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00:09For 270,000 years, our species, Homo sapiens, lived in a world inhabited by other types of human.
00:22We hunted and foraged for food, alongside many of our human relatives.
00:32But one by one, we out-survived them, and spread across the planet, as small bands of nomads.
00:45Until we'd reached almost every corner of the globe.
00:55But a great landmass still evaded us.
01:05The Americas.
01:11As we entered this new world, we would face ferocious predators.
01:20And towering giants.
01:26But how we took on these challenges, and the ways we began to tame nature in our journey through the
01:35Americas,
01:37would set us on a path to how we live today.
01:48It's a chapter of our story that begins in one of the coldest and most dangerous times humans have ever
01:57known.
02:00in ship.
02:26We are never near the אפs that ealy inside the meand of the island.
02:33At the height of the last ice age, a time when sea levels were lower than today, people
02:41were spreading from East Asia into a place that no longer exists.
02:48A vast land bridge called Beringia, and in this frozen north, small groups of travellers
03:00dispersed ever eastward, and found themselves stepping into a new land.
03:46If you were asked to conjure up in your own land, you could have been a new land, and
03:47mind a world that was magical that was pristine that was primal you could imagine something like
03:54this the northwest coast of america absolutely takes your breath away
04:05we don't know exactly when humans first arrived in north america
04:11but many archaeologists believe it was sometime around 20 000 years ago
04:17a time when this would have been a challenging place to live
04:26they were here at one of the coldest moments homo sapiens had ever known
04:34and the landscape would have looked so different there would have been very few trees
04:39and as far as the eye could see there would have been barren icy rock
04:49they knew how to survive in the barren lands of beringia that they'd come from
04:55but their new environment was different in a few crucial ways
05:02the northern half of this continent was covered in a vast towering ice sheet
05:11from here in the northwest this wall of ice blocked roots into the deep interior
05:19the dark of the desert in the boros and south africa
05:20largely confining people to the ice-free land nearer the coast
05:39all that's left from their time here the footprints, stone tools and animal bones
05:45Now, we know that they sometimes would have hunted seal,
05:48they would have eaten fish,
05:50they would have eaten seabirds if they could catch them.
05:57Only tiny fragments of evidence remain
06:02that hint at how they survived.
06:14And whilst this northwest coast
06:17offered them steady but limited sustenance,
06:20the strip of land between the shore and the ice sheets
06:24promised new opportunities to find food.
06:31But also hid unexpected new dangers.
06:45Oh.
06:48This is a now extinct predator
06:51and it would have roamed these parts in the northwest
06:54when the first people arrived in the Americas.
06:57And they actually call it the short-faced bear.
07:01And there is nothing short about this bear.
07:04When it stood on its hind legs,
07:05it would have been about 11, 12 feet tall.
07:09That's about four meters.
07:10And so it would have made the grizzly bear
07:12look actually somewhat manageable.
07:15And then look at these teeth.
07:18Look at these canines.
07:19The stuff that nightmares are made of.
07:22And when it bumped into humans,
07:25it must have been absolutely terrifying.
07:29And just like those humans,
07:31these bears too would have been hungry.
07:40But the early people of the northwest
07:43did not run from the monsters
07:46that roamed this land.
07:52Instead, it seems,
07:54they went on the offensive.
08:15Signs of their bravery remain in caves
08:18along the Canadian coast.
08:35Here, archaeologists sift through
08:37the muddy layers of time
08:41to find out more about the risks
08:44these early people took to survive.
08:53You know when people talk about archaeology?
08:55Yes.
08:56At the back of a cave digging mud is...
08:59This is the hard stuff.
09:01One thing that has been found
09:02in a number of caves
09:04on the northwest coast
09:06is spear points
09:09in association with bare bones.
09:10Yeah.
09:11And these date as far back
09:12as 13,000 years.
09:15So is this one of these spear points?
09:17This is a fragment of a spear point
09:19that was found in a cave
09:21not too far from here.
09:22Yeah.
