En todo el mundo, muchas especies de grandes mamíferos, como mamuts, osos de las cavernas y perezosos gigantes, se extinguieron al final de la última Edad de Hielo. ¿Los humanos provocaron una extinción masiva o estos gigantes fueron víctimas del cambio climático?
Category
😹
FunTranscript
00:00The last glacial period. Millions of large animals roam the earth.
00:07It is an era of giants.
00:13But with the increase of temperatures, three-quarters of these species were extinguished.
00:19They could not adapt or fell victims of our ancestors.
00:25At the end of the day, it was during this period that the human being accomplished the conquest of the world.
00:32Was it man or the climate?
00:35To find the answer, researchers from all over the world have set out in search of remains of extinct animals.
00:42This has allowed them to draw an increasingly precise portrait of the life of our ancestors.
00:50In New Mexico, they discover traces of a last struggle for survival.
00:57And the genetic analysis of the first human beings could be the decisive clue that helps us solve the mystery of the giants of the ice age.
01:08The mystery of the giants of the ice age.
01:18Canada, 35,000 years ago.
01:22The sun rises over an ice-covered world.
01:27Immense glaciers have advanced from the north, burying vast portions of land in their wake.
01:35But not the entire planet is frozen.
01:38Beyond the ice, a vast steppe extends.
01:42When spring arrives, these meadows become pastures for many large animals.
01:49The long-nosed mammoths, with their 2.5-meter fangs, are the great icons of the ice age.
01:56They can weigh up to 6 tons.
01:59And they eat up to 200 kilos of grass a day.
02:02Only these open meadows offer them optimal living conditions.
02:10The mammoths share their habitat with the steppe bison, relatives of the current bison.
02:18The concentration of herbivores attracts a series of fearsome predators, like the lion of the caves.
02:24Its main prey is the deer.
02:28But the biggest predator of all is the sable tooth.
02:34It swallows its prey with its long canines.
02:41Until then, there had not been so many huge mammals on earth.
02:45How did they manage to spread all over the world?
02:49Millions of years ago, the continental plates of North and South America
02:54drifted from one place to another.
02:57Volcanoes emerged from the sea, and more than 2.5 million years ago,
03:01they created a continental bridge, Central America.
03:05Central America interrupts the connection between the Pacific Ocean and the Atlantic.
03:11The Gulf Stream intensifies and transports large amounts of warm water to the north.
03:17The water evaporates and the winds transfer the humidity to the earth.
03:22It begins to rain more frequently, so more fresh water flows into the Arctic Ocean.
03:28The salt content of the frozen ocean decreases and freezes faster.
03:33The sea, covered in ice, reflects the sunlight, so it can hardly retain the heat.
03:39Through this complex process, the whole earth is slowly cooling down.
03:44The angle of the axial inclination of the earth with respect to the sun reaches 1,000 degrees.
03:51It reaches a natural minimum.
03:53The temperatures drop even more, and the age of ice begins.
03:58In the northern hemisphere, huge ice caps are formed,
04:02which retain the water and make the sea level descend considerably.
04:07A cold, but dry climate prevails.
04:10Where the forests covered the earth before, today the pastures extend.
04:15This type of habitat is known as the mammoth steppe,
04:19which offers the ideal conditions for the huge herbivores.
04:23It is a period of life explosion in a global cold serengeti.
04:29Until that age of ice ends, and most of the large animals are extinct,
04:34what could have happened?
04:36According to the most widespread theory, what killed these animals was climate change.
04:43When the ice melted 12,000 years ago, the sea level rose,
04:48and it began to rain more often.
04:56The steppe became again a wooded area,
04:59and the habitat of mammoths and other large animals disappeared without more.
05:06But can this massive extinction be explained only through environmental changes?
05:12The territory of Yukon, in the heart of northwestern Canada.
05:19Here there were also vast pastures inhabited by animals of the ice age.
05:28Hardly anyone lives in this region, located north of the Arctic Circle.
05:32There is only one town left, Olgrove.
05:35It is the main settlement of the Buntu ethnic group,
05:39the native inhabitants of this area of Yukon.
05:44This is where the expedition begins after the trace of the extinct giants.
05:48Two experts in the ice age, Dick Moll and Grant Zazula,
05:52want to find out how much pressure was subjected to the animal kingdom,
05:56as a result of global warming.
06:03This is the town where?
06:05This is town 11.
06:07I'm interested in town 47.
06:10Yes, of course, and I think I know why.
06:13Why?
06:14Because it has very old mammoth fossils.
06:16Yes.
06:17This is the head of the river.
06:19Yes.
06:20Since the ground is always frozen in Yukon, just below the surface,
06:24more fossils of animals of the ice age have been preserved here,
06:27than in many other places on earth.
06:31The quantity and nature of these findings
06:34give us elements to determine whether the extinction of many animals
06:38was due to the human being or to the climate.
06:42Dick Moll is known as Don Mammoth.
06:45He is considered one of the greatest experts in the world on this animal.
06:49This Dutchman has traveled the world in search of bones and teeth
06:53of extinct animals of the ice age.
06:55New fossils appear on the banks of the Olgrove River every year.
06:59We have to take a look at the shore when we go down there.
