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Twenty thousand
years ago,
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the world was in the grip
of an ice age.
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Much of the northern hemisphere
was blanketed by snow
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and crushing glaciers,
miles thick.
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An iced earth.
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Great beasts,
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some familiar and
some strange, lived here.
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Adapted for the
punishing cold.
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This was the world
of the mammoths.
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Kingdom of the titans.
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An age of ice.
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These bones
belonged to giants,
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but unlike dinosaurs,
these animals,
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shared the planet with humans.
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We can only imagine
their strange calls
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that once haunted the dreams
of our ancestors.
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What happened to these great
beasts that once walked among us?
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Why was extinction their fate?
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The stories of their lives
continue to unfold,
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as strange new creatures
are uncovered.
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In 2007, a reindeer herder
in northern Russia
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discovered this mummified
baby woolly mammoth.
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She had been buried
and frozen for 42,000 years.
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Her skin and organs, some fur and even
her eyes are extremely well-preserved.
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Her tiny tusks,
not yet visible.
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Named lyuba,
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she is the most
intact mammoth ever found.
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And a rare window
to our frozen past.
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Two and a half million years ago,
an ice age began with a snowflake.
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One of nature's
most beautiful creations.
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One by one they fell,
billions upon billions.
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Blanketing the north,
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chilling the planet.
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The pleistocene epoch, our
most recent ice age, was born.
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Our story begins near the
end of the last ice age,
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roughly 20,000 years ago.
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It was an environment
well suited to giants.
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Woolly mammoths.
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This icon of the pleistocene
spread through Europe, Siberia,
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and into northern parts
of north America,
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roaming grasslands
called the mammoth steppe.
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It is likely the herds
were constantly on the move,
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seeking their
favorite vegetation.
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Individuals eating
up to 400 pounds per day.
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Similar to her
elephant cousins,
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baby lyuba would have lived in a
family clan of about 10 members,
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protected by a dominant
female, the matriarch.
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Standing up to 10 feet and
weighing as much as eight tons,
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woolly's huge mass helped
them to retain body heat.
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Three layers of hair and wool,
a layer of insulating fat,
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and small fur-lined ears also
helped them cope with the cold.
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Massive curved tusks,
up to 16 feet long,
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could be used as plows to reach
grass buried under the snow.
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The calves were curious and playful,
but vulnerable to predators,
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and always under the watchful eye
of their mother.
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Sometimes a male bull would challenge
another for dominance of the herd.
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A clash of these titans
could be a violent affair.
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Since the birth of our planet,
the climate has been changing,
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cycling, temperatures
rising and falling.
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There have been at least
five major ice ages.
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Some may have covered
the whole planet in ice.
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Climate cycles have been
fundamentally shaped by variations
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in the earth's orbit
over time.
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These variations alter the way
the sun strikes the earth,
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and can lead to cooling
on the surface.
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As the ice caps grow,
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they act as a mirror, reflecting more
sunlight away from the shining ice,
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causing heat to escape
from the atmosphere.
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So cooling speeds up,
then more ice,
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more reflection
and more cooling.
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00:10:11,861 --> 00:10:16,658
Greenhouse gases in the atmosphere
such as methane and carbon dioxide
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counterbalance the cooling, trapping
the sun's heat like a greenhouse
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around the planet.
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Volcanoes can produce
these gases naturally.
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Plants and trees recycle the
gases and keep them in check.
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Too much greenhouse gas,
and the planet can warm.
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Too little, and it cools.
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Each of these factors,
the earth's orbit,
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angle to the sun
and atmosphere,
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00:10:48,731 --> 00:10:52,110
all work together
to shape earth's climate.
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This is the
clockwork of nature.
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Even the tiniest variation
can tip the scale
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with profound consequences.
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During our most
recent ice age,
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glaciers blanketed the north.
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But most wildlife
lived south of the ice sheets
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on vast grassy plains.
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The grasslands supported
immense herds of grazers.
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Like today,
there were seasons,
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but each was about
16 degrees fahrenheit cooler,
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and with so much water
locked up in ice,
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there was less snowfall
on the plains.
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Animals we know today,
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lived among mammoths,
mastodons and big cats.
