The History of Australia Podcast

Episode 4 - Out of Africa

October 18, 2020 Jasmin O'Connor Season 1 Episode 5
The History of Australia Podcast
Episode 4 - Out of Africa
Show Notes Transcript

Ancient humans journeyed out of Africa and made it all the way down to modern day Indonesia, right to the doorstep of Australia, and lived there for millions of years. Did any ancient humans make it to Australia before homo sapiens?

The History of Australia Podcast

Transcript - Episode 4 Out of Africa


Welcome to the History of Australia Podcast, Episode 4 - Out of Africa. Last Episode, we traversed the fossil record of Australia through the Jurassic and Cretaceous periods, and looked at some of the dinosaurs and other animals that walked and swam Australia at this time. That included plesiosaurs, the muttaburrasaurus and the prehistoric platypus steropodon galmani. During that period, Australia separated from Gondwanaland and made the slow drift northward, until it collided with South East Asia and got its first colonisers, rats and mice. 

This week we are up to the Pleistocene Epoch, which is the time for the genesis of humans. We are going to look at members of the genus Homo but not species sapiens. And the reason we are going to do this is because these ancient humans made it all the way down to modern day Indonesia, right to the doorstep of Australia, and lived there for millions of years. And it’s still up for debate, did any ancient humans make it to Australia? So, this then sets us up nicely to then look at the amazing journey of homo sapiens, the ancestors of the Aboriginal and Torres Strait islander people and all of us, all the way to Australia 70,000 years ago. 

Humans first evolved in East Africa about 2.5 million years ago from an earlier genus of apes called Australopithecus, which means ‘Southern Ape’. About 2 million years ago, some of these early men and women left their homeland to journey through and settle vast areas of Northern Africa, Europe and Asia. The fossil record is patchy, so it’s hard to identify exactly who took that first great step of leaving Africa. A good contender is homo ergaster, otherwise known as African homo erectus

So what were these first early explorers like? Well, if you met them on the street, then this would be someone that you go  “yes this is a human being”. They would have walked and probably run proficiently; they were tall and slender like us; and probably about a similar height really. They would have been distinctly different to modern great apes that have shorter legs, longer more muscular arms and are broad chested. There would have been many similarities to homo sapiens in the face as well, though there would have been some differences as you looked closely - they would have had prominent brows and no real chin and a smaller skull cap than modern humans that housed a brain that was still only half the size of ours.

And this last physical difference helps us start to piece together who homo ergaster really was, how did they live and how were they able to make that first crossing out of Africa, but why maybe they weren’t successful like homo sapiens at making it all the way to Australia. 

This is a species that’s starting to trade off muscle power for brain power. They are humans that are using their brains to adapt to their environment and innovate in response to challenges. They were also using stone tools. A partial skull discovered in 1969 in South Africa by Ronald Clark was in the company of stone tools. These were “Oldowan” or “Mode 1” stone tools that consisted of a stone that has been sharpened by chipping off one or more flakes of rock using another stone, so there is a cutting edge. The stones used were ones that had been rounded by water, so there is a smooth surface that can be easily held in the palm of the hand, and it’s not going to damage your hand as your wielding the tool, while the flaked edge is facing away from the hand and used as the cutting instrument. The sharp little flakes that come off of the main tool could have been held in the fingers and used for cutting as well. We know other great apes today use sticks and branches as rudimentary tools in foraging, so it’s likely that homo ergaster was doing this as well, though given the perishable nature of wood, no evidence of this survives until today. Ronald Clark’s skull-discovery was also in the company of burned bones. So this indicates a species that is maybe butchering and cooking meat in fire, whether that’s a man-made fire or a naturally started one that’s then opportunistically taken advantage of. 

And all these innovations by Homo Ergaster point to why humans were able to journey out of Africa, across the deserts in the north, 2 million years ago. Being upright, with an economical stride, meant these early humans were able to efficiently travel long distances. These humans were smarter than those that came before, so they’ve got the intellect necessary to cope with unfamiliar environments, and adapt rapidly to changes in climate that come when you’re travelling large distances quickly. And they were able to use stone tools and fire to cook meat and access varied foods to sustain themselves when they left the abundant and familiar plants and other foodstuffs of the African savanna. 