07:02In fact, we should go now.
07:04Grandzazula knows exactly where the best deposits are.
07:08We should find things there.
07:13Yes, look, I'm seeing some things on that surface.
07:16I don't know if they're bones, but they look like large fragments.
07:24After spending millennia underground,
07:26the fossils have turned black.
07:33Sometimes the fossils are nothing more than branches of a tree or stones.
07:39At first glance, the straight bones usually look like pieces of wood.
07:46However, an incredible amount of remains ends up coming to light.
07:51There is no doubt.
07:53For tens of thousands of years of the ice age,
07:56even here, north of the Arctic Circle,
07:59nothing seems to have seriously threatened the existence of large animals,
08:03but quite the opposite, as shown by a fossil of the most special.
08:07There's a lot of things here.
08:09It's a good beach.
08:11Come on, look here, Grand, look.
08:13Take it.
08:14Wow.
08:15Jeez.
08:16Look, the tip is completely intact.
08:19How wonderful.
08:20It's the closest you can get to touching a mammoth,
08:22to touching the tip of the fang.
08:24Do you think it's likely to be a young mammoth?
08:26It's not very big and thick.
08:28There's something missing here.
08:30It's broken.
08:31It is.
08:32It must be a female.
08:33Do you think so?
08:34Yes, yes, yes.
08:35It's quite straight.
08:36Yes.
08:37And it's not very long.
08:38Wow.
08:39It's wonderful.
08:40Good beach.
08:41Yes, it's not so common to find fangs with the tip intact, right?
08:44They're often broken.
08:46We found this five minutes from here, on the beach.
08:49It's fabulous to be able to make this kind of discoveries.
08:52What I have in my hands is pure ivory,
08:54and the tip is beautiful,
08:56and it gives us a lot of information about the environment in which the mammoth lived.
09:00The landscape must have had a very different look than the one we see today.
09:05There were animals that lived and ate and used their fangs.
09:08That's why they're so clean.
09:11It's a sign that the animal was probably in very good condition when it died.
09:19Only in this narrow strip on the shore,
09:21the researchers collect entire bags of fossils.
09:28They come from mammoths, horses, bison, and almizcleros fangs.
09:34Did these animals survive the hottest climate in North America?
09:43Although these first specimens are in excellent condition,
09:47the researchers have no clue about the extinction of these species.
09:52Until finally, Moll and Zazula find a fossil that doesn't quite fit with the rest.
09:57Look at this.
09:59It's great.
10:00We've never seen one like this.
10:02Come have a look.
10:03That looks like the root.
10:04Yeah, for certain.
10:05Oh, wow.
10:06This striking tooth belongs to a species of beaver that went extinct.
10:11These are bigger beavers than Dick Moll.
10:14That's awesome.
10:17Yeah, just the inside.
10:22Like this?
10:23Yeah, yeah, yeah.
10:24I love it.
10:25This is the best thing we've found so far.
10:28How exciting.
10:29This is an inferior incisive of a giant beaver.
10:33The Castoroides ogioensis.
10:35It's an amazing animal.
10:37It's a symbol of the Ice Age.
10:39It was a beaver the size of a brown bear.
10:41It was taller than me.
10:43I can't imagine running into one face to face.
10:46But we know that this is an animal that only lived in wooded areas.
10:50So we know it didn't live in the steppe or in the tundra,
10:53along with the mammoth, the bison, and the bison.
10:55So this is an animal that didn't live in warm areas where there were trees.
10:59And the last time that there was that kind of climate and environmental condition
11:03in the north of Yukon was about 125,000 years ago.
11:08The discovery of the giant beaver
11:10shows that long before the end of the Ice Age,
11:13temperatures had increased drastically on one occasion,
11:17modifying the environment.
11:20However, steppe animals like mammoths
11:23required a cold and dry climate, as well as large pastures.
11:26What happened to them during that first warmer period?
11:30Why did they extinguish us then?
11:35The experts continue to investigate.
11:38On a cliff wall 40 meters high,
11:41they finally find the remains of large trees.
11:45They are almost the same age as the beaver fossil,
11:48and have been perfectly preserved thanks to permafrost.
11:54So that this kind of tree could grow here,
11:57it had to be as hot then as it is today,
12:00because even in a hot period like the current one,
12:03the area is located in the northern part of the forest.
12:06Trees grow very slowly,
12:08and a few kilometers north of here,
12:10everything is a deforested tundra.
12:16But judging by the rings on its trunk,
12:18this tree grew without any problem in the middle of the Ice Age.
12:23Wow!
12:24Wow!
12:26How many rings!
12:28Here we have found a lot of remains of an old forest.
12:32Trees, logs...
12:35There are pine cones, there are leaves...
12:38All this indicates that about 125,000 years ago,
12:41there was a pine forest here.
12:44It was not the kind of landscape that many associate with the Ice Age,
12:47that is, a tundra, a mammoth steppe.
12:49This was not a steppe, it was a forest,
12:51just like the ones we have today.
12:56In a landscape like this,
12:57characterized by its dense coniferous forests,
13:00surely there was not enough food for the steppe animals.
13:04So they had to leave this region
13:06and find a habitat that would meet their needs.
