Episode 1: Americas
As early humans spread out across the world, their toughest challenge was colonizing the Americas because a huge ice sheet blocked the route. It has long been thought that the first Americans were Clovis people, who arrived 13,000 years ago. But an underwater discovery in Mexico suggests people arrived earlier — coming by boat, not on foot. How closely related were these early Americans to today’s Native Americans? It’s an emotive issue, involving one of the most controversial fossils in the world, Kennewick Man. (Wednesday, 9 p.m.)
Episode 2: Africa
About 200,000 years ago, a new species, Homo sapiens, appeared on the African landscape. While scientists have long imagined eastern Africa as a real-life Garden of Eden, the latest research suggests humans evolved in many places across the continent at the same time. Now the DNA of a 19th-century African-American slave reveals that during the early days of our species, our ancestors continued meeting, mating and hybridizing with other human types in Africa — creating ever-greater diversity within us. (Wednesday, 10 p.m.)
Episode 3: Asia
What happened when early humans ventured out of Africa and into Asia? Where did they go and whom did they meet along the way? The latest evidence suggests they left far earlier than previously thought and interbred with a newly discovered type of ancient human — the Denisovans, whose existence was established only four years ago when geneticists extracted DNA from a tiny fragment of finger bone. Because our ancestors mated with them, their genes found a home within our DNA. More than that, they’ve helped us survive and thrive. (July 1, 9 p.m.)
Episode 4: Australia
When humans arrived in Australia, they were, for the first time, truly alone, surrounded by wildly different flora and fauna. How did they survive and populate a continent? There is a close cultural and genetic link between early Australians and modern-day Aborigines; here the ancient and modern story intersect as nowhere else. The secret to this continuity is diversity. Intuitively, early Australians found the right balance between being separate and connected. (July 1, 10 p.m.)
Episode 5: Europe
When Homo sapiens turned up in prehistoric Europe, they ran into the Neanderthals. The two types of human were similar enough to interbreed — and both created artifacts of similar complexity. As more and more Homo sapiens moved into Europe, the balance of power shifted. Neanderthals were overwhelmed. Ever since, we’ve had Europe and the rest of the world to ourselves. (July 8, 9 p.m.)
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?
"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?"
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."