09:25We have uncovered a bone
09:27in the wall of this unit.
09:29And it's 20 centimetres below the surface.
09:33And so I'm going to pull it
09:35and we'll see if it moves.
09:37All right.
09:38And we don't know what species it is
09:41or what bit of bone it is.
09:42There's not enough here
09:43to know for sure,
09:44but it is a pretty big mammal
09:47for certain.
09:49Oh, it's not ending.
09:53Just make sure it slides out.
09:57Ah, it's a rib, isn't it?
09:59It looks like a rib.
10:00Yeah.
10:00Yeah.
10:01So that could be a bare rib.
10:05It's probably most likely what it is
10:07because it's quite robust.
10:09Oh, amazing.
10:11What age do you think it is?
10:13Well, we have some other samples
10:16from above where this bone is.
10:19And they're coming back
10:21around 14,000 years old.
10:23Okay, so it's old.
10:24So it could be the same age or older.
10:26Yeah.
10:27You know, one of the most wonderful things
10:30about archaeology is that
10:32sometimes you uncover something
10:34that hasn't seen the light of day
10:35in thousands of years,
10:37and in this case,
10:38well, maybe 14,000 years.
10:40Well, we're interested in
10:42where bears were hunted in the past.
10:45And in the winter,
10:46when there's not as many resources around
10:49and people are feeling a bit hungry,
10:51knowing where there is a bear den
10:53is quite a valuable thing
10:55because you can come up there
10:58and dispatch the bear,
11:01you'll have a load of meat,
11:03fur, as well as bones.
11:08One theory of how they hunted bears
11:10would have meant getting perilously close.
11:16Essentially, a hunter would go with a party
11:20to a cave, smoke the bear out of the cave,
11:24and entice that bear to attack a single hunter.
11:30That hunter would be armed with a bracing spear.
11:34A bear would come to take the hunter up in a bear hug,
11:39which is a common thing that they do.
11:41And the idea is a bear would take that hunter
11:44and essentially give him a good crushing.
11:48The hunter, at the same time,
11:50would brace the spear on the ground
11:51and aim it at the bear's heart.
11:54And so essentially, the bear would take
11:55the hunter and the spear into the bear hug,
11:59thereby spearing itself through the heart.
12:15A successful bear hunt
12:17could have meant food through the winter.
12:26But not every hunter survived.
12:43This is the bone cast of the oldest adult
12:46who have been found along this coast.
12:48They were born 10,000 years ago.
12:50And this individual has been given a name, Shuka Ka.
12:53And there's so much we don't know about this person.
12:56We don't know about their family life.
12:58We don't know if they had children.
13:00But the amazing thing about bones
13:02is that they can tell a story if you know how to read them.
13:06We know that this individual was a male.
13:09We can tell that from various features,
13:11like the squareness here of the chin,
13:14like the back of the mandible,
13:18like the angle here on the pelvis.
13:20On a female, you would typically expect that angle
13:23to be much wider.
13:25And it's kind of sad because you can also
13:29tell quite a tragic story on the bones as well.
13:32If you notice here, that is a puncture wound.
13:38And it fits quite well with the canine of a bear.
13:42And so we think that this individual
13:44possibly met their demise
13:46because they were hunting for bears.
13:54The dangers early humans faced down
13:56in order to survive are hard to imagine now.
14:01But their precarious relationship
14:03with this unforgiving land had begun to shift.
14:10Thanks partly to a surprising form of help.
14:26By hunting in packs,
14:28wolves can bring down prey
14:29far larger than themselves.
14:33A person, especially on their own,
14:36would be highly vulnerable.
14:57Wolves are, and always have been,
15:00wild animals.
15:04Shelley, am I able to come a bit closer?
15:07Yep.
15:12I think the question is how much it is.
15:17It's funny.
15:18I can feel it in my shoulders.
15:20My shoulders are a little bit tense.
15:31But given time, wolves are able
15:35to habituate to humans.
15:39Hello.