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The plains of ice age Europe,
Asia and north America
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were like the
African serengeti.
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And like the serengeti,
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where there are grass eaters,
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there are meat eaters.
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Dire wolves.
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These intelligent, social carnivores,
lived and hunted in packs.
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At up to 150 pounds,
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they were more powerfully built
than today's gray wolves.
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And they were
aggressive hunters.
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The wolves are not alone.
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Sabre-toothed cats
smell the fresh kill,
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and an opportunity.
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With large curved fangs and nearly twice
the weight of a modern African lion,
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they are the top predator.
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During the pleistocene epoch,
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so much of the earth's water
was frozen into the ice caps,
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that sea level dropped by over
300 feet, connecting continents.
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Many ice age animals arrived
in north America from Siberia,
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over this land bridge,
called beringia.
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But they were not the only
ones to discover the passage.
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Humans made their way to this
vast, untamed continent.
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Though not physically equipped
for a harsh and bitter climate,
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our intelligence,
curiosity and language
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allowed us to cope
with new challenges.
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Ice age humans were the first to leave
symbolic records of their lives.
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Their drawings, mostly
found in European caves,
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evoke a world of fire and ice,
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of mammoths,
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bison
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and horses.
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As the ice age giants
disappeared,
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the bones they left behind fueled
wild and chilling speculation.
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Siberians imagined that hulking
skeletons rising from melting ice
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must belong to giant moles
that lived in hell.
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A mammoth's skull may have been
the inspiration for the cyclops
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of Greek mythology.
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Even early attempts by scientists
to assemble mammoth bones
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were often just as wild.
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Scientists were equally confounded
by massive boulders standing alone.
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After centuries
of speculation,
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geologists determined that the
boulders, called "erratics,"
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had been carried thousands
of miles on rivers of ice,
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and left behind
when the ice melted.
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And the mysterious bones
from mythology
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belonged to extraordinary
animals from that lost world.
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One unusual place,
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hidden within the
ice age scrub lands,
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tells an exceptional, though grim, story.
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Tar pits.
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A columbian mammoth, lured by
drinking water, has perished,
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likely from dehydration
and exposure
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after getting trapped
in the tar.
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Its carcass is of interest
to this sabre-toothed cat.
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She's hungry.
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A mammoth is a temptation
worth the risk.
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On this day, the tar has
claimed another victim.
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And the smell of death
attracts others.
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For forty thousand years,
countless predators and prey
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were mired in this deathtrap.
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Their bones sinking into and
preserved by the tarry asphalt.
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Bones that continue to be pulled
from the la brea tar pits today,
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in the heart
of downtown Los Angeles.
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Walls now surround the tar pits to allow
the bones to be safely excavated.
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These sticky deposits were naturally
formed when asphalt, deep in the earth,
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gradually rose to the surface,
seeping into pools.
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Since 1906, more than
three millions fossils
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have been recovered
from over 400 species.
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Making this one of the world's richest
repositories of ice age animals.
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I've never seen that before.
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In a glass-walled lab
called "the fishbowl,"
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la brea paleontologists and volunteers
separate ice age fossils from the tar.
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They're exposing the skull and
jaws of their biggest find yet,
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a nearly complete mammoth.
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Discovered under
a nearby parking lot,
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the team has named him zed.
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La brea's tar is an ideal
medium to preserve bone.
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It penetrates them, protecting everything,
from the most delicate bird bone
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to zed's 200-pound skull.
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The bones are so saturated that tar
continues to ooze from zed's skull today.
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From the size, width and condition
of his two large molars,
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they confirm zed is a male.
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A columbian mammoth,
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who was between 48 and
52 years old when he died.
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When zed's 10-foot tusks
were excavated,
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they were encased in a
protective jacket of plaster.
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As the plaster is removed,
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the tusks are seen
for the first time
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in possibly 40,000 years.
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Ice age secrets
come in all sizes.
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As the asphalt matrix is
cleaned from tar pit fossils
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like this dire wolf skull,
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it is sorted and what remains
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is a treasure trove
of tiny micro fossils.
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In this spoonful of sediment are the
fossilized bones from two snakes,
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a mouse elbow,
and the legs of two beetles.
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Even plant seeds
and leaves are found.
