What Makes Us Human

And one percent Neanderthal

You're 15, You're Beautiful, and You're Mayan

Genetic analysis links early skeletons to modern Native Americans.

The Washington Post led its story with an evocative image:

"She was only 15 years old when she wandered into the cave on the Yucatan Peninsula, and in the darkness she must not have seen the enormous pit looming in front of her."

We might question whether the romantic image of a teenager "wandering" conjured up precisely captures the likely life of a young woman of this age, 12,000 years ago.

Coverage by the National Geographic describes the skeleton—discovered underwater in 2007—as showing "signs of tooth decay and osteoporosis, perhaps as a result of becoming pregnant at an early age." Archaeologist Dominique Rissolo suggests she entered the cave looking for water.

Whatever the reasons, her death and the preservation of her skeleton as water levels rose have made this young woman an important character in one of the sharpest debates in recent archaeology and physical anthropology of the Americas.

The editor of a report on new research,  published in May in Science, summarized its significance:

 

"Modern Native American ancestry traces back to an East Asian migration across Beringia. However, some Native American skeletons from the late Pleistocene show phenotypic characteristics more similar to other, more geographically distant, human populations. [The authors] describe a skeleton with a Paleoamerican phenotype from the eastern Yucatan, dating to approximately 12 to 13 thousand years ago, with a relatively common extant Native American mitochondrial DNA haplotype. The Paleoamerican phenotype may thus have evolved independently among Native American populations."

What this means: very early skeletons from the Americas—those dating earlier than 9000 years ago (Palaeoamerican)—don't look much like modern Native Americans ("phenotypic characteristics" loosely translating into appearance). This girl looks like other Palaeoamericans—but the genetic code she inherited through her mother's line (mitochondrial DNA) matches a variant (haplotype) typical of Native American skeletons.

Why is that noteworthy?

Early American skeletons have been said to look more like people from outside the Americas. One noteworthy illustration of this was a (much debated) reconstruction of Kennewick Man, an early skeleton discovered in Washington State, looking eerily like Patrick Stewart (Captain Picard for the Star Trek fans).

This has been at the heart of a political controversy about the application of US law, the Native American Graves Protection and Repatriation Act (NAGPRA), with arguments advanced that these early skeletons shouldn't be subject to the law because they might not be ancestral to contemporary tribes.

The authors of the Science article on the young girl whose remains were found in Yucatan summarize the other part of the science: what genetics has to say:

"Genetic studies of contemporary Native Americans and late prehistoric skeletal remains from the Americas have consistently supported the idea that Native Americans are descended from Siberian ancestors who moved into eastern Beringia between 26,000 and 18,000 years ago ... A complete genome analysis of the [12,600 year old] Anzick infant from Montana, and mitochondrial DNA (mtDNA) from the [14,100 year old] coprolites from Paisley Caves in Oregon, and mtDNA from other early [10,500 to 10,200 year old] remains from Nevada and Alaska support this hypothesis. With Anzick linked to the Clovis culture and Paisley Caves to the Western Stemmed tradition—North America’s two widespread early archaeological complexes—the genetic evidence for a Beringian origin of the earliest inhabitants of western North America is compelling."

Compelling—but not yet completely accepted by the proponents of ancient Americans unrelated to modern Native Americans. One hold out was quoted in the Washington Post article as saying the new data came from “a sample of one," and continuing to think:

"When there is a rapid change in the appearance of a population “I have to think you’re talking about migrations and people coming in."

The new genetic data, however, seem definitive. They reinforce previous studies that have traced in detail mitochondrial DNA variants, including the D1 haplotype of the girl recovered in Yucatan, in the Americas, including in Mexican Americans with indigenous ancestry.

While I may be taking liberties, it looks like we can paraphrase Ringo Starr:

"You're 15, you're beautiful, and you're Mayan (or something close!)"

Rosemary Joyce, Ph.D., is a professor of anthropology at UC Berkeley.

more...

Subscribe to What Makes Us Human

Current Issue

Let It Go!

It can take a radical reboot to get past old hurts and injustices.