13:17During the Ice Age,
13:18a new period of heat began every 100,000 years
13:21and lasted for at least 10,000 years.
13:25The steppe herbaceous, indicated in yellow,
13:28withered,
13:29and many animals had to retire in these last reductions.
13:34Only when the climate became colder again
13:36and the glaciers expanded to the south,
13:38their habitat spread again
13:40and they experienced another boom in their population.
13:44This adaptation to climatic conditions in mutation
13:47is one of the greatest successes in the history of life.
13:51It shows us how flexible many animal species were.
13:57There is no doubt,
13:58climate change was not the only cause
14:00of the extinction of the great animals of the Ice Age.
14:06This layer of soil is from the modern era in which we live.
14:10From a geological point of view,
14:12it is also a warm period,
14:14and as we go down,
14:16we see deposits of the Ice Age,
14:18periods of cold, warm periods,
14:20periods of cold, warm periods,
14:22and we find thousands and thousands of fossils.
14:25But this is the border.
14:27This soil began to form 11,000 years ago
14:29and in this layer we find nothing.
14:31It is proof that there was an important turn in the history of life.
14:40The disappearance of the giants of the Ice Age
14:42is one of the biggest waves of extinction
14:44of the last two million years.
14:47If environmental changes are not enough to explain it,
14:50what can it be due to?
14:53Already at first,
14:54researchers suspected that the human being
14:56could have played a role in this process.
15:00Almost overnight,
15:01the great animals were literally exterminated.
15:06There has even been talk of a war without a barracks
15:08of the human being against the giants of the Ice Age.
15:12What is this hypothesis based on?
15:17The extinction of the megafauna of the Ice Age
15:19coincides with the expansion of our ancestors
15:21throughout the Earth.
15:26But were the first hunter-gatherers
15:28able to kill such dangerous animals
15:31that weighed tons?
15:34Isn't it more likely that they stayed away from those giants?
15:44The search for traces of human influence
15:46in the massive extinction of the Ice Age
15:48leads us to Europe.
15:57Coming from Africa,
15:58our ancestors arrived in Europe
16:00approximately 45,000 years ago.
16:03They had never advanced so much to the north.
16:07There, for the first time,
16:08they came across the megafauna of the Ice Age.
16:13The south of the Czech Republic.
16:16Since 1920,
16:17numerous human settlements of the Ice Age
16:19have been excavated in this valley
16:21near Doln and Vestonice.
16:25They are about 30,000 years old.
16:28Here, Dick Moll and the Czech anthropologist Jiri Svoboda
16:31want to reconstruct the encounter
16:33of the human being with the megafauna.
16:40What we have here is a group of settlements
16:42of hunter-gatherers
16:44of relatively large dimensions.
16:47We have exhumed the surface of those camps
16:49and remains of bonfires
16:51around which we can imagine,
16:53with greater or lesser precision,
16:55structures similar to tents.
16:58And it seems that, next to the settlements,
17:00there were places where the bones were kept.
17:06There are historical photographs
17:07that show us the enormous dimensions
17:09of these mysterious piles of bones.
17:13Did they keep remains of the corpses
17:15that were found
17:17to use them as fuel
17:19or raw material to make their tools?
17:21Or did they kill themselves?
17:26One thing is clear.
17:28These discoveries are not isolated cases.
17:32As if it were a cobweb,
17:34these settlements cover an entire region
17:37that extends from Austria to Bologna.
17:40Yes, it is Polish.
17:43The archaeological remains discovered in the camps
17:46provide the first clues
17:48about the existence of those piles of bones.
17:51And it is 30,000 years old.
17:53A particularly exceptional discovery.
17:55This mammoth ivory tip.
17:57And they shaped it.
17:59Yes, it can be seen that it has been worked here,
18:01on the tip.
18:02Yes, without a doubt.
18:03To sharpen it.
18:04And this comes from Pavlov?
18:05Yes.
18:06Is it possible that it is a spearhead?
18:08With a weapon like this,
18:10they could have inflicted lethal wounds
18:12on large animals.
18:14These tools are also very interesting.
18:17Among the exhumed objects
18:19there are also numerous leaves
18:21of Silex arrow.
18:23Now, Silex is not abundant
18:25naturally in the region.
18:27So the humans brought it from afar.
18:30If you look at this part,
18:32it is retouched.
18:33Yes, it is retouched.
18:35And it is so sharp
18:36that I could cut myself with it.
18:39According to experts,
18:41they would be large spearheads.
18:43Animals.
18:49But even with these weapons,
18:51could the human being
18:53fight the most imposing beasts
18:55of the Ice Age?
18:57A lone hunter, of course not.
18:59But in groups, it was possible.
19:01As long as they had a good strategy.
19:05While some distract the animals,
19:07others attack them from behind.
19:09A hunting tactic
19:11depends on the distribution of roles
19:13and communication.
19:21In the small town of Predmosti,
19:23a fraction of an immense
19:25collection of bones has been preserved.
19:29In the past, this type of archaeological
19:31settlement covered hundreds of square meters.
19:33Humans were not afraid of any animal.
19:37I see there are many mammoths.
