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Turkana Boy

Turkana Boy


Reconstructing the thorax of the Turkana Boy

Since I saw my first original hominin fossil, the Bodo skull, back in the late 1990ies at the University of Vienna, I have been attracted by the idea of “repairing” broken fossils and assembling them to improve our ideas about the morphology of our fossil ancestors. Another aspect that has always fascinated me is measuring and analysing fossils with sophisticated technology I like the moment when the unknown fossils plot in statistical spaces and when the 3D analysis reveals the details in which they differ or are similar to other, better-known fossils or structures.

Using these research methods, one can suddenly see new aspects of ancient humans emerging on the computer screen. What’s more, after 3D printing these “new fossils”, they can be investigated physically, which is highly inspiring and stimulates research ideas.

The project of thorax reconstructions in fossil hominins started some 10 years ago. Previously I had worked on cranial cavities, the cranial base of the brain, and the nasal cavity. In the context of the latter, my interest shifted to the evolution of the non-cranial part of the respiratory system, the rib cage.

Yet, it was clear that this was going to be a long and difficult research avenue. Not only because our Virtual Morphology Lab had yet to be developed, but also because fossils of the rib cage do not preserve well. However, even when ribs are complete, such as in the Nariokotome Homo erectus skeleton (also known as "Turkana Boy"), it is extremely difficult to measure them appropriately, as ribs do not really offer a lot of anatomical information. Therefore, new methods for their measurements had yet to be developed.

To do so, back in 2012 I offered a MSc thesis in geometric morphometrics of ribs to Daniel García-Martínez (that led to his PhD thesis afterwards) and since then, together, we have been measuring hundreds of 3D curve semilandmarks on hundreds of individual ribs and vertebrae from different ages and species. Our eyes turned dry and red due to the concentration when placing all these measurement points staring at the virtual 3D models of the computer screens.

We also spent considerable amounts of time on developing methods for serial missing data estimation, because some of the ribs and vertebrae of the Nariokotome Boy were missing, or incomplete. However, we did not only want to study his rib cage morphologically. We were also interested in how its adult thorax morphology might have looked like, and what this morphology might have meant functionally.

We used two different kinds of data: Computed Tomography data and surface scans of the originals. It was fun travelling to KNM Nairobi for scanning and studying the original fossils of the Nariokotome Boy and to attend the EAAPP 2019 conference, where we presented our preliminary work.

At the KNM Nairobi, studying the original remains of KNM-WT 15000, from left to right: Markus Bastir Nicole Torres-Tamayo Dani García-Martínez. Licence CC-BY-NC-ND 4.0 Copyright M Bastir

A big difficulty was to get comparative 3D data, because the rib cage is not a very frequently studied anatomical element. In addition, the rib cage is a metameric structure: it consists of many different bones that look pretty similar. Thus, we needed to analyse at 36 different bones (24 ribs, 12 vertebrae, sternum excluded) in adults and juveniles and the analysis of each of these bones required samples of just this bone that were large enough to cover at least the minimally necessary features of variation.

Individual fossils of ribs and vertebrae of the Turkana Boy (KNM-WT 15000) that were used to reconstruct its rib cage using virtual computer techniques. The bones are shown as surface models derived from computed tomography scans. Licence CC-BY-NC-ND 4.0 Copyright Fred Spoor.

We further wanted to validate our methods to know the bias we might introduce when putting together individual vertebrae to build a complete thoracic spine. So we carried out reconstruction experiments with different researchers reconstructing the rib cages independently and reapeatedly, like putting together a 3D puzzle.

This research process was accompanied buy 3D printing the pieces and glueing them together to see how it looks like.

Glueing the 3D printed ribs to the reconstructed thoracic spine in the MNCN lab. Licence CC-BY-NC-ND 4.0 Copyright M Bastir.

Moreover, we further needed reference models of modern humans that could tell us something about the functional anatomy of the rib cage and its role in the breathing function. So we participated in a bigger study of respiratory function at the La Paz University Hospital, Madrid (IdIPAZ) and below you can see some examples when producing the data. This enabled us to simulate for the first time the breathing motion in Homo erectus and to compare this motion in 3D with modern humans.

