'We certainly weren't exceptional, but now we're the only ones left': In new PBS series 'Human,' anthropologist Ella Al-Shamahi explores how humans came to dominate Earth

When Homo sapiens first emerged in Africa some 300,000 years ago, we did not roam the planet alone.

Our species lived alongside at least six, and possibly more, other human species, from Homo erectus, the first hominin species to venture out of Africa; to Neanderthals and Denisovans, contenders for our closest relatives; all the way to Homo floresiensis — less than 4-foot-tall (1.2 meters) "'hobbits"' who lived on the Indonesian island of Flores.

It's an origin story that Ella Al-Shamahi, a British Arab paleoanthropologist, presenter and explorer, often likens to the Lord of the Rings. Yet, despite its intriguing details, it's also one she says we don't talk about enough.

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So Al-Shamahi embarked on a three-year journey across the globe, piecing together our earliest steps and boldest migrations from locations that include Morocco, Namibia, Botswana, Ethiopia, the United Arab Emirates, Sri Lanka, Norway, Romania, France, Canada and Peru. The result is her latest five-part BBC series, "Human," which tells the surprising history of how we came to reshape our planet.

Ahead of the show's Wednesday (Sept. 17) U.S. premiere on PBS, Live Science sat down with Al-Shamahi to discuss it, where we came from, and how H. sapiens became the dominant species on Earth.

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Ben Turner: People are going to learn all kinds of things from watching "Human," but most viewers won't come in as experts in the field. I want to know, from your perspective, what did you learn from making it?

Ella Al-Shamahi: There was only one thing that I didn't know going into making the show, and that was the incredible alphabet situation. It's almost at the end of the series that we reveal the real story of how the alphabet was invented. And it turns out it was actually invented by some lowly people, some would call them slaves, in Egypt. They were illiterate, and they were just copying the [hieroglyphs written by] higher-ups on the hierarchy.

But then there was a real thing for me, a thing that I was desperate to do. This has been my subject for 20-odd years, I think it's an absolutely mesmerizing subject area. And I have never understood how people don't know certain things.

Like, for example, I've never understood how people don't know that we were born into a world of many [human] species. There were at least six other species around at the same time [300,000 years ago] as us — I actually think that number is probably much, much higher, and will probably get higher over the coming years — and for me, that becomes like a Lord of the Rings type universe. That captures the imagination, that is a fantastical story.

But add to that, if there were that many species, we think we were probably the underdog of the group. We certainly weren't exceptional, but now we're the only ones left. That then becomes a crazy mystery, and it's actually quite profound. How come we're the ones that did so well? How come we're the ones that won out and won out in such a huge way? And so for me it was this opportunity to scream from the rooftops and to let people know the real story of our origins.

When you're doing these shows, it's hard not to be moved. You turn up to a cave where they're looking at ritual, for example. Or you see an incredible pair of footprints that look like they came from a mother and child walking in the Americas, in New Mexico. I mean, it's just the opportunity of a lifetime to be able to communicate this.

BT: I'm not an expert, but whenever I see stuff like that it surprises me at how emotive it can be. It's not even comparatively that old, but the Cueva de las Manos in Argentina gets me every time I look at it. Is there something — an artifact, a relic, ritual or cave painting — that stands out as a tear-jerker for you?

EAS: There are so many, that's the incredible thing. If I had to pick one, there's a cave called Rhino Cave [in Botswana]. It has an outcrop where the rock itself is shaped like a serpent, it even has a slit for the mouth. And these humans came along and they essentially chipped what looked like scales, like hundreds of these scales, into the rock, to really make it look like a serpent. They made these stone tools, which were beautiful, and then they destroyed them before using them, which you don't tend to do unless you're making an offering.

Caves are a magnificent thing to be in at the best of times. We waited until the evening, and we basically put in something that looks like candle light, so we got the full effect. And it was magnificent. It was really magnificent because we are the only animal that does ritual in that way. You don't see chimpanzees, [one of] our closest living relatives, doing that kind of thing. It's the ability to see beyond what is in front of you, and to imagine a different world. And it was really profound, because so far we think that's the earliest site of ritual that we have evidence for.

And you wondered when you sat there what people were wishing for, what these offerings were about.

BT: You mentioned earlier that modern day humans were one of at least seven known human species at the time of their emergence. And you also said we were underdogs. Is there anything that sets us apart, aside from the ostensible fluke that we're still around?

