The ice bridge through which the first American settlers came from Asia was neither made of ice nor a bridge. And according to new evidence, it might have not been the only way in which the continent was populated.
Previously dismissed blasphemous theories about the first Americans are enjoying a come-back, and it’s finally time to give them a chance to explain themselves. Here are some of them.
You shall only speak Clovis
For the past 50 years, archaeologists and anthropologists had been fairly convinced that they knew exactly how and when humans had arrived in the New World. The how was a land bridge from Siberia (so no ice, and the bridge was actually as wide as Alaska). The when, the last ice age. The people who made the crossing were called the Clovis culture, and for half a century they kept the title of presumed pioneers.
Everyone thought the Clovis, who made a distinctive kind of arrow head uncovered all across north america, were the first ones to arrive. Any attempts to depose them was in vain. The evidence from earlier sites was not to be trusted, assumed contaminated and ignored and any alternatives theories dismissed.
Although these other hypothesis are interesting, when I was studying anthropology, they were mentioned but never thoroughly analysed. Our south-american dating had to match the Clovis time frame, or we were doing our jobs wrong.
Writing about these topics then had a high price:
“I was once warned not to write about coastal migration in my dissertation. My adviser said I would ruin my career.” — Jon Erlandson, archaeologist at the University of Oregon in Eugene
But over the last few years, this scenario has been changing. New evidence and re-examination of old one have shown conclusively that humans reached the Americas way before the Clovis started making their arrow heads.
The question now is: How?
The South wasn’t lying
Let’s go back a few years. In the 1970s, an archaeologist called Tom Dillehay from Vanderbilt University in Nashville, Tennessee, uncovered the remains of a large campsite in southern Chile. Through radiocarbon dating on the wood and other organic remains found in the site, he determined the site was 14,600 years old. This is 1000 years before the first Clovis tools, but Dillehay had to wait twenty years for someone else to re-examine the site and accept his dating.
To his relief, ancient DNA testing made population genetics, and migration theories in particular, bloom. Suddenly, sites were giving older and older dates. A large mastodon hunt-site confirmed as previous occupation, a Texan excavation full of stone tools and artifacts was dated as going back a millennium before the Clovis… But who were these people we were now beginning to place in time and space, and how had they made it into the New World?
(Not so) Blasphemous Theory #1: Down the coast by feet
Migration North-South is a sort of given, but how it was done is a different story.
The Coastal Migration Model states that a small group of big-game hunters made it into the Western Hemisphere over land too, but earlier than Clovis.
Coastal paths seemed to be supported by the study of DNA mutation rates. Mutation rates try to calculate a molecular clock to time how long the diversity between Americans and Asians took to develop. They can do this by looking at modern DNA and comparing the differences.
Thanks to these rates, there’s a few things we now know about these pioneers: They were perhaps just a few thousand hardy settlers, and they made a long stop somewhere around Beringia. This time was long enough to create new genetic variations and pass them on to their descendants. Not all that shines is gold, though, and genetic clocks are very, very difficult to calibrate so we can’t really talk about certain dates. When calculating rates, it’s important to account for whole branches of the population disappearing due to bad luck, illnesses, conflict and/or starvation. And we all know America has had plenty of those during the last 500 years.
This is the reason why ancient DNA is the perfect candidate for mapping migrations. Modern DNA is too mixed, too chopped and too diverse. Of course the issue that remains is how to get hands on materials from which to extract ancient DNA, as early American bodies are a rarity and whatever DNA is left in a sample will be a pain to extract without contamination. Not long ago, a 4,000 year old skeleton from Greenland was analysed. The story the genes told was one of constant change: It showed that there had been multiple waves of migration into the land.
While ancient DNA opens up intellectual frontiers, archaeologists are still searching for ways to test the migration theories in the field. Unfortunately, coastal migration is a toughy: Whatever archaeological remains there are left, they are probably under water. Thank the last ice age.
(More) Blasphemous Theory #2: From Asia by boat
A more daring theory is that these first peoples used boats to navigate along the coast of Siberia and across to the Americas. There is a hypothesis, the Solutrean hypothesis, that goes a little further than the previous one. It suggests that coastal migration from Asia might have been supplemented by parallel migrations through the coast and across the Atlantic.
