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Ancient DNA could unlock South Florida secrets

About 14,000 years ago, modern humans roamed to South Florida and lived side by side with mammoths, mastodons and saber-tooth tigers.

Ancient DNA could unlock South Florida secrets
Archaeologists tag artifacts found at the Old Vero Man site, where the bones of several 
extinct animals were found [Credit: Mercyhurst University Archaeological Institute]
That, at least, is what Florida Atlantic University scientists hope to prove by analyzing ancient DNA found at an archaeological dig in Vero Beach.

If they can confirm the age of some very brittle bones, it will fill a major gap in human history, said Greg O'Corry-Crowe, an FAU associate research professor. "It would imply that humans were on this continent much longer than originally thought," he said.

Officially called the Old Vero Man site, the dig is considered one of the most important archaeological finds in North America. A large number of animal and human bones were discovered there, providing a rare glimpse of the Florida landscape at the end of the last Ice Age.

The site was originally discovered in 1915 when a farming company dredging a relief canal spotted part of a human skull and 44 other bones from up to five individuals, male and female.

After inspecting the bones, Dr. E.H. Sellards, the state geologist in the early 1900s, developed a controversial theory: the bones were up to 14,000 years old so therefore humans co-existed with large prehistoric animals. Most experts at the time believed humans arrived in North America 4,000 to 6,000 years ago, long after those animals went extinct.

Mercyhurst University Archaeological Institute, based in Erie, Pa., and which is overseeing the Vero Beach dig, wants to prove Sellards was correct.

It recruited FAU, which operates one of the few ancient DNA laboratories in the nation, to determine the age of the bones. FAU already has pinpointed the age of ancient Beluga whales and other prehistoric mammals in Florida and Alaska.

FAU "is certainly the preeminent facility for doing this kind of work," said James Adovasio, provost of the Mercyhurst Institute and a world-renowned archaeologist.

Adovasio said FAU initially will analyze animal fossils because Mercyhurst is still trying to locate all the human bones found at the Vero site. He said many were dispersed over the decades to various museums, such as the Florida Museum of Natural History in Gainesville.

The overall idea, he said, is to establish how long it took humans to migrate to Florida and how they adapted once they arrived. It's part of the quest to piece together the big picture of human history.

Ancient DNA could unlock South Florida secrets
An aerial view of the Old Vero Man site, where the bones of ancient humans
 were found [Credit: Mercyhurst University Archaeological Institute]
Based on the fossil record, here is what many archaeologists believe:

Modern humans first appeared about 195,000 years ago in East Africa. Likely chasing prey, they moved across Asia and what was then a land bridge to Alaska, arriving in North America about 20,000 to 25,000 years ago. They then took 5,000 to 6,000 years to cross the continent to Florida.

"The old model basically had these folks sprinting across North America, chasing and killing big animals," Adovasio said. "We know now they moved very gradually.''

They finally reached Vero Beach about 13,000 to 14,000 years ago, as the Pleistocene Epoch and the last Ice Age were drawing to an end. At the time, Florida was almost double its current size, extending out into the Gulf of Mexico and the Atlantic, and much of the state was more than 300 feet above sea level, said Andy Hemmings, lead archaeologist for the Mercyhurst Institute.

"The landscape was so different than what it is today," he said.

Florida also was home to tapirs, sloths, camels, bison and horses — in addition to mastodons and mammoths. Many converged at what was then an "oasis" of streams and rivers about 35 miles inland from the ocean. Today, that is the Old Vero Man site and it's about five miles inland, Hemmings said.

"It was a fairly constant source of fresh water and a tremendous draw to animals and human beings," he said.

Growing in numbers and becoming more skilled hunters, the humans continued forging south, evidenced by the Cutler Fossil Site on the Charles Deering Estate in south Miami-Dade County. That site, dating back almost 12,000 years, was excavated in the mid-1980s by archaeologist Bob Carr, of Davie.

He said his team found bones from Paleo-Indians and "103 species of animals, including mammoths, a saber-tooth cat, a paleo-lama, and a California condor."

The Cutler site was the only one in this region that dated back to the end of the Ice Age; usually sites that old are buried far below the surface or paved over by development, Carr said.

By the time humans arrived in what is now South Florida, the Ice Age was almost over. Mastodons and their ilk were going extinct, likely because of climate change, Adovasio said.

Hoping to firm up this chronology, archaeologists excavated the Old Vero Man site earlier this year, and another dig is planned for January.

Potentially, they could unearth some of the oldest human remains in the United States, and "there is every possibility they could be among the most informative," Hemmings said.

However, extracting ancient DNA will be a major problem because it has been degraded by time, said O'Corry-Crowe, who works at FAU's Harbor Branch Oceanographic Institute in Fort Pierce.

Still, even a small amount would tell whether the bones were male or female and just how far removed those modern humans were from their ancestors, he said.

"With ancient DNA, you're time traveling," he said. "It provides us with a unique opportunity to look into Florida's past."

Author: Ken Kaye | Source: Sun Sentinel [September 20, 2014]

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