Blazing the Trail | Episode 1: Who are we? What it means to be human

In this first episode of Blazing the Trail, join host Dr. Amy Mosig-Way and special guests Dr. Emma Mbua, Prof. Chris Stringer, Dr. Kathryn Ranhorn, and Dr. Keneiloe Molopyane in a discussion of the origins of Homo sapiens in Africa and the traits that make our species unique. The story of human evolution was not a linear progression when we first emerged around 300,000 years ago, but a complex process involving co-existing with multiple human species. Join us as we explore this fascinating story of where we come from, and what makes us human.

Creators and Guests

Host

Dr Amy Way

Dr Amy Mosig Way is a research archaeologist holding a joint position between the Australian Museum and the University of Sydney, where she lectures in First Nations archaeology and Archaeological field methods. Her expertise lies in high-resolution stone artefact analysis and Amy is working on projects examining the first human occupation of Central Europe and occupational change over time in mountain and arid zone environments in Australia. At the Australian Museum, she leads the archaeological research program with key responsibility for implementing long-term community-centred archaeological projects in NSW. Previously, she has held a coveted Postdoctoral Fellowship at the Evolutionary Studies Institute, University of the Witwatersrand, South Africa, where she researched Middle Stone Age stone artefact assemblages.

Writer

Madeline Robinson

Madeline G.P. Robinson is a PhD candidate and Archaeology Support Officer in the Department of Archaeology at the University of Sydney. She specialises in photogrammetry, 3D modelling, photography, and spatial archaeology, with a focus on early coastal adaptations during the mid to late Holocene. Madeline has conducted research and fieldwork across diverse locations, including Australia, Saudi Arabia, Turkey, Malta, Alaska, Arizona, Cambodia, and most recently in Sri Lanka.

Editor

Peter Adams

Media Producer for University of Sydney School of Humanities. Has an Honours Degree in Screen and Sound and has decades of experience in the media industry.

What is Blazing the Trail ?

This podcast series explores our shared epic human journey. Our story begins in Africa, when our family included other human species. Through time, our intelligence and curiosity developed, we learnt how to create and control fire, how to communicate with each other, and ultimately thrive in every environmental niche on this planet. Join us in this series as we investigate where we come from, and what makes us human.

This series a co-production between University of Sydney, Australian Museum, BreakThru Films, University of Liverpool, and University of Wroclaw.

Episode 1. Who are we? What it means to be human
AW: Amy Way, EM: Emma Mbua, CS: Chris Stringer, KR: Kathryn Ranhorn, KM: Keneiloe Molopyane, MR: Madeline Robinson

Intro: Welcome to Blazing the Trail, the podcast where we explore our shared epic human journey. Our story begins in Africa, when our family included other human species. Through time, our intelligence and curiosity developed, we learnt how to create and control fire, how to communicate with each other, and ultimately thrive in every environmental niche on this planet. Join us in this series as we investigate where we come from, and what makes us human.

AW: Hello and welcome to the first episode of Blazing the Trail, the show where we investigate the stories of our origin so we can answer the question - what makes us human? I’m your host, Dr Amy Mosig Way, archaeologist and lecturer at the University of Sydney and the Australian Museum. In today’s episode, we are looking at the origin of modern humans and tracing the ancestry of all living people back into the deep past to answer the question: who were the first homo sapiens? This story begins in Africa.

EM: Modern Humans, also known as Homo sapiens, are classified under the genus Homo.

AW: That’s Dr Emma Mbua, paleoanthropologist at the National Museum of Kenya and the first female palaeontologist in East Africa. Dr Mbua is a leading expert on the origins of humankind, with a particular focus on the evolution of modern humans in Africa.

EM: Modern humans did not evolve from living apes that are alive today, but like chimpanzee, but we have a common ancestor with chimpanzees that lived around 7 and 6 million years ago. That is why we share many similar features with modern apes. Environmental pressures split the ancestor group into two lines, with one branch evolving to modern apes, which includes chimpanzees, gorillas and bonobos. We, however, as humans followed a different evolutionary path, which culminated in the emergence of our species today.