19:39They have a scapula, a fang,
19:41part of a jaw, a few vertebrae.
19:43Most of the bones
19:45are of small specimens,
19:47young or individuals of 2-3 years.
19:49I have excavated mammoths
19:51all over the world,
19:53but I had never found
19:55such an accumulation of bones.
19:57There are remains of more than
19:59a thousand mammoths here.
20:01And if we examine their bones,
20:03we realize that they are
20:05all relatively young.
20:07As a human being,
20:09it could be said that it is a carnivore
20:11of the Ice Age.
20:13But the settlement
20:15brings another surprise to Digmore.
20:17In the middle of the numerous
20:19bones of mammoths,
20:21he identifies the skeleton of a wolf.
20:23How did the remains
20:25of this predator end up here?
20:33Since the first excavations
20:35in the Czech Republic,
20:37in the 1880s,
20:39the bones of more than 100
20:41of these wolves of the Ice Age have come to light.
20:43Could it be that these shy animals
20:45were attracted by the prey
20:47of humans and were slaughtered?
20:49I think it's a dog.
20:51When examined more closely,
20:53some of the skulls
20:55have atypical characteristics.
20:59It measures more or less
21:019.3 centimeters.
21:03For Digmore,
21:05these anatomical peculiarities
21:07point to a different hypothesis.
21:09Some of the skulls
21:11stand out for their relatively small size.
21:13When measuring them,
21:15we see that the area of the palate
21:17is rather wide in relation to its length
21:19and the snout is very short.
21:21These are characteristics of dogs.
21:23In that case, they would be very old dogs,
21:25almost the oldest dogs
21:27in the world.
21:29And they appeared shortly after
21:31to domesticate wolves.
21:35So,
21:37these hunters could be
21:39among the first humans
21:41to use dogs as prey
21:43to chase fast and resistant animals
21:45like bison,
21:47until they exhausted them and cornered them.
21:49With this method,
21:51our ancestors could rise
21:53to the top of the food chain.
21:55But were they really able
21:57to precipitate the disappearance
21:59of all the great animals of the Ice Age?
22:05At the University of Tubinga,
22:07paleontologist Hervé Beaucharon
22:09studies how extensive
22:11these hunting strategies were.
22:17His goal is to reconstruct
22:19the successful hunting techniques
22:21and eating habits
22:23of the first Europeans
22:25in as many regions as possible.
22:27First, he has to analyze
22:29the chemical composition
22:31of bone and tooth fossils.
22:35Each species stores in its body
22:37the carbon and nitrogen variants
22:39it gets from its food in a specific portion.
22:41Those who usually consume
22:43certain animal meats
22:45store the chemical fingerprint
22:47of these in their bones.
22:49This is visible through a single substance,
22:51collagen.
22:53We know that reindeers were mainly
22:55prey for the lions of the caves,
22:57and that mammoths,
22:59of human beings more than other carnivores,
23:01apparently, humans had
23:03a special predilection,
23:05as predators, for mammoth meat.
23:07In the case of some
23:09exhumed modern humans
23:11in Central Europe,
23:13we are talking about consumption rates
23:15of up to 60%,
23:17with a margin of error of 10%.
23:19Beaucharon has it clear.
23:21With the arrival of man,
23:23the animals of the Ice Age
23:25were subjected to greater pressure.
23:27Without humans,
23:29mammoths were safe
23:31from predators,
23:33but with the appearance of these,
23:35they ceased to be.
23:37That is why the number of mammoths
23:39in the environment changed.
23:41When the mammoth hunt was launched,
23:43our ancestors knew how to take advantage
23:45of a resource that,
23:47until then, had not been exploited.
23:49But there is another reason
23:51why mammoths were also
23:53very attractive,
23:55and that is that they provided
23:57the populations with an abundance
23:59of something that many smaller animals
24:01did not have, fat.
24:03Humans cannot feed
24:05only on lean meat.
24:07They contain, comparatively,
24:09little energy in the form of proteins,
24:11and their assimilation produces toxins
24:13that can only be excreted
24:15in limited quantities.
24:17That is why we also need
24:19fat or vegetable carbohydrates,
24:21but vegetables were scarce
24:23in the glacial environments.
24:25Another advantage
24:27of high-fat food
24:29is that in cold climates
24:31it allows heat to enter.
24:35It is a diet comparable
24:37to that of the peoples of the Arctic.
24:43Traditionally, the Inuit
24:45ingest numerous vital nutrients
24:47by consuming the layer of fat
24:49of seals and whales,
24:51which they often eat raw.
24:53Uncooked meat contains
24:55many vitamins.
24:57Just as it happened
24:59in the Ice Age,
25:01in this environment
25:03there are hardly any vegetables available.
25:09The theory according to which
25:11the man of the Ice Age
25:13was a carnivore
25:15is not true.
25:17Starting from bones and teeth
25:19well preserved from our ancestors,
25:21researchers at the Max Planck Institute
25:23of Human History in Germany
25:25can extract genetic material
25:27even from thousands of years ago.
25:35Once extracted,
25:37the old DNA has to be multiplied.
25:41The process is entirely automated.
25:45Finally,
25:47the genetic information
25:49is processed by a sequencer
25:51and the genetic profile
25:53of the primitive Europeans can be reconstructed.
