can't tellus very much

13600:08:49,233 --> 00:08:50,667about an individual,

13700:08:50,733 --> 00:08:53,400so having a nearlycomplete skeleton,


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13800:08:53,467 --> 00:08:55,500we can start to askbig questions.

13900:08:57,567 --> 00:09:01,967

NARRATOR:The first big question was,what did he look like?

14000:09:02,033 --> 00:09:05,167His skeleton tells us he wasfive feet, three inches tall,

14100:09:05,233 --> 00:09:08,733with a build closer to a man'sthan an ape's.

14200:09:10,200 --> 00:09:11,767But how close?

14300:09:15,000 --> 00:09:17,633Paleoartist Viktor Deakspecializes

14400:09:17,700 --> 00:09:20,933in painting and sculptingour human ancestors

14500:09:21,000 --> 00:09:23,400with precise anatomicalaccuracy.

14600:09:30,533 --> 00:09:32,867Viktor is going to addTurkana Boy

14700:09:32,933 --> 00:09:36,133to his familyof ancient faces.

14800:09:36,200 --> 00:09:38,667DEAK:At this stage of the game,

14900:09:38,967 --> 00:09:41,500I know that Turkana Boyis not an ape.

15000:09:41,567 --> 00:09:44,333He is a very early true human,

15100:09:44,400 --> 00:09:46,967


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and so here we havea modern human skull.

15200:09:47,200 --> 00:09:50,667The faces are very similarto one another,

15300:09:50,733 --> 00:09:53,833but Turkana Boy's skullis a bit more primitive

15400:09:53,900 --> 00:09:59,500and has a lower forehead anda much smaller brain capacity.

15500:09:59,567 --> 00:10:05,000NARRATOR:Viktor will build Turkana Boy'sface muscle by muscle,

15600:10:05,067 --> 00:10:10,667based on his studies of cadaversand modern anatomy.

15700:10:13,733 --> 00:10:16,600While his head may be primitive,

15800:10:16,667 --> 00:10:20,433Turkana Boy's skeleton issurprisingly human.

15900:10:20,500 --> 00:10:23,967His hips are a little wider,his arms a little longer,

16000:10:24,033 --> 00:10:28,633but his overall body shapeis just like ours.

16100:10:28,700 --> 00:10:30,967DEAK:Turkana Boy and erectus--

16200:10:31,033 --> 00:10:32,700that's something thatif you were to see

16300:10:32,767 --> 00:10:35,267from a hundred feet away,you'd think,

16400:10:35,333 --> 00:10:38,600well, there's a large naked manthere, or woman or, you know.


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16500:10:38,667 --> 00:10:40,033But it's a human.

16600:10:45,033 --> 00:10:51,700NARRATOR:

It will take Viktor a weekto flesh out Turkana Boy's face.

16700:10:51,767 --> 00:10:55,967Meanwhile, a team of animatorsis at work creating scenes

16800:10:56,033 --> 00:11:00,500that will bring Turkana Boyand his people to life.

16900:11:00,567 --> 00:11:03,467To make sure they do itaccurately, they have enlisted

17000:11:03,533 --> 00:11:07,767the help of Harvardanthropologist Dan Lieberman.

17100:11:07,833 --> 00:11:09,233They had a moreforward position

17200:11:09,300 --> 00:11:10,933of the palms when they ran,

just slightly.

17300:11:11,000 --> 00:11:12,867There you go.

17400:11:12,933 --> 00:11:17,100NARRATOR:The blue-suited actors are thereto create movement references

17500:11:17,133 --> 00:11:19,267for the artists.

17600:11:19,333 --> 00:11:22,100In the final animations,they will be replaced

17700:11:22,167 --> 00:11:23,633by Homo erectus bodies...

17800:11:23,700 --> 00:11:25,967DIRECTOR:


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And... action!

17900:11:26,033 --> 00:11:29,467NARRATOR:...their heads and faces basedclosely on Viktor's model.

18000:11:32,267 --> 00:11:35,633As Turkana Boy's forensicallyreconstructed head

18100:11:35,700 --> 00:11:41,267nears completion, a face emergesthat looks a lot like us.

18200:11:43,567 --> 00:11:47,100Now for the first time ina million and a half years,

18300:11:47,167 --> 00:11:50,167here he is, our ancestor,

18400:11:50,233 --> 00:11:54,367the Homo erectuscalled Turkana Boy.

18500:11:54,433 --> 00:11:59,467But what he looked like is onlythe beginning of his story.

18600:11:59,533 --> 00:12:04,300To reconstruct his life, we needto find out how old he was.

18700:12:04,367 --> 00:12:07,867And if we lookat his skeleton, we can see

18800:12:07,933 --> 00:12:10,100that the growthplates on his limbs

18900:12:10,167 --> 00:12:14,700that would fuse when he'sfully adult are all unfused,

19000:12:14,767 --> 00:12:18,300so even though he's very tall,we know that he's still growing.

19100:12:19,967 --> 00:12:23,067NARRATOR:The fact that Turkana Boywas not fully grown


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19200:12:23,133 --> 00:12:26,067has turned out to bea boon to researchers.

19300:12:26,133 --> 00:12:28,067

MEAVE LEAKEY:You can answer questions like,

19400:12:28,133 --> 00:12:31,333did the boy grow up likea modern human?

19500:12:31,400 --> 00:12:34,333Or did he grow upmore like an ape?

19600:12:34,400 --> 00:12:38,433NARRATOR:Turkana Boy was alreadyfive feet, three inches tall.

19700:12:38,500 --> 00:12:42,167When scientists comparedhis bones and teeth to ours,

19800:12:42,233 --> 00:12:45,767he seemed to beabout 14 years old.

19900:12:45,833 --> 00:12:48,133But when dentalspecialist Chris Dean

20000:12:48,200 --> 00:12:51,700began to study his teeth,he was in for a shock.

20100:12:53,900 --> 00:12:57,400It turns out that all teeth--fossil or not--

20200:12:57,467 --> 00:13:01,800preserve a remarkably preciserecord of childhood.

20300:13:01,867 --> 00:13:04,267DEAN:This is a fossil tooth

20400:13:04,500 --> 00:13:06,500and we can see the enamel cap

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00:13:06,567 --> 00:13:10,100which covers the core of thetooth, which is made of dentine.

20600:13:10,167 --> 00:13:12,867Dentine is just another wordfor ivory.

20700:13:12,933 --> 00:13:16,767And within the enamel you cansee the rods, which are running

20800:13:16,833 --> 00:13:18,467from the enamel-dentine

junction here

20900:13:18,533 --> 00:13:21,300out to the surfaceof the tooth.

21000:13:21,367 --> 00:13:23,967NARRATOR:Enamel has a regulargrowth pattern,

21100:13:24,033 --> 00:13:26,900like the rings of a tree.

21200:13:26,967 --> 00:13:28,900Under an electron microscope,

21300:13:29,000 --> 00:13:32,133it looks like rodsmade of tiny beads.

21400:13:32,200 --> 00:13:35,100DEAN:Each of the little beadsalong these prisms

21500:13:35,167 --> 00:13:36,933represent one day's growth,

21600:13:37,000 --> 00:13:39,500because the cellswhich produce enamel

21700:13:39,567 --> 00:13:43,500are actually under the influenceof a circadian, or daily, clock.

21800:13:43,567 --> 00:13:46,767And those secretionsduring the day


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21900:13:46,833 --> 00:13:49,233speed up and then slow down,

22000:13:49,300 --> 00:13:53,000and there's a permanent record

of that in every tooth.

22100:13:53,067 --> 00:13:57,800So you can see rods running allthe way through this tissue,

22200:13:57,867 --> 00:14:01,367and every day along the rodthere is a wobble

22300:14:01,433 --> 00:14:03,533where the tissue slows down

22400:14:03,600 --> 00:14:05,767and then speeds up.

22500:14:05,833 --> 00:14:08,467NARRATOR:So if you count the beadsin these strings,

22600:14:08,533 --> 00:14:11,367you can figure outexactly how many days

22700:14:11,433 --> 00:14:14,133that tooth has been growing.

