June 09, 2021
from ScienceNews Website
Coxcatlan Cave entrance
New radiocarbon dates for rabbit bones
excavated in the 1960s
at Mexico’s Coxcatlan Cave (shown here)
raise the possibility that humans
lived there roughly 30,000 years ago.
from a Mexican rock-shelter
point to humans arriving earlier
than often assumed...
The latest evidence comes from animal bones that biological anthropologist and archaeologist Andrew Somerville and two Mexican colleagues found stored in a Mexico City lab.
The bones had been excavated in the 1960s at a rock-shelter called Coxcatlan Cave.
Radiocarbon analyses of six rabbit bones from the site’s deepest sediment yielded unexpectedly old ages, the researchers report online May 19 in Latin American Antiquity.
That sediment also contained chipped and sharp-edged stones regarded as tools by the site’s lead excavator.
Higher sediment layers yielded clearer examples of stone tools and other remnants of human activity dating to nearly 9,900 years ago.
Somerville, of Iowa State University in Ames, initially suspected that rabbit bones from the deepest sediment were perhaps around 12,000 years old.
Somerville will next determine whether other animal bones from the ancient sediment display butchery marks, breaks where marrow was removed or burned patches from cooking.
He also wants to locate and study possible stone tools from that same sediment that may be stored in the same lab.
Based on additional radiocarbon dates and comparisons with stone-tool finds from other Mexican sites, Somerville suspects that a separate occupation of Coxcatlan Cave occurred between 13,500 and 9,900 years ago.
Regional food and water sources may have dwindled when the last Ice Age peaked between 26,000 and 19,000 years ago, causing the earliest settlers to leave and delaying further occupations until conditions improved, Somerville speculates.