AW: From this early common ancestor that was living in Africa 6-7 million years ago, a branch evolved that we call Australopithecus, from which our Homo lineage likely came from. It is important to note here that the term human refers to all members within our family tree: this includes the ‘Homo’ genus (which we are part of) and all our earlier ancestors, including Australopithecus and Ardipithecus who lived around 4-6 million years ago. We also refer to this group as hominins.
When our direct ancestor Homo erectus, or upright human, came along around 2 million years ago, we really start to see features that are a lot closer to what we see in humans today. This first upright human, Homo erectus, had a body better adapted to running and hunting than earlier species, which is one of our key traits.

EM: Only after the savannahs opened up did we start to walk upright habitually. Standing upright has many benefits, hands are now free to signal, to throw things, and to make tools. Over time, walking upright changed our skeleton, making our hips smaller while other factors contributed to massive skulls and larger brains allowing our intelligence to develop.

AW: As time went on, and the climate of Africa changed, these early members of the Homo lineage evolved.

EM: Slowly different genetic groups begin to emerge and branch out forming a diverse range of new species of bipedal humans. Over time, other species of humans evolved.

AW: So this diverse range of bipedal humans – as in humans walking on two legs – were all part of our human family. It is strange to think that after all this time, we are now alone, but once upon a time we were only one branch of a much larger group. And this family history is still continually growing today as new fossils are unearthed across Africa. Dr Mbua and her team have recently discovered a remarkable new fossil site, just outside of Nairobi, Kenya. At this site, they found the remains of some 30 animals and one archaic human, thought to have lived 3.5 million years ago - Australopithecus afarensis. This remarkable site is called Kantis Fossil Site.

EM: Human fossils from Kantis fossil site include juvenile and adult remains and are dated to 3.5 million years. Their females grew to only a little over a meter in height, their brain was tiny and the skull retained many ape like features. They mostly consumed a diet of plants.

AW: Our earliest ancestors inhabited Africa around 6-7 million years ago and since then, a variety of human species evolved from them. We used to think that this evolution happened in a straight line, from one ancestor to the next, all gradually evolving, in one place, up to us today. However, it has now become clear the story is much more intricate than originally thought. Around 300,000 years ago, when modern humans appeared, Africa was still inhabited by other archaic humans. Over time these other species became extinct, leaving us as the sole surviving human species on earth today.

CS: When we look at recent human evolution, there's been a predominant view of a unilinear gradual process where modern humans evolve gradually in one area or maybe in many areas through time. But we now know that the situation is much more complex than that, both within Africa and outside of Africa.
AW: Our guide as we take a closer look into the evolution of the homo lineage is Professor Chris Stringer from the Natural History Museum, London. Chris is a leading authority on human evolution and a research leader in Human Origins.

CS: The modern human lineage was evolving with a lot of diversity. Different populations, at times separated from each other by the climates and the environments, and at other times coming together and exchanging genes and behaviour. But alongside that complex evolution of our own lineage Homo sapiens in Africa, we know that there were other, what I would call distinct species still around.

AW: At this time, around 300,000 years ago, there were at least three lineages of humanity evolving in Africa.

CS: There were three main late branches of humanity evolving. There were the Neanderthals, there was the Harbin clade, and there was us Homo Sapiens. Now, of course genetically, we know there was an extra lineage in Asia called the Denisovans. So an interesting question is, is the Harbin Clade the same as the Denisovans? And it would make things a lot simpler if we could say that Harbin is a Denisovan. So Harbin shows us that there's even more diversity when we look at an area like China. And that again, we have there a distinct mixture of features distinct from the Neanderthals, that combination, and distinct from homo sapiens.

AW: So at the time when the first definitively modern humans emerged in Africa around 300,000 years ago, there were other humans already present - the Neanderthals, the Denisovans, and many others. So from this sea of diversity and variety, I asked Professor Stringer, which features do scientists look for to know that a fossil is from the modern human lineage?

CS: That's a difficult question and scientists will have different answers to that. So, from my point of view, there's obviously a suite of features that we share today - the high rounded brain case and the narrow pelvis. So where we've got relatively complete fossils, we can see how they compare with that suite of modern features, but of course the fossil record has incomplete fossils. And then it's more difficult, we have to judge on what is preserved and, we know that all of those features did not evolve as far as we know, rapidly in one place. They probably evolved at different rates in different parts of Africa and then coalesced together. So, it's not a simple question really to answer. But I would say that, I'd like to see at least one of those distinctive modern human features in an African fossil to place it on the modern human lineage.