22800:14:14,200 --> 00:14:16,367When Chris lookedat the fossilized teeth

22900:14:16,433 --> 00:14:20,000of Turkana Boy,he got a huge surprise.

23000:14:20,067 --> 00:14:22,633

Turkana Boywasn't 14 years old.

23100:14:22,700 --> 00:14:24,467He was eight.

23200:14:24,533 --> 00:14:29,333DEAN:What that implies is thatthe growth of the Turkana Boy


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23300:14:29,600 --> 00:14:32,167resembled more closelythat of chimpanzees today.

23400:14:32,233 --> 00:14:35,933

NARRATOR:To be five-foot threeat age eight,

23500:14:36,000 --> 00:14:39,000Turkana Boy must havegrown up very fast,

23600:14:39,067 --> 00:14:43,300at a rate closer to chimpsthan us.

23700:14:43,367 --> 00:14:45,333A chimpanzee's childhoodis short.

23800:14:45,400 --> 00:14:49,767It is sexually matureat about seven.

23900:14:49,833 --> 00:14:55,267Human childhood is longer;we reach puberty at about 12.

24000:14:55,333 --> 00:15:01,133So as humans evolved from apes,childhood was extended.

24100:15:01,200 --> 00:15:03,667But what advantagecould be gained

24200:15:03,733 --> 00:15:07,633by having helpless childrenaround to feed and care for

24300:15:07,700 --> 00:15:10,500who take so long to grow up?

24400:15:10,567 --> 00:15:14,433The mystery of prolongedchildhood is at the heart

24500:15:14,500 --> 00:15:16,700of human evolution.

24600:15:16,767 --> 00:15:19,833


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It may be related to brain size.

24700:15:23,167 --> 00:15:26,767We humans have the biggestbrains in the animal kingdom

248

00:15:26,833 --> 00:15:29,767in relation to our body size.

24900:15:29,833 --> 00:15:33,133They're so big that most ofour brain growth has to happen

25000:15:33,200 --> 00:15:34,667outside the womb

25100:15:34,733 --> 00:15:38,433or our heads would neverget through the birth canal.

25200:15:38,500 --> 00:15:42,100A long, slow childhoodgives our brains time

25300:15:42,167 --> 00:15:44,533to grow after birth

25400:15:44,600 --> 00:15:48,100and time to learn everythingwe need to function

25500:15:48,167 --> 00:15:51,433in our complex human societies.

25600:15:51,500 --> 00:15:54,767That's the advantageof prolonged childhood

25700:15:54,833 --> 00:15:57,000for us, at least.

25800:15:57,067 --> 00:16:00,367But what about Turkana Boy?

25900:16:00,433 --> 00:16:03,567His brain was900 cubic centimeters,

26000:16:03,633 --> 00:16:09,233smaller than ours but more thantwice as large as a chimp's.


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26100:16:09,267 --> 00:16:15,000So was he on the way to thinkingand talking like us?

26200:16:15,067 --> 00:16:18,133Ralph Holloway believes he was.

26300:16:18,200 --> 00:16:21,933He's been collecting the brainendocasts of human ancestors

26400:16:22,000 --> 00:16:23,700for over 30 years.

26500:16:23,767 --> 00:16:29,433An endocast is a mold takenfrom the inside of the skull

26600:16:29,500 --> 00:16:32,200which reveals the shapeof the brain.

26700:16:32,267 --> 00:16:34,133Ralph is particularly interested

26800:16:34,200 --> 00:16:37,533in something calledthe Broca's area.

26900:16:37,600 --> 00:16:39,100HOLLOWAY:Broca's area is involved

27000:16:39,167 --> 00:16:40,533with memory functions,

27100:16:40,600 --> 00:16:44,933executive functions, but it doeshave a very important role

27200:16:45,000 --> 00:16:47,600to play in the motor aspectsof speech.

27300:16:47,667 --> 00:16:52,433NARRATOR:In the brain of Turkana Boy,Ralph believes he sees evidence

27400:16:52,500 --> 00:16:54,333for something remarkable--

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00:16:54,400 --> 00:16:59,400a change in the Broca's areatied to communication.

27600:16:59,467 --> 00:17:01,300HOLLOWAY:Broca's caps regions

27700:17:01,367 --> 00:17:03,100on the Turkana Boy

27800:17:03,167 --> 00:17:06,167are fully modern in termsof their appearance.

27900:17:06,233 --> 00:17:10,567It is good, solid evidencefor having the ability

280

00:17:10,633 --> 00:17:13,867of symbolic communication--in other words, language.

28100:17:13,933 --> 00:17:16,567NARRATOR:It's a controversial idea

28200:17:16,633 --> 00:17:21,767and we'll never know for sureif Turkana Boy could speak.

28300:17:21,833 --> 00:17:24,633But there are other cluesto his intelligence--

28400:17:24,700 --> 00:17:29,133the stone toolshe left behind.

28500:17:29,200 --> 00:17:32,200Homo erectus made toolslike this hand ax here.

28600:17:32,267 --> 00:17:34,033It's been chipped extensivelyon both sides.

28700:17:34,100 --> 00:17:36,133The point enables one to dopiercing tasks,

28800:17:36,200 --> 00:17:38,267the heavy bit here can be usedfor cracking bone


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28900:17:38,333 --> 00:17:39,667or chopping wood.

29000:17:39,733 --> 00:17:43,033It's a very, very versatile tool

and a sharp one.

29100:17:43,100 --> 00:17:47,033NARRATOR:It may not look like much,but the stone hand ax

29200:17:47,100 --> 00:17:50,867marks the birth of technology.

29300:17:50,933 --> 00:17:56,433Homo erectus has left us manysigns of his inventiveness.

29400:17:56,500 --> 00:18:00,133Here in central Kenya,Rick Potts has been studying

29500:18:00,200 --> 00:18:05,533a treasure troveof Homo erectus stone tools.

29600:18:05,600 --> 00:18:08,667POTTS:Stone tools representeda momentous change,

29700:18:08,733 --> 00:18:10,933because once you had toolsin your hands,

29800:18:11,000 --> 00:18:14,200all the foods in the worldcould open up to you.

29900:18:14,267 --> 00:18:17,700That represented a tremendoussurvival advantage.

30000:18:19,733 --> 00:18:23,900NARRATOR:Here is a cacheof over 500 stone hand axes

30100:18:23,967 --> 00:18:26,533made by Homo erectus.

302


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00:18:26,600 --> 00:18:28,633Just a mile away,Rick visits the quarry

30300:18:28,700 --> 00:18:32,467where for thousandsof years these ancestors came

30400:18:32,533 --> 00:18:38,300to shape stone into tools,leaving behind unused fragments.

30500:18:38,367 --> 00:18:40,700In the crevicesat my feet,

30600:18:40,767 --> 00:18:43,233there were thousandsof fragments of stone

30700:18:43,300 --> 00:18:44,467from tool making.

30800:18:44,533 --> 00:18:47,767And there are several scarswhere Homo erectus

30900:18:47,833 --> 00:18:49,767struck huge flakes.

31000:18:49,833 --> 00:18:53,000We also see evidence that theycould recognize flaws.

31100:18:53,067 --> 00:18:56,433They could see which ones wouldbreak if they took them away,

31200:18:56,500 --> 00:18:58,800so they simplydiscarded them here.

31300:18:58,867 --> 00:19:01,567What's amazing about that isyou could imagine

31400:19:01,633 --> 00:19:06,100an early Homo erectus sittingright here, making decisions.

31500:19:06,167 --> 00:19:08,400NARRATOR:The kind of decision-makingit takes


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31600:19:08,467 --> 00:19:12,167to create a stone tool has beenresearched extensively

31700:19:12,233 --> 00:19:13,833

by John Shea.

31800:19:13,900 --> 00:19:16,533SHEA:I'm just going to tap ita little bit.

31900:19:16,600 --> 00:19:19,633I'm just checking it out to seeif there's any internal flaws

32000:19:19,700 --> 00:19:20,833before I do it.

32100:19:20,900 --> 00:19:22,133There may be one here.

32200:19:22,200 --> 00:19:24,000It feels like there might besomething in there,

32300:19:24,067 --> 00:19:26,367but I like a challengeso I'll knap it anyway.