EAS: I think it's fair to say it's probably a combination of things, but if you put 10 different anthropologists in a room, we would all come up with slightly different answers to that.

I think we [in the show] argue very heavily that it's cooperation. We are an incredibly cooperative species. There's this thing called cumulative culture, which is a theory that I've been trying to get on television for like, seven odd years.

It doesn't particularly sound sexy, if I'm gonna be honest, but it's the idea that every generation builds upon previous generations — their technology and science and art. We basically argue, like a lot of paleoanthropologists, that, as a species, there were a lot of us and we were very cooperative.

Cumulative culture, because of the way our brains were, came into play. And it came into play in a big, big, big way. Suddenly you ended up with technology that was just so much better because we were this highly cooperative species. It's kind of funny to think about it, because at the end of episode one, I basically say: "Look, we're the friendly species," and that really does raise people's eyebrows, because they're like: "We? Homo sapiens? The friendly species?"

I put it to you that cooperation is friendliness. Cooperation is the ability to be friendly and work with the people around you. What other species has built what we've built? Name them. We're clearly highly cooperative.

We also argue that climate came into play, and for various reasons, including the fact that we have a source population in Africa, we were doing better. And our technology was able to adapt better because of the cooperation that we had. But I also think there's just an element of luck.

BT: Us being the "friendly" species contradicts some of the older ideas about what made us survive. It's like the depiction of humans in William Golding's [1955] novel The Inheritors, the idea that we beat these other species through sheer brains, or brawn, or a combination of both. That's what a lot of people still assume.

EAS: Yeah we've got no evidence that we made war with any of these species. Ironically, we do have evidence we made love with them.

There's suggestions that we might have fought, but there's no conclusive evidence. I think what is more likely, and this is my own reading of the data, is that we were formidable competition. In the end, by the time we had become the species we know today, we were formidable.

But honestly, I think it's more subtle than people realize. I think the fact that we're here and they're not is — oh, it was close. There's a mountain in Israel called Mount Carmel, and there's two caves. For about 30,000 years, maybe, give or take, we think that Neanderthals were living there [in one cave]. And in another cave on that same mountain, Homo sapiens were living there.

Which, first of all, amazing. Like how cool is that, on the same mountain? But secondly one of them went locally extinct, and it wasn't the Neanderthals. It took a few more tens of thousands of years for us to get the upper hand. So it was close, at times it was really close.

Related: Did we kill the Neanderthals? New research may finally answer an age-old question.

BT: You mention making love and not war. There's another old idea, famously summed up in Rudolph Zallinger's March of Progress illustration, that we didn't really interbreed that much with other Homo species and instead cut a fairly linear evolutionary path, from chimp-like apes through Homo erectus to modern-day humans. That's got to be pretty misleading, right?

EAS: Yeah, it's funny, I speak about that image a lot in my talks. There are a few issues with the image, but the primary one is that it gives the impression that evolution is linear: one species leads to another species, and that first species all becomes extinct; and then that second species leads to the third species, and then that second species all becomes extinct. And we know that's just not the case.

It's certainly not the case with our species and our relatives. We were splitting at various points on this family tree, with other species sharing an ancestor with them. We call the Neanderthals our sister species, which effectively means they were our closest relatives, like a cousin. But when we met them again, we would occasionally have sex with them. Evolution is not that straight line, it's this complicated bush, and it makes it so much more interesting. I just think it's fantastic. What would it have been like to live in that world?

BT: This is a slightly silly question, but I have to ask it. Do you have a particular Homo species you'd have been most interested to meet?

EAS: It used to be Neanderthals, they're my subject area, but with time it became Homo floresiensis or "hobbits." They're basically these tiny, miniature humans that lived on the island of Flores [in Indonesia].

They were recently described as "humans the size of penguins" and on the island there were giant, flesh-eating, carnivorous marabou storks that were taller than me, over 6 foot [1.8 meters]. There were giant rats, massive komodo dragons, but also miniature elephants called stegodons that were the size of cows. And you think, well that's interesting, wouldn't mind meeting that lot, finding out what's going on there.

Then there are Denisovans. They've been this mystery that's been unfolding since 2010 [following their initial discovery] you know, who were the Denisovans? Turns out we now know who the Denisovans are, but it's still quite a mystery.

But, gun to my head, I would probably go with the hobbits. That's probably not an answer anyone's expecting.

BT: I mean I get it, there's something really Swiftian [the Anglo-Irish writer of Gulliver's Travels] about them. Living on this fantasy island of disproportioned creatures.