AW: So one of the main features is that our skulls are high and rounded, with a small face. We know that the higher rounded brain case evolved to accommodate our bigger brains, but why we have these small faces, is a bit of a mystery and one that really gets to the heart of what it means to be human.
CS: So one idea is that, of course we processed our food to a much greater extent. So that led to a reduction of the size of the teeth, of the muscles that work our jaws. So that reduction then led to a reduction of the size of the face. So that is one view. Another view is that along with our large brow reduce, we had a reduction of these big brows and a reduction in the size of the face. And that might be to do with signalling between humans that perhaps, as modern human groups, cooperated more. There was less aggression between individuals within groups. And that meant that overall there was a reduction of what you might call signalling that could be linked with aggression, such as that big brow ridge, such as a big face, such as bearing large teeth. Those are all things which in other mammals may be used to, certainly primates, we know that primates use their faces to signal to each other. So perhaps our smaller faces are linked to a reduction in aggression in the modern human lineage.

AW: You’re listening the Blazing the Trail. Here’s Madeline Robinson with a background briefing to help situate these complex ideas.

MR - News story: Dates for the appearance of Homo sapiens in the African fossil record have become progressively earlier over the last decade or so with new fossils from Omo-Kibish I in south-western Ethiopia, Florisbad in South Africa, and most recently the Jebel Irhoud site in Morocco which has pushed back the evidence from 100,000 years to as early as 315,000 years ago. Of course, there are more known sites with stone tools but no fossils, making it very difficult to directly attribute those tools (and occupation sites) to one of the surviving Homo species.

AW: You’re listening to Blazing the Trail and in this episode we are discussing the origins of how modern humans evolved. So far, we have heard from Dr Emma Mbua and Professor Chris Stringer and we have found out that the story of human evolution is a complex one. There was no single branch of evolution that eventually led to the emergence of modern homo sapiens, but a web of different branches, different populations and groups that intertwined along the way. This complex evolution ultimately created the human form we see today. But what did life look like back then, in the early days of our ancestors? What behaviours or practices did these early people have? We have with us Dr. Kathryn Ranhorn, Assistant Professor in the School of Human Evolution and Social Change at Arizona State University and expert on early human behaviour, to tell us what life looked like around 150,000 years ago.

KR: We know that this period of time is incredibly important for understanding how many of the cultural behaviours that define our species emerged. In terms of what was happening around our species back then in the local environment, variation was the norm. The Pleistocene as a whole is defined on variation, and that climate variation influenced local environments that hominins inhabited to some extent. By 150,000 years ago, humans lived in many different kinds of environments, and some have argued that adaptations to this environmental variability has been going on for over a million years.

AW: Early modern humans, just like later humans, responded to these changing environmental conditions by adapting their lifestyles and making new tools and products.

KR: Recent evidence from Morocco implies humans made clothes by working different kinds of animal hide. And in South Africa there's evidence that humans used insect repelling plant materials as a bedding. These kinds of innovations likely helped humans succeed in multiple diverse environments.

AW: One of the main ways that our ancestors were able to adapt so successfully was through the sharing of information through social networks.

KR: A likely but somewhat untestable scenario is that over the last several hundred thousand years, multiple groups of hominins varied their behaviour over time and space in a similar way, and that that information was transmitted in structured ways following demographic or natural boundaries, or perhaps both. The ability to build and maintain extensive social networks is one of these curious behaviours that seems to be unique to humans. But then with a broader look, we see many organisms like ants living elaborate social lives. So I personally became very interested in understanding how human social organization and cultural transmission shape human evolution. These areas of research were previously considered, quote unquote, archaeologically invisible, at least for those of us focusing on deposits that are really old, like older than 30,000 years. And this is simply not the case anymore thanks to a lot of advaces in archaeological science.

AW: So how can we possibly see things like social networks in the archaeological record? What should we be looking for?

KR: One of the best pieces of evidence that we have for studying networking in this time comes from studying the trade or the movement of stone for making stone tools. Some types of stone, like obsidian, have unique geochemical signatures, and that allows us to track where on earth the stone came from. When we find tools that are made on stone that has been moved from great distances, it can sometimes provide pretty good evidence for some kind of social network. For example, in Kenya, there's evidence indicating long distance transport of obsidian, which is very similar to glass, between 320 and 200,000 years ago. The obsidian there has been transported in from as far away as 160 kilometres. And so either these humans walked around for a 10 day trip to gather this stone and to do other things or possibly they negotiated access or acquired it through long distance trade networks. In either case, they would've been connecting with, and negotiating to some extent with neighbouring groups. And so that's one aspect of the archaeological record that we can study that, we're just now starting to scratch the surface on, especially in the time period that I study in Eastern Africa.