32400:19:26,433 --> 00:19:31,133NARRATOR:Even for an expert, makinga hand ax is not easy.

32500:19:31,200 --> 00:19:33,433SHEA:Yeah, there's the flaw,but we can get around it.

32600:19:33,500 --> 00:19:35,400NARRATOR:A good toolmakerhas to understand

32700:19:35,467 --> 00:19:36,933the properties of stone.

32800:19:37,000 --> 00:19:40,267To make this thing niceand thin, easier to carry,

329


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00:19:40,333 --> 00:19:42,500easier to transport and moreof a sharp cutting edge,

33000:19:42,567 --> 00:19:44,533I'm going to do somethingkind of counterintuitive.

33100:19:44,600 --> 00:19:48,100I'm going to dull the edge sothat the next time I strike it,

33200:19:48,167 --> 00:19:51,600it won't fail until I havea lot of pressure on it.

33300:19:51,667 --> 00:19:54,300So if I hit it really hard, thefracture will go much further

33400:19:54,367 --> 00:19:55,633than it otherwise would.

33500:19:55,700 --> 00:19:58,267So that Homo erectus did this

33600:19:58,333 --> 00:20:00,933tells us they were capableof thinking ahead

33700:20:01,000 --> 00:20:03,033and planning the consequencesof their actions.

33800:20:03,100 --> 00:20:04,400So let's have a look here.

33900:20:04,467 --> 00:20:05,833What'll happen here?

34000:20:05,900 --> 00:20:08,833NARRATOR:Many of these stoneshave hidden defects.

34100:20:08,900 --> 00:20:11,333Failing to spot themcould spell disaster.

34200:20:11,400 --> 00:20:13,133There's stilla flaw in there.

343


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00:20:13,200 --> 00:20:14,633I can hear it.I can tell.

34400:20:14,700 --> 00:20:15,633Yeah, see this?

34500:20:15,700 --> 00:20:17,133It's right there.

34600:20:17,200 --> 00:20:20,333Now, I've worked around it,but if I were an early human

34700:20:20,400 --> 00:20:23,300and spotted this, I would stopmaking the hand ax right now.

34800:20:23,367 --> 00:20:26,800If I'm out running around in thesavannas, chasing a rhinoceros

34900:20:26,867 --> 00:20:28,033and, you know,or butchering a rhinoceros

35000:20:28,100 --> 00:20:30,200as the lions are circlingand my hand ax breaks,

35100:20:30,267 --> 00:20:31,633I'm in trouble.

35200:20:31,700 --> 00:20:34,300So, you know, I go home tonight,I'm still going to get fed,

35300:20:34,367 --> 00:20:36,367even though I didn't makea perfect hand ax.

35400:20:36,433 --> 00:20:39,100As Homo erectus, I might end upbeing the meal instead.

35500:20:41,433 --> 00:20:42,933NARRATOR:A skilled craftsman,

35600:20:43,000 --> 00:20:48,567Homo erectus had evolveda new type o f intelligence.

357


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00:20:48,633 --> 00:20:53,000But his bigger braincame with hidden costs.

35800:20:53,067 --> 00:20:57,733Modern brains consume25% of our body's energy.

35900:20:57,800 --> 00:21:00,667DONALD JOHANSON:Our brain happens to bethe hungriest organ in the body.

36000:21:00,733 --> 00:21:02,800And in order to supporta brain our size,

36100:21:02,867 --> 00:21:04,000we need lots of calories.

36200:21:04,067 --> 00:21:06,767NARRATOR:With his big brain and body,

36300:21:06,833 --> 00:21:12,000a Homo erectus like Turkana Boyneeded more nutrition

36400:21:12,067 --> 00:21:14,300from his savanna environment.

36500:21:14,367 --> 00:21:16,433SHEA:Turkana Boy, had he grownto adulthood,

36600:21:16,500 --> 00:21:18,467would probably have stoodabout six feet tall.

36700:21:18,533 --> 00:21:20,167This is a big, strong creature

36800:21:20,233 --> 00:21:21,800that would have hada huge energy budget.

36900:21:21,867 --> 00:21:25,833One can satisfy an energy budgetlike that by eating plants,

37000:21:25,900 --> 00:21:29,233but you have to eat a lot,a lot of plants.


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37100:21:29,300 --> 00:21:32,767NARRATOR:But there's one food that cansupply the nutrients

372

00:21:32,833 --> 00:21:35,267a growing brain and body need...

37300:21:35,333 --> 00:21:37,700and Africa was filled with it.

37400:21:37,767 --> 00:21:41,300LIEBERMAN:The one high-quality resourcethat's probably most important

37500:21:41,367 --> 00:21:43,167for the evolutionof the genus Homo is meat

37600:21:43,233 --> 00:21:46,833and meat byproducts suchas brain and marrow and fat.

37700:21:46,900 --> 00:21:50,000They're high in protein,they're high in calories,

37800:21:50,067 --> 00:21:51,433and they're easy to digest.

37900:21:51,500 --> 00:21:55,033But the one problem with gettingmeat is that it's hard to get.

38000:21:55,100 --> 00:21:58,767NARRATOR:Most predators relyon strength or speed

38100:21:58,833 --> 00:22:00,800to kill their prey.

38200:22:00,867 --> 00:22:04,233Our ancestors had neither.

38300:22:04,333 --> 00:22:08,533Today we are on top of the foodchain, so it's hard to imagine

38400:22:08,600 --> 00:22:12,267the predicament


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of those early humans.

38500:22:12,333 --> 00:22:17,200Here was a slow-moving creaturewith no claws or fangs,

386

00:22:17,267 --> 00:22:20,933easy prey for the hungrypredators around him.

38700:22:23,100 --> 00:22:26,200POTTS:This is a fossil foreheadand brow ridge

38800:22:26,267 --> 00:22:27,600of a Homo erectus,

38900:22:27,667 --> 00:22:31,700and on the brow ridgeyou can see the bite mark

39000:22:31,767 --> 00:22:33,500of a carnivore.

39100:22:33,567 --> 00:22:37,367Well, this reminds us thatthese Homo erectus individuals

39200:22:37,433 --> 00:22:40,133weren't at the topof the food chain.

39300:22:40,233 --> 00:22:42,133NARRATOR:So how did Turkana Boy,

39400:22:42,200 --> 00:22:45,933a weakling with a big brainwhich needed calories,

39500:22:46,000 --> 00:22:48,300get his meat?

39600:22:48,367 --> 00:22:50,133SHEA:Homo erectus faced a problem:

39700:22:50,200 --> 00:22:51,633How do you kill a big,dangerous animal

39800:22:51,700 --> 00:22:53,267


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that has lots of meatand fat in it

39900:22:53,333 --> 00:22:54,933

without that animalalso killing you?

40000:22:55,000 --> 00:22:59,433I think the answer to that was avery clever set of innovations,

40100:22:59,500 --> 00:23:01,433and that is endurance running

40200:23:01,500 --> 00:23:05,000and high activityin the middle of the day.

40300:23:05,067 --> 00:23:10,967

NARRATOR:The ancestors of Homo erectus,small, hairy apes like Lucy,

40400:23:11,033 --> 00:23:16,000

were bipedal but probablydidn't do much running.

40500:23:16,067 --> 00:23:20,867But Turkana Boy's kind werebuilt to run like us.

40600:23:20,933 --> 00:23:22,867This isan accelerometer.

40700:23:22,933 --> 00:23:25,800NARRATOR:Dan Lieberman believes theycould run long distances

40800:23:26,033 --> 00:23:30,667because, like us, they had losttheir thick coat of body hair

40900:23:30,733 --> 00:23:33,533and could keep cool by sweating.

41000:23:33,600 --> 00:23:37,700This was the keyto their success.

41100:23:37,767 --> 00:23:40,500But how do we knowif these crucial changes


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41200:23:40,567 --> 00:23:43,767go back all the wayto Turkana Boy's time,

41300:23:43,833 --> 00:23:47,333

over a million years ago?