25:57Something that particularly surprised us
25:59was that hunters and gatherers
26:01looked more like the people
26:03who live today in the south of the Sahara.
26:05At least they do not have the genes
26:07that we find today
26:09in the Central European population
26:11and that are the cause
26:13of the decline of the population
26:15of Western Eurasia.
26:17And that's where the problem lies.
26:19We can ingest vitamins
26:21through food,
26:23but there is a vitamin,
26:25specifically vitamin D,
26:27which is only synthesized
26:29by absorbing sunlight
26:31through the skin.
26:33Today, if you have dark skin
26:35and live in a relatively dark place,
26:37you cannot produce vitamin D
26:39by absorbing sunlight
26:41because the animal origin,
26:43for example, fish or meat,
26:45does contain it.
26:47Genetic evidence shows
26:49that light skin did not spread
26:51until after the Ice Age,
26:53when our ancestors changed their diet.
26:55From hunter-gatherer,
26:57man became sedentary
26:59and began to domesticate animals
27:01and cultivate the land.
27:03The first farmers were vegetarians
27:05and had a big problem.
27:07They had to adapt to a vegetarian lifestyle
27:09where there was hardly any light.
27:11And so their skin became lighter and lighter.
27:13Caucasian skin color
27:15became common.
27:17It was a direct adaptation
27:19to agriculture and low-light conditions
27:21in Europe.
27:23In the Ice Age,
27:25before the introduction of agriculture,
27:27it was vital that our ancestors
27:29could have enough meat and fat
27:31at all times,
27:33so they accumulated provisions.
27:35An option was to bury parts of the prey
27:37in the frozen ground.
27:43It is also likely that they dehydrated the meat,
27:45exposing it to the cold wind
27:47in the open air.
27:55In addition, it is very possible
27:57that humans already knew how to preserve meat
27:59by smoking it
28:01in smoking tents made with animal skin.
28:03All the clues converge
28:05to form an unequivocal image.
28:07The human being was a skilled hunter
28:09for whom the animal world
28:11was not prepared.
28:13But were there really so many humans at that time
28:15as to endanger
28:17entire species of animals?
28:23Determining the population figures
28:25in such a remote period
28:27is one of the most difficult tasks
28:29in the research of the Ice Age.
28:31But in the caverns of the Jura de Suabia,
28:33archaeologists have given numerous proofs
28:35of a rapid population development
28:37that began with the arrival in Europe
28:39of our ancestors.
28:41One of the most famous
28:43landscapes is that of the cave of
28:45Holle Fels.
28:47In the deposits of one meter thick
28:49located at the bottom of this cave,
28:51they have found remains
28:53of up to 65,000 years old.
28:55At that time, another human species
28:57lived in Europe, the Neanderthal man.
28:59Although they visited the cave frequently,
29:01the Neanderthals barely left
29:03any traces here.
29:05They went extinct about 40,000 years ago.
29:07The upper layers, on the other hand,
29:09date back to the time
29:11of our direct ancestors
29:13who began using this cave shortly after.
29:15In these layers, scientists have found
29:17many more tools and bones
29:19of processed animals,
29:21among other remains.
29:23In the case of the Neanderthals,
29:25we must start from the basis
29:27that they were very small.
29:29Compared to the remains of modern human beings,
29:31at that time so remote,
29:33their density is extremely low.
29:35However, if we compare the situation
29:37of modern humans with that of Neanderthals
29:39who lived here, there is a difference
29:41that stands out.
29:43We clearly see that the population density
29:45of modern humans
29:47was at least 10 times higher
29:49than that of Neanderthals.
29:55The figures fluctuate,
29:57but a plausible extrapolation
29:59indicates that in that period
30:01around 10,000 modern humans lived
30:03throughout Europe,
30:05that is, Homo sapiens,
30:07compared to just 1,000 Neanderthals.
30:11But did only 10,000 humans
30:13pose a serious threat to the fauna?
30:17The story of another giant of the Ice Age,
30:19less known,
30:21provides clues about it.
30:23Numerous fossils of an imposing animal
30:25were found in the cave.
30:29The Bear of the Caverns.
30:33The Bears of the Caverns
30:35looked like brown bears,
30:37but they were much more voluminous
30:39and could weigh up to a ton and a half.
30:41They must have been
30:43formidable creatures.
30:47The Bears of the Caverns
30:49survived comfortably
30:51for many, many thousands of years.
30:53There are many remains of bears
30:55of the caverns in the region,
30:57but from, let's say,
30:5928,000 years before Christ,
31:01they disappear.
31:03Is it plausible that the first humans
31:05led these huge bears
31:07to the brink of extinction?
31:09Some bear bones have cut marks,
31:11so it is likely that our ancestors
31:13cut the flesh of the bone
31:15with sharp stone blades.
31:17The bear teeth
31:19were also coveted trophies.
31:25Our ancestors
31:27used perforated teeth
31:29as jewelry.
31:33A few years ago,
31:35we made a very important discovery.
31:37In Hohle Fels we found
31:39a thoracic vertebra of a bear of the caverns
31:41that had a stone projectile stuck.
