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UA Researcher in PBS Series on Early Humans

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Posted June 23, 2015

About 200,000 years ago, our ancestors took their first steps on the African savanna. Today, 7 billion of us live across the planet. How did we beat the odds and spread from continent to continent?

A Tam Pa Ling woman sheltering from a storm 63,000 years ago. Image credit: PBS

A Tam Pa Ling woman sheltering from a storm 63,000 years ago. Image credit: PBS

First Peoples” is a global detective story that traces the arrival of the first Homo sapiens on five continents. Airing at 9 and 10 p.m. Wednesday and July 1 and at 9 p.m. July 8, the five-part series is part of PBS‘ “Think Wednesday” programming block (watch a clip here).

“First Peoples” tells the story of how early Homo sapiens moved around the globe and became the dominant human species. Each episode of the series focuses on a different continent and meets the earliest Homo sapiens on that continent — the Americas, Africa, Asia, Australia and Europe. Where did they come from? How did they get there? What role did art, culture and technology play in their lives? Whom did they meet along the way? It used to be thought that our ancestors kept a distance from other types of humans. But now DNA reveals they mated with them and interbred. As a result, our species is a patchwork of modern and ancient genes — we are all hybrids.

With a camera crew winging its way around the world, “First Peoples” dives into the underwater caves of Yucatan, soars above the Australian outback and journeys to the Himalayas. In every location, key experts are on hand to reveal their findings, but the biggest breakthroughs are taking place in genetic laboratories. It is now possible to extract high-quality DNA from ancient fossils, and the sequences that emerge are rewriting the human story.

One of the experts featured in “First Peoples” is Michael Hammer, a research scientist at the Arizona Research Laboratories Division of Biotechnology at the University of Arizona, whose team is at the forefront of untangling the complex relationships among the earliest human ancestors in deep time. Hammer is featured in Wednesday’s second episode of the series, which looks at our origins on the African continent.

“If you could take a time machine back 50,000 years, you’d find people looked really different,” said Hammer, also a member of the UA’s BIO5 Institute. “The question is, where did those features we consider anatomically modern traits come from?”

Around 200,000 years ago, a new species, Homo sapiens, appeared on the African landscape. Image credit: PBS

Around 200,000 years ago, a new species, Homo sapiens, appeared on the African landscape. Image credit: PBS

While it has now been widely accepted that anatomically modern humans of the species Homo sapiens originated in Africa and eventually spread throughout the world, it wasn’t clear until very recently whether they exchanged genetic material with other, now-extinct archaic hominin varieties in Africa, through a process called admixture.

Since no one so far has been able to successfully extract DNA from early hominin fossils found in Africa, as Hammer explained, his group decided to approach the mystery by looking for “genetic fossils.” Hammer’s team developed a method to use genomic data and look for expected signatures of mixing, and used that to screen genomes of populations living in Africa today.

Hammer’s group is one of few in the field of palaeoanthropology that have been able to trace extensive mixing among early humans before they left Africa to settle in other parts of the world.

“There has been this idea that modern humans evolved in the same place, in isolation from other forms,” Hammer said, “but our research group has found evidence that deconstructs this notion of specialness. The reality, we now know, was much messier, much more complex.

“If you look at variation in the genome, you find many regions of DNA that appear to have come in from other hominin groups. When it comes to mating with different-looking forms, it turns out humans are just like most other species in nature.”

John Hawks, a paleoanthropologist at University of Wisconsin, Madison, who worked as a consultant and appears in each episode, said, “‘First Peoples’ is the first chance most people will get to see extraordinary new research in human origins brought to life — real science, happening in remote places around the globe, with an international team of leading scientists. The series is grounded in the latest genetics, archaeology and anthropology research, yet it also shines a light on different viewpoints from an indigenous perspective.”

According to series producer Tim Lambert, “We learned that our family tree is not a simple one. It looks more like a bush, with interweaving branches and tangled roots. We are the product of many species that were similar and different at the same time. Using dramatic re-enactments and movie-style prosthetics, we have tried to tell this compelling story and explain how our ancient ancestors survived and ultimately thrived.”

Source: University of Arizona

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