41400:23:47,400 --> 00:23:51,067Skin and hair are rarelypreserved in the fossil record,

41500:23:51,133 --> 00:23:53,600so to find out, we have to lookto a creature

41600:23:53,667 --> 00:23:57,933that's been intimately connectedwith hair for a long time:

41700:23:58,000 --> 00:23:59,367the louse.

41800:23:59,433 --> 00:24:00,633MARK STONEKING:All animals seem

41900:24:00,700 --> 00:24:03,600to have some type of liceto parasitize them.

42000:24:03,667 --> 00:24:05,867Mammals have them,birds have them,

42100:24:05,933 --> 00:24:07,833even fish have types of lice.

42200:24:07,900 --> 00:24:10,467But most other creatures haveonly one type of lice

42300:24:10,533 --> 00:24:12,667

that parasitize them.

42400:24:12,733 --> 00:24:15,867NARRATOR:Humans have one kind of louseon their heads

42500:24:15,933 --> 00:24:17,900and another in the pubic area.


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42600:24:17,967 --> 00:24:22,100Geneticist Mark Stonekingasked himself why.

42700:24:22,167 --> 00:24:23,600

STONEKING:The answer that seems obvious

42800:24:23,667 --> 00:24:26,233is that when we had body hairall over our bodies,

42900:24:26,300 --> 00:24:28,033

we had one type of lice.

43000:24:28,100 --> 00:24:29,533But then we became hairless

43100:24:29,600 --> 00:24:32,767until we only had hair on ourheads and in our pubic region,

43200:24:32,833 --> 00:24:34,367and so thereforeyou would have

43300:24:34,433 --> 00:24:38,767this hairless geographic barrierto contact between the two.

43400:24:38,833 --> 00:24:40,800NARRATOR:Mark was surprised to find out

43500:24:40,867 --> 00:24:43,367that the human pubic louseis very different

43600:24:43,433 --> 00:24:45,533from the human head louse.

43700:24:45,600 --> 00:24:50,667

Somehow in the past, it seemsto have come from gorillas.

43800:24:50,733 --> 00:24:53,300STONEKING:Because the pubic lice isactually more closely related

43900:24:53,367 --> 00:24:54,667to gorilla lice.


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44000:24:54,733 --> 00:24:57,333Now, how it is our ancestors gotpubic lice from gorillas

44100:24:57,400 --> 00:24:59,967

I wouldn't care to speculate.

44200:25:00,033 --> 00:25:03,333But nonetheless,one needs gorilla lice

44300:25:03,400 --> 00:25:07,533in order to really workthis whole thing out.

44400:25:07,600 --> 00:25:12,033NARRATOR:The most likely scenario is that

when we lost our body hair,

44500:25:12,100 --> 00:25:16,033the original human lousemigrated to our heads,

44600:25:16,100 --> 00:25:21,133leaving the pubic areatemporarily unpopulated by lice.

44700:25:21,200 --> 00:25:24,500When our ancestors had contactwith gorillas,

44800:25:24,567 --> 00:25:26,833perhaps sleeping in their nests

44900:25:26,900 --> 00:25:29,800or scavenging their bodiesfor meat,

45000:25:29,867 --> 00:25:34,133the gorilla louse colonizedtheir pubic region.

45100:25:34,200 --> 00:25:39,200Eventually, it turned intothe human pubic louse of today.

45200:25:39,267 --> 00:25:41,133So if we could find out

45300:25:41,200 --> 00:25:45,467when the human pubic louse and


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the gorilla louse diverged,

45400:25:45,533 --> 00:25:50,633we would have a rough ideaof when we lost our body hair.

455

00:25:50,700 --> 00:25:54,133Fortunately, there's a wayto figure that out:

45600:25:54,200 --> 00:25:59,267the genetic dating techniqueknown as the molecular clock.

45700:25:59,333 --> 00:26:02,833It's based on the fact thatthe sequence of chemical bases

45800:26:02,900 --> 00:26:07,700which make up DNAmutate at a regular rate.

45900:26:07,767 --> 00:26:10,367STONEKING:It's just a very simple idea

46000:26:10,667 --> 00:26:12,967that the rate of changein DNA sequences

46100:26:13,033 --> 00:26:15,200is more or less constantover time.

46200:26:15,267 --> 00:26:18,533And that means that you havea way of determining

46300:26:18,600 --> 00:26:21,667when two species last shareda common ancestor.

46400:26:21,733 --> 00:26:25,033NARRATOR:By counting the numberof differences

46500:26:25,100 --> 00:26:27,200in the genetic codeof two species,

46600:26:27,267 --> 00:26:31,133scientists can determine howlong they've been evolving


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46700:26:31,200 --> 00:26:33,233away from each other.

46800:26:33,300 --> 00:26:36,633When Mark used the molecular

clock to count the differences

46900:26:36,700 --> 00:26:41,333between the DNA of gorilla liceand human pubic lice,

47000:26:41,400 --> 00:26:44,833he came up with a datefor their divergence.

47100:26:44,900 --> 00:26:47,000STONEKING:The estimated datefor the divergence

47200:26:47,067 --> 00:26:49,133is roughlythree million years ago.

47300:26:49,200 --> 00:26:53,500NARRATOR:That means longbefore Turkana Boy,

47400:26:53,567 --> 00:26:54,967maybe even around Lucy's time,

47500:26:55,033 --> 00:27:01,867our ancestors had slowly begunto lose their body hair.

47600:27:01,933 --> 00:27:06,033Turkana Boy was mostly hairless,

just like us...

47700:27:08,667 --> 00:27:13,667...and that may be what gave himan edge over other predators.

47800:27:13,733 --> 00:27:18,033Most animals are at adisadvantage in the midday sun

47900:27:18,100 --> 00:27:19,533because they overheat.

48000:27:19,600 --> 00:27:22,500


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They can only cool downby panting.

48100:27:22,567 --> 00:27:26,633And when they run fast,they can't pant.

48200:27:26,700 --> 00:27:31,700That means they can only runin short sprints.

48300:27:31,767 --> 00:27:34,367LIEBERMAN:Quadrupeds can gallopfor about 10 to 15 minutes

48400:27:34,433 --> 00:27:35,500and then they overheat,

48500:27:35,567 --> 00:27:39,033but hominids can cool downby sweating.

48600:27:39,100 --> 00:27:43,433They use their entire bodylike a dog's tongue.

48700:27:43,500 --> 00:27:48,233NARRATOR:Our hairless bodies allow airto circulate freely on our skin

48800:27:48,300 --> 00:27:51,367and cool us downas sweat evaporates.

48900:27:51,433 --> 00:27:54,433This makes us one of the bestlong-distance runners

49000:27:54,500 --> 00:27:57,433in the animal kingdom.

49100:27:57,500 --> 00:28:00,833Dan Lieberman believesthis gave our ancestors

49200:28:00,900 --> 00:28:03,667the ability to huntin a very unusual way.

49300:28:03,733 --> 00:28:06,733It's called persistence hunting.


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49400:28:08,733 --> 00:28:12,133And he believes the modernethnographic record

49500:28:12,200 --> 00:28:14,800can show us how it was done.

49600:28:17,067 --> 00:28:21,467The Bushmen of the Kalaharioffer us an insight

49700:28:21,533 --> 00:28:27,200into how Homo erectus might havehunted two million years ago.

49800:28:27,433 --> 00:28:32,467The Bushmen know that at middayanimals rest in the shade,

49900:28:32,533 --> 00:28:36,433which is why it's the perfecttime to be hunting.

50000:28:36,500 --> 00:28:41,033Once they locate their prey--in this case a kudu--

50100:28:41,100 --> 00:28:43,000the marathon begins.

50200:28:48,700 --> 00:28:54,667Their strategy is simple:run it to exhaustion.

50300:28:54,733 --> 00:28:59,100Every time the animal tries torest, the hunters track it down

50400:28:59,167 --> 00:29:00,600and get it moving again.

50500:29:00,667 --> 00:29:04,433They never give it a chanceto cool down.

50600:29:04,500 --> 00:29:09,500And the reason they can keepgoing is that they can sweat.