31:43The tip of a spear
31:45had penetrated the bone of the bear
31:47and broke when the hunters
31:49impaled the animal.
31:51It is proof that these hunters
31:53also measured with the bears
31:55of the caverns.
31:59This discovery underlines
32:01the ability with which our ancestors
32:03hunted animals that could
32:05be dangerous to them.
32:07They used their knowledge
32:09about the natural behavior
32:11of giants of the Ice Age.
32:15The situation plays in favor
32:17of the human being.
32:19If you enter a cavern in winter,
32:21the bears are hibernating,
32:23so it is assumed that they will
32:25be relatively easy to eliminate.
32:27If the hunters knew exactly
32:29where to find the bears of the caverns
32:31and at what time of the year
32:33they became a threat to the animal,
32:35it is clear that man
32:37contributed to their extinction.
32:39The premature extinction
32:41of the bear of the caverns
32:43is proof of how a small population
32:45of human beings was enough
32:47to put an entire animal species
32:49in check.
32:51Once they conquered Eurasia,
32:53our ancestors continued to triumph
32:55over the rest of the world.
32:57They adapted to each new environment
32:59and developed increasingly better weapons
33:01until they finally crossed the Bering Strait
33:03heading for North America.
33:05An ice cap
33:07blocked their way to the south.
33:09When they retired,
33:11they could continue to migrate.
33:13Here, too, humans crossed
33:15with animals they had never seen.
33:27New Mexico, 13,000 years ago.
33:31A voluminous and hairy animal
33:33is looking for fresh leaves
33:36This strange creature
33:38is a lazy giant.
33:40It is the size of a bison
33:42and weighs more than a ton.
33:47Few species expanded
33:49with such success in America
33:51during the Ice Age.
33:57In the warmer phases,
33:59the lazy giant
34:01was implanted even in the current
34:03of the Bering Strait.
34:05And yet,
34:07after this unique story of success,
34:09it also ended up
34:11extinguishing itself
34:13about 12,000 years ago.
34:17Did humans also play
34:19a role in its extinction?
34:29There, where the lazy giant
34:31could migrate on the banks of the rivers,
34:33today there is a desert
34:35with little vegetation.
34:37The wind has been blowing
34:39plaster particles
34:41throughout the last millennium.
34:43And this is how white sand emerged,
34:45the largest clay dune field
34:47in the world.
34:51From time to time,
34:53sand storms are unleashed.
34:55As if it were an abrasive agent,
34:57the wind discovers
34:59underground tunnels,
35:01unearthing fascinating treasures
35:03of the Ice Age.
35:05But this rich paleontological legacy
35:07was discovered only a few years ago.
35:09Today, researchers
35:11are eager to collect and evaluate
35:13the findings.
35:15The special thing is that they are not bones,
35:17but footsteps of animals
35:19of the Ice Age,
35:21about 13,000 years old.
35:25They can only be distinguished
35:27by a trained eye.
35:31But as soon as they begin
35:33to delimit the footprints,
35:35the outlines become more precise.
35:37It is a fragile piece
35:39of natural history.
35:41They carefully remove
35:43the soft sediment.
35:45Little by little,
35:47a striking hollow shape
35:49becomes visible.
35:51It is the footprint
35:53of a giant lazy foot.
35:55They can reconstruct
35:57how these footprints were formed.
35:59If you look at the morphology
36:01of a lazy foot,
36:03it has a very wide heel
36:05that would be here.
36:07And then you can see
36:09the fingers in the front
36:11leaving footprints on the ground
36:13as the animal moves.
36:15But this is the opposite side
36:17because this is the left hind leg
36:19and this is the right one.
36:21We have the last phalanx
36:23that would be here
36:25and then we have the nail
36:27that would be attached to it.
36:29Yes, exactly.
36:31So what we are seeing
36:33is that this bone here
36:35is exactly the same as this one.
36:37Correct.
36:39What a good specimen.
36:41Here, it's wonderful.
36:43The reason why the footprints
36:45of the lazy foot
36:47are not similar
36:49to those of any other animal
36:51is because the lazy foot
36:53rests on the side of the foot.
36:55That is, all its weight
36:57rests on the heel
36:59and the external face
37:01of the arch of the foot.
37:03And that creates a pattern
37:05that makes the footprints
37:07have the shape of a kidney.
37:09That is, they are very wide
37:11in the back
37:13and they narrow
37:15towards the front.
37:17That's why you don't see
37:19the thousands of human footprints
37:21that are discovered
37:23over and over again
37:25next to the footprints of animals.
37:27The amazing thing about white sands
37:29is that there are fossil traces
37:31that extend over more than a kilometer.
37:33Many of the footprints found
37:35travel long distances
37:37and leave evidence of different interactions
37:39between animals and people
37:41and between some animals and others.
37:43In some cases,
37:45there are groups of 15 or 20 people
37:47walking and then,
37:49apart from the group,
37:51there is someone running.
37:53And we know that
37:55because the footprints
37:57of the fingers are deeper.
37:59In other cases,
38:01we see someone walking backwards
38:03or turning around
38:05and there is even someone limping.
38:07Yes, the footprints
38:09tell us an incredible story.
38:11There is an amazing variety.