The hypothesis is supported by archaeological sites that indicate that people in skin-covered boats moved along the Pacific coast into Alaska and northwest Canada, eventually reaching Peru and Chile during the past ice age.
Incorporating boats to the equation makes for a much solid explanation as to why the migrations seem to have happened so fast.
The coastal environment would have provided more subsistence than an interior route, especially because during the last ice age the majority of possible paths across America would have been blocked by ice. Glaciers didn’t go all the way to the coast in many spots, providing vegetated “steppingstones” where maritime travelers could survive. Food would have been plentiful from the ocean!
I personally prefer this theory to any others. And the evidence is pretty strong, if you ask me: Studying coastal caves in southeast Alaska, looking for evidence of early inhabitants, E. James Dixon, curator of archaeology for the Denver Museum of Natural History found in 1996 the bones of a 23-year-old man in a small cave on Prince of Wales Island. The remains were between 9,200 and 9,800 years old, and the man’s diet consisted primarily of…. drumroll… marine mammals!
Archaeologists would be all over the coast if they didn’t have the same problem that the by-feet people have: Tons of water over their sites.
(Incredibly not so) Blasphemous Theory #3: From Australia!
In July 2015, two groups were looking at ancient and modern American DNA, when both discovered a hint of something nobody was anticipating. Some Native Americans in South America share ancestry with native peoples in Australia and Melanesia. This was new.
The two groups gave different explanations for their Oceanic markers. One concluded that the genes were probably added by recent recently. The other group went a little further: Harvard Medical School geneticist David Reich and colleagues thought that the DNA had to have arrived in the Americas very long ago. They also affirmed that the founding migrations had occurred in more than one wave.
It was crazy and unexpected and very weird and we spent the last year and a half trying to understand it. People in Amazonia have ancestry from two divergent sources…we think this is a real observation,
Everything seems to indicate that more sampling in the future might uncover evidence of a two distinct ancient migrations. We don’t have DNA samples from Native Americans from around 12,000 to 24,000 years ago, unfortunately. Should we secure some, and sequence them, we would know finally when the Australo-Melanesian DNA joined the pioneer party, and we would have a much better image of who was who and where they were back in the ice age days.
More evidence for a wacky world scenario
If these potentially complicated migration patterns don’t do it for you yet, here are some stranger theories around a more fluid world scenario. Read with caution!
- The sweet potato, which is native to the Americas, was widespread in Polynesia when Europeans first reached the Pacific. It has been suggested that it was brought by Polynesians who had traveled to South America and back, or that South Americans brought it to the Pacific.
- A 2013 genetic study suggests the possibility of contact between Ecuador and East Asia. The study suggests that the contact could have been trans-oceanic or a late-stage coastal migration that did not leave genetic imprints in North America. This contact could explain the alleged similarity between the pottery of the Valdivia culture of Ecuador and the Jōmon culture of Northeast Asia.
- The existence of chicken bones dating from 1321 to 1407 in Chile and thought to be genetically linked to South Pacific Island chicken species suggested further evidence of South Pacific contact with South America.
- A team of academics headed by the University of York’s Mummy Research Group and BioArch, while examining a Peruvian mummy at the Bolton Museum, found that it had been embalmed using a tree resin. The resin was from an Araucaria conifer related to the ‘monkey puzzle tree’, a variety found only in Oceania and New Guinea.
- Smithsonian archaeologist Betty Meggers wrote that pottery associated with the Valdivia culture of coastal Ecuador dated to 3000–1500 BCE exhibited similarities to pottery produced during the Jōmon period in Japan, arguing that contact between the two cultures might explain the similarities. Alaskan anthropologist Nancy Yaw Davis claims that the Zuni people of New Mexico exhibit linguistic and cultural similarities to the Japanese.
- Proposed claims for an African presence in Mesoamerica stem from attributes of the Olmec culture, the presence of an African plant species in the Americas, and interpretations of certain European and Arabic historical accounts.