Documentary, Extinct Complete Series Episode 3 - The Mammoth
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#ExtinctCompleteSeries #Mammoth #ExtinctMammoth #Mammoth
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AnimalsTranscript
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00:40For millions of years a magnificent animal dominated the northern hemisphere.
00:49Thriving on lush ice-age grasslands, huge herds spread across continents.
00:54The mammoth shared a common ancestor with today's elephants.
01:02The two species diverged five million years ago.
01:12But while the elephant has survived, this creature succumbed to extinction.
01:20What killed off the mammoth?
01:22Nature?
01:24Man the hunter?
01:25Or something even more destructive?
01:41This is the new frontier of mammoth paleontology.
01:46Not Siberia, but Mexico City.
01:52Here, discoveries are challenging the two heavyweight theories, climate change and human hunting, that have long been invoked in the passionate debate on the demise of the mammoth.
02:07I can imagine mammoths as very noble animals, and to me, to imagine this completely different landscape only 11,000 years ago, is quite amazing.
02:22I want to find out more, and I want to find out why they died.
02:25Geologist Silvia Gonzalez lives in Liverpool, but is Mexican by birth.
02:32She's returned to Mexico City to study one of the most revealing mammoth graves in the world.
02:39This dusty suburb called Toquila seems an unlikely setting for an important archaeological investigation.
02:54But in 1996, workmen laying foundations for a new cantina, hit something buried 15 feet underground.
03:09Archaeologists quickly uncovered over 1,200 bones, of what can only be a doomed family group of seven mammoths.
03:16Toquila is a very important site, because we have an instant photograph of the environment 11,000 years ago, which is preserved.
03:28These remains have been carbon dated to 11,000 years old, the very time when mammoths disappeared.
03:35So studying this site is vital to discover if climate change or human hunting wiped out the mammoth.
03:51Mammoths are usually associated with the deep freeze of the Siberian steppes.
03:57But the American or Colombian mammoth, as scientists classify it, was an even more impressive animal.
04:05It weighed almost twice as much as its woolly Siberian cousin.
04:11An adult male could stand 13 foot high, and boast spiral tusks over 10 feet long.
04:20The basin of Mexico in the late ice age.
04:26Average temperatures are 10 degrees Celsius, some 5 degrees cooler than today.
04:32The Toquila family are on the move.
04:36They have the characteristic sloping back and domed head of their species.
04:39But their hairy coat has thinned out to adapt to the relative heat of the Americas.
04:42Like elephants today, our family migrates hundreds of miles every year to seek out the best places for grazing.
04:46They have the characteristic sloping back and domed head of their species.
04:50They have the characteristic sloping back and domed head of their species.
04:54But their hairy coat has thinned out to adapt to the relative heat of the Americas.
04:58Like elephants today, our family migrates hundreds of miles every year to seek out the best places for grazing.
05:11They live for up to 70 years, and spend two-thirds of every day feeding on grass to sustain their 10-ton bulk.
05:21Here at Toquila, the scattered bone bed confirms that Colombian mammoths lived in small family herds.
05:34There are the bones of an infant, and this 50-year-old female is believed to be the matriarch who led the group.
05:42We know that elephants living today are very social animals, and we can extrapolate that information.
05:51Imagine that these mammoths were very sociable as well.
05:55And in fact, the evidence from Toquila is telling us that, because we have the social structure of the herd preserved there.
06:02Adult mammoths were impregnable tanks of the plains.
06:06But their young took up to 15 years to reach full size, and were vulnerable to the Ice Age's most powerful predators.
06:22The Toquila family stick together to provide protection.
06:26But danger is never far away.
06:44A sabre-toothed tiger notices the infant has strayed from the herd.
06:50The infant runs for its life.
06:52The herd is quickly mobilized to form an impenetrable defensive wall.
07:03Working together, the herd has little to fear from even the fiercest predators.
07:12Yet catastrophe did catch up with this family.
07:15How did they end up in this mass grave?
07:22Was their death tied up with the extinction of the entire species?
07:30At first sight, it would seem more likely that they were killed by a specific local event,
07:36because they're buried in volcanic mud.
07:38This is a piece of pumice, volcanic glass, and we know that all of these mammoths are embedded in this material.
07:49So this is the evidence for a volcanic mud flow.
07:53Soil deposits reveal that Popo Catepetl volcano, only 12 miles from Toquila, was active 11,000 years ago.
08:03Were the mammoths killed by a volcanic eruption?
08:07Were the mammoths killed by a volcanic eruption?
08:13The chaotic nature of the bone bed makes Sylvia skeptical.
08:17The main reason to believe that they were not killed by the volcano, and the subsequent mud flow, is because if that was the case when the animals were alive, you should find the whole complete animal.
08:35And in the side we only have bits and pieces of the body.