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These micro fossils are a record of
what lived in the la brea ecosystem
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40,000 years ago,
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and clues to the environment
and climate at the time.
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Zed may have been attracted to
la brea's marsh-like setting,
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unaware of its hidden dangers.
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00:22:02,321 --> 00:22:05,866
Once he stepped in,
his fate was sealed.
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00:22:17,545 --> 00:22:21,465
Some creatures trapped in la
brea's tar were quite bizarre.
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00:22:23,259 --> 00:22:25,261
A shasta ground sloth.
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00:22:26,762 --> 00:22:31,058
This furry plant eater roamed the
American west and northern Mexico.
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00:22:33,769 --> 00:22:38,148
It's massive fore claws may have helped
to fend off sabre-toothed attacks.
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00:22:43,279 --> 00:22:45,155
Though it was as big
as a black bear,
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it had relatives that were 20 feet
long and weighed 6,000 pounds.
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00:22:54,290 --> 00:22:57,042
But the shasta is best known
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00:22:57,126 --> 00:23:00,212
for the unlikely climate clues
it left behind
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in the darkness of caves.
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00:23:07,469 --> 00:23:11,682
Sloth dung is so
well-preserved in some caves
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that it smells like
fresh manure when broken open.
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The content of the dung reveals
what these animals ate.
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Knowing their diet
and the age of the dung,
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00:23:23,402 --> 00:23:28,324
scientists can track how vegetation
and climate was changing.
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00:23:41,795 --> 00:23:44,840
Larger and less hairy
than their woolly cousins,
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00:23:45,257 --> 00:23:49,011
columbian mammoths ranged
all across north America
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00:23:49,053 --> 00:23:51,013
and into present-day Mexico.
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00:23:53,140 --> 00:23:56,602
In some places, the warm
waters of natural hot Springs
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00:23:56,685 --> 00:24:00,648
lured them to succulent
grasses, even in winter.
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00:24:10,532 --> 00:24:13,118
But a misstep could be fatal.
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00:24:20,542 --> 00:24:24,922
There was no escape from
these steep, slippery sides.
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00:24:35,683 --> 00:24:39,645
Over thousands of years, the
hot Springs turned into this.
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00:24:41,563 --> 00:24:44,858
An ice age tomb
in south Dakota.
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00:24:48,362 --> 00:24:52,074
It holds the largest concentration
of mammoths ever found.
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Looking like an ancient
burial ground,
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00:24:57,871 --> 00:25:01,417
57 columbian mammoths,
three woolly mammoths,
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00:25:01,500 --> 00:25:04,878
and 28 other ice age animals
have been discovered.
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Dozens more lie buried still.
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One by one,
mammoths died here,
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over a period
of several hundred years
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near the end of the ice age.
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00:25:23,313 --> 00:25:27,776
The position of this mammoth,
facing upward with limbs sprawled,
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00:25:27,860 --> 00:25:31,613
is sad witness that he died
while struggling to climb out.
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Every bone here tells a
story, like a diary.
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Even ancient tusks give us information
about the mammoth's life.
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Tusks are made of a hard
material called dentin,
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similar to our teeth.
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00:26:01,435 --> 00:26:05,481
Each year of tusk growth is
recorded in a layer of dentin,
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like a tree ring.
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00:26:08,650 --> 00:26:10,819
A cross section
of the tusk shows
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00:26:10,861 --> 00:26:14,073
that in years with good
climate and plenty to eat,
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00:26:14,156 --> 00:26:17,576
tusks grew faster
and rings are thicker.
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00:26:18,327 --> 00:26:22,122
In times of severe weather and
less food, the rings are narrow.
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00:26:27,002 --> 00:26:32,174
Mammoths grew six sets of teeth over
their roughly 60-year lifetime,
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like elephants today.
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00:26:34,468 --> 00:26:37,096
By determining which
teeth were present,
244
00:26:37,179 --> 00:26:39,890
we can know the mammoth's
age when it died.
245
00:26:41,683 --> 00:26:45,771
Understanding the health and age
of the mammoths helps us to know
246
00:26:45,854 --> 00:26:48,148
what was happening
in their environment.
