18 July 2025 The Future is the Product of the Past

New Evidence could Change the Date People First Arrived in North America

While investigating the origins of agriculture, researchers made an unexpected discovery.

According to an unexpected finding made by an Iowa State University researcher, the earliest people may have arrived in North America more than 30,000 years ago – over 20,000 years earlier than previously assumed.

Andrew Somerville, assistant professor of world language and cultural anthropology, said he and his colleagues made this discovery while studying the origins of agriculture in the Tehuacan Valley in Mexico.  As part of this work, they wanted to date the earliest human occupation of Coxcatlan Cave in the valley, so they obtained radiocarbon dating of several rabbit and deer bones that were collected from the cave in the 1960s as part of the Tehuacan Archaeological and Botanical Project. The date of the bones took the work of Somerville and his colleagues in a different direction.

The date range of the bone samples at the bottom of the cave ranged from 33,448 to 28,279. The results were published in the academic journal “Latin American Antiquity“. Somerville said that although previous research did not determine the age of the objects at the bottom of the cave, he did not expect such an old age. These findings add to the debate about a long-standing theory that the first humans crossed the Bering Land Bridge into the Americas 13,000 years ago.

“We weren’t trying to weigh in on this debate or even find really old samples. We were just trying to situate our agricultural study with a firmer timeline,” Somerville said. “We were surprised to find these really old dates at the bottom of the cave, and it means that we need to take a closer look at the artifacts recovered from those levels.”

Somerville says the discoveries provide researchers with a better understanding of the region’s chronology. Earlier research relied on charcoal and plant samples but says bones were the better material for dating. However, questions still remain. Most importantly, is there a human connection to the lower layer of the cave where the bones were found?

Coxcatlan Cave
Coxcatlan Cave. Source

To answer that question, Somerville and Matthew Hill, ISU associate professor of anthropology, plan to take a closer look at the bone samples for evidence of cut marks that indicate the bones were butchered by a stone tool or human, or thermal alternations that suggest the bones were boiled or roasted over fire. He says the possible stone tools from the early levels of the cave may also yield clues.

“Determining whether the stone artifacts were products of human manufacture or if they were just naturally chipped stones would be one way to get to the bottom of this,” Somerville said. “If we can find strong evidence that humans did in fact make and use these tools, that’s another way we can move forward.”

It took a year to find the bones

The Tehuacan Archaeological-Botanical Project’s artifacts were dispersed to various museums and labs in Mexico and the United States in the 1960s, but it was unknown where the animal bones were sent.

After a year of searching, the lab director, Joaquin Arroyo-Cabrales, agreed to give Somerville and Casar a tour to help search for the missing collection. The tour proved to be beneficial. Among the countless boxes of artifacts, they found what they were looking for.

Andrew Somerville
Andrew Somerville made an unexpected discovery while studying the origins of agriculture. Photo by Christopher Gannon

“Having spent months trying to locate the bones, we were excited to find them tucked away on the bottom shelf in a dark corner of the lab,” Somerville said. “At the time, we felt that was a great discovery, we had no idea it would lead to this.”

Once he located the bones, Somerville got permission from the Mexican government to take small samples – about 3/4 inch in length and 1/4 inch in width – from 17 bones (eight rabbits and nine deer) for radiocarbon dating. If closer examination of the bones provides evidence of a human link, Somerville says it will change what we know about the timing and how the first people came to America.

“Pushing the arrival of humans in North America back to over 30,000 years ago would mean that humans were already in North America prior to the period of the Last Glacial Maximum, when the Ice Age was at its absolute worst,” Somerville said. “Large parts of North America would have been inhospitable to human populations. The glaciers would have completely blocked any passage over land coming from Alaska and Canada, which means people probably would have had to come to the Americas by boats down the Pacific coast.”

Isabel Casar, a professor at the National Autonomous University of Mexico, and Joaquín Arroyo-Cabrales, a researcher with the National Institute of Anthropology and History in Mexico, contributed to this research. The work was funded by the National Science Foundation and the Wenner-Gren Foundation.