I don’t know whether this is something that would have helped or hindered Homo Ergaster on their cross continental journey, but they were very much a social and a caring species. There is fossil evidence that they cared for the old and the infirmed in their groups. And on the face of it, would caring for family groups, including those beyond their prime, have slowed down the travel of this species? Maybe. But then, as the saying goes, if you want to go fast, go alone, if you want to go far, go together. For example, some theoretical and modelling studies conclude that care-giving can limit the transmission of disease throughout a broader population and reduce the severity of outbreaks. Which I think these findings ring true with our own experiences today, particularly in the time of coronavirus. Another theory suggests that even millions of years ago, these early humans were taking care of the elderly because they valued the knowledge, skills and wisdom of older members of the group. This knowledge becomes increasingly important as these ancient humans are building up an increasing variety of learned skills like tool making, butchering and cooking.  

It is hard to pinpoint which innovation it was that really made the difference for homo ergaster, but whichever one it was, it really worked. This was a species that burst out of Africa and massively expanded its geographical reach in a blink of the eye. Once there, daily survival in the frosty forests of northern Europe looked nothing like living in tropical South-East Asia and over time the human populations diverged into different species. 

Humans in Europe and western Asia evolved into Homo neanderthalensis also known as Neanderthals. Neaderthals, bulkier and more muscular than us Homo Sapiens, were well adapted to the cold climate of Ice Age Europe. Neanderthals had big brains, as big or even bigger than ours, lived in social groups, used sophisticated tools, controlled fire, built shelters, wore clothing, made symbolic and ornamental objects and may have even spoken a language that would have been intelligible to us today. They survived in Europe up until 40,000 years ago, and would have been living alongside homo sapiens for maybe 20,000 years. 

Further East, in Siberia, humans evolved into another species Homo Denisova, a species still closely related to Neanderthals. The fossil record of the denisovans is relatively scant, but this was a species that had a broad face and bulky muscular body that too was adapted to cold climates. 

Neanderthals and Denisovans are fairly amazing and probably deserve to be covered in more depth, but we are really interested in learning about the early humans that lived in Indonesia and were within a stone’s throw of Australia. 

The more eastern regions of Asia were populated by Homo erectus, ‘Upright Man’, who survived there for close to 2 million years, making it the most durable human species ever. DNA evidence doesn’t exist for Homo erectus, like it does for neanderthals and denisovans and sapiens, but this may have been a super archaic human, maybe actually the same species as homo ergaster, and a common ancestor for all three of these species, that then actually managed to survive even as more advanced species developed. 

Homo erectus ranged from about 145cm - 185 cm tall (that’s 4 ft 9 in - 6 ft 1), so very similar to modern homo sapiens. They would have been  40 - 68 kg (88 - 150 lbs) in weight. Homo erectus’ brain size was smaller than that of humans today - in some cases nearly half the size - and their skulls were thicker. Like Neanderthals, their skull was long and low, rather than rounded like our own. They still had a prominent brow ridge and a large face and lacked a chin.

Soon after we see evidence in the fossil record of Homo erectus, we also see evidence for the first major innovation in stone tool technology (by about 1.76 million years ago). Known as the Acheulean stone tool industry. These were sophisticated stone tools crafted on two sides. They would have taken time and a degree of skill to create, requiring repeated blows from another rock or hard bone to systematically chip away rock flakes to form a teardrop shape with two sharp edges. Examples of acheulean stone tools include handaxes and cleavers. By a hand axe I mean you have basically a stone axe head that isn’t attached to a wooden shaft, but is instead held in the palm of the hand and it’s the hand and the arm that’s directly wielding the axe head. They were probably used to butcher meat, but also to chop wood, dig up tubers, crack nuts and crack bones. Later Homo erectus peoples produced a wider range of stone tools and were probably active hunters. The wider variety of stone tools would have further enhanced homo erectus’ ability to survive in changing climates and access even more varieties of food, including more meat, which it’s thought may have further supported greater brain development because of the energy-rich nature of that food. 

The increasing use of fire in cooking would have reinforced this. The earliest evidence of hearths (campfires) occur during the time of Homo erectus

The use of fire is an important milestone in human evolution, granting access to light, warmth, protection from predators and the ability to cook food - each of which aids survival.