15:42Hello.
15:48From around 40,000 years ago,
15:52probably in Siberia,
15:54before humans had even reached North America,
15:58the threat they faced from wolves
16:00began to transform into something different.
16:07Now, we're not exactly sure of the details,
16:09but it might have gone something like this.
16:12Wolves would gather around human campsites.
16:14Now, at first, maybe humans were terrified.
16:17Maybe they thought that they wanted to eat them.
16:20But actually, some of those wolves weren't interested in that at all.
16:24They were looking for scraps.
16:27And as they were doing that, maybe they started fending off other predators and protecting our combined territory.
16:36And because of this, humans started tolerating some of the least aggressive,
16:40some of the most docile of these.
16:42Maybe they even started feeding them.
16:47We were reshaping wolves into dogs
16:53and began to use them
16:56to guard our camps,
17:01hunt prey
17:04and pull sleds.
17:09Generation after generation,
17:11we selected the most docile animals
17:14and reared their pups,
17:19driving the evolution of a cooperative behavior
17:23that suited our needs.
17:27This marked a turning point for the human species.
17:33Living with dogs helped us hunt for food and survive.
17:37It gave us this much-needed edge over hunger,
17:41but it also marked this profound and completely unprecedented shift
17:46in our relationship with nature,
17:49because never before had any living thing,
17:52whether plant or animal, been domesticated.
17:54This was a complete first.
18:06Unbeknownst to us,
18:07we were becoming curators of nature
18:10and gaining more control over our own fate.
18:16But powerful forces far beyond the control of any human
18:21were about to open new gateways
18:23into the North American continent.
18:28And as people answered the call of the interior,
18:33far beyond the mountains and glaciers,
18:36they would be forced to find entirely new ways to survive.
18:55A fresh wave of human innovation would be triggered around 15,000 years ago,
19:02when the climate began to warm.
19:11The ice sheets and glaciers started to retreat.
19:28And as they did,
19:30the last major barrier blocking routes into the continent fell.
19:58The first people to enter into the Americas were coastal people in the North West,
20:03but it's likely that they eventually traveled incredibly rapidly down south,
20:09all the way to Central America,
20:11and then carried on all the way to the tip of South America.
20:17Because remember, they were coastal people.
20:20It's likely that they were using some kind of seafaring methods.
20:24So very early on,
20:26some humans would have started to enter the continent from along this sea route.
20:33But when the ice sheets eventually started to retreat,
20:37many new routes would have opened up.
20:43More people started traveling into the interior of the country
20:48and finding these completely new landscapes.
20:58Some of the first humans to reach the interior left traces here in New Mexico.
21:08Fossilized footprints.
21:12Left in the muddy shore of an ancient lake.
21:25The people who made them may have been part of one of the very earliest waves
21:30of what was to become 10,000 years of human migration inland.
21:40Where there is now desert, they saw rich grasslands.
21:49The fossilized footprints of these continental pioneers reveal
21:53what kind of a world they'd stepped into.
21:58These are the footprints of an actual human being
22:02who stood basically where I'm standing.
22:05And we think she was a female.
22:08And if you look closely at those footprints,
22:10what you see is that at times the footprints,
22:12they get broader and they slip a little in the mud.
22:27And that's because she was carrying a child.
22:31Sometimes on this hip, and sometimes on this hip.
22:47Then at other times, she stopped and put the child down,
22:51and you end up with two sets of footprints.
23:03And she walked for at least a kilometer north,
23:07and then heads back south.
23:09And I just can't think of anything more,
23:12more human than a mother and a child walking together.
23:17And a mother carrying her child.
23:20And it's interesting because this whole journey
23:22has been us tracing the footsteps of our ancient ancestors.
23:27And in a moment like this, that's actually literal.
23:45Archaeologists are finding more of these footprints,
23:48left by a female or possibly an adolescent male carrying a child,
23:53hidden beneath the hard packed sand.
23:57It's allowing us to piece together an ever more detailed snapshot
24:02of what happened in the moments captured here.