08:39This must mean the Toquila mammoths were dead already, their carcasses decaying and easily shattered when the volcano hit them.
08:50So the question remains, what killed them in the first place?
08:56When it comes to the extinction of the mammoth, one of the heavyweight theories has pointed the finger at climate change.
09:07Carbon dating of American finds reveals the number of mammoths dropped as the ice age ended and the world warmed up.
09:2320,000 years ago, temperatures started to rise.
09:27They rose some 7 degrees Celsius, transforming the American environment.
09:32Pollen samples revealed that the grasslands of the American southwest gave way to the desert of thin scrub and cacti that remains today.
09:45The mammoths there could not sustain their diet, and many would have died out.
09:52But as a geologist, Sylvia Gonzalez believes the high altitude near Mexico City made it a special case.
09:59Soil samples here show it was a kind of oasis.
10:04The basin of Mexico, 11,000 years ago, was the perfect habitat for these animals.
10:11It was a very lush and rich landscape, plenty of grass for them to eat, and it was a kind of mammoth Shangri-La.
10:20Climate change couldn't have killed every mammoth. It certainly doesn't solve the particular mystery of Tokwila.
10:30Scientists have been forced to consider another possibility.
10:36No one knows precisely when people first colonized the Americas.
10:46But by 12,000 years ago, archaeological sites proved they had spread all the way from Arctic Canada to the tip of South America.
10:54If the basin of Mexico was a refuge, a Shangri-La in the desert, man would compete to have a piece of it too.
11:12Here was a new sophisticated predator for the Colombian mammoth to contend with.
11:22Did man destroy the mammoths at Tokwila?
11:27Did man destroy the mammoths at Tokwila?
11:46The mammoth thrived for millions of years and spread from southern Europe through Siberia, all the way to Central America.
11:54But what caused the extinction of this well-adapted giant?
12:06Today, it's in Mexico that cutting-edge research is uncovering new clues that shed more light on the traditional theories about what killed the mammoths.
12:16In this mammoth graveyard, paleontologists are finding evidence of man's presence.
12:24This is one of the bones that potentially are showing the interaction between humans and mammoths.
12:30Over here, you can see this sharp edge, and it's possible that humans were breaking the bone to make use of this kind of resource.
12:40The best-known early humans who entered the Americas are known as the Clovis people, after the site in New Mexico where their culture was first uncovered.
12:56They had developed a new technology, the fluted flint spear point.
13:01These have been found amongst mammoth bones at a handful of sites.
13:09For many American archaeologists, there was only one conclusion.
13:14Clovis man hunted the mammoth to extinction across the entire continent.
13:18The circumstantial evidence seemed compelling.
13:26Man arrived just as the mammoth population went into steep decline.
13:35But later research calls into question this traditional hunting theory.
13:39Paleontologist Eileen Johnson is an expert in bone forensics.
13:48Such is the importance of toquila that she's come from Texas to determine whether this mammoth herd was hunted down by man.
13:57This looks like a tibia that's coming out.
14:01This bone was broken fresh.
14:02We have really nice helical fractures and that's kind of the evidence we have here as part of that circling fracture.
14:12For Eileen, the distinctive helical fractures indicate Clovis man was present, breaking these bones sharply to make tools.
14:22This is a beautiful fracture surface here.
14:26This may even be a remnant of the blow, the initial blow.
14:30To test her theory, Eileen tries to replicate the bone fractures she's identified.
14:38She uses modern cow bones and a primitive yet effective technology.
14:44And we're going to do a one anvil over the shoulder technique on this one.
14:51So you need to hold the femur here so it's steady.
14:54You need to come up and take your hand back as far as you can.
15:00And then you want to see where you're going to hit it.
15:04And then you want to bring the rock down as hard and as fast as you can.
15:08Okay, try again because you've cracked it.
15:13Very good.
15:18Very, very good.
15:21That's a beautiful helical fracture.
15:25The force coming down through the hammer stone actually flexes the bone.
15:30And you get a rebound action that helps continue that fracture.
15:37So basically they understood physics.
15:41Good.
15:43Clovis people splintered mammoth bones to make tools.
15:47But that does not necessarily mean they killed the mammoths.
15:50That's a beautiful technological flake coming out.
15:55To clinch the hunting theory, Eileen would need to find direct evidence of Clovis weapons being used.
16:03At the moment we have no projectile points, nothing that, no stone tools of that nature.
16:12So we cannot say that man played a direct role in the killing of these animals.
16:18Of the 1,500 mammoth sites across North America, just 60 contain any evidence of the presence of man.
16:31Of these, only a dozen contain Clovis spear points, proof of hunting.
16:37The remainder merely have scavenged broken bones, showing man only made use of them when the mammoths were already dead.
16:48The orthodoxy of hunting as a cause of extinction is increasingly being questioned.