50700:29:12,533 --> 00:29:16,800So if the theory is right, theBushman hunt may help explain


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50800:29:16,867 --> 00:29:21,433how Turkana Boy got his meat.

50900:29:21,500 --> 00:29:25,933Homo erectus had come up

with an innovative way

51000:29:26,000 --> 00:29:27,967of feeding his hungry brain.

51100:29:32,200 --> 00:29:37,267In this modern hunt, the Bushmenran in the fierce heat

51200:29:37,333 --> 00:29:40,467for over four hours.

51300:29:40,533 --> 00:29:45,033The kudu was finally immobilizedby heat stroke.

51400:29:47,600 --> 00:29:50,167Turkana Boy wouldn't havehad steel-tipped spears

51500:29:50,233 --> 00:29:55,000like the Bushmen, but hewouldn't have needed them.

51600:29:57,033 --> 00:30:00,633SHEA:Homo erectus probably huntedwith close-quarters weapons--

51700:30:00,700 --> 00:30:03,633with spears that were thrown atanimals from a short distance,

51800:30:03,700 --> 00:30:05,833clubs, throw rocks,weapons like that.

51900:30:05,900 --> 00:30:07,567They weren't using long-distanceprojectile weapons,

52000:30:07,667 --> 00:30:09,233that we know of.

52100:30:12,833 --> 00:30:17,767NARRATOR:The Homo erectus huntwas simple but effective.


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52200:30:17,833 --> 00:30:20,600It fed not justtheir larger brains,

52300:30:20,667 --> 00:30:25,833

but the growing complexityof that early human society.

52400:30:28,733 --> 00:30:34,067There are other social animals,but none quite like us.

52500:30:37,567 --> 00:30:40,967Society is in every cornerof our lives--

52600:30:41,033 --> 00:30:43,800our relationships,communication,

52700:30:43,867 --> 00:30:46,933rules, symbolism--

52800:30:47,000 --> 00:30:50,367all the thingsthat bind us together.

52900:30:50,433 --> 00:30:51,667What's behind it?

53000:30:51,733 --> 00:30:55,000Why did we become so social?

53100:30:55,067 --> 00:30:59,967Could it have something to dowith another innovation,

53200:31:00,033 --> 00:31:05,067something unprecedentedin our evolution,

53300:31:05,133 --> 00:31:08,833

building fires and cooking?

53400:31:08,900 --> 00:31:11,867Here we go to erectus, the firstspecies that looks like us,

53500:31:11,933 --> 00:31:14,200and I think only cooking canexplain the magnitude


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53600:31:14,267 --> 00:31:15,633of this change.

53700:31:15,700 --> 00:31:19,533NARRATOR:The earliest evidencethat our ancestors

53800:31:19,600 --> 00:31:22,167deliberately used firefor cooking

53900:31:22,233 --> 00:31:26,033dates to longafter Turkana Boy's time.

54000:31:26,100 --> 00:31:30,967But Richard Wrangham is sureHomo erectus was building fires

54100:31:31,033 --> 00:31:33,600much earlier.

54200:31:33,667 --> 00:31:36,600WRANGHAM:Now for the first time we hada species that was committed

54300:31:36,667 --> 00:31:38,000to living on the ground,

54400:31:38,067 --> 00:31:40,333because they losetheir climbing adaptations.

54500:31:40,400 --> 00:31:43,033Well, how were they sleeping?

54600:31:43,100 --> 00:31:47,633They had to be able to protectthemselves from wild animals.

547

00:31:47,700 --> 00:31:52,267NARRATOR:On the African savanna, fullof predators who hunt by night,

54800:31:52,333 --> 00:31:54,833Richard believes Turkana Boyand his people

54900:31:54,900 --> 00:31:58,800


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couldn't have survivedwithout fire.

55000:31:58,867 --> 00:32:01,967And he thinks only cooking,

551

00:32:02,033 --> 00:32:04,100which makes food more softand digestible,

55200:32:04,167 --> 00:32:08,233can explain why Homo erectusevolved smaller teeth

55300:32:08,300 --> 00:32:10,533and a much smaller gut.

55400:32:10,600 --> 00:32:12,200WRANGHAM:These things are compatible

55500:32:12,267 --> 00:32:14,133with the reduced costof digestion

55600:32:14,200 --> 00:32:15,233produced by cooking food.

55700:32:15,300 --> 00:32:16,633Nothing else is.

55800:32:16,700 --> 00:32:21,100NARRATOR:As our ancestors reapedthe benefits of cooking,

55900:32:21,167 --> 00:32:25,667something else happened too,at least according to Wrangham--

56000:32:25,733 --> 00:32:28,767we became more social.

561

00:32:28,833 --> 00:32:31,233WRANGHAM:Humans have this wonderfullycalm temperament

56200:32:31,300 --> 00:32:33,200compared to chimpanzees, say.

56300:32:33,500 --> 00:32:35,200Where did it come from?


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56400:32:35,267 --> 00:32:39,100We were drawn to a common place,the fireplace.

56500:32:39,167 --> 00:32:43,600

NARRATOR:Wrangham believes we learnedto share and communicate

56600:32:43,667 --> 00:32:50,100sitting around fires,waiting for food to cook.

56700:32:50,167 --> 00:32:53,933It's speculative,but one thing is for sure:

56800:32:54,000 --> 00:32:56,067In the Homo erectus world,

56900:32:56,133 --> 00:33:00,333new social relationshipshad to be evolving.

57000:33:00,400 --> 00:33:03,400The bonds between mothersand children must have been

57100:33:03,500 --> 00:33:05,767very different from the apes.

57200:33:07,700 --> 00:33:12,933SARAH HRDY:For example, a mother orangutanwill not allow

57300:33:13,000 --> 00:33:15,667any other individualto take her infant,

57400:33:15,733 --> 00:33:18,700will be in constantskin-to-skin contact

57500:33:18,933 --> 00:33:22,433with that baby for at leastthe first six months of life.

57600:33:22,500 --> 00:33:25,100Not a moment out of contact.

57700:33:25,167 --> 00:33:28,600


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NARRATOR:Secure in this unbreakablemother-infant bond,

57800:33:28,667 --> 00:33:32,767ape babies need less capacityto read the intentions of others

57900:33:32,833 --> 00:33:36,467than human babies, whose bondwith their mothers

58000:33:36,533 --> 00:33:40,367is surprisingly less secure.

58100:33:40,433 --> 00:33:44,467The shocking fact is that humanmothers abandon their infants

58200:33:44,533 --> 00:33:46,933much more oftenthan ape mothers.

58300:33:47,000 --> 00:33:51,700Infanticide by a motheris more common among humans

58400:33:51,767 --> 00:33:54,300than any other higher ape.

58500:33:54,367 --> 00:33:55,533HRDY:Maternal commitment

58600:33:55,600 --> 00:33:57,567is a lot more contingentin humans

58700:33:57,700 --> 00:34:00,200than it seems to bein other apes.

58800:34:00,267 --> 00:34:02,467NARRATOR:Unlike most primates,

58900:34:02,533 --> 00:34:07,100human mothers share parentingwith others.

59000:34:07,167 --> 00:34:11,467A child's survival can dependon making itself appealing


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59100:34:11,533 --> 00:34:13,933to a number of caregivers.

59200:34:14,000 --> 00:34:17,500Perhaps that's why human infantshave evolved

59300:34:17,567 --> 00:34:20,367a uniquely acute sensitivity.

59400:34:20,433 --> 00:34:25,200HRDY:Human infants are bornconnoisseurs of mothers,

59500:34:25,267 --> 00:34:31,067reading her facial expression,looking for signs of commitment.

59600:34:32,567 --> 00:34:35,300NARRATOR:We are born hard-wiredwith an awareness

59700:34:35,367 --> 00:34:39,267of the intentions and emotionsof others,

59800:34:39,333 --> 00:34:42,733which is uniquein the animal world.

59900:34:42,800 --> 00:34:46,533HRDY:When did humans developthis gift

60000:34:46,600 --> 00:34:50,433for attributing mental statesand feelings to others

60100:34:50,500 --> 00:34:54,200and for caring about what othersthought about them?