24:07Let's see if we can define the footprint a little bit.
24:10Yeah. It's always scary when you start these things.
24:14You've got to take them out.
24:18There's a subtle difference between the soil and the print.
24:21It's looser. It's a little damp.
24:23So it's going to smear a bit today, but it will come out.
24:31You see it so, so clearly.
24:35Okay. So how have you, so you've just traced along the...
24:38I just, I've literally just broken the surface with the dental pick.
24:45Yeah.
24:46And then this particular example just brushes out with a little bit of encouragement.
24:51Yeah.
24:51You can see the contrast between the white.
24:55Yeah.
24:55And the fill in there.
24:57I'm removing the sediment that's blown into the footprint.
25:03So we think she was walking quite quickly then?
25:05Yeah, she's walking at about 1.6 something like metres per second.
25:10And a comfortable, normal sort of walk is about 1.3 to 1.5.
25:15So she's moving.
25:16And this surface is wet.
25:17It's slippy.
25:18We do know that this was a mission.
25:21They were on a mission.
25:23They were moving quickly at speed for whatever reason.
25:25And the footprint tells that story.
25:34Why that person was hurrying might be explained by evidence nearby.
25:47Other footprints, each one around two feet in diameter.
25:55Left by mammoths.
26:02And criss-crossing the footprints of the mother and child are the tracks of a giant ground sloth.
26:14Out in the open, with dangerous animals close by, the mother was perhaps seeking safety for herself.
26:21And her child.
26:25This landscape would have been filled with mammoth and mastodont and sabre-toothed cats.
26:31Just huge animals.
26:33They would have dwarfed us.
26:36The mammoth alone would stand at about 4 metres high.
26:39That's about 13 feet at the shoulders.
26:42And the mastodont were only slightly smaller.
26:46For the humans here, this was their new world.
26:51The early people of the plains would have given these prehistoric mammals
26:58a wide berth.
27:11But they must have realised that those animals also represented opportunity.
27:20That these grazing giants could provide them with food.
27:28But they must have realised that those animals also represented opportunity.
27:30to find a way to bring them down.
27:35We know they eventually found a way to do this because they left a massive clue.
27:46Skeletons of this megafauna.
27:51Some clearly killed by humans.
27:57Humans would have exploited some megafauna, some large land animals on the coast.
28:02But it was once they hit the interior that they saw them on a scale like something else.
28:17But how on earth could people hunt these giants?
28:34One animal still exists, which gives us a sense of just how difficult that would have been.
29:00This beast can sprint at up to 40 miles per hour.
29:05The male's horns are over two feet long.
29:10And 14,000 years ago, these bison had an even bigger prehistoric relative
29:17of roaming these parts.
29:22Absolutely incredible, but they're also so big.
29:29They're about one tonne in size.
29:32And the giant bison, the one that's now extinct but would have been around back then,
29:38was up to 50, 50% bigger.
29:45It's one of those things I think today, you can romanticize the idea of these hunts,
29:51and you think about them as some kind of, you know, adrenaline-filled adventure.
29:56But it's harder to grasp that actually back then, it would have been filled with fear and risk.
30:08Only a powerful spear thrust could penetrate the giant's hides.
30:22So hunters needed to get close.
30:47Many hunts ended in failure.
30:55They needed a technology upgrade.
31:01Up until this time, the way spear points were attached to their shafts was a serious weakness.
31:11Spear points frequently broke on impact.
31:18Until the design was altered.
31:24A subtle shift at first glance, but one that would change everything.
31:31This is special.
31:33So it's about 18 centimetres long.
31:37It's pretty sharp.
31:38If we look at the shape, it's long and narrow with the broadest point being quite low down.
31:46Notice also this thinning here compared to the middle.
31:50It's thought that the shape might help with the penetration of hides.
31:53And it's thought that this might help with reducing shattering on impact.
32:00We call it a Clovis point because it was found near Clovis in New Mexico.
