The scientific history of the North American continent

The PBS science program Nova has an excellent three-part series that was first broadcast in 2015 on the history of the continent. They use nice special effects to bring vividly to life the very slow processes of geology and biology. Each episode lasts about 50 minutes.

The first one deals with the geologic history.

The second deals with the evolution of life.

The third deals with humans. I had thought that there were just two theories for how humans arrived on this continent. Either they came from the east and crossed the Bering Strait land bridge that was exposed during the last Ice Age when ocean levels receded. Or they came from the west by ships that hugged the North Atlantic coastlines. [Correction: I had misremembered. I recalled something about people coming to the Americas earlier from the west but that ‘earlier’ only meant before Columbus and not that they were the first inhabitants.] But this program says that the earliest human remains have been found on islands in the Pacific just off the west coast of the continent, indicating that they must have come from the east by boats. This was new to me and I need to look into it.

Whenever I see these programs, I am always impressed by the grandeur of the story being told and the dogged work of so many scientists who have been able to piece together the narrative of things that occurred long before there were any humans to observe them.

And that feeling is always followed by a sense of sadness that those who believe in a 6,000 year old Earth are missing out on that sense of wonder. Oh sure, maybe the belief that “God made everything” fills them with a different sense of wonder but that seems so shallow to me.


  1. DonDueed says

    Mano, I think in each of those cases, the migration would have come from the west, not the east. That is, unless the North American continent was populated from Atlantis!

  2. DonDueed says

    Oops, I missed the case of the North Atlantic route… which would have been from the east, not the west.

  3. flex says

    Many, many, years ago now I read a paper describing how for some reason the earliest meso-American cities seemed to radiate from a point on the pacific coastline. I can’t remember if it was in Mexico or Guatemala now. The paper didn’t draw any conclusions from it, but I suspect the authors had their own opinions and they were “adjusted” during the per-review process.

    So, for a high-school project, I researched the possibility that there was a landing point by Polynesians at that spot. I found enough evidence to convince me it was possible. The ages of cities do all appear to come from the point on the Pacific coast; although dating city remains is not perfect, and there are other possible reasons why a culture could have an origin point at any location. Then there were a number of myths that pointed in the same direction, but that really didn’t mean proof either.

    Now high school was decades ago for me, but I am not surprised that as we lose our predisposition that western culture is the most technologically advanced, and always as been, we might find even more concrete evidence that the Polynesian sea-faring culture did reach the coast of meso-America. And maybe even made it back. After all, it was only a decade or so ago that the great Chinese ships of exploration became generally known in the western world.

    It is amazing to me that 20 years ago the fact that pre-clovis sites existed at all was not generally accepted by archeologists. Now the evidence is overwhelming that human beings occupied America prior to clovis. As we learn more about other humans, we learn more about ourselves.

    What else have we been missing?

  4. moarscienceplz says

    I am not aware of any serious scientists who argue for the Americas to have been settled from the Atlantic coast. AFAIK, all the First Peoples have been comfirmed to be genetically most closely related to Asiatic people.
    As to the route they took, walking across the Beringia land bridge (sea level was much lower during the ice age, because so much water was locked up in glaciers) and then down a fairly ice-free corridor somewhere in the middle of Canada has been the dominant theory for several decades. I always felt the ice-free corridor to be a bit problematic: you have a sheet of ice miles thick that stretches from the Atlantic to the Pacific but it leaves a lovely highway down the middle of the ice right where your theory needs one? How obliging!
    More recently, it has been proposed that the people who came were not big game hunters but rather shore dwellers who lived mostly off shellfish they collected using canoes possibly made of reeds. The natives of the SF bay area were using such canoes when the Spaniards found them. Please note that this theory does not suggest anyone set out to paddle thousands of miles in canoes in one giant expedition. Rather, it is imagined that these people simply kept paddling eastward and southward a few miles per year as they sought food sites that had not already been picked over.
    A third theory ditches the canoes but keeps the Pacific coastal route. The lower sea level that connected North America to Asia also exposed the continental shelf west of the current coastline for several miles. In fact one could have walked from San Francisco to what are now the Farralon islands, which presently involves crossing over thirty miles of ocean. This ancient land area was very flat and would have been easy to walk along, while providing both seafood AND land animals to eat. Unfortunately, since it is now under water it would be difficult to find much archeological evidence to support this theory.

  5. Mano Singham says

    I had misremembered. I recalled something about people coming to the Americas earlier from the west but that ‘earlier’ only meant before Columbus and not that they were the first inhabitants.

    Sorry about that!

  6. Rob Grigjanis says

    flex @3: The easternmost known Polynesian settlement was Rapa Nui, around 1000 CE. The earliest (?) mesoamerican civilization was the Olmecs, before 1000 BCE, about 2,000 years before Rapa Nui, and on the east coast of Mexico.

    I’ve certainly heard of the notion that Polynesians may have reached South America before the Spaniards, but not 2,000 years earlier.

  7. brucegee1962 says

    Those Polynesian colonizers were amazing. They must have been somehow capable of packing up their entire civilization — men and women — and sailing off over the horizon for days, just in hopes of finding new lands. Or else explorers must have sailed off and discovered those lands, then come back and packed up the rest of the family to move on to the next island by navigating perfectly for days out of sight of land — something the supposedly brilliant Greeks and Romans and Europeans weren’t capable of doing until centuries later.

