Extinción de Grandes Mamíferos: ¿Causada por Humanos o Cambio Climático al Final de la Edad de Hielo?
Descubre el misterio detrás de la extinción de grandes mamíferos al final de la última Edad de Hielo y si fueron los humanos los responsables o si el cambio climático desempeñó un papel crucial en su desaparición. Desde los majestuosos mamuts hasta los imponentes osos de las cavernas y los lentos perezosos gigantes, estas criaturas colosales enfrentaron un destino incierto en un mundo en transformación. A través de este viaje educativo, exploraremos las teorías y evidencias que sugieren tanto la influencia humana en la caza excesiva como los efectos del cambio climático en la pérdida de hábitats y recursos. Sumérgete en la compleja interacción entre seres humanos, naturaleza y megafauna prehistórica para comprender mejor los eventos que marcaron el fin de una era. ¡Acompáñanos en esta exploración histórica y científica que arroja luz sobre un capítulo intrigante de nuestro pasado!
### Hashtags:
#ExtinciónMamíferos, #EdaddeHielo, #CambioClimático
extinción, grandes mamíferos, humanos, cambio climático, Edad de Hielo, mamuts, osos de las cavernas, perezosos gigantes, caza excesiva, hábitats
Descubre el misterio detrás de la extinción de grandes mamíferos al final de la última Edad de Hielo y si fueron los humanos los responsables o si el cambio climático desempeñó un papel crucial en su desaparición. Desde los majestuosos mamuts hasta los imponentes osos de las cavernas y los lentos perezosos gigantes, estas criaturas colosales enfrentaron un destino incierto en un mundo en transformación. A través de este viaje educativo, exploraremos las teorías y evidencias que sugieren tanto la influencia humana en la caza excesiva como los efectos del cambio climático en la pérdida de hábitats y recursos. Sumérgete en la compleja interacción entre seres humanos, naturaleza y megafauna prehistórica para comprender mejor los eventos que marcaron el fin de una era. ¡Acompáñanos en esta exploración histórica y científica que arroja luz sobre un capítulo intrigante de nuestro pasado!
### Hashtags:
#ExtinciónMamíferos, #EdaddeHielo, #CambioClimático
extinción, grandes mamíferos, humanos, cambio climático, Edad de Hielo, mamuts, osos de las cavernas, perezosos gigantes, caza excesiva, hábitats
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DiversiónTranscripción
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!