247
00:26:49,691 --> 00:26:54,196
Curiously, the bones at the mammoth
site reveal another interesting fact.
248
00:26:57,157 --> 00:27:00,828
All of the mammoths that
perished here were young males.
249
00:27:14,424 --> 00:27:18,887
Perhaps a little more adventurous
and a little less cautious
250
00:27:18,929 --> 00:27:21,557
than the female and adults.
251
00:27:24,685 --> 00:27:29,064
Hot Springs and tar pits preserve
many clues about ice age animals,
252
00:27:29,731 --> 00:27:33,402
but these traps did not
cause a mass extinction.
253
00:27:35,320 --> 00:27:39,491
Something else was happening at
the end of the last ice age.
254
00:27:40,993 --> 00:27:43,996
The world of the mammoth
was warming.
255
00:27:46,957 --> 00:27:51,295
Animals adapted for a cooler climate
faced a changing landscape.
256
00:27:53,422 --> 00:27:57,801
Forests encroached on the grasslands,
altering the food chain.
257
00:27:59,094 --> 00:28:03,265
And just as a warming planet
created ecological challenges,
258
00:28:03,348 --> 00:28:07,394
another new threat
to wildlife appeared.
259
00:28:40,844 --> 00:28:44,640
A mammoth was no match
for human Spears.
260
00:28:45,974 --> 00:28:50,979
Mammoth gifts of food and fur and bone
were invaluable survival resources,
261
00:28:52,147 --> 00:28:55,484
but our greatest
adaptation to winter
262
00:28:55,567 --> 00:28:58,445
was the remarkable human mind
263
00:28:58,487 --> 00:29:00,739
and the ability to tame
the world around us,
264
00:29:00,822 --> 00:29:04,326
to harness the power of fire
and flint and bone.
265
00:29:08,789 --> 00:29:12,501
Our ancestors met the cold
with a burst of innovation.
266
00:29:12,584 --> 00:29:17,422
They crafted bone tools and needles
to sew clothing from hides.
267
00:29:19,841 --> 00:29:23,637
Learn to paint, make music and sing.
268
00:29:33,063 --> 00:29:37,567
They were creative, intelligent
beings whose language and song
269
00:29:37,651 --> 00:29:40,570
gave new calls
to the winter night.
270
00:29:45,117 --> 00:29:49,121
What ultimately drove
the mammoths to extinction
271
00:29:49,204 --> 00:29:50,747
is difficult to know.
272
00:29:51,873 --> 00:29:54,334
Some speculate that
the warming climate
273
00:29:54,376 --> 00:29:57,212
reduced mammoth populations
dramatically,
274
00:29:57,254 --> 00:30:01,258
just as humans arrived
to deal the final blow.
275
00:30:02,509 --> 00:30:07,389
Roughly 4,000 years ago, while the
pyramids were being built in Egypt,
276
00:30:08,056 --> 00:30:10,559
the last mammoth perished
277
00:30:11,310 --> 00:30:14,646
and the species
ceased to exist.
278
00:30:28,160 --> 00:30:31,955
About 12,000 years ago,
the ice began to melt.
279
00:30:33,498 --> 00:30:38,420
The world's climate had shifted again,
marking the end of the pleistocene
280
00:30:38,962 --> 00:30:41,465
and the dawn
of the holocene epoch.
281
00:30:42,466 --> 00:30:45,719
Our modern climate era
had begun.
282
00:30:49,348 --> 00:30:51,683
As the glaciers melted,
283
00:30:51,767 --> 00:30:53,894
trickles became torrents
284
00:30:53,935 --> 00:30:57,606
and north America was awash in
rivers and floods.
285
00:31:06,531 --> 00:31:08,992
By the end
of the last ice age,
286
00:31:09,076 --> 00:31:14,956
70% of the world's largest
land animals had vanished,
287
00:31:15,957 --> 00:31:17,292
gone forever.
288
00:31:25,300 --> 00:31:28,428
A global temperature rise
of just 16 degrees fahrenheit
289
00:31:28,470 --> 00:31:32,140
was enough to change
the entire face of the planet.
290
00:31:34,309 --> 00:31:39,981
Melt water drained back into the oceans,
and sea levels rose once again.