    I thought about them a lot when I was reading Kim Stanley Robinson’s Aurora. The premise of that novel is that space colony ships are a terrible idea, condemning future generations who never asked for it into precarious colony efforts that were probably doomed. I wondered what the Polynesians would have thought of that.

  8. Marja Erwin says

    The Polynesians usually colonized against the wind, so if they didn’t find new land, then they could return.

    I could be wrong, but I think human settlement in Polynesia is fairly well dated. Human settlement in the Americas is not-- datings for Monte Verde, Topper, Meadowcroft Rockshelter and other pre-Clovis sites are widely disputed.

    The Solutrean hypothesis, that Clovis-style stone blades arrived from Europea, doesn’t work out because there are several thousand years between the Solutrean and Clovis cultures.

  9. flex says

    @Rob Grigjanis, #6,

    True, but think what we might know tomorrow?

    Oh, I’m not saying that we currently have any evidence for any of my speculations. And the cultures are certainly somewhat different. But it is not an impossibility that early Polynesians were blown off course and arrived in meso-America long before Rapa Nui was settled. Even a couple millennia before. But I will concede that regular trade is probably beyond any reasonable probability.

  10. says

    I recently discovered a podcast that’s all about this topic. Pretty cool, so far. Tides of History
    Fascinating topic! I learned about Doggerland last year, which was seriously eye-opening, and it never occurred to me that the coastlines of North America would be equally different. Forehead-slappingly “duh”, Marcus.

  11. says

    I’ve long loved underwater photography, and have loved the idea, at least, of underwater archaeology for almost as long. Knowing that human populations concentrate on shore lines and knowing that the sea levels had risen in the last 15ky, I’ve been interested in underwater digs along the west coast of N. America for a long time -- at least since 2002. In fact, if I had a couple million dollars to spare, I would definitely want to set up my own project exploring the seafloor between Vancouver Island the Lower Mainland in BC (staying south of Quadra, probably, but maybe not).

    With the right tech and a good houseboat (the waters are calm there, though they are subject to tides) you could make exploratory dives every day for months of the year, escaping the worst of the heat as well. (Yes, I’m a heat wimp.)

    Of course, I’d need the boat and the diving equipment and infinite time without work, and a way to pay the bills and buy groceries, but let’s not fuss around with trivialities.

  12. says

    I’ve heard the phrase and theory “Iberia not Siberia”, suggesting people from Europe crossed the Atlantic during the ice age while crossing near the ice’s edge (both walking and boats). Was that in the show?

    I like the pun but doubt the theory. It’s based solely on artifacts (handmade tools) and not DNA. It’s entirely possble different people in different places could develop the same tool making skills.

  13. sonofrojblake says

    I think throughout this past that when you say “from the west” you mean “westwards” and vice versa. Either way, West and East are reversed in all mentions.

  14. lumipuna says

    Jared Diamond once argued that sporadic evidence of pre-Clovis American settlement should be treated with extreme caution, because it’s sporadic. That is, the original settlers would likely take only a couple thousand years to procreate and spread all over empty American continents and fill the earth to capacity. You wouldn’t have a long period of just a little settlement here and there.

    As for Polynesians, they didn’t reach even Eastern Polynesia until a couple thousand years ago. After that, they did have apparently repeated contact with tropical Americas, but couldn’t leave any significant imprint on a continent that was already densely populated by agricultural peoples. Chickens were brought to South America and sweet potatoes were brought to parts of Polynesia before European contact.

  15. Mobius says

    NOVA has also recently aired a similar 3 part series on Australia. Both the North America and Australia series receive my recommendation.

  16. publicola says

    Speaking of Doggerland. I learned of it just yesterday from a video on U-Tube called, “Ten things you probably didn’t know about prehistoric Europe”. It was an interesting 15 minutes. As for pre-Clovis/Solutrean settlement, the first explorers probably didn’t have women with them, and may never have made it back to the homeland to report and return with colonists. Just a wild guess, but it’s fun to speculate.

  17. Owlmirror says

    This was just published recently, so:

    Native South Americans were early inhabitants of Polynesia

    The genetic signals in Polynesia from South America seem to be recent (beginning to mid second millennium CE).

    Native American gene flow into Polynesia predating Easter Island settlement


    The possibility of voyaging contact between prehistoric Polynesian and Native American populations has long intrigued researchers. Proponents have pointed to the existence of New World crops, such as the sweet potato and bottle gourd, in the Polynesian archaeological record, but nowhere else outside the pre-Columbian Americas, while critics have argued that these botanical dispersals need not have been human mediated. The Norwegian explorer Thor Heyerdahl controversially suggested that prehistoric South American populations had an important role in the settlement of east Polynesia and particularly of Easter Island (Rapa Nui)2 Several limited molecular genetic studies have reached opposing conclusions, and the possibility continues to be as hotly contested today as it was when first suggested. Here we analyse genome-wide variation in individuals from islands across Polynesia for signs of Native American admixture, analysing 807 individuals from 17 island populations and 15 Pacific coast Native American groups. We find conclusive evidence for prehistoric contact of Polynesian individuals with Native American individuals (around ad 1200) contemporaneous with the settlement of remote Oceania. Our analyses suggest strongly that a single contact event occurred in eastern Polynesia, before the settlement of Rapa Nui, between Polynesian individuals and a Native American group most closely related to the indigenous inhabitants of present-day Colombia. Genomic analyses of DNA from modern individuals show that, about 800 years ago, pre-European contact occurred between Polynesian individuals and Native American individuals from near present-day Colombia, while remote Pacific islands were still being settled.

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