60200:34:55,667 --> 00:34:58,100NARRATOR:Could these social instinctshave developed

60300:34:58,167 --> 00:35:00,200with Homo erectus,

604


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00:35:00,267 --> 00:35:03,733along with cooperative hunting,bigger brains,

60500:35:03,800 --> 00:35:09,333longer childhoodsand the use of fire?

60600:35:09,400 --> 00:35:13,133Perhaps Turkana Boyand his people already had

60700:35:13,167 --> 00:35:16,867social skills that would befamiliar to us.

60800:35:16,933 --> 00:35:19,267Here were intelligentsocial beings

60900:35:19,333 --> 00:35:23,667with an increasing capacityfor cooperation.

61000:35:27,133 --> 00:35:29,667It may bethis that made possible

61100:35:29,733 --> 00:35:32,867another great achievement--the exodus from Africa.

61200:35:35,400 --> 00:35:37,000For millions of years,

61300:35:37,067 --> 00:35:41,333our earliest ancestors stayedon the African savannas.

61400:35:41,400 --> 00:35:44,667But at some point,they started to leave.

61500:35:46,100 --> 00:35:49,467Ancient fossil skullsand tools have been found

61600:35:49,533 --> 00:35:53,433as far awayas China and Indonesia.

61700:35:53,500 --> 00:35:58,700The question is, when didthey leave Africa, and why?


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61800:36:00,333 --> 00:36:02,367When Turkana Boy was found,

61900:36:02,433 --> 00:36:05,267scientists thought

they had the answer.

62000:36:05,333 --> 00:36:08,600Here was a strong,large-brained ancestor

62100:36:08,667 --> 00:36:11,833capable of an arduous migration.

62200:36:11,900 --> 00:36:15,300He had the lookof a world conqueror.

62300:36:15,367 --> 00:36:17,100ANTN:I the mid-1980s,

62400:36:17,167 --> 00:36:20,600we were thinking that a hominidlike this one had left Africa

62500:36:20,667 --> 00:36:24,967but had done it maybeabout a million years ago.

62600:36:25,033 --> 00:36:27,767NARRATOR:For decades, scientists believed

62700:36:27,833 --> 00:36:30,467big, strapping humanslike Turkana Boy

62800:36:30,533 --> 00:36:33,600left Africa a million years ago.

62900:36:33,667 --> 00:36:37,733

But new discoveries are showingthe migration may have started

63000:36:37,800 --> 00:36:40,133a lot earlier than that.

63100:36:41,700 --> 00:36:44,833Dmanisi, Georgia.


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63200:36:44,900 --> 00:36:46,800The mountains and plainsof the Caucasus,

63300:36:46,867 --> 00:36:50,467thousands of miles

from the Great Rift Valley,

63400:36:50,533 --> 00:36:56,467had never produced any fossilsof early human ancestors.

63500:36:56,533 --> 00:37:01,267But then an astonishingdiscovery was made.

63600:37:01,333 --> 00:37:04,367(man speaking Georgian)

63700:37:04,433 --> 00:37:09,500(translated):It was a lower jaw,with teeth downward...

63800:37:09,567 --> 00:37:12,467this way in the ground.

63900:37:12,533 --> 00:37:16,500So when I started to clean,those front teeth came to light.

64000:37:16,567 --> 00:37:21,500It became obvious to me that wehad found some kind of hominid.

64100:37:21,567 --> 00:37:23,500But what kind?

64200:37:25,167 --> 00:37:29,467NARRATOR:The jaw seemed to be a primitiveform of Homo erectus,

64300:37:29,533 --> 00:37:34,800but at first hardly anyonebelieved it.

64400:37:34,867 --> 00:37:37,500In '91, when we found this jaw,

64500:37:37,567 --> 00:37:41,933this was... a lot of scientistswere quite skeptical about it,


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64600:37:42,000 --> 00:37:45,467because it was very hardto imagine Georgia, Caucasus,

64700:37:45,533 --> 00:37:48,167

to be on the mapof the human evolution.

64800:37:49,933 --> 00:37:54,133NARRATOR:Since then, Dmanisi has been puton the map of human evolution

64900:37:54,200 --> 00:37:55,533in a big way.

65000:37:55,600 --> 00:37:58,600The site has turned upa treasure trove

65100:37:58,667 --> 00:38:01,533of Homo erectus fossils.

65200:38:01,600 --> 00:38:03,933They've transformedour understanding

65300:38:04,000 --> 00:38:07,500of who left Africa and when.

65400:38:07,567 --> 00:38:10,567They showed that the firsthumans to leave Africa

65500:38:10,633 --> 00:38:13,867

were much more primitivethan TurkanaBoy.

65600:38:13,933 --> 00:38:17,167JORDI AGUST:People thought thatthe hominids that left Africa

65700:38:17,233 --> 00:38:18,333were very tall

65800:38:18,400 --> 00:38:21,600like Turkana Boy,with big brains,

65900:38:21,667 --> 00:38:23,000advanced technology,


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66000:38:23,067 --> 00:38:25,000and Dmanisi proved the opposite.

66100:38:25,067 --> 00:38:28,533NARRATOR:

At 4 1/2 feet tall,

66200:38:28,600 --> 00:38:31,400they were smallerthan Turkana Boy,

66300:38:31,467 --> 00:38:36,067with more apelike shouldersand a simple stone technology.

66400:38:36,133 --> 00:38:38,200LORDKIPANIDZE:They are much more primitive.

66500:38:38,267 --> 00:38:39,767They have small brains

66600:38:39,833 --> 00:38:42,233and the same time,they were using

66700:38:42,300 --> 00:38:44,033very primitive stone tools.

668

00:38:45,667 --> 00:38:50,033NARRATOR:The next surprise camewhen they dated the site.

66900:38:50,100 --> 00:38:54,467The ancient Dmanisi landscapehas been built up layer by layer

67000:38:54,533 --> 00:38:57,967over millions of years.

67100:38:58,033 --> 00:39:03,600

1.81 million years ago, massivevolcanic eruptions deposited

67200:39:03,667 --> 00:39:06,467a layer of ash.

67300:39:06,533 --> 00:39:09,500The fossils sat on topof this ash,


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67400:39:09,567 --> 00:39:11,933so must have beenslightly younger--

67500:39:12,033 --> 00:39:16,467around 1.8 million years old.

67600:39:16,533 --> 00:39:19,233To the vast majorityof scientists who believe

67700:39:19,300 --> 00:39:22,133that all our ancestors evolvedin Africa,

67800:39:22,200 --> 00:39:24,500this was a stunning surprise.

67900:39:24,567 --> 00:39:29,633How had a small, primitiveHomo erectus migrated

68000:39:29,700 --> 00:39:33,000to the Caucasusalmost two million years ago,

68100:39:33,067 --> 00:39:36,300long before Turkana Boy?

682

00:39:36,367 --> 00:39:40,667Scientists now accept that assoon as Homo erectus appeared

68300:39:40,733 --> 00:39:44,300on the savannas of Africa,they started to leave.

68400:39:46,033 --> 00:39:48,833Suddenly with the originof Homo erectus we get

68500:39:48,900 --> 00:39:51,267

this shift in body shapeand then boom,

68600:39:51,333 --> 00:39:52,800they're out of Africaright away.

68700:39:54,200 --> 00:39:55,567NARRATOR:The Georgia fossils proved


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68800:39:55,633 --> 00:39:59,033that Homo erectus left Africamuch earlier

68900:39:59,100 --> 00:40:01,167

than previously thought.

69000:40:01,233 --> 00:40:03,033An even more provocative find

69100:40:03,100 --> 00:40:08,767shows the migration may havestarted even earlier.

69200:40:08,833 --> 00:40:13,3335,000 miles from Africa...

69300:40:13,400 --> 00:40:19,333the island of Flores, Indonesia.

69400:40:19,400 --> 00:40:23,100In 2003, researchers madea discovery so strange,

69500:40:23,167 --> 00:40:26,567nobody knew what to make of it.

69600:40:26,633 --> 00:40:30,267They found the bones

of a tiny human ancestor,

69700:40:30,333 --> 00:40:32,600

just over three feet tall--

69800:40:32,667 --> 00:40:35,667even smallerthan the Dmanisi fossils.

