The first people to reach The Americas almost definitely came across from Siberia
and upon making it deeper into the continent, they must have quickly discovered that the animals in
America were vastly different from what they were used to, or even that we see here today. Sure,
the woolly mammoths, giant cats and bears might have been familiar enough,
but there were also Giant Camels, Massive Ground Sloths and Nature’s mini-tank the Glyphtodon.
And these are but a few of the many never before seen animals. It must have felt like being
transported to a completely new world, so today I’m going to try to tackle of the most difficult
questions in archaeology. When did this happen? My name is Riley Harnett and this is The HEAP.
Twenty years ago, if you asked an American Archaeologist when the first Americans came,
you’d mostly likely be told around 13,000 years ago. Up until very recently,
this was the general consensus and it’s known as the Clovis-First paradigm.
Clovis refers to a specific stone tool industry that feature these very beautiful spear points,
unsurprisingly known as Clovis points. A lot of these have been found across North America,
especially in the US. Oh, and the first find was in Clovis, New Mexico,
and that’s where the name comes from . Anyway, these Clovis points weren’t the
only points found in the Americas. But when radiocarbon dating became available
in the 1960s, it did appear that they were the oldest. Despite how common they were,
the dates for Clovis points fell within a fairly tight timeframe, 11,500-11,000 years ago.
This was later recalibrated to 13,200-12,900 years ago . Around the same time, geologists
announced that the great ice sheets that would have blocked entry into North America from Alaska
had melted sufficiently to allow passage in the form of a corridor just a few hundred years
earlier. For 15,000 years before that happened, there would have been no walking to North
America . You’d need to go hundreds and hundreds of kilometers without food or shelter in frigid
temperatures. It’s just not happening. You’d have better luck trying to settle Antarctica.
Naturally, finding artifacts that date slightly after these ice sheets receded
creates a strong case that the people who made Clovis points were the first in North America,
but it gets better. The arrival of Clovis also seemed to coincide with the extinction of those
giant American mammals: the megafauna. The sizable geographic range where clovis tools were found
and the short time frame in which they were used suggested that these toolmakers were nomadic.
This gave rise to the idea that they likely followed the herds of these giant animals,
eventually hunting them to extinction in only a few hundred years. After all, the North American
megafauna had not encountered human hunters before and were likely evolutionary unprepared for them .
Other lines of evidence, linguistic, dental, genetic, also didn’t refute Clovis-First . Sites
discovered in the 20th century that claimed to be older than Clovis appeared to just be the result
of bad science. Most had issues with providing concrete dates, but some people ruined their
careers championing bad ideas. Louis Leakey, one of the all-time greats in finding evidence
of our early past in Africa, visited the Calico Hills in Southern California in 1963. There he
found thousands of rocks that to him appeared to be stone tools in excess of 100,000 years old.
Thing is, this entire area is like mother nature’s rock crusher. So when you’ve got
millions of broken rocks, some of them are going to look like they were made by humans . His wife,
and equally accomplished paleoanthropologist, Mary Leakey, reports in her autobiography:
“And it was Louis’s attempt to fulfill this desire at Calico Hills in the Mojave Desert that was so
catastrophic to his professional career and was largely responsible for the parting of our ways .”
Louis died a few years later, a pretty ignoble end for a guy whose contributions to the understanding
of our origins are pretty significant, to put it mildly. Now let’s be clear, relationship problems
are always more complex than a single sentence quote can tell. Mary Leakey’s autobiography is an
amazing read and the chapter that quote is from is a heartbreaking tale of life circumstance.
But you get the idea, Louis Leakey had a bad take. Okay so back to Clovis-First. As you’d expect,
it became scientific canon. When did people settle the Americas?
Around 13,000 years ago. Period. Case closed. It’s so elegant, it simply must
be true. And then the last 20 years happened. But to understand those, we first have to go to 1975.