Scientists don't know when humans were first able to make fire at will. Early humans probably captured natural fires and kept them alight for as long as they could. H. erectus may have been the earliest human to have controlled fire.

Despite these developments, their cognitive ability fell a long way short of modern humans. There is currently no evidence that Homo erectus was capable of undertaking modern behaviours such as using language or making art...though there also isn’t enough evidence to rule it out either. 

Scientists rely on circumstantial evidence when trying to determine language capabilities, including physicality, genetic information and tools and other artefacts. On the first, homo erectus had a smaller brain and spinal cord than homo sapiens, which indicates they may not have had the physical ability to undertake complex speech. Speaking requires controlled breathing, and so there needs to be a lot of interaction between the lungs and the brain via the nervous system. This means in humans we have a thicker spinal cord. Looking at the fossilised vertebrae and and skulls of homo erectus, they didn’t have the same sized nervous system, so this indicates maybe they weren’t capable of complex speech. 

With regard to DNA, there really isn’t a lot that can be said for Homo erectus specifically, because scientists haven’t found any surviving DNA. In a roundabout way, something may be able to be inferred. Given both Neanderthals and sapiens share that same genetic adaptations that allow language, I’m referring to the FOXP2 gene specifically here, it’s probably the case that this mutation was actually present in an older, common ancestor, like maybe homo erectus or homo ergaster.   

Other human developments that may give weight to the assumption of language development, don’t come about until 40,000 years ago, when modern homo sapiens were around. This includes the manufacture of highly complex tools, the production of symbolic art and the existence of widespread trade systems.

But you never know, maybe Homo Erectus was capable of language and we just haven’t discovered the evidence yet to support that. It wouldn’t be the first time that scientists have been proven wrong. Previously, it was widely accepted that Homo erectus was not able to undertake water crossings, though new evidence has come to light showing that they were present in a number of islands in south east asia where deep sea voyages would have been required across distances of tens of kilometres. 

Remains of Homo Erectus found on Flores in Indonesia have been dated to 840,000 years ago indicating these ancient people travelled far and made numerous water crossings in ancient times. 

As a bit of a tangent, on the small island of Flores homo erectus (or maybe another early human species) underwent a process of dwarfing. Humans first reached Flores when the sea level was low, and  the island was more easily accessible via a shorter voyage from mainland Indonesia. When the seas rose again, some people were trapped on the island, which was poor in resources. Over the generations, the people of Flores became dwarves, adapted to the limited resources and small size of the island. This species, Homo floresiensis, reached a maximum height of only one metre and weighed no more than twenty-five kilograms. They made and left thousands of stone tools, and hunted komodo dragons and young pygmy elephants. Homo floresiensis survived to at least 38,000 if not 18,000 years ago. 

In the Philippines, 57 stone tools have been found associated with an almost-complete disarticulated skeleton of Rhinoceros philippinensis, which shows clear signs of butchery, together with other fossil fauna remains attributed to stegodon, Philippine brown deer, freshwater turtle and monitor lizard. All finds are dated to between 777 and 631 thousand years ago. The homo erectus who made it all the way to the Philippines must have come originally from Borneo to the southwest or Taiwan to the north. 

It’s not really clear how deliberate it was that homo erectus reached these far flung islands. It could be that they were swept out to sea by a tsunami, crossing the ocean clinging to debris. Or they could have been using rudimentary watercraft like logs, or bamboo lashed together to access deep water fish as a source of food. Maybe they even had canoes or rudimentary boats. There is no evidence either way to support a theory about purpose built watercraft or boats. Like with wooden tools, any evidence would have perished many hundreds of thousands of years ago. 

Given that Homo erectus had made water crossings almost 1 million years previously it is conceivable that they also crossed to Australia - or ended up there by accident. This is what probably happened to smaller mammals like rats and mice that could have survived at sea on branches and debris. It would have been a much greater feat for a mammal as large as a human to be accidentally swept to Australia. Though it would be possible, and when you consider homo erectus were living in Indonesia for millions of years, the probability that at some point, someone could have ended up in Australia becomes more distinct. The possibility has been discussed, but as yet there is insufficient archeological evidence to support it. By that I mean, there are no fossils of homo erectus or any other hominids aside from homo sapiens in Australia. 