AW: Here’s Madeline Robinson with a background briefing to help situate these complex ideas.
MR - News story: New research, led by our Blazing the Trail host Dr Amy Mosig Way, on stone tools in southern Africa shows these social connections were stronger and wider than previously thought before the large “out of Africa” migration. The key to observing these early social networks lay in the study of a small stone blade, commonly known as the stone Swiss army knife. Across southern Africa, these blades could have been made in any number of different shapes in different places. However, around 65,000 years ago, it turns out that they were made in a very similar shape across thousands of kilometres and multiple environmental zones. This similarity points to strong social connections between geographically distant groups across southern Africa at this time. Importantly, this shows for the first time that the social connections which are key to our adaptive success, were in place in southern Africa before the big “out of Africa” migration.

AW: Another feature of modern humans is the use of symbols to communicate and connect with other people and groups. I asked Dr Ranhorn what kind of evidence can be seen in the archaeological record for humans communicating through the use of decoration.

KR: Some of the most exciting evidence for early symbolic behaviour comes from the use of paints and jewellery. There are many sites, that have several kilograms of ochre present, and we're still trying to understand what all of that ochre was being used for. While we know it had a functional purpose, for example, being used as a compound in glue making, especially to join stone tips to wooden shafts to make spears and other composite tools. There's also very good evidence that ochre use was not only functional and that it might have had other, perhaps symbolic purposes as well. Theres evidence of ochre exploitation in Kenya, at a site called Olorgesailie, dating to around 320,000 years ago. At Pinnacle Point in southern Africa there's evidence of ochre use as a pigment for body painting and perhaps painting other things as well.

AW: It’s really important to see that these features, which are so fundamental to our humanity, the ability to communicate across different groups through the use of symbols such as body paint and jewellery, these were all in place a long time ago.

KR: We know that body ornaments, such as beads, can provide information about the wearer to other people about their beliefs or their position or status in a group. No other mammal shares the same systematic vocabulary of body decoration that humans do. In human culture, beliefs, feelings and identity can be encoded in objects. A practice many of us participate in today with tattoos, earrings, fashion.

AW: So our early human ancestors developed an awareness and understanding that it was possible to communicate non-verbally through the use body decoration such as jewellery and body paint. It is interesting that we haven’t changed that much today, and that it is a distinctly human thing to ornament our bodies to advertise to the world who we are. But how about verbal communication? At this time, are we also using language?

KR: Did they have language? Did they not have language? We don't really know because while we really can't dig up language. But the proliferation of tool manufacture that required learning and teaching, the proliferation of symbolic items like beads, body paints and the ability to exploit various food sources such as marine resources along the coast, and the movement of resources across long distances, all of these things do indicate the use of some kind of complex communication system, and while that does not necessarily indicate spoken language, that would seem to be the most likely explanation. And while it is really impossible to know, my guess is that by a 71,000 years ago people probably did have language and this would have created some kind of positive feedback loop between technology and language. Particularly because language fuels social connections and it allows people to tell stories like the conversation we're having right now, and to share knowledge and in that way to ultimately build a system of meaning through which the world can be understood.
AW: If you are interested in the development of human language, be sure to listen to our later episode ‘Finding our Voice’ in the Blazing the Trail podcast series where we delve deeper into our unique ability to communicate through spoken language.

AW: In this episode of Blazing the Trail we’ve heard from archaeologists and paleoanthropologists on what the evidence suggests the first homo sapiens looked like and how they lived. Finding these fossils is extremely exciting, and often involves complicated underground journeys. We asked Dr Keneiloe Molopyane, from the University of the Witwatersrand in South Africa and a National Geographic Emerging Explorer, what it’s like to uncover fossils of our early ancestors in these deep underground cave systems.

KM: I've been spoiled, I've been very spoiled in terms of my introduction to paleoanthropology because I started working at the Rising Star Cave system.
AW: The spectacular and numerous finds of a new Homo species discovered in the Rising Star cave system in South Africa have complicated our human origin story even more, and we’ll be meeting these new relatives (along with others) in the next episode.