291
00:31:41,566 --> 00:31:45,487
As the glaciers melted away, the
sheer power of the bulldozing ice
292
00:31:45,570 --> 00:31:49,199
was revealed
in newly-created geography.
293
00:31:51,993 --> 00:31:56,790
Trapped inland water
pooled to form huge lakes.
294
00:31:57,749 --> 00:31:59,876
The Great Lakes.
295
00:32:01,503 --> 00:32:04,256
Where cathedrals of ice
once stood,
296
00:32:05,006 --> 00:32:06,925
cities of steel arose.
297
00:32:09,511 --> 00:32:11,096
Humans flourished.
298
00:32:13,432 --> 00:32:16,852
Our population grew from
one million during the ice age
299
00:32:16,935 --> 00:32:18,854
to many billions today.
300
00:32:20,355 --> 00:32:24,401
Now, our industries create
so much greenhouse gas
301
00:32:24,943 --> 00:32:29,448
that we humans have become
participants in the climate equation.
302
00:32:34,369 --> 00:32:38,039
As the frozen footprint of the
ice age continues to shrink,
303
00:32:38,415 --> 00:32:41,042
the earth is becoming warmer
than it has been
304
00:32:41,084 --> 00:32:43,879
in the last 120,000 years.
305
00:32:50,051 --> 00:32:52,929
Now, as at the end
of the last ice age,
306
00:32:53,513 --> 00:32:56,391
many animal species
are threatened by extinction.
307
00:32:58,143 --> 00:33:00,979
Wildlife again
confronts a warming climate,
308
00:33:01,438 --> 00:33:05,317
habitat loss and the pressures
of a changing world.
309
00:33:15,827 --> 00:33:19,623
The ice age has left behind
cautionary reminders.
310
00:33:21,166 --> 00:33:24,836
And as global warming melts the
permafrost of the far north,
311
00:33:25,378 --> 00:33:29,090
occasionally, an entire
frozen mammoth is revealed.
312
00:33:36,598 --> 00:33:38,725
Baby mammoth lyuba
313
00:33:38,767 --> 00:33:42,521
was discovered when
her icy tomb melted away.
314
00:33:46,608 --> 00:33:48,944
She astounded biologists
315
00:33:49,027 --> 00:33:52,948
because of her completeness
and incredible preservation.
316
00:33:55,116 --> 00:33:59,955
Ct scans reveal that all of her
internal organs are intact.
317
00:34:03,458 --> 00:34:06,419
And the discovery of mud
in her throat and lungs
318
00:34:06,461 --> 00:34:09,297
suggests that she died
in a shallow lake.
319
00:34:15,720 --> 00:34:19,432
Lyuba was only one month old
when she died,
320
00:34:19,474 --> 00:34:24,145
a sad fate for this young
mammoth, but a gift to us
321
00:34:24,229 --> 00:34:30,569
that she has traveled 42,000 years
to share her ice age secrets.
322
00:34:33,989 --> 00:34:37,909
We visit ice age relics
and hold them in awe,
323
00:34:37,993 --> 00:34:39,786
for they connect us
to the past.
324
00:34:42,330 --> 00:34:45,667
To look at lyuba
is to look back in time.
325
00:34:46,459 --> 00:34:50,463
Woolly mammoths,
once titans of the ice age,
326
00:34:50,505 --> 00:34:52,173
are now extinct,
327
00:34:52,257 --> 00:34:55,677
while we who lived
among them, live on.
328
00:34:58,013 --> 00:35:02,767
Creatures from our frozen past continue
to yield clues about their lives.
329
00:35:04,060 --> 00:35:08,857
And the more we learn about their world,
the better we understand our own.
330
00:35:10,400 --> 00:35:13,528
But perhaps the greatest
gift of the ice age
331
00:35:13,570 --> 00:35:15,739
is neither bone nor hide.
332
00:35:16,656 --> 00:35:20,535
It is our minds that
helped us survive the ice.
333
00:35:25,540 --> 00:35:26,833
And only our wisdom
334
00:35:27,584 --> 00:35:30,712
may guide us toward
a sustainable future.
335
00:35:32,380 --> 00:35:37,886
For the ice age is a climate story
more relevant now than ever.