16:54When Paleo-Indian studies were beginning in this country, Clovis peoples were looked at as simply mammoth hunters.
17:03We're now beginning to move into a much broader view.
17:07They hunted horses, they hunted camels, they hunted smaller game, muskrats, ducks, a variety of animals made up their diet.
17:18If Clovis man could sustain himself on animals that were easy to hunt in the lush basin of Mexico, why risk attacking a mammoth?
17:31Simple logic makes large-scale hunting of mammoth herds unlikely.
17:37The evidence suggests we should rethink the relationship between man and mammoth.
17:58and mammoth.
18:11Neither climate change nor hunting can provide a full explanation for the mammoth's demise.
18:16Evidence like that a tequila forces scientists to think again.
18:30Amongst the bones there may be one new lead.
18:35This set of lower molars is unusual.
18:37While the right side shows healthy normal growth, the left is misshapen and warped.
18:44When you examine the molars, they look deformed.
18:48And in other sides as well, not only tequila, show us that there are some malformations of the spine.
18:55Again, malformations of the molars.
18:58So there is evidence that they were under stress.
19:01And we need to find out what exactly is this stress.
19:04A completely new theory about the mammoth's extinction comes from thousands of miles away.
19:18And from a different branch of science.
19:25Previously there were two ideas as to what caused the extinction of mammoths.
19:29Either climate change or hunting by humans.
19:31Or humans.
19:32And now there is a new idea.
19:33One that blames humans but in a less direct, more subtle way.
19:42Peter Datchak is not a paleontologist.
19:45But a New York based virologist.
19:48His research has brought world attention to bear on a disease so virulent.
19:52It crosses species barriers and is currently rendering entire populations of frogs extinct.
20:00He now believes disease may also have wiped out the mammoths.
20:05If we think about the diseases that we worry about as humans, diseases like flu, these are really diseases of other animals.
20:14These are chicken viruses mixing with pig viruses and then infecting humans.
20:18AIDS originally, if we believe the current research, came from chimps in Africa.
20:24It's very easy for these viruses to jump from one host to another and then expand their range.
20:33Virologists used to believe that a virus would not kill off its host.
20:36But Peter has shown that when a disease jumps the species barrier, the result can be more devastating than ever imagined.
20:46As a disease moves into a population that's never experienced it before, either recently or in history,
20:53it has no immune response to this pathogen and it can be wiped out very quickly.
20:57And this may well be the scenario that allowed a pathogen to wipe out populations of mammoths in North America.
21:05This theory, known as hyperdisease, may help explain the signs of stress evident amongst the tequila bones.
21:14It also fits with the timing of man's arrival and the decline of the mammoths.
21:20The point about these mammoth populations is that they've never experienced humans before.
21:24Humans moved into what are known as naive populations, so they had no defences.
21:29And the diseases were quite capable of wiping them out completely.
21:36Back in Mexico, the idea of disease wiping out a population has a special poignancy.
21:43When the Spanish conquistadors encountered the Aztecs in the 16th century,
21:47the measles and flu they brought with them had more devastating effect than gunshot and sword.
21:57But the Aztecs and Spanish met at close quarters.
22:01How could Clovis man get close enough to mammoths to transmit disease?
22:06Not man, but man's best friend may provide the answer.
22:11Clovis man brought the dog to North America.
22:15Clovis man brought the dog to North America.
22:22Dogs could carry rabies and distemper that are known to cross species barriers.
22:28As we introduce species like domestic dogs, we also introduce the viruses and the pathogens that these dogs carry.
22:33So we spread disease that way. We call this process pathogen pollution, and that's one of the greater implications of the work that we've been doing.
22:48Dogs also transmit disease through fleas.
22:51It may have been that diseases were able to jump host from dogs via fleas into a larger mammal like a mammoth.
23:00And certainly as humans move throughout the North America, dogs would have been able to make close contact with wildlife.
23:07And this happens all over the planet right now.
23:08Hyper disease is a compelling new theory.
23:25And virologists are extracting DNA from mammoth bones, looking for sequences that indicate they encountered anthrax, distemper or herpes.
23:35Or herpes.
23:50The extinction of the mammoth is one of the most controversial mysteries in paleontology.
23:58Climate change and man cannot fully explain it.
24:01Now it is time to consider the role of disease in prehistory.
24:10In the age of AIDS and Ebola, the bones of Tokwila may be a timely reminder that we must take disease seriously as a possible cause of extinction.
24:21For any species.
24:22We now know for sure that diseases are capable of wiping out species.
24:29And that's a very significant step forward.
24:31We really need to use that information to look at how other species became extinct.
24:35The map of Ebola became extinct.
24:37The map of Ebola became extinct.
24:39And it became extinct.
24:41Transcription by CastingWords
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