69900:40:35,733 --> 00:40:41,533They called this baffling newancestor Homo floresiensis

70000:40:41,600 --> 00:40:46,100and, because of its tiny size,nicknamed it "The Hobbit."

70100:40:48,200 --> 00:40:51,133HOLLOWAY:This has created a tremendousamount of grief


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70200:40:51,200 --> 00:40:56,033because we're not really surewhat we're seeing here.

70300:40:56,100 --> 00:41:00,200The size of the Hobbit brain

endocast is roughly 400 cc.

70400:41:01,800 --> 00:41:05,600NARRATOR:That's barely biggerthan the brain of Lucy,

70500:41:05,667 --> 00:41:08,467the famous bipedal apefrom three million years ago.

70600:41:11,500 --> 00:41:14,500RICHMOND:

It's not just a small brainand a primitive-looking face,

70700:41:14,567 --> 00:41:15,833but the foot's primitive,the hand's primitive,

70800:41:15,900 --> 00:41:17,367the leg is primitive.

70900:41:17,600 --> 00:41:20,767SUSAN LARSON:The lower limb is very much like

the Lucy skeleton.

71000:41:20,833 --> 00:41:23,133That was a big surprise.

71100:41:24,233 --> 00:41:25,367NARRATOR:And in the cave

71200:41:25,433 --> 00:41:27,133where this primitive creaturewas found,

71300:41:27,367 --> 00:41:32,500they also uncovered stone tools,something Lucy never had.

71400:41:33,833 --> 00:41:35,433SHEA:People for a long time said,

715


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00:41:35,500 --> 00:41:37,800"You need a big brain to makestone tools."

71600:41:37,867 --> 00:41:39,967Well, okay, if Homo floresiensisis making stone tools,

71700:41:40,033 --> 00:41:42,100this creature has a brainthe size of an orange;

71800:41:42,167 --> 00:41:43,467clearly that equation's gone.

71900:41:45,900 --> 00:41:49,967NARRATOR:Everything about thesecreatures is an enigma.

72000:41:50,033 --> 00:41:53,467Where did they come fromand what were they?

72100:41:53,533 --> 00:41:55,033RICHMOND:Some researchers have argued

72200:41:55,100 --> 00:41:57,967that floresiensis is justa dwarfed population

72300:41:58,033 --> 00:42:01,467of modern people thatsuffered some kind of disease

72400:42:01,533 --> 00:42:03,167that caused them to both dwarf

72500:42:03,233 --> 00:42:05,133and have relativelysmall brains.

72600:42:05,200 --> 00:42:09,133NARRATOR:But when scientists tooka closer look,

72700:42:09,267 --> 00:42:12,133most saw no evidenceof disease.

72800:42:12,200 --> 00:42:16,333The stone tools and the shape


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of the face moved the focus

72900:42:16,400 --> 00:42:19,167to our old friend, Homo erectus.

73000:42:19,233 --> 00:42:20,700

RICHMOND:Some researchers think

73100:42:20,933 --> 00:42:25,667that Homo floresiensis evolvedfrom Homo erectus.

73200:42:25,733 --> 00:42:29,033NARRATOR:But how did they get so small?

73300:42:29,100 --> 00:42:33,933Something called island dwarfism

may be the answer.

73400:42:34,000 --> 00:42:36,800Isolated on islands

with limited food,

73500:42:36,867 --> 00:42:40,500large mammals sometimes shrinkover time.

73600:42:40,567 --> 00:42:47,000On Flores, there were once pygmyelephants the size of cows.

73700:42:47,067 --> 00:42:50,133Could the sameevolutionary pressure

73800:42:50,200 --> 00:42:54,200have acted on Homo erectusto produce the Hobbit?

73900:42:54,267 --> 00:42:57,167Or was this mysteriouscreature descended

74000:42:57,233 --> 00:43:02,100from an even moreprimitive ancestor?

74100:43:02,167 --> 00:43:04,067So perhaps we're samplinga period

742


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00:43:04,133 --> 00:43:06,633which is at the very beginningof the Homo lineage.

74300:43:06,700 --> 00:43:12,200NARRATOR:So whatever the Hobbit was,

perhaps its ancestors were

74400:43:12,267 --> 00:43:16,500the very first waveof migration out of Africa,

74500:43:16,567 --> 00:43:20,967some unknown creature:part bipedal ape like Lucy

74600:43:21,033 --> 00:43:23,900and part Homo erectus.

74700:43:28,300 --> 00:43:29,633LIEBERMAN:So if that's the case,

74800:43:29,700 --> 00:43:32,333then what we see in Indonesiamakes sense.

74900:43:32,400 --> 00:43:33,867It's a kind of a body

75000:43:33,933 --> 00:43:37,967that existed before human bodiesbecame more modern.

75100:43:41,833 --> 00:43:47,033NARRATOR:What would push such primitivecreatures out of Africa?

75200:43:51,333 --> 00:43:54,300A key driving forcebehind the migration

75300:43:54,367 --> 00:43:58,000was probably a climate shift

75400:43:58,067 --> 00:44:02,033which spread grasslandsfrom Africa into Asia.

75500:44:05,867 --> 00:44:09,967And with the grasseswent the game animals.


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75600:44:10,033 --> 00:44:12,267LIEBERMAN:Animals are going to be movingout of Africa,

757

00:44:12,333 --> 00:44:14,833and the hominids will just bekeeping pace with those animals.

75800:44:14,900 --> 00:44:16,200After all,that's their livelihood.

75900:44:16,500 --> 00:44:20,133NARRATOR:Of course, our ancestorsdidn't know

76000:44:20,200 --> 00:44:21,900they were leaving Africa.

76100:44:21,967 --> 00:44:24,733They just followed the animalsthey depended on,

76200:44:24,800 --> 00:44:29,000through the Sinai, up intothe Middle East and beyond.

76300:44:31,067 --> 00:44:33,567It's often been calledan exodus,

76400:44:33,633 --> 00:44:36,000but it really wasn't like that.

76500:44:36,067 --> 00:44:37,700SHEA:When people think of an exodus

76600:44:37,767 --> 00:44:39,767they think of the Bibleor they think of migration,

76700:44:39,833 --> 00:44:42,200they think of Europeans comingover here to the New World.

76800:44:42,267 --> 00:44:46,100It probably wasn't likeany historical migration,

769


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00:44:46,167 --> 00:44:47,967this dispersal of humansout of Africa.

77000:44:49,533 --> 00:44:53,500NARRATOR:The process was probably

very, very slow,

77100:44:53,567 --> 00:44:57,300much like the spreadof any other animal species

77200:44:57,367 --> 00:44:59,467into new territories.

77300:44:59,533 --> 00:45:02,533ANTN:You could imaginea group of Homo erectus

77400:45:02,600 --> 00:45:04,667moving their range

77500:45:04,733 --> 00:45:07,667a kilometer a yearin one direction.

77600:45:07,733 --> 00:45:12,100And doing that continually overa long enough period of time,

77700:45:12,167 --> 00:45:15,967you can get a distance fromAfrica to Indonesia covered

77800:45:16,033 --> 00:45:18,833in, say, 15,000 years.

77900:45:20,867 --> 00:45:24,933NARRATOR:By a million years ago, ourancestors had populated Asia

78000:45:25,000 --> 00:45:30,467from the Caucasus to Indonesia.

78100:45:30,533 --> 00:45:32,267And they were in Europe too,

78200:45:32,333 --> 00:45:35,500as a recent discoveryin Spain has shown.


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78300:45:35,567 --> 00:45:41,300Homo erectus had conqueredthe Old World.

78400:45:45,933 --> 00:45:49,700The fact that they made it

so far with limited technology

78500:45:49,767 --> 00:45:51,800and relatively small brains

78600:45:51,867 --> 00:45:57,767makes them seemeven more remarkable.

78700:45:57,833 --> 00:45:59,933And their longevitywas astonishing.

78800:46:00,000 --> 00:46:02,200A few pockets of Homo erectus

78900:46:02,267 --> 00:46:05,467may have been stillclinging on in Asia

79000:46:05,533 --> 00:46:08,133

just 50,000 years ago.

