We modelled how early human ancestors ran – and found they were surprisingly slow
The hyenas win and the crocodile retreats with only a leg. After having their fill, the hyenas slope off. Some funny-looking apes approach, walking upright. They have what appear to be stones with sharp edges in their hands. They hurriedly cut off some scraps of meat and start chewing at them.
Their squabbling attracts the attention of a nearby Homotherium (an extinct, scimitar-toothed big cat) who creeps up and suddenly breaks cover. Will these strange apes survive the encounter? Can they run fast enough, and far enough?
Our team's research modelled the anatomy of these early humans, Australopithecus afarensis, to find out how well they could run. Australopithecus afarensis is one of the best-known early human ancestors dating from 2.9-3.9 million years ago.
The partially complete Australopithecus afarensis skeleton Lucy, or Dinkʼinesh (Amharic: ድንቅ ነሽ, lit.'you are marvellous') is globally iconic as a representation of early bipedalism (the ability to walk on two legs). Found in the Afar Depression in north east Ethiopia, this discovery received worldwide attention when it was made in 1974. It was evidence that brain expansion evolved after human ancestors started walking on two legs, as scientists had long believed.
Some researchers have also linked Australopithecine anatomy to an, as yet unknown, knuckle-walking common ancestor of humans, gorillas and chimpanzees. This hypothesis has since been refuted.
Scientists now believe that knuckle-walking probably evolved several times in apes, as the style of walking and internal architecture of ape hands and elbows are subtly different from each other. Researchers also think that the anatomy we see in hominins reflects an adaptation for upright movement in trees in a distant ancestor.
Early bipeds, such as Ardipithecus kadabba which looked a bit like a gorilla, lived in Africa between 5.8 and 5.2 million years ago. They lived in mosaic habits (a mixture of open and wooded landscapes) so some adaptation to moving in trees would make sense.
Until recently, scientists thought that only animals of the genus Homo, which emerged around 2 million years ago, made stone tools. The discovery of cut-marked bones in Dikika, Ethiopia (in 2009) dated at 3.4 million years, and in 2011 of stone tools at Lomekwi, Kenya from 3.3 million years ago, changed scientists' ideas of how much access Australopithecus had to meat.
The debate is now more a matter of whether Australopithecus regularly killed animals themselves, or if they were eating from carcasses after other predators (secondary access).
For primary access and regular kills, they needed to be able to do two things. Run fast (bursts of speed to outpace an unaware animal), and run for long amounts of time (to wear down a prey animal).
This is the endurance running hypothesis. The emergence of this behaviour is thought to coincide with more modern anatomy, such as seen in Homo erectus, who lived from around 2 million years ago to around 1 million years ago. The best way to test if Australopithecus was capable of endurance running at what we consider 'modern' speeds is to reconstruct the skeleton of Australopithecus afarensis and simulate how they may have moved.
To try and answer this question, my team reconstructed the complete skeleton of Lucy, using 3D modelling. Where parts were missing, we estimated these using scaled versions of other Australopithecus skeletons. Since Lucy is a shared ancestor for chimpanzees as well, we also morphed Australopith and modern human and chimpanzee skeletal material, using an analytical technique called geometric morphometrics.
We then started putting muscles onto the bones of the pelvis and lower limbs of Australopithecus and a modern human model, using the open source software Gaitsym. Muscles and other soft tissues are not preserved in fossils so we varied the muscle properties from chimpanzee-like to human-like, producing a range of estimates for running speed and economy.
We also ran multiple simulations where we added and removed a long Achilles tendon, which chimpanzees don't have, as it is thought to affect running speed and energy use by enhancing recovery.
This was a team effort, with reconstructions across multiple labs. The simulations were run on the high performance computing facilities at the University of Liverpool.
These simulations revealed that Lucy wasn't as good at running as modern humans. The top speed our simulations could produce was 11mph, with a minimum of about 3.35mph. Elite sprinters, however, can reach peak speeds of more than 20mph. Even non-elite sprinters can reach around 17.6mph.
We also found that the metabolic cost of transport (how much energy it takes to move) was between 1.7 and 2.9 times higher in Lucy than in a modern human. The more 'ape like' you make the muscle architecture and the shorter you make the Achilles tendon, the higher this cost is.
It appears that modern human limb proportions, combined with key changes in architecture of the calf muscle (such as relatively short fibres and large cross sectional areas), plus a long Achilles tendon, enabled much faster running in the genus Homo.
This means that it was probably not physiologically possible for Australopithecus afarensis to engage in persistence hunting, unlike later species of the genus Homo species.