32:08The narrow base of the Clovis points allowed them to be slotted firmly into the spear shaft.
32:16Better absorbing the force of impact.
32:25From archaeological finds, we know this new design rapidly spread across the continent.
32:40And the technology continued to develop.
32:46Within 500 years, these points had evolved into more slender and sharper forms.
32:55Able to penetrate deeper into prey.
33:08And archaeologists think these spear points were delivered with such lethal force.
33:15Because of another piece of technology.
33:20Whose use was exploding.
33:37So this is a replica spearhead and it's been hafted or attached on to a wooden shaft.
33:45So this would have been quite an effective weapon.
33:50But this is where technology gets really interesting because it's thought that one of the ways
33:54that they threw these spears is with a spear thrower.
33:59So you'd attach it to the top here.
34:01And then you would effectively use it to propel the spear forward.
34:30At that velocity, you're more likely to pierce the hide of an animal.
34:38And to me it's...
34:40It's especially interesting because what you get with this is the ability for female hunters
34:47to be more effective because suddenly it's not just about strength, it's also about skill.
35:05The new hunting technologies allowed people to take down the largest animals in their world.
35:23The new hunting technologies allowed people to take down the largest animals in their world.
35:24Humans had become the apex predator of the plains.
35:28And now feasted on a glut of meat.
35:38Our hunting prowess was shaping society here.
35:51This is absolutely stunning.
35:54It's one of the most striking spearheads I've ever seen.
35:57It's so well crafted and it shines and it looks like it was made of glass.
36:03But actually it's made of quartz so it's incredibly strong and it's sharp.
36:08And yet it doesn't have any signs that it was actually ever used.
36:12And that, along with the fact that it's so beautiful, suggests that it was ceremonial.
36:17Now, when you've got an everyday object and it's made to look so, so beautiful and so striking,
36:25it implies that it had become a symbol.
36:28We're not sure of what, perhaps of how important hunting was,
36:31but perhaps of a cultural identity, perhaps of who they were.
36:35We're not sure of what, perhaps of a cultural identity, perhaps of who they were.
36:47Feasts began to bring different communities together.
36:53And cement social ties.
36:59Sharing meat fostered cooperation.
37:06Food was fueling a culture.
37:13In the midst of this abundance, it must have felt as if it would go on forever.
37:28But their world was changing.
37:39The end of the ice age that had gifted them this warm world of plenty
37:45was now beginning to have an effect they could not have foreseen.
37:58It's thought that melting ice at the poles disrupted ocean currents.
38:04Temperatures in the northern hemisphere rapidly cooled by several degrees.
38:12A cross North America, the vegetation had begun to alter in unpredictable ways.
38:22In some areas, trees and shrubs began to replace grassland and tundra.
38:30Woolly mammoths could not effectively chew or digest these woodier plants.
38:39And as their environment transformed,
38:44the giant herbivores dwindled.
38:53Over the space of just a few hundred years,
38:56three-quarters of the large animal species in North America became extinct,
39:04vanishing forever.
39:08I imagine it must have been a shock for the early people here to witness the megafauna disappearing.
39:19Because that's what they would have seen.
39:21And they're such a part of your culture and your diet and your lifestyle.
39:26And suddenly they're not.
39:29That must have been quite difficult to comprehend.
39:36Now, the main cause of the giant megafauna extinction is climate change.
39:41But it's likely that human hunting played a role.
39:45That it was this final nail in the coffin.
39:48And so perhaps unknowingly, we humans tipped the balance of nature.
39:59The once bountiful land of giants had become a pile of bones.
40:08All the hunting technology in the world could do nothing to reverse this catastrophe.
40:22The people here were plunged back to a time before the feasts.
40:34With these animals gone, how would they now find enough food?
40:42A clue lies in ancient holes carved in the rock.
40:50People needed to branch out and exploit every part of the food chain.
40:55All the way through to something you probably don't think of as food.
40:59And that's acorns.
41:01Now, these are incredibly bitter because they're full of tannic acid.