38:13Also in the New World,
38:15there is still this layer of gravel
38:17at the base.
38:19And the lazy giant
38:21was a very desirable prey.
38:23The footprints
38:25offer us an instant in time
38:27with a degree of detail
38:29almost photographic.
38:31Reading the footprints on the ground
38:33is like interpreting the scene of a crime.
38:35Who is the killer?
38:37Who killed the animal?
38:39And that is what we are dedicated to.
38:41The level of knowledge
38:43is something that cannot be obtained
38:45by examining the bones.
38:47One morning,
38:49we were excavating
38:51a trace of the footprints of the lazy giant
38:53and we found a human footprint
38:55inside, aligned with the footprints
38:57of the animal.
38:59We got excited
39:01and we continued to excavate
39:03because we realized
39:05that the same human footprint
39:07was repeated all the way.
39:09So someone had been deliberately
39:11following the trace of the lazy one.
39:21We think that what happened
39:23was that there was someone
39:25following the lazy one
39:27or stalking him rather,
39:29but at the same time,
39:31he was licking him,
39:33imitating him,
39:35probably screaming.
39:37The lazy one must have been upset.
39:39He began to wobble his legs
39:41and when he lost his balance,
39:43he scratched the ground with those sharp claws
39:45that they have.
39:47And then there is another footprint
39:49that comes from one side.
39:51We think that they are from a second hunter
39:53who came to attack the lazy one.
39:57If an injured animal escaped them,
39:59humans patiently waited
40:01for it to succumb.
40:03Look here. One, two, three.
40:05But the lazy giants
40:07were not the only giants
40:09of the ice age in this area.
40:11The largest footprints are from mammoths.
40:13But not the slender mammoths
40:15of the northern regions,
40:17but their southern cousins,
40:19the mammoths of the meadows
40:21that only lived in North America.
40:23They are wonderful.
40:25They are.
40:27Perhaps they are the most perfect
40:29that I have ever seen.
40:31They are excellent.
40:33They are wonderful.
40:35And there are smaller ones,
40:37bigger ones.
40:39Exactly, of different sizes.
40:41A small group in motion.
40:43Then the experts find the proof
40:45of a meeting between the human
40:47and the mammoth.
40:49Did our ancestors also stalk
40:51the largest of all animals
40:53of the ice age?
40:55Look at this.
40:57There is a human footprint.
40:59Beautiful.
41:03This is the left foot, right?
41:05And there is a human footprint inside.
41:07That's it.
41:09When measuring the footprint,
41:11they should be able to answer
41:13an important question.
41:1524, something like that.
41:17Yes, it could be a female
41:19or a teenage male.
41:21It's a little small for an adult male.
41:23It's wonderful.
41:25We've been here for just half an hour
41:27and we've found human footprints
41:29mixed with mammoth footprints.
41:31As far as I know,
41:33nothing like this has ever been found.
41:35For a mammoth fan like me,
41:37this is quite an experience.
41:39We can say that mammoths
41:41and human beings
41:43lived together in this area
41:4511,000, 12,000, 13,000 years ago.
41:47They lived together in this landscape
41:49during that period.
41:51Along with lazy giants, horses.
41:53The mammoths of the meadows
41:55could measure up to 4 meters
41:57and weigh up to 9 tons.
41:59They were bigger than
42:01the current African elephants.
42:03With just one to hunt,
42:05a group of humans
42:07could eat for weeks.
42:09But the king of this
42:11American animal kingdom
42:13was the saber-toothed tiger
42:15or Smilodon,
42:17weighing up to 280 kilos
42:19and armed with 20-centimeter
42:21fangs.
42:23Despite being a super predator,
42:25Smilodon
42:27went extinct
42:29about 12,000 years ago.
42:31Could the man
42:33have something to do
42:35with its disappearance?
42:39Phoenix, Arizona.
42:41Dick Moll meets up with
42:43John Barbiaz,
42:45an expert in this felid
42:47to unravel the mystery.
42:51During the Ice Age,
42:53several species of saber-toothed
42:55lived in America.
42:57All of them
42:59were among the most dangerous
43:01predators of that period,
43:03but none had the longest fangs
43:05than the Smilodon.
43:07Is it an original?
43:09It's an original,
43:11and this is the lower jaw.
43:13The shape of the skull
43:15and the anatomy of these extinct animals
43:17reveal a lot about their unique way of life.
43:19Well, the Smilodon
43:21was quite subtle.
43:23It would have the same dimensions
43:25as a lion,
43:27but it was pure muscle.
43:29It looked like a lumberjack
43:31in an American football team.
43:33You'd better not cross with any
43:35because you'd have all of them to lose,
43:37even with the biggest rifle you had.
43:39The Smilodon
43:41was typically a stalker.
43:43They couldn't run very fast,
43:45so they would rather launch lightning
43:47and they would wait,
43:49and they would run over their prey.
43:59So they would use their forearms
44:01as a mechanism to immobilize the prey
44:03while they would position it
44:05to give it the blow of grace.
44:13The lower jaw would open
44:15and then, of course,
44:17with these long canines,
44:19it would bite the animal in the neck
44:21and then it would retreat
44:23and wait for the prey to bleed
44:25which should not take long.
