By Anna Daniels
Who knew that the Cerutti Mastodon site along SR54 in San Diego may be “the oldest in situ, well-documented archaeological site in North America and, as such, substantially revises the timing of arrival of Homo into the Americas”? And what does that actually mean?
San Diego has been a rich source of paleontological discoveries. A 300,000 year old mammoth was excavated during the construction of the Thomas Jefferson School of Law in downtown San Diego. Additional excavation ten feet below the skull and tusks of the mammoth revealed the 500,000 year old skeleton of a California Gray Whale.
The significance of these two sites are quite different. The mastodon site is about much more than the animal life in the region one hundred and thirty thousand years ago. According to a paper recently published in Nature, the San Diego Natural History Museum paleontologist-authors maintain that the bones show signs of percussion (breakage) associated with “humans with manual dexterity and the experiential knowledge to use hammerstones and anvils…”
This assertion, if correct, is an astounding revision to what we know about the timeline for human habitation in the Americas. The dominant theory that most of us learned was that humans crossed the Bering Strait via a land bridge between Siberia and Alaska between 15,000 and 20,000 years ago and quickly colonized North America before heading into South America. The Nature paper pushes the timeline back 115,000 years.
The findings are controversial. No corroborating human bones have been found from that time period at the Cerutti site. Beyond the need for broader consensus about the nature of the percussion signs on the bones loom much more tantalizing questions–if true, how did those first humans arrive here, well before the appearance of the land bridge, and what happened to them?
Less than a week ago, 15,000 people marched on behalf of science in the streets of San Diego. The recently published work by Thomas Deméré and the team of San Diego paleontologists is a reminder of how science works, what science does–and why it matters. From extensive work in the field to the submission of papers to the controversies and further searches for evidence, scientific inquiry continues to break new ground, establish a new understanding of our world and directs us toward a whole slew of new questions. It’s happening right here, in San Diego.