Going back to our story at the start, it is likely the Australopithecines in this group wouldn't have escaped the big cat. They simply couldn't run fast enough, or for long enough.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Tom O'Mahoney does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
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The continent of Africa is recognized as the place where humankind originated and evolved over millennia. From famous ancestors like Lucy, the Australopithecus afarensis remains unearthed in Ethiopia in 1974, to the Turkana Boy, a Homo erectus fossil found in Kenya in 1984, archaeological evidence has shown time and again that Africa is the ultimate homeland of not just early hominins, but also modern Homo sapiens, who arose about 300,000 years ago and departed in successive waves to populate much of Earth. Of course, the story of humans in Africa doesn't end with their migration away from the mother continent. After all, many stayed put. But there's a big information gap. Although researchers have plumbed much of humankind's deep past, far less is known about what was happening across much of Africa at the time when permanent settlements were emerging elsewhere starting some 6,000 years ago: in places like Mesopotamia, for example, and later in China and India, as well as Egypt in Africa's northeastern tip. In part, that's because African individuals did not cram together as closely as they did in more well-known cradles of civilization. So it's less likely that modern archaeologists will discover major towns or cities. Another factor is the slave trade that slashed a 400-year wound through African history and led many communities to be abandoned. Longstanding biases about the continent, too, have left the full story of Africa's cultures, trade and urbanism out of many history lessons. That's starting to change. Recent advances in East African archaeology reveal advanced civilizations that established international trade relationships and developed powerful and practical technologies during the most recent 11,700 years — the Holocene Epoch — as Chapurukha M. Kusimba, an archaeologist at the University of South Florida in Tampa, describes in the 2024 Annual Review of Anthropology. Kusimba, who grew up in Kenya and has regularly returned there for research, says East African archaeology is evolving as more Africans and women join the field. Knowable Magazine spoke with Kusimba about African civilization and the practice of archaeology there today, as well as threats new and old that the research must contend with — from ongoing demolition of ancient sites to make way for growing populations to recent funding cuts by US institutions that long supported such studies. This conversation has been edited for length and clarity. I'd like to start with a question you raised in your review: Whose past is East African archaeology about? East Africa is homeland to all of us. I've sometimes joked with Kenyan politicians that any human being entering Kenya should not have to present a passport, because they're actually coming home. I think when many of us think about East Africa, we think about the seminal work of anthropologists Louis and Mary Leakey on human origins, and the discovery of the hominin Lucy. But what do we know about the rise of civilization among modern humans, , in Africa? The human origins question has been settled, but we know precious little about the emergence of civilization in Africa. Most Holocene archaeologists define civilization, in part, in terms of settling down in one place, which happened elsewhere starting around 6,000 years ago. But I think in Africa, that model creates a major problem because Africa is so huge, and population numbers remained low, so it was very difficult to have a critical mass of people to congregate together. So you can't find many places in Africa that you can compare with, for example, the Near East. That doesn't necessarily mean settlements didn't exist. But the jury's still out, because we don't have the kind of intensified site research that's been carried out in other places. And it's very difficult to conduct surveys, say, under the dunes of the Sahara Desert. That desert would have been much more habitable during the humid 'Green Savannah' period 14,500 to 5,000 years ago, but it's just impossible to find sites under those massive sand dunes. We do know of some sites. For example, people were settling together as early as 3000 BCE in the site of Kadero along the Nile. There is evidence of houses, stone tools, pottery and jewelry, as well as bones of people and domesticated animals. Still, Africanists can't compete with Mesopotamia, with Egypt, with Mesoamerica. The result is that when you pull out any book that teaches civilization, there is only a very small section devoted to sub-Saharan civilizations. So what was going on in Africa as Mesopotamia and other regions were tending farms and building cities? The African communities appear to have been mobile much longer. We think this is true because there are few sites of long-term settlement. The sites that are well preserved tend to be rock-shelter sites that were probably temporarily inhabited. Nonetheless, these people were highly advanced; they ate well and lived healthy lives. For example, the Sangoan peoples of eastern and central Africa had advanced stone tool technologies and bone fishhooks. As early as 900 BCE, people in modern Uganda developed techniques to produce high-carbon steel. There is often a tendency to think of the European Stone Age as the first, the original, the most sophisticated phase of stone working. But you have stone tool technologies in modern-day Ethiopia and Kenya starting 2.8 to 3 million years ago, earlier than it began in Europe. Of course, the European Paleolithic tools were incredibly sophisticated, but the core stone was relatively easy to work; in contrast, African stone is much harder to work than European stone. If you give any modern flintknapper African rock, they immediately recognize how difficult it is. But Africans were using these very tough materials to make extremely sophisticated tools. And what happened when Africans finally started to settle down? In most cases, permanent settlements appear in Africa 3,000 or 4,000 years after they did in places like the Near East. About 8,000 years ago, we begin to see more extensive evidence of settled life in modern-day western Kenya, eastern Uganda and the African Great Lakes region — and I think climate change might have been a reason behind that societal change. Suddenly, around 7,000 to 8,000 years ago you have a dry spell that lasts for about 700 years, and that's when you see the introduction of pastured livestock. So Africans did get there eventually, but we don't see the real emergence of highly complex chiefdoms and societies, with more division of wealth, in much of Africa until about 2,500 years ago. That division of wealth is apparent in differences between households. Some have exotic items from distant places and most others didn't. Just like today, there are things that only elites can acquire. Most likely, they were gifts, given to grease the wheels of business for trade of desirable items. For example, the port town of Mtwapa, near modern-day Mombasa, Kenya, was inhabited from about 1100 to 1750 CE. Wealthy inhabitants possessed multiroom homes with coral door frames and roof tiles, indoor plumbing and wells; poorer denizens lived in single-room homes of mud and wood, with grass or coconut thatch roofs. Wealthy citizens also reserved the right to the most sacred burial places, near a key religious site. From about 2,000 years ago, there were towns all over sub-Saharan Africa, including inland and along the coasts. But many African settlements were smaller in size compared to similar communities elsewhere. For example, the medieval site of Gedi, in modern-day Kenya, was massive by African standards, but at about 48 acres of built-up areas, it was much smaller than contemporary sites in India, China or the Near East. But we believe these sites were built and inhabited by Africans, not immigrants from other civilizations, because 96 percent of artifacts such as pottery, metals and beads found in those cities are of local origin. A perfect example of an advanced community, located inland, would be the region of Great Zimbabwe, which was inhabited from about the 11th to 15th centuries CE. It covered about 50,000 square kilometers, including early village settlements and a stone city built later. Great Zimbabwe is an amazing place, but the residential quarters were built out of mud, stone and thatch so they didn't preserve well archaeologically. How did these societies interact with the rest of the world? My work and the work of others shows that before the African slave trade, which reached the continent's interior with slave caravans starting in the 17th century, Africans were trading with other cultures. We've found glass and carnelian beads of Indian origin in every archaeology site in sub-Saharan Africa. Chinese and Indian historians also describe the presence of African mariners in their own towns, so the trade was bidirectional: Africans traded ivory and gold for products such as Chinese porcelain and Indian cloth. Crops were also exchanged. For example, sorghum is a traditional African crop. It's hard to date its origins, but it was being cultivated in Africa from at least the fourth millennium BCE. And it arrives in places like India later. Meanwhile, the banana, first domesticated in southeast Asia, arrived in central Africa more than a thousand years ago. And Africans were trading as equals. Here's one reason I think so: From at least 800 CE, there is clear evidence that people were engaging in the ivory trade, but they traded in mostly cut ivory. This allowed them to weigh it, grade it, and assign value consistent with quality. Cut ivory was also easier to transport from inland to trade partners on the coast. Before the slave trade Africans financed and were in charge of the ivory and other industries. Later, around the 1500s when smaller-scale slave trading began in some regions, that evidence disappears and you begin to see transportation and sale of whole, unprocessed ivory tusks. Similarly, around that time, the evidence of industries such as iron smelting and weaving disappears. The emergence of slavery led to loss of control of their own industries. Work is outsourced, and materials such as cloth are imported. So as people lose skills and become more dependent on external trade, you begin to see a real decline in the political economy of these places. How else did the slave trade impact African civilizations? The 400 years of slavery had a huge, huge effect on this continent. Africans were being invaded both from the Islamic world and, of course, the Western world. Up to that point, communities had settled in comfortable places, such as plains and valleys. There are numerous abandoned settlements with single-household villages, but also remnants of crops such as mangoes, oranges and rice in what is now the Tsavo National Park. These communities provided food to more urban cities along the coasts. But then, suddenly, they all disappeared. From around the 1450s up to the time of the colonial period beginning in the 1870s, we have found little evidence of new, permanent buildings in the interior of Africa — why is nothing being constructed there? In Tsavo, for example, people migrated to uninhabitable but defensible lands, such as hillsides and mountains, for safety. They could not go back to the plains because they were not safe. As these events were happening inland, we also begin to see the abandonment of the coastal towns. They lost their inland food supply. Prior to the slave trade, there were 250 thriving towns in Kenya and Somalia alone. By the time the 400 years of slavery are over, there were, perhaps, less than 10 of those towns still being sustainably inhabited. Slavery and the slave trade led to a loss of knowledge, of power, of memory. This violent gap that history created would open Africa for others to exploit while also conveniently blaming Africans for not being innovative, for not having industries, for not contributing much to global history, even though they did have advanced societies and technologies. Yet despite this, I think we must credit Africans for their resilience. Despite the genocide that they experienced, they're still standing. How has East African archaeology changed over your career? I'm now in my 60s. In my time, there were a handful of African-born archaeologists, probably fewer than five. But today the number of African-born archaeologists, most of whom are our students, has grown. It's rare to see a major paper on East Africa that does not include African authors — though, unfortunately perhaps, the names of those in leadership positions, such as museum directors and department chairs, are often on these publications, which creates the impression that young scientists who do most of the research are not being fully acknowledged. On the other hand, in Europe and the United States, there has been a huge increase in the number of women archaeologists. Obviously, during the colonial period, most of the archaeologists were men, and perhaps they were not much interested in questions of gender dynamics in prehistoric societies. Today most active North American archaeologists working in East Africa are women. This presents a lot of opportunities: For the first time, we have a moment in which women can have a real footprint in the kinds of topics they want to pursue — for example, what role did prehistoric African women play in shaping these societies? But there are also challenges for these scholars, because there are parts of East Africa and elsewhere where it might be much harder for women leading an expedition to get the kind of respect they richly deserve and have earned. What would you like to see archaeologists in East Africa pursue in the future? We are in the news all the time with major discoveries — but most of the time, it's new information about large sites that are already well known, and that have been studied since the colonial period. A lot of studies are being done on museum collections in Europe and North America, too. Many of these artifacts were collected during the colonial period and are often criticized today because some of them were looted from their original locations, and many people think these artifacts should be returned to their original countries. We are not seeing surveys and descriptions of new sites, and that concerns me. I think that East African archaeology is very much tied to global climate change, and this is something that is really important to us today. If you look at the history of people living in East Africa for 4 million years: What did they do to survive? How did they cope with climate change? We could learn a lot from that research. Many sites that have been all but forgotten, but deserve attention, are Homo erectus sites. Homo erectus is, anatomically, our direct ancestor. They lived from about 1.9 million to 110,000 years ago. Homo erectus is credited with learning to manage fire, which may have enabled their kind to leave Africa and inhabit other parts of the world. We've seen so many advances in biochemistry and in the study of ancient DNA, and I hope these techniques could be applied to Homo erectus sites to reveal more than we know now. But their rapid destruction in Kenya is alarming. What other sites have been lost, or are at risk? The Leakeys did a great job in sensitizing East Africans to their long past and their responsibility to care for that history. You can go to any part of Tanzania, Kenya or Ethiopia and find people who are proud of that past, who welcome archaeologists to do all kinds of research. But we are also dealing with population growth. When I was young, Kenya's population was about 8 million, then 15 million, and now it is more than 55 million. There's been similar population explosions in Tanzania, in Uganda, in Rwanda, in Burundi, in Ethiopia. And these people must live somewhere. As in the past many people have migrated. And they move into new areas where they are less emotionally engaged in local histories; they destroy archaeological sites that hold the histories and sacred knowledge of earlier residents. So we have lost a lot of urban sites along the east coast of Africa. I think we archaeologists need to communicate their importance better, and these nations need to manage the heritage sites better. If we can conserve some of these sites, we can make our case for their future study. If we don't, we will fail future generations of young men and women who want to be archaeologists. Stay in the KnowSign up for the Knowable Magazine newsletter today Will East African archaeology be able to continue in the face of such threats, including the loss of those sites and funding woes? Most African governments, with the exception of South Africa and Egypt, do not have dedicated funds for this kind of research. The bulk of funding for archaeology has always come from the United States and Europe. For example, the US National Science Foundation has been one of the engines that funded a lot of archaeology research around the world, but US funding of research has been slashed recently. I think that those moments of change are very important, not only for people in East Africa, but for the rest of us. These funding cuts are very tragic, but this research is very important, and despite threats to supporting research on our origins, I remain optimistic that we'll find a way to continue research of the deep history of humankind in East Africa. This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter. Solve the daily Crossword
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