Native Americans lost half of population in European conquest, new research shows

Dec 6, 2011

A new study is shedding some light on a long-debated question about Native Americans. Just how much smaller was the indigenous population in North and South America after the European conquest? 

Clues can be found in DNA, according to research conducted at the University of Washington and University of Goettingen in Germany. 

Historical accounts are pretty clear that a lot of Native Americans were killed in wars and by diseases when Europeans first came to the Americas. Scholars aren’t debating that. What they do disagree on is how much that affected the overall population.

Documenting a suspicion

Brendan O’Fallon says genetic data he analyzed in his post doctoral studies at the UW holds the answers:

“We really saw a big, sudden decrease in population among the Native Americans about 500 years ago," he said. "That’s, of course, right when the Europeans first arrived. It was sort of a new line of evidence that, really, confirmed, I think, what a lot of people’s previous suspicions were but maybe hadn’t really been documented in this one area.”

While not providing the actual number of Native Americans at the time, the study he co-authored with Lars Fehren-Schmitz shows the population of Native people plummeted by as much as half in the 200 years after European contact. 

Constructing population history

The method they used to approximate the population drop was to draw a family tree from the DNA of contemporary Native people to their ancient ancestors. Then they analyzed the shape of that tree:

“The basic idea behind that is that when a population size is fairly small, lots of people tend to share the same ancestors at about the same time. The bigger the population size, the longer it takes everyone to find a common ancestor. So, the tree is just overall bigger.”

The spindly shrub he found in the 1500's has apparently blossomed again. He says Native Americans regained their original numbers within a couple of centuries. 

Yet, he admits the conclusions do have a significant margin of error and make certain assumptions. For instance, the study only used mitochondrial DNA, or genetic information from females, and inferred the same trends were true for Native men. 

O’Farrell says, regardless of the uncertainties, the study is at least one more piece of evidence to clarify the stories in the history books.