44:27It was essential to be successful
44:29when hunting
44:31because the saber-toothed
44:33needed meat in abundance.
44:35They were perfectly adapted
44:37to hunt large prey.
44:39At the end of the Ice Age,
44:41they were also subjected to pressure
44:43from human competition.
44:55These large fangs
44:57become an obstacle
44:59because once the megafauna has disappeared,
45:01what do you eat?
45:03What are they for?
45:05They are useless
45:07while a lion has teeth
45:09adapted to different types of prey
45:11and smaller animals.
45:13In other words,
45:15it is a more diversified predator.
45:17If you are able to diversify
45:19your hunting technique,
45:21you have more possibilities
45:23to live than if you specialize.
45:25Humans, on the other hand,
45:27were extremely flexible.
45:29Step by step,
45:31they were conquering new territories
45:33and were able to hunt in groups
45:35animals so large
45:37that even the saber-toothed
45:39could not reach them.
45:43Humans were gradually
45:45overtaking an ecosystem
45:47that had existed for millions of years.
45:55And then,
45:57the world was freed
45:59from the iron grip of the cold.
46:03In the north,
46:05the glaciers receded.
46:09The forests began to spread
46:11replacing the steppe
46:13in many regions.
46:15The increase in temperatures
46:17fell on an animal world
46:19already weakened
46:21and thus began the Great Extinction.
46:23In the south,
46:25climate change
46:27dried up the kingdom
46:29of the lazy giant.
46:31This time,
46:33the animals had no greener shelters
46:35to escape to
46:37and their herds fell into the pit.
46:43This climatic instability
46:45forced many of the giants
46:47of the Ice Age to retreat further north.
46:49But most of the animals
46:51were unable to adapt
46:53with one exception.
46:55The mammoth.
46:59A small group retreated
47:01to the northeast of Siberia.
47:03There, the animals survived
47:05for thousands of years.
47:07As the sea level increased,
47:09it left the last specimens
47:11trapped on an island.
47:13There, they died
47:15about 3,700 years ago
47:17of pure drowning.
47:23With their disappearance,
47:25the era of the megafauna glacier
47:27concluded.
47:29Climate change and the human being
47:31turned out to be a deadly combination.
47:35Humans and mammoths
47:37lived together
47:39for a relatively long time.
47:41Humans hunted mammoths
47:43and the pressure
47:45they were subjected to,
47:47together with climate change,
47:49precipitated their extinction
47:51at the end of the Ice Age.
47:53And not only did the mammoths disappear,
47:55but also the rest of the great animals
47:57of that time.
47:59Other smaller animals,
48:01such as reindeer,
48:03being generalists,
48:05were able to adapt
48:07to the new environment
48:09and coexist with us.
48:13Reindeer are not delicate
48:15when it comes to looking for food.
48:17Just as they were able to survive
48:19in the steppes of the Ice Age,
48:21today they survive in the tundra.
48:25The Almizcleros oxen
48:27found refuge
48:29in the desert extensions of the Arctic.
48:31In ancient times,
48:33they lived with the mammoth.
48:41Wolves also came out winning
48:43with the transition to the warmer period.
48:45In the Ice Age,
48:47they shared their habitat
48:49with the lions of the caves
48:51and the saber-toothed.
48:53But they were more adaptable hunters.
48:55During the Ice Age,
48:57brown bears lived with the bears
48:59of the caves.
49:01Only they survived,
49:03although mainly in the regions
49:05without human population.
49:11By the end of the Ice Age,
49:13the human being has gone very far.
49:15He is intelligent,
49:17he is able to cooperate
49:19and communicate,
49:21he controls fire
49:23and eats everything,
49:25plants, meat.
49:27He has the possibility
49:29to adapt to any environment.
49:31That is why so many animals
49:33died and the man survived
49:35and will continue to do so for a long time.
49:37From the point of view of evolution,
49:39we humans
49:41are the most successful
49:43of all large animals.
49:45We have survived the Ice Age
49:47and we have conquered the Earth.
49:49Today, there are almost no
49:51large terrestrial animals
49:53outside of Africa.
49:55Elephants are close relatives
49:57of the mammoth,
49:59but when they are studied more closely,
50:01they turn out to be
50:03especially sensitive animals.
50:05Once decimated,
50:07their populations take a long time
50:09to recover.
50:11Elephants have very few young,
50:13which require many years of care.
50:15And the same could be said
50:17of mammoths.
50:21According to estimates,
50:23200 years ago,
50:25there were several million elephants in Africa.
50:27The most recent census
50:29shows a figure of
50:31about 350,000 specimens.
50:35The causes of this demographic decline
50:37are hunting and the disappearance
50:39of their habitats.
50:43The illegal hunting of rhinos
50:45threatens their existence.
50:47Their horns are sold in the black market.
50:49Many of these icons
50:51of African fauna
50:53can only survive in protected areas.
50:55They are still a testimony
50:57of the animal world
50:59that once reigned over our land,
51:01much earlier than the human being.
51:03But this time,
51:05it is in our hands to protect them
51:07and prevent the last of their species
51:09from disappearing forever.
51:19Thank you for watching!