79100:46:08,200 --> 00:46:12,200That's a spanof two million years.

79200:46:13,667 --> 00:46:20,133Our own species has onlybeen around for 200,000.

79300:46:20,200 --> 00:46:26,100What was the secretof Homo erectus's success?

79400:46:26,167 --> 00:46:32,167The amazing finds at Dmanisihave given us one last clue.

79500:46:32,233 --> 00:46:34,900One of the skullsbelonged to an old man.

79600:46:34,967 --> 00:46:38,133His jaw bone revealedhe had lost all his teeth


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79700:46:38,200 --> 00:46:40,533well before he died.

79800:46:40,600 --> 00:46:42,067AGUST:That was a real surprise.

79900:46:42,133 --> 00:46:44,167It means that this individual

80000:46:44,233 --> 00:46:47,000survived two yearswithout teeth.

80100:46:47,300 --> 00:46:51,933NARRATOR:For an elder to have survivedthat long without teeth

80200:46:52,000 --> 00:46:56,200must mean that others inthe group were feeding him,

80300:46:56,267 --> 00:46:59,500perhaps even chewinghis food for him.

80400:46:59,567 --> 00:47:01,167HRDY:I love this story.

80500:47:01,233 --> 00:47:05,500This was a remarkable testimonyfrom the past

80600:47:05,567 --> 00:47:07,967about the qualityof emotional life

80700:47:08,033 --> 00:47:10,700that may have characterizedHomo erectus.

80800:47:12,500 --> 00:47:15,467NARRATOR:Here is a tantalizing clueto what may be

80900:47:15,533 --> 00:47:19,433this ancestor'smost important legacy:

81000:47:19,533 --> 00:47:22,533


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the instinctto look after each other.

81100:47:25,400 --> 00:47:29,333And it helps us imagine TurkanaBoy's final day on earth.

81200:47:35,933 --> 00:47:43,000In the animators' scenario,he starts the day out on a hunt.

81300:47:43,067 --> 00:47:46,767But he has trouble keeping upwith the hunting party.

81400:47:46,833 --> 00:47:49,467Why?

81500:47:49,533 --> 00:47:53,800The evidence from his skeletonis that he was sick and in pain

81600:47:53,867 --> 00:47:55,933at the time he died.

81700:47:56,000 --> 00:47:58,333If we look at his lower jaw,

81800:47:58,400 --> 00:48:01,100we can see right here,under the teeth,

81900:48:01,167 --> 00:48:04,133that we've got a bit ofan abscess and an infection.

82000:48:04,200 --> 00:48:06,767That kind of an infectioncould have entered

82100:48:06,833 --> 00:48:09,300the rest of his body,could have killed him.

82200:48:09,367 --> 00:48:12,500NARRATOR:An abscess that ateaway that much of his jawbone

82300:48:12,567 --> 00:48:16,467would have been agonizing.

82400:48:16,533 --> 00:48:19,167


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Turkana Boy is in so much pain,

82500:48:19,233 --> 00:48:22,600he's unable to continuethe hunt.

826

00:48:24,733 --> 00:48:26,533Knowing he would belooked after,

82700:48:26,767 --> 00:48:30,500perhaps he returned to hiscampsite to find comfort

82800:48:30,567 --> 00:48:34,367among the females.

82900:48:34,433 --> 00:48:36,600I think he was probablya miserable fellow,

83000:48:36,667 --> 00:48:38,867in a lot of painand very dependent

83100:48:38,933 --> 00:48:40,467on support and handouts.

83200:48:40,533 --> 00:48:44,367So it was a speciesthat already felt

83300:48:44,667 --> 00:48:47,300that here's one of our weaklingsthat, you know, we love

83400:48:47,367 --> 00:48:50,733and must protect and carefor to have got him that far.

83500:48:52,833 --> 00:48:56,100NARRATOR:But however much they may havewanted to help him,

83600:48:56,167 --> 00:48:59,300there was nothing they could doabout the infection

83700:48:59,333 --> 00:49:02,600that was probably spreadingthrough his body.

838


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00:49:05,500 --> 00:49:07,467DEAK:From what the evidence suggests,

83900:49:07,533 --> 00:49:12,233I just always imagined him notknowing what was wrong with him,

84000:49:12,300 --> 00:49:14,867and there's a sadness to it,

84100:49:14,933 --> 00:49:19,633but ultimately from that comesthis immortal being.

84200:49:22,100 --> 00:49:27,767NARRATOR:His skeleton was so complete,it is likely he died in water,

84300:49:27,833 --> 00:49:31,433which would have protected him.

84400:49:33,533 --> 00:49:36,133MEAVE LEAKEY:It's very unusualto get a skeleton,

84500:49:36,200 --> 00:49:38,767because normally these thingsare eaten by carnivores,

84600:49:38,833 --> 00:49:40,267and in this case, it seems

84700:49:40,333 --> 00:49:42,767that the boy's bodywas washed into a swamp,

84800:49:42,833 --> 00:49:45,533and so the carnivores never sawit and never destroyed it.

84900:49:45,600 --> 00:49:49,567And it gradually decomposedand as the rivers flooded,

85000:49:49,633 --> 00:49:52,600brought in more sediment,buried it,

85100:49:52,667 --> 00:49:54,433and you could see footprintsof hippos


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85200:49:54,500 --> 00:49:56,433that had walkedall over the bones,

85300:49:56,500 --> 00:49:59,467

and some of the ribs and thingswere standing vertically

85400:49:59,533 --> 00:50:01,467instead of lying flaton the ground.

85500:50:01,533 --> 00:50:03,467You could sort of reconstructthe situation

85600:50:03,533 --> 00:50:06,400and how the boy... what hadhappened after he died

85700:50:06,467 --> 00:50:08,600and why he was complete.

85800:50:08,667 --> 00:50:11,800It was just... it really was anamazing experience to see it.

85900:50:15,333 --> 00:50:17,933NARRATOR:For almost two million years,

86000:50:18,000 --> 00:50:21,100his bones were preservedby the earth.

86100:50:21,167 --> 00:50:26,767Their discovery opened a windowfor us on an unknown world,

86200:50:26,833 --> 00:50:32,333the world of the most successfulhuman ancestor of all time,

86300:50:32,400 --> 00:50:36,167Homo erectus.

86400:50:36,233 --> 00:50:39,433They've revealed to usthat mysterious moment

86500:50:39,500 --> 00:50:42,667when almost everything human


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was born:

86600:50:42,733 --> 00:50:47,800our bodies, our minds,our emotions.

867

00:50:50,333 --> 00:50:53,800Think of all we've become.

86800:50:58,400 --> 00:51:00,633Trace the threads of our origins

86900:51:00,700 --> 00:51:04,133back through the ancestorswho went before.

87000:51:04,200 --> 00:51:08,367They all lead backto Turkana Boy and his kind,

87100:51:08,433 --> 00:51:10,567the first humans.

87200:51:20,767 --> 00:51:23,600NOVA's got a brand-newevolution Web site,

87300:51:23,667 --> 00:51:25,533with lots to exploreabout our ancestors.

87400:51:25,600 --> 00:51:27,467We want to knowwhat you think.

87500:51:27,533 --> 00:51:30,667Bookmark it today,and give us your feedback.

87600:51:30,733 --> 00:51:33,633Find it at pbs.org.

87700:51:35,467 --> 00:51:39,367

Major funding for NOVAis provided by the following:

87800:51:39,433 --> 00:51:41,233ExxonMobil,

87900:51:41,300 --> 00:51:44,033taking on the world'stoughest energy challenges.


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88000:51:44,100 --> 00:51:45,800And by:

88100:51:50,200 --> 00:51:52,100And...

88200:52:01,367 --> 00:52:04,433And by the Corporationfor Public Broadcasting

88300:52:04,500 --> 00:52:07,533and by contributionsto your PBS station from:

88400:52:12,167 --> 00:52:14,767Captioned byMedia Access Group at WGBH

88500:52:15,767 --> 00:52:25,767Downloaded From www.AllSubs.org

02 - becoming human - birth of humanity edited for evol fall2010

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