DNA evidence however, throws a real curveball. Recent DNA sequencing of modern day people living in New Guinea suggests that sometime between 50,000 and 15,000 years ago, they were interbreeding with a denisovan population of humans. Interbreeding between different human “species” is something that is actually quite common. If you are of Eurasian descent, about 2% of your human specific DNA is actually neanderthal. And some Eastern-European, East-Asian and Native American humans also have a small amount of Denisovan DNA as well. But then out of the blue, new research suggests that humans living in New Guinea share up to 5% of their DNA with what appears to be Denisovan humans. Now New Guinea is part of Australasia. New Guinea, mainland Australia, and Tasmania were all connected in a continent called Sahul, spelt S-A-H-U-L, also referred to as greater Australasia, during the Pleistocene when sea levels were lower and these islands were all connected. Getting to New Guinea still meant undertaking a long distance ocean voyage as it’s never been connected to South East Asia via land. Depending on the timeframe, it would have been about 8-10 sea crossings in to get there from mainland Indonesia. So if this new research is correct, and you’ve specifically got homo sapiens on New Guinea living and breeding with denisovans, then maybe this is indicating that denisovans actually made it all the way to Australasia too. Subsequent studies that looks at the genetic makeup of Melanesian people - that is people living in Vanuatu, the Solomon Islands, Fiji, Papua New Guinea, New Caledonia, West Papua, and the Maluku Islands and aboriginal australians, conclude it’s not denisovan DNA, but likely another, unknown species of humans altogether. So the plot just thickens further and it will be really interesting to see, as more scientific studies are undertaken, what more can be deduced about different human populations living in Australasia. 

I just want to finish off the story of Homo Erectus in Indonesia. Precisely when - and why - Homo erectus disappeared is unclear, but it appears to have survived in parts of Indonesia until at least 250,000 years ago. Disputed evidence of the very late survival of H. erectus on the Indonesian island of Java exists in the form of fossil braincases (the part of the skull that encloses the brain) and a few other fragments. Some methods have dated these to older than 200,000 years, others to less than 50,000 years. If this dating is correct, it suggests that they coexisted with Homo sapiens in Indonesia.

We are going to leave it there for today. Next episode is going to take a little detour away from the chronology to look at fire hawks, and that may seem a little random, but there is method in the madness, which will hopefully become apparent during that episode. In the episode after that, episode 6, we are going to cover the homo sapien discovery of Australia. 

As always, I would love to hear what you think of the podcast, so please reach out at historyofaustraliapodcast@gmail.com. Until next episode, keep safe and I’ll see you soon!

Bibliography
Blaxland, B. and Dorey, F. 2020, The first migrations out of Africa, Australian Museum, https://australian.museum/learn/science/human-evolution/the-first-migrations-out-of-africa/#:~:text=Homo%20ergaster%20(or%20African%20Homo,by%201.75%20million%20years%20ago., (Accessed 21 September 2020)

Blaxland, B. and Dorey, F. 2020, Homo ergaster, Australian Museum, https://australian.museum/learn/science/human-evolution/homo-ergaster/ (Accessed 21 September 2020)

Brumm, A. 2018, Rhino fossil rewrites the earliest human history of the Philippines, The Conversation, https://theconversation.com/rhino-fossil-rewrites-the-earliest-human-history-of-the-philippines-95879, (Accessed 18 September 2020)

Cane, S. 2013, First Footprints The Epic Story of the First Australians, Allen & Unwin Australia

D’Anastasio R, Wroe S, Tuniz C, Mancini L, Cesana DT, Dreossi D, et al. (2013) Micro-Biomechanics of the Kebara 2 Hyoid and Its Implications for Speech in Neanderthals. PLoS ONE 8(12): e82261. https://doi.org/10.1371/journal.pone.0082261

Dediu, D., Levinson, S. (2013) On the antiquity of language: the reinterpretation of neanderthal linguistic capacities and its consequences. Frontiers in Psychology 4(397), https://doi.org/10.3389/fpsyg.2013.00397   

Dorey, F. 2018, How do we know if they could speak?, Australian Museum, https://australian.museum/learn/science/human-evolution/how-do-we-know-if-they-could-speak/, (Accessed 18 September 2020)