EAS: Yeah! There was actually a second hobbit-like species living on the islands of the Philippines.

BT: So what's the relevance of all this to the present? What can studying our past teach us about ourselves today? If anything?

EAS: Well, I would say that we're forged in the Paleolithic, and we are a byproduct of our DNA. In fact, that DNA has actually moved on very, very, very little in the intervening years.

You can see the origins of so much when you study our history. But it's more than that, I think it gives us the context for so many things that are right, and wrong, about ourselves. So there's ritual and the way we see the world, the fact that we take risks the way we do, our imagination and creativity that no other species has, our cooperation, our love of dogs, and how much we need other humans — we don't do well as loners.

I often describe cities and agriculture as the biggest trade-offs we've ever made. Because, on the one hand, more of us are able to survive. But on the other hand, we're surviving in a way that is no longer the world that our DNA was built for. It's suboptimal, we weren't designed to be staying in one place, our biology isn't really about that. It gives us a lot of context for who we are and why things don't always fit.

What was really interesting about this series is that, when we started making it, one of the things that I kept getting told was we need to be explaining to the public why human evolution is so fascinating. I had all the usual answers, we've sequenced the Neanderthal genome, and we've now got ancient DNA and our family tree's bigger and all this stuff. But there was another answer that I had, which was that nobody ever asks us to justify why space is fascinating or relevant. You often hear from astronauts that when they look back at our tiny, little blue dot, that it gives them context and it gives them perspective.

When I sit on top of deep-time archeological sites and know the stories of the people that are underneath me — fascinating stories about people that seemed really resilient who suddenly disappeared; people that were a Neanderthal group suddenly overtaken by a Homo sapiens group; sometimes scandalous stories, cannibalism, inbreeding, etcetera — it gives you perspective. I often think that space is magnificent, but time is who we are.

BT: It's interesting that, despite how much we know, so much of the story remains undiscovered. We emerged from Africa, but DNA degrades quite easily in the warmer conditions there and so the genomic maps are all from the Eurasian hinterlands. Are there any scientific questions you're excited about that could fill these gaps in our knowledge?

EAS: Oh, so many. There's a lot of talk about Denisovans and their relationship to us in the family tree. Traditionally, we saw the Neanderthals as our sister group closest to us, but there is a suggestion that maybe it's the Denisovans which then makes us more centered, but it's just too early [to know].

I think it would be very helpful to know just how many other human species [there are]. It would also be really quite helpful to understand, beyond just theories, what it was that eventually made us "Homo sapiens 2.0." There's a suggestion that something happened in our brains. It would be really fascinating to know for sure if that was the case.

But for some of these questions, the answers to them may not come for a very, very long time. I think just knowing the way science is, they'll come. We just don't know how long we'll be waiting for them.

BT: You also did a TED Talk on the "The fascinating (and dangerous) places scientists aren't exploring." So what about the non-scientific barriers? They're all places that were cradles of our species. What could we be missing out on due to scientists not having easy access to vast regions of the Middle East, like Yemen and the Sinai, and Asia, North and Central Africa?

EAS: It's like low-hanging fruit. There are incredible archeological discoveries being made in New Mexico, for example. You know how many archeologists there are in New Mexico? A lot. There are incredible archeological discoveries being made in France. Again, lots of archeologists working in France.

So then imagine places we would call "red zones" or places that are politically unstable that barely have any archaeologists working in them. I work in Somaliland, if you look at the countries that neighbor it, they're all paleo dreams, places with significant human fossils. Are we to believe that our ancestors didn't enter Somaliland [from these places]? Of course they did. We just have no evidence because nobody's looking, and we're all poorer for it.

But I also think there's a bigger issue, which is that I think science is best when everybody is at the table. It's a tragedy that so many people in those places don't have access to becoming these kinds of scientists.

BT: To round this off, I know we've already touched on some of the unanswered questions, but you said many of them could take some time. Are there any you see us answering sooner, in the near future?

EAS: I think we'll be adding more species to the family tree, and also understanding those relationships a little better. I also suspect at some point we'll get closer to understanding what's going on with FOXP2.

FOXP2 is described in some circles as "the language gene" but it's clearly so much more than that. It looks like it's different between us and the Neanderthals. The question is what is it about? I think it's something about the way our brains process [information].

Editor's note: This interview has been condensed and edited for clarity. Human will premiere in the U.S. on PBS on Nova on Sept. 17.