Two new studies have revealed that humans may have first settled in the Americas much earlier than previously thought.
Archaeologists suggest that pieces of limestone found in a cave in Mexico may be the oldest human tools ever found in the Americas.
It was previously believed that the first humans to have reached the Americas entered by crossing a narrow land bridge between Siberia and glacier-covered Alaska some 14,000 years ago, during the last ice age.
However, findings drawn from 15 years of fieldwork carried out in sites across North and Central America suggest that people were living there up to 33,000 years ago.
The research also suggests that instead of entering North America from Asia via the now-submerged land bridge Beringia, they may have entered along the Pacific Coast instead.
Ciprian Ardelean, a researcher and lecturer at the Universidad Autónoma de Zacatecas, and his colleagues discovered these findings during years of excavations at a cave in Zacatecas, in central Mexico.
Through careful digging, they found multiple stone tool artefacts that date back as far as 33,000 years ago, long before the Clovis people arrived.
The results were published in the journal Nature on Wednesday.
The fieldwork also indicates that the cave was occupied by ancient human groups over a period of 20,000 years.
Ardelean told ZME Science that the “peopling of America” is one of the “last legitimate mysteries” in world archaeology.
It has long been assumed that the Clovis people were the first natives in America but growing archaeological evidence since the start of this millennium has suggested that it was likely there were multiple migrations from Asia.
Another study, published in Nature on the same day, led by Lorena Becerra-Valdivia and Thomas Hingham from the University of Oxford, shows that by at least 15,000 years ago humans were widely settled across the North American continent.
The results drawn from 42 different archaeological sites suggest a human presence before the Clovis era.
Ardelean hopes that archaeologists will now look for evidence of human occupation using the proposed dates from these studies.