KM: That was my first fossil site that I ever worked at, and there were just fossils coming out of the ground every five minutes. You know, where at most fossil sites, it takes at least two, three days before you actually find something significant, or maybe weeks, months, and years. Here I was in a chamber where every piece of bone that we were picking up was significant because it was a whole new species of a hominid. I mean, that was an incredible feeling to know that I am digging up something that the world has never seen before, or something that we don’t even know too much about.

AW: The cave system, just outside of Johannesburg in South Africa, has a deep web of underground chambers, which archaeologists have to crawl through to excavate the fossils. In fact, the cave system is so narrow that only 48 archaeologists have ever have made it through. One particularly narrow passage is called Supermans’ Crawl.
KM: There are some points where the tunnel is so small that you have to put one arm in front of you and the other one behind you, posing like Superman, so that's why it's called Superman's Crawl. You're doing this crawling once you get through Superman's crawl, which is about maybe, I'll say 10 meters long, or 15, then you get into the Dragon's Back chamber, and that's where we are putting on our harnesses because at this moment we are about to climb up a dolomite ridge which fell from the ceiling and it's sort of created this lovely bridge up into the next chamber, which is above us. So you get the harness on, and then you begin your ascent up 20 meters on dragons back. And you're clipping in your safety ropes as you go along because if you slip and fall from Dragons Back, you're literally going to fall into an abyss. It's just black. There is absolutely nothing beneath you. So once we are at the top of Dragons Back then we go through the leap of faith, which is a one meter gap between Dragons Back, the top of it, and what I call the crystal chandelier room, which is just a small little area in which we take off our harnesses and prepare to go down into the chute. The chute is another narrow chimney that goes straight down at least 15 meters into the Dinaledi chamber, which is where all the fossils were found. So once you get through the chute, you will find yourself a little wooden ladder. If you feel that ladder, you've made it, you now in the chamber and then your full day of work starts.
AW: So what do you do when you find a fossil?

KW: So when you find your fossil, you need to bag and tag it, but before you bag and tag it, you need to record where it, it occurs within your excavation grid. So again, that's being very, that's playing around with our plum bob, and a laser level. So you need to get your level measurements correct to pinpoint exactly where that fossil came from, and then the fossils get a little bit more love and attention than the actual scientists, because we wrap them up in millions and millions of layers of bubble wrap. And then they're put into a container, and then that container is then put into a bag, which is lovingly carried out through the system. We like to protect the fossils rather than ourselves. We can afford the bruises. Broken fossils, not so much.

AW: With such an amazing place to work, and with such a rich source of archaeological material, I asked Dr Molopyane what she thinks the next big finds will be for human evolution:

KM: That's a very difficult question to answer. Perhaps we have found the next big thing and we just don't know about it because we haven't studied too much of it, you know? So I often get asked, what are you hoping to find next? Have you completed the family tree? I don't know. I don't think there really is a way of finding out if we've completed the family tree because of all the members that we have on our tree we've only scratched the surface of studying that material.

AW: Modern humans evolved in Africa from a long line of ancestors. These ancestors lived during a time when there were many other archaic species of Homo still living on this planet, creating a very complex and diverse landscape of evolution. The features which make us human really start to be seen around 2 million years ago, with the first upright human, Homo erectus, who can run and hunt. A suite of modern features are in place by around 300,000 years ago, such as our high and rounded skulls with small faces, and social features, uniquely human such as symbolism, body painting and jewellery are all in place by around 150,000 years ago. All of this laid the foundation for the complex communication networks we have in place today, and are part of what makes us human.

AW - End Credits: You have been listening to Blazing the Trail, investigating where we come from and what makes us human. Thank you to our special guests; Dr Emma Mbua, Professor Chris Stringer, Assistant Professor Kathryn Ranhorn and Dr Keneiloe Molopyane for featuring in today’s episode. Blazing the Trail is a joint production between the University of Sydney, the Australian Museum, University of Wroclaw, the University of Liverpool and BreakThru Films. Stay tuned for the next episode – We weren’t alone? Where we learn about the other humans who once walked this earth.

AW - Acknowledgements: This was Blazing the Trail, hosted by me, Dr Amy Mosig Way. Sound editing by Peter Adams, sound mixing by Michal Jankowski, and the music was composed by Eric Wainaina.