Dorey, F. 2018, Homo erectus, Australian Museum, https://australian.museum/learn/science/human-evolution/homo-erectus/ , (Accessed 18 September 2020)

Harari, Y. N. 2015, Sapiens - A Brief History of Humankind, Vintage, London

Hendry, L. Human Evolution - Homo erectus, our ancient ancestor, Natural History Museum, https://www.nhm.ac.uk/discover/homo-erectus-our-ancient-ancestor.html, (Accessed 17 September 2020)

Hogenboom, M. 2013, Neanderthals could speak like modern humans, study suggests, BBC News, https://www.bbc.com/news/science-environment-25465102#:~:text=Neanderthals%20could%20speak%20like%20modern%20humans%2C%20study%20suggests,-By%20Melissa%20Hogenboom&text=An%20analysis%20of%20a%20Neanderthal's,just%20like%20a%20modern%20human's. (Accessed 26 September 2020)

Ingicco, T., van den Bergh, G.D., Jago-on, C. et al. Earliest known hominin activity in the Philippines by 709 thousand years ago. Nature 557, 233–237 (2018). https://doi.org/10.1038/s41586-018-0072-8

Jacobs et al. Multiple deeply divergent Denisovan ancestries in Papuans Cell, 11 April 2019, DOI: 10.1016/j.cell.2019.02.035

Kessler, S. E., Bonnell, T. R., Byrne, R. W. & Chapman, C. Selection to outsmart the germs: The evolution of disease recognition and kin selection. J. Hum. Evol. 108, 92 (2017).

Kessler, S.E., Bonnell, T.R., Setchell, J.M. et al. Social Structure Facilitated the Evolution of Care-giving as a Strategy for Disease Control in the Human Lineage. Sci Rep 8, 13997 (2018). https://doi.org/10.1038/s41598-018-31568-2

Malaspinas, A., Westaway, M., Muller, C. et al. A genomic history of Aboriginal Australia. Nature 538, 207–214 (2016). https://doi.org/10.1038/nature18299

Muffat, I. 2019, A snapshot of our mysterious ancestor Homo erectus, The conversation, https://theconversation.com/a-snapshot-of-our-mysterious-ancestor-homo-erectus-101122#:~:text=Previously%2C%20it%20was%20widely%20accepted,line%20to%20travel%20further%20east., (Accessed 18 September 2020)

Price, M. (2019) Ancient DNA puts a face on the mysterious Denisovans, extinct cousins of Neanderthals, https://www.sciencemag.org/news/2019/09/ancient-dna-puts-face-mysterious-denisovans-extinct-cousins-neanderthals  (Accessed 21 September 2020)

Pringle, H. 2010, Primitive Humans Conquered Sea, Surprising Finds Suggest, National Geographic, https://www.nationalgeographic.com/news/2010/2/100217-crete-primitive-humans-mariners-seafarers-mediterranean-sea/#:~:text=At%20present%2C%20the%20earliest%20widely,at%20least%20ten%20ocean%20straits., (Accessed 23 September 2020)

Rogers, A.R., Harris, N.S., Achenbach, A.A. Neanderthal-Denisovan ancestors interbred with a distantly related hominin. Science Advances 6(8) (2020). https://doi.org/10.1126/sciadv.aay5483

Smithsonian National Museum of Natural History, ‘What does it mean to be human?’, https://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus, (Accessed 17 September 2020)

Van Arsdale, A. P. (2013) Homo erectus - A Bigger, Smarter, Faster Hominin Lineage. Nature Education Knowledge 4(1):2

Van Den Bergh Et Al., Did Homo Erectus Reach the Island of Flores?, Indo-Pacific Prehistory Association Bulletin 14, 1996 (Chiang Mai Papers, Volume 1)

van den Bergh, G., Li, B., Brumm, A. et al. Earliest hominin occupation of Sulawesi, Indonesia. Nature 529, 208–211 (2016). https://doi.org/10.1038/nature16448

Zhu, Z., Dennell, R., Huang, W. et al. Hominin occupation of the Chinese Loess Plateau since about 2.1 million years ago. Nature 559, 608–612 (2018). https://doi.org/10.1038/s41586-018-0299-4