Outside of the Chilean city of Puerto Montt, locals discovered the bones of a Gomphothere,
an elephant relative. This fossil eventually made its way to the proverbial desk of Dr. Tom
Dillehay who, with a team of archaeologists, began excavating the site where it was found in 1977.
There he finds a peat bog and bogs are great for preserving many things that decay in the open
air . This is the site of Monte Verde, and we’ve found the remains of wood, fruit, seaweed,
animal hides, fish, stone tools, firepits. The list goes on. This is a rare thing in archaeology,
but when it was dated, the dates that came back were over a thousand years older than Clovis.
So as you’d imagine, Clovis-first was dead. Just kidding, the dates were met with broad
skepticism and lots of critiques. I mean, imagine being a proponent of Clovis-First and
then hearing about this site. It would initially seem more likely that these dates were wrong than
years of scientific investigation further north. This site is in South America! If it were found
closer to the Bering Strait, that’s one thing. But it takes awhile to walk from Alaska to Chile.
Extraordinary claims require extraordinary evidence after all. So Dillehay dug in, he’s
published two heavy volumes on the site and has done more than a normal amount of due diligence to
fight for those pre-clovis dates. It’s been a slow climb, but Monte Verde is now generally accepted
as being 500-1000 years older than Clovis. So back to those last 20 years. Monte Verde
didn’t do it alone. While it was still being scrutinized and coming into acceptance,
other pre-Clovis sites popped up too. We have Paisley Caves in Oregon, the Schaefer
site in Wisconsin, the Meadowcroft Rockshelter in Pennsylvania, the Debra L Friedkin site in Texas,
the Page-Ladson site in Florida and many more. All of these were dated in the last 20 years
and some are up to 2000 years older than Clovis. So at this point in history we’ve got some
problems, not everyone accepted pre-clovis. Some holdouts still exist today. But by pushing back
the dates for people in the Americas, you also need to come up with a way for them to have passed
that glacial barrier. This led to the resurgence of an older idea: that the first Americans might
have travelled along the coast rather than wait for those glaciers to recede and travel through
an ice-free corrido r. Even during periods of glaciation, a suitably marine-adapted group
could find plenty of food just offshore due to the abundance of kelp forests along the pacific rim.
This is known as the Kelp Highway Hypothesis . So now, once again, everything makes sense. Clovis
wasn’t the first, people came 15-16 thousand years ago, likely down the coast, harvesting marine
resources. Once passing the glaciers, some people would venture inland, while some others would
continue down the coast, eventually leaving traces of their presence for us to find in Monte Verde.
And then we found even older stuff. Just last year, stone tools from Chiquihuite
Cave in Mexico were dated as being twice as old at around 32 thousand years. Just like Calico,
these tools were criticized as not being made by humans, and instead were rocks mistaken for
human-made tools . I mean they’re limestone tools in a limestone cave surrounded by
broken limestone rocks. You definitely need to ensure they’re made by humans.
The original researchers responded and explained the processes involved to make these tools
and consequently argued that they were not made by natural processes. Here’s the kicker, they
only argued for the stone tools that were found in a layer that was dated between 12.2 and 16.5
thousand years ago. That’s not old enough for me. Luckily they alluded to their next publication
further defending their case. For Chiquihuite to hold weight as the earliest sturdy evidence of
people in the Americas, we’re going to have to hold our breath for a little bit longer.
But while we’re waiting, just a few weeks ago one of the coolest things you can find was announced.
In White Sands National Park, New Mexico, we found fossilized human footprints that are 21-23
thousand years old. How do you date footprints you ask? Well you just carbon-date the seeds in
the sediments above and below . The footprints in between are within that range of dates.
It’s simple and effective work. And as of today this site is the strongest evidence for people
in the Americas before 16,000 years ago. I imagine it’ll be carefully scrutinized like
any other oldest site, but today, we can allow ourselves to be a little awestruck.