Source: Iowa State University

Related Articles

In the Black Sea, there is a “Ship Graveyard” with 2,500 years of wrecked ships

15 February 2022

15 February 2022

The Black Sea is the inland sea lying between Europe and Asia. Blacksea is located in Eurasia, surrounded by Europe,...

Roman-era chambers and clay offering vessels found in Antiocheia Ancient City, in southern Turkey

24 October 2022

24 October 2022

During excavations in southern Turkey’s ancient city of Antiocheia, archaeologists discovered late Roman-era chambers and clay offering vessels. Antakya, better...

Researchers Discovered Wreckage of a Schooner that Sank in Lake Michigan in Late 1800s

27 July 2024

27 July 2024

Maritime historians from the Wisconsin Underwater Archeology Association discovered the wreckage of a schooner that sank in Lake Michigan in...

Khufu Boat moved to its New Museum by Smart Vehicle

8 August 2021

8 August 2021

A 4,600-year-old intact wooden boat bearing the name of an Egyptian pharaoh, Khufu, was transported to a new museum about...

Digitally Reconstructed: Roman Roads That Shaped 1,000 Years of Travel Across Medieval Britain

21 May 2025

21 May 2025

Researchers digitally reconstruct medieval England and Wales’ travel routes, revealing how Roman roads shaped post-Roman mobility over a thousand years....

Archaeologists unearth 6,000-year-old two monumental mounds containing wooden grave chambers in Germany

16 March 2024

16 March 2024

Archaeologists from the State Office for Heritage Management and Archaeology Saxony-Anhalt (LDA) have uncovered a significant Neolithic burial landscape on...

Ancient Tombs and 2-Meter Sarcophagus with Hieroglyphics Unearthed Near Aga Khan Mausoleum in Aswan

11 July 2025

11 July 2025

A joint Egyptian-Italian archaeological team has unearthed a significant collection of ancient rock-cut tombs near the Aga Khan Mausoleum on...

Urfa Castle Yields Mysterious Rock-Cut Tomb Possibly Tied to Abgar Dynasty—Early Christian Allies of Jesus

5 July 2025

5 July 2025

A recent archaeological breakthrough in southeastern Turkey has stirred excitement in the academic world. Deep within the inner citadel of...

Complex Of Early Neolithic Monuments Discovered In Herefordshire, England

22 July 2023

22 July 2023

Archaeologists discovered a remarkable complex of early Neolithic monuments while investigating the area around Dorstone Hill in Herefordshire, England. The...

4,000-Year-Old Seal Found at Tavşanlı Mound in Western Türkiye

17 August 2024

17 August 2024

4,000-year-old seal were found at the Tavşanlı Mound (or Tavşanlı Höyük) in Türkiye’s Kütahya province—located in the west of the...

Three-room Urartian tomb with liquid offering area (libation) found in eastern Turkey

18 January 2023

18 January 2023

A three-room Urartian tomb with a rock-cut libation (liquid offering area) to offer gifts to the gods was unearthed in...

Forged 5,000 Years Ago: The World’s Oldest Swords Discovered at Arslantepe Mound, Türkiye

10 June 2025

10 June 2025

In the arid plains of Eastern Anatolia, nestled along the western bank of the Euphrates River near Malatya, Turkey, lies...

First direct evidence of drug use as part of Bronze Age ritual ceremonies in Europe

6 April 2023

6 April 2023

An analysis of human hair strands recovered from a burial site in Menorca, Spain, reveals that ancient human civilizations used...

Queen Kubaba: Some 4,500 years ago, a woman rose to power and reigned over one of the largest civilizations in ancient Mesopotamia

28 December 2023

28 December 2023

Is it possible to say who was the first queen in history? Given the size and diversity of human civilization,...

A cobbled ford uncovered near Evesham could be the finest Roman example of its type in Britain

19 October 2022

19 October 2022

A cobbled ford believed to be of Roman construction has been discovered near Evesham in Worcestershire, England. If the path...