41:05And to get rid of some of that, what they would do is they would firstly get rid of the
41:10shells.
41:11And then they would grind the nuts up with water in the hopes of getting rid of some of that
41:21bitterness.
41:24And honestly, acorns sound disgusting.
41:27And they taste disgusting.
41:29They're still incredibly bitter.
41:31And yet it's likely that the flour from these and the paste from these were some of the earliest processed
41:38plant food.
41:39We actually have some of the grinding stones preserved in the archaeological record.
41:44And if you look at all this, it seems so clever.
41:46It seems so inventive.
41:48And yet it's a lot of effort to go to for what are essentially some really unpleasant calories.
41:57If you were starving, no question you'd do this.
42:02And with the loss of the megafauna, people's survival now hinged on smaller game and foraging for plants.
42:32The solution people came up with in the Americas would be found in tropical forests to the south.
42:54This place, it has real challenges.
43:01There are plants, so many of them look edible, and yet some of them are definitely poisonous.
43:06It requires a process of trial and error to find the actual food.
43:17It was in a forest, archaeologists think, in present-day Mexico, that a momentous change took place.
43:26And it began with the simplest of actions.
43:32Every so often, someone would have come across a plant that was safe to eat.
43:39And would have sought out more of it.
43:45An example of this is this grass called Tiosinti.
43:50Now, the seeds are incredibly small and hard, but they can be ground up into an edible flower.
43:57So that same ingenuity that humans brought to acorns, they were now bringing to this grass.
44:09Where people found Tiosinti growing, they encouraged it by weeding out other plants.
44:16And collected seeds and collected seeds for food.
44:21This may have continued for centuries.
44:26Until one individual would have become the first person in the Americas to do something completely original with a Tiosinti
44:36seed.
44:57There is something so magical about planting a seed, watering it,
45:04and hoping that it sprouts and becomes a tiny little delicate green shoot.
45:18And there would have been somebody who planted the very, very first seed.
45:24And they would have known that it would require effort and care and protection from herbivores
45:32if it was to ever become something big enough to feed their families with.
45:37And anybody who's ever had an allotment or a garden or a balcony knows how much care and commitment goes
45:47into it.
45:57This was an idea whose time had come.
46:07Because humans all over the planet started to plant seeds and grow them for food.
46:15And it was an experiment that began to pay off.
46:20Because across the world, the people who did this were creating a more dependable way of feeding their families.
46:29And so triggered a pivotal moment for our species.
46:38In different places all over the earth, humans were inventing farming.
46:47Probably first, around 10,000 years ago, in the fertile crescent of the Middle East,
46:53where we domesticated wheat.
46:57Then rice in China, sugarcane in present-day New Guinea.
47:07Farming emerged independently in separate locations across the globe.
47:15Central and South America among the first.
47:24Here, people created what would become one of the three most important staple crops for feeding the world.
47:36Because as the early farmers planted and harvested Tiosinti, they began to shape it into a new kind of plant.
47:50Every so often, a genetic mutation would arise in Tiosinti that would actually be quite beneficial for humans.
47:57That would give rise to, say, larger seeds, or more seeds, or sweeter seeds.
48:03And perhaps most important of all, would get rid of the hard seed covering.
48:08And humans started selecting for these better varieties.
48:12And over thousands of years, they created something new that looked very different from Tiosinti.
48:20Because they created maize.
48:24It was no longer a wild plant.
48:27It was now a domesticated crop.
48:38The invention of farming was to set in motion a change that would go far beyond how we fed ourselves.
48:50The clue is in that word, plant, to be put down in one place.
48:57And just like the plants that they grew, those early farmers would have had to have adopted a very similar
49:05lifestyle.
49:06Because you couldn't exactly keep moving if you had to tend to your crops.
49:12And so, for the very first time since the birth of Homo sapiens, we were no longer a completely nomadic
49:20species.
49:22More and more of us were quite literally putting down roots.
49:32Farming supercharged our capacity to fuel human activity.
49:39And what emerged was extraordinary.
49:50Here in South America, there's a place where they began a new way of living on an unprecedented scale.
50:13The stepped pyramids of Karel were once lost under the desert sand.
50:24Archaeologists are now uncovering a vast complex of structures.
50:41And what made it possible to build these extraordinary edifices were the fields of crops that surrounded them.
50:57Karel became an immense hub for trading food.
51:06It represented a new path humans could take towards permanence and stability.
51:17But for our species to choose that path was not a foregone conclusion.
51:37I just can't help but think what would it have been like
51:41for people visiting it for the first time back then.
51:45Because they would have never seen a city before.
51:49It must have been so alien to them.
51:51It must have looked like a place from a different world.
51:58This was a commitment to a static way of life.
52:03And yet we don't consider how tumultuous the process might have been.
52:08And how much social upheaval might have been involved.
52:12Because for those who chose to lead this life.
52:16It must have come with a huge cultural shift.
52:21Because humans were becoming an urban species for the very first time.
52:34Humans across the planet stood at a fork in the road.
52:41For almost 300,000 years, we had survived as nomadic hunter-gatherers.
52:49But settled lives as farmers promised a more reliable way to feed ourselves.
52:56And plan for the future.
53:10The choice most of our species took would bring dilemmas and dangers we could never have imagined.
53:31In this episode, we filmed at a place I'd long dreamt of visiting.
53:37White sands in New Mexico.
53:44Underneath the surface of the desert are sets of fossilized footprints.
53:53They've become the subject of some of the most groundbreaking,
53:58but also most hotly debated research in archaeology.
54:08In 2018, the discovery of the double footprints, possibly a mother and child,
54:15revealed vivid details about who the early people here were.
54:21And what animals roamed alongside them.
54:27When we first started seeing the human prints walking alongside a mammoth print,
54:32when I first seen them, I was, uh, that's not possible.
54:35But it takes a while to understand what you see, and then you go back and you start to understand
54:40them.
54:42But the prints themselves were just the start.
54:45Because in 2021, new research on their age sent shockwaves through the scientific world.
54:54There's been a lot of ideas when people got to the Americas.
54:58Some of the main theories is there's a large ice sheet,
55:01and people weren't really able to enter this area until about 14,000 years ago, until that ice sheet melted.
55:08When humans first arrived in North America, an ice sheet covered the northern half of the continent.
55:16If no humans had been able to penetrate the interior until it had melted,
55:21then the oldest the footprints could possibly be is around 14,000 years.
55:28But the dating of the footprints seemed to overturn that conventional view.
55:36We put in a trench at the edge of the lakeshore, and we're finding prints that were dated above and
55:41below the prints,
55:42so we can see the soil chronology.
55:45The footprints themselves can't be carbon dated.
55:50But fossilized plant seeds trapped in the mud near the footprints can be.
55:56And carbon dating of seeds in the layers above and below these footprints were explosive.
56:06So we don't know exactly how old they are, but we're looking at the lake sediments,
56:10and what we see is there's at least 11 different layers right now.
56:14And those range from the top of the sediment to the bottom from 21 to 23,000 years old.
56:22The dating research suggested the footprints went as far back as 23,000 years ago.
56:33If true, it would mean humans had set foot in North America thousands of years earlier than many scientists had
56:43long believed.
56:48So at White Sands, we see that people were here before the last glacier maximum,
56:52before there was these last ice sheets. People were already here.
56:56The very early dates are controversial. Further research will be needed to confirm
57:02how old the White Sands footprints truly are. If they date to before the melting of the ice sheets,
57:11did those pioneers travel around the ice? Despite the debate, the footprints remain one of the most
57:19important archaeological finds of recent history, with huge significance for the entire question
57:28of when humans first set foot in the Americas.
57:36Next time, in the final chapter of our human story, we begin to live together in ever larger numbers,
57:47of death and chaos, as we seek ways to harness human knowledge on our path to the modern world.
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