And none of it would exist if those kids and teenagers didn’t frolic in those muddy waters
that just happened to dry up long enough to preserve these footprints. If this find holds
up to that scrutiny, and personally, I think it’s looking good, then we have a very rare chain of
events to thank for this deeper understanding. It pushes back the earliest evidenced dates by
like 6000 years. That’s a heckuva lot. Did those kids come from a culture that travelled down the
coast and eventually made their way inland to New Mexico? Or were their ancestors in
North America before that glacial barrier even existed? I don’t know, but I really want to.
The Americas, especially the United States, is also home to a great many archaeologists.
Why haven’t we been able to find evidence this old before? Or at least this good?
Well, if the coastal migration hypothesis is correct, then many of those coastal sites
are underwater. Sea levels are of course lower during periods of mass-glaciation.
The Clovis-First idea is at least partly to blame, and there are a number of ways you can
point your finger at it for causing problems. The first and most important side-effect of
this paradigm is how convinced people were that it was true. If you find an older site,
you can rest assured knowing that it’s going to be heavily scrutinized, and your
report will need to uphold a level of quality above and beyond that of normal archaeology.
Volumes were published on Monte Verde, and even Chiquihuite Cave, despite the reasonable doubts,
has an excellent description of the cave sediments and uses two dating systems that agree with
each other. It’s good work. But sites vary in their ability to be interpreted convincingly,
archaeology rarely gets it as easy as the White Sands Footprints. I can see someone having an
older site and not being able to provide enough convincing evidence that they’re right. Maybe
you’ve heard of the Cerutti Mastodon site. It made the case that some humans butchered a mastodon 130
thousand years ago. Their evidence isn’t very convincing, and it’s certainly not enough on
its own to push the dates back over 100 thousand years. This is very very extreme example, but take
it back a notch and it’s not hard to imagine other old sites where the evidence just isn’t there.
If you go to bat for older sites, you can get yourself in trouble too. Academics who don’t
believe there is anything older than Clovis are not going to think much of people who do.
Especially if their work doesn’t withstand scrutiny. I talked about Louis Leakey’s failure
at Calico earlier, but, there’s a long history of people claiming older sites that received
no support. In 1964, Alex Krieger suggested 50 pre-clovis sites . I have no idea what came of
any of these, just that they never amounted to anything. An archaeologist at the Meadowcroft
Rockshelter site understood that his pre-clovis dates meant that his career,
and I quote, “was about to veer off into the archaeological badland s.” Which I think
is a beautiful way of putting it. But you’re also not going to bat
for older sites if you don’t believe them possible. Tom Dillehay, the Monte Verde guy,
was surprised at his own dates, he acknowledged that he was taught they weren’t possible . Imagine
where we’d be now if he didn’t change those beliefs and prove his own education wrong.
How many archaeologists found pre-Clovis sites, thought them impossible, and left them unreported?
I know what you’re thinking, I’m not describing science, I’m describing politics.
Science should be open to information that deepens our understanding. I agree, but this
is what happened. It’s a pretty embarrassing moment in Archaeology. We should also consider
the real-world effects this has. Many indigenous oral histories disagreed with Clovis-First,
and despite this, many archaeologists didn’t think that this was evidence at all.
Imagine hearing that, the people who took your ancestral homelands from you,
telling you that you’re wrong about your own history. Imagine then watching them discredit
the sites that support your beliefs. Considering the historical oppression
of indigenous Americans at the hands of European colonists, imagine how infuriating this must be.
Whatever the good intentions, bad ideas can still amount to cultural erasure. Archaeology
has taken steps over the last 30 years to mend this relationship with Indigenous Americans,
but of course, there’s much work to be done. For reasons that I’ve hopefully made clear by now,
this is a pretty sensitive topic. I hope I’ve done it justice,
and I hope you’ve enjoyed this journey through the history of archaeological thought on the peopling
of the Americas. I’ve posted social media links in the description if you’d like to follow me.
Otherwise, if you’ve got the time, I’d love it if you threw on another video. Thanks for watching.