Working hard to get good CT and respiratory data, at the La Paz Madrid University Hospital. Licence CC-BY-NC-ND 4.0 Copyright M Bastir

All this work and data were accomplished by multiple collaborations with many different experts and at the end, after several years of data collection, after almost 2 PhDs, and 2 Master theses, we got our results: the first quantitatively reconstructed 3D thorax model of the Nariokotome H. erectus.

And, surprisingly, it did not seem as modern as we expected at the beginning of this project.

The shapes of the ribcages of modern humans (left), Turkana Boy (middle) and Neanderthal (right), shown in frontal view (top row) and left side view (bottom row). The ribcage of the Turkana Boy (Homo erectus) is deeper, wider and shorter than seen in modern humans, with similarities to the ribcage of Neanderthals. Licence CC-BY-NC-ND 4.0 Copyright M Bastir.


Gum disease. The Turkana Boy (Homo ergaster) lived in Africa about 1.5 million years ago. Instead, his jaw shows that he had a diseased gum where a deciduous molar – one of his baby teeth – had been shed. An infection seems to have set in and he probably died of septicaemia (blood poisoning).

It was a skeleton of a young boy, discovered at Lake Turkana in the deserts of northern Kenya. He died when he was about eight years old and his bones sank into the sediments of the lake, where they were preserved for 1.5 million years.


How was Turkana Boy dated?

Click here to know more about it. Considering this, how did Turkana boy die?

Gum disease. The Turkana Boy (Homo ergaster) lived in Africa about 1.5 million years ago. Instead, his jaw shows that he had a diseased gum where a deciduous molar &ndash one of his baby teeth &ndash had been shed. An infection seems to have set in and he probably died of septicaemia (blood poisoning).

Likewise, what does Turkana Boy represent in terms of human evolutionary history? The 'Turkana Boy' skeleton has allowed scientists to find out a lot of information about body size, body shape, and growth rates of Homo erectus. Although he had a disability which hindered his movement, his body shows long legs and narrow shoulders typical of humans who live in hot, dry climate today.

Also, what is special about the Turkana Boy?

Turkana boy, or Nariokotome boy, is the fossil KNM-WT 15000. It is a nearly complete skeleton of a hominid who died in the early Pleistocene 1.5 million years ago (mya). This specimen is the most complete early human skeleton ever found.


NYC - AMNH: Spitzer Hall of Human Origins - Turkana Boy

This nearly complete 1.6-million-year-old skeleton, found near Lake Turkana, Kenya, belonged to an eight-year-old-boy. Nicknamed "Turkana Boy," the fossil is more than five feet tall and much more fully developed than a modern eight-year-old. Yet analysis of the teeth and bones indicate the boy was still growing and probably would have reached six feet as an adult. Turkana Boy is a member of the species, Homo ergaster, the first early human with long legs, short arms and a tall stature--body proportios essentially like our own.

When this fossil was found in 1984, the only other reasonably intact ancient hominid skeleton known was Lucy. But Turkana Boy is much more complete. This fossil taught scientists a great deal about the body proportions of the species. While Lucy was quite small and probably still lived in the trees part of the time, Turkana Boy and his kind were tall and lanky--and completely at home striding out on the open savanna.

The Anne and Bernard Spitzer Hall of Human Origins pairs fossils with DNA research to present the remarkable history of human evolution. The hall covers millions of years of human history, from early ancestors who lived more than six million years ago to modern Homo sapiens, who evolved 200,000 to 150,000 years ago.


The remote lake that tells the story of humanity's birth

Our ancient human ancestors were an elusive lot. Their remains are literally thin on the ground, and even when fossils are unearthed it is rare for them to be complete. Sometimes they must be pieced together from dozens of fragments.

That is why a staggering find in 1984 excited the entire field, and continues to do so today over 30 years later.

It was a skeleton of a young boy, discovered at Lake Turkana in the deserts of northern Kenya. He died when he was about eight years old and his bones sank into the sediments of the lake, where they were preserved for 1.5 million years. He was, and is, the most complete early-human fossil ever discovered.

Yet "Turkana Boy" is just one of many early human fossils discovered near the lake. Together they span four million years of human evolution. This one spot has told us a huge amount about where we came from and how our ancestors lived.

Today Lake Turkana lies in the midst of a dry, hostile desert environment. But this was not always the case.

About two million years ago, the lake was much larger and the surrounding area was greener. Since then, rapid changes in the climate have periodically caused the lake to shrink, and occasionally it has disappeared altogether.

Before long fossils of numerous species were tumbling out of the ground

During the wetter times, it was an ideal place for early humans to live, and when they died it was a perfect place for their remains to fossilise. That's because Lake Turkana lies in a volcanic area, where tectonic activity can move Earth's crust and create new layers. It is within these layers that fossils from different time periods are found.

"Those are all great circumstances where you can have bones that get buried in the sand and that becomes sandstone," says Fred Spoor of University College London in the UK. Periods of heavy rainfall have since eroded many of these layers, exposing the fossils more clearly.

Excavations at the lake started in 1968 when Richard Leakey of the Turkana Basin Institute led a group to the eastern side, known as the Koobi Fora. It was an enormous area, but aerial views had suggested that there were lots of fossils to be found.

"My idea was to start at one end and work our way to the other end," says Leakey. The first few years were "a bit of an adventure", but before long fossils of numerous species "were tumbling out of the ground".

Humans used to be a diverse group of species, not just one as we are today

In 1972, Leakey's team uncovered the skull and some limb bones of a 1.9 million-year-old Homo rudolfensis, known as "skull 1470".

The discovery reinforced an idea that was emerging at the time: that there was not a single line of early humans, but multiple lineages. It was already known that three other species were living in Africa around the same time: H. habilis, H. erectus and Paranthropus boisei. H. rudolfensis added to this diversity.

In other words, humans used to be a diverse group of species, not just one as we are today. Later finds from Koobi Fora suggest that the three Homo species coexisted between 1.78 and 1.98 million years ago.

But it was not until the discovery of Turkana Boy, also known as Nariokotome Boy, that we began to learn about perhaps the most important of these species: H. erectus.

"Turkana Boy is one of the monumentally important fossils that radiates new questions about human evolution," says paleoanthropologist John Shea of Stony Brook University in New York, US.

For one thing, H. erectus are thought to be our direct ancestors. They were the first hominins to migrate out of Africa, spreading into Europe and Asia.

It's a step in the direction of the way we humans walk around

In some ways they were strikingly similar to us. They had significantly bigger brains than the slightly older H. habilis, and were much taller.

What's more, Turkana Boy revealed that his species walked more like us than older hominins did. He centred his weight over his pelvis as he walked, just like us. He also had arched feet and a relatively long stride.

Turkana Boy was also able to carry things in his free hands while walking.

"It's a step in the direction of the way we humans walk around, away from the way other ancestral hominins and primates moved around," says Shea.

"He would have been a good endurance runner and very good at carrying things. If you're able to run, you can chase, so what were they chasing? What were they carrying?"

Other studies offer some clues.

His family may have been carrying hunting tools like spears. The anatomy of their hands strongly suggests they could do so. Spears do not fossilise, but a 2013 study suggested that H. erectus had evolved the ability to throw.

In contrast, our closest ape relatives have very little throwing power. Our more ape-like ancestors, who spent more of their time in trees, were probably similarly bad at throwing.

This suggests that H. erectus could hunt more intensively than older species, helping them to expand out of their territory.

That would have been useful, because during Turkana Boy's time the climate was extremely variable. The forests his ancestors had thrived in began to change into more open grasslands, leaving early humans fewer places to hide from large predators.

These hominins faced a choice, says Shea: retreat to the remaining trees, or deal with these threats head-on. They seem to have chosen the latter.

They may have found some safety in numbers. Groups that live, work and hunt together are less vulnerable than lone individuals. This may have given H. erectus the drive they needed to become more social.

There is some evidence that they shared information and worked in teams.

Stone tools called Acheulean hand-axes date from this time. They have been found throughout Africa and in other parts of the world. This suggests that early humans could both make them and share the ability with others.

Hand-axes were involved in dismembering and chopping limbs apart and cutting through the flesh

The earliest known Acheulean hand-axes were discovered near Lake Turkana in 2011. They are 1.76 million years old and were probably made by H. erectus.

Once the Acheulean technology emerged, it persisted for over a million years, says Ignacio de la Torre of University College London in the UK. For good reason: the hand-axes were multi-functional tools, the Stone Age equivalent of the Swiss army knife.

For example, they would have been ideal for butchering animal carcasses. "It is a reasonable explanation that hand-axes were involved in dismembering and chopping limbs apart and cutting through the flesh," says de la Torre.

Given how long they persisted, it must have been easy to teach others how to make them.

That does not mean H. erectus had language. Shea has taught about 500 students to make similar stone tools, and they can easily teach others without talking. Still, they are harder to create than the Oldowan stone flints attributed to the smaller-brained H. habilis.

Lake Turkana has also helped reveal what was happening even earlier in human evolution, before the Homo genus arose.

In 1974, researchers in Ethiopia discovered a 3.2-million-year-old fossil Australopithecus afarensis, nicknamed "Lucy". Lucy's species was immediately hailed as a key contender for our direct ancestor.

"When Lucy was found there was very little known earlier. All the specimens were known after the age of Lucy," paleoanthropologist Meave Leakey told the Royal Society in October 2015.

"The obvious interpretation of that was that there was nothing happening before [Lucy]," Leakey added. There was a single lineage descending from apes through to Lucy, "and then out pops our immediate ancestors". To her, that did not make sense.

So Meave Leakey made it her mission to find fossils of other species from the same period as Lucy. That meant going back to Lake Turkana.

Her team found fossils on the western shore of lake that demonstrated there was "diversity at the age of Lucy".

In the 1990s, her team discovered a possible ancestor of Lucy's species, known as A. anamensis. This was the oldest species known from Lake Turkana, having lived about four million years ago.

There were now several contenders for the common ancestor

A few years later, again on the west of the lake, her team discovered another new species called Kenyanthropus platyops, or "flat-faced man". This species lived 3.5 million years ago, when other members of Lucy's species also roamed.

That meant there were now several contenders for "the common ancestor" of Homo, and largely killed off the idea that humans evolved on a single line.

Lake Turkana shows no signs of losing its status as a key source of fossils. A recent find has once again shaken up our ideas about what our ancient ancestors could do.

In the summer of 2015, researchers announced the discovery of the oldest known stone tools, dating to 3.3 million years ago. It had been assumed that only Homo species could make stone tools, but the tools were older than any known Homo fossils, suggesting that older species like A. afarensis or K. platyops could also make stone tools.

"We didn&rsquot think they were intelligent and skilled enough to be able to make the stone tools," says de la Torre.

It was a crucial discovery. There was thought to be a "substantial link between the emergence of humans (Homo) and the emergence of technology", says de la Torre, but it now seems this is not necessarily true.

When you look at all these finds together, it is abundantly clear that Lake Turkana has played a pivotal role in our understanding of human evolution. But that is not to say the area was particularly significant for the early humans themselves.

Lake Turkana was simply an ideal place for fossils to be preserved, says Spoor. "That doesn't mean human evolution doesn't happen everywhere else in Africa."

What you're seeing is Turkana connects the dots

For instance, many of our ancestors might have lived in rainforests, where the ground is too acidic for fossils to survive. "Absence of evidence does not mean evidence of absence," says Spoor.

But that does not diminish the importance of the site itself.

"To some degree, what you're seeing is Turkana connects the dots," says Shea. It allows us to see multiple species that lived millions of years apart, and compare them.

We are lucky that this one area was a geological trap, allowing us a glimpse into the lives of so many of the early humans that preceded us on Earth.

Melissa Hogenboom is BBC Earth's feature writer, she is @melissasuzanneh on twitter.


Case Study: Koobi Fora Research Project

A case study that illustrates the Koobi Fora Research Project&rsquos amazing finds in the field of paleontology.

National Geographic Explorer-in-Residence and paleontologist Meave Leakey works in the remote Lake Turkana region of Kenya and Ethiopia. She, her husband, Richard, her daughter Louise, and a team of scientists have been researching fossils in the Koobi Fora area of the Lake Turkana Basin for more than 30 years. Koobi Fora is a ridge of sedimentary rock on the eastern shore of Lake Turkana, Kenya.

The Koobi Fora Research Project (KFRP), initiated in 1968, forms the backbone of the Turkana Basin Institute (TBI). Almost 10,000 fossils have been discovered in Koobi Fora, more than 350 from ancient hominin species. The investigation of the evolution of human beings and hominin relatives is the primary&mdashalthough not the only&mdashscientific goal of the KFRP.

&ldquoThe continued research in the Turkana Basin will further the global understanding of human origins and the context in which it occurred through the recovery and investigation of new fossil material from deposits in northern Kenya,&rdquo according to the project&rsquos mission statement.

Located in northern Kenya, the Turkana Basin is a 70,000-square-kilometer (27,027-square-mile) region that is home to Lake Turkana, the most saline lake in East Africa and the largest desert lake in the world. The area includes three national parks: Sibiloi National Park, South Island National Park, and Central Island National Park.

Lake Turkana, nicknamed the &ldquoJade Sea&rdquo due to its striking color, is a major stopover for migrating waterfowl. The surrounding area is a major breeding ground for Nile crocodiles, hippopotamuses, and a range of venomous snakes.

The basin surrounding Lake Turkana is arid and receives little rainfall outside the &ldquolong rain&rdquo season of March, April, and May.

Due to the extreme climate conditions around Lake Turkana, there is a low human population in the basin. The people who live in the area are mostly small-scale farmers and pastoralists.

The Turkana Basin has become known around the world for its amazing fossil deposits. In particular, the area has a wealth of hominin fossils that have contributed greatly to our understanding of human evolution.

Even before the Koobi Fora Research Project began, the Turkana Basin was known for its fossils. A French expedition in 1902 and 1903 first discovered vertebrate fossils in the lower Omo Valley. (The Omo River flows south from Ethiopia into Lake Turkana.) During World War II, Allied troops stationed in southern Ethiopia collected fossils from the lake and its nearby hills.

But it was a 1968 investigation of Lake Turkana&mdashthen known by its colonial name, Lake Rudolf&mdashby paleontologist Richard Leakey that uncovered a cache of fossils that would lead to the start of the Koobi Fora Research Project.

Flying over the region in a helicopter, Leakey noticed unusual rock formations on the eastern side of Lake Turkana. The features were thought to be igneous rock&mdashhardened lava. To Leakey, however, the features appeared to be sedimentary rock, which is slow to accumulate and often preserves fossils. The 1968 expedition showed Leakey was right the rocks turned out to be fossil-rich sediments.

In addition to plant and animal fossils, Koobi Fora has yielded an array of hominin species: Homo habilis, Homo rudolfensis, Homo erectus, Paranthropus boisei, Paranthropus aethiopicus, Australopithecus anamensis, and Kenyanthropus platyops.

The purpose of the Koobi Fora Research Project is nothing less than to uncover how we became human.

&ldquoWe are trying to find evidence of our ancestors in order to chart the evolutionary history of our species,&rdquo says Meave Leakey, who currently runs KFRP with her daughter and fellow Explorer-in-Residence, Louise.

To fully understand how our species evolved, KFRP looks for clues to what the habitats of our ancient ancestors were like.

&ldquoWe ourselves have a very good field team who finds fossils, and we are trying to find actual fossil evidence of our ancestors,&rdquo Meave Leakey says. &ldquoBut we are also interested obviously in the other fossils&mdashthe fossils of the fauna and of all the animals that lived alongside our ancestors&mdashbecause from the evolution of these animals we can learn what may have happened during our own evolution, the evolution of our species.&rdquo

Paleontologists, anthropologists, geologists, and other scientists involved with the Koobi Fora Research Project often have conflicting ideas about how things happened in the past. Following the scientific method, the project&rsquos theories change and evolve as more research is conducted and the theories are tested by field work and new technologies.

&ldquoObviously there are many different ways of interpreting some of the evidence, and that&rsquos why we are always looking for more, because we get closer and closer to the truth with the more evidence we find,&rdquo Leakey says. &ldquoControversy is the word that is generally used when people come up with alternative theories, but that&rsquos the way science progresses. It&rsquos a normal process. People will interpret one set of evidence one way and other people another way. And then you find more evidence. And then you all come to an agreement, hopefully, in the end.&rdquo

Two discoveries associated with the Turkana Basin are examples of conflict whose resolutions are being pursued through rigorous scientific inquiry and research.

In 1984, TBI paleoanthropologists discovered &ldquoTurkana Boy,&rdquo a nearly complete 1.5 million-year-old skeleton of a hominin with proportions similar to our own. Turkana Boy is the most complete early human skeleton ever found. Despite Turkana Boy being one of the most-studied hominin fossils in history, paleoanthropologists still debate whether the specimen is Homo erectus or Homo ergaster.

Other KFRP discoveries include species, such as Kenyanthropus platyops, found nowhere else in the world. There is only one K. platyops specimen, and it remains a source of scientific conflict. Some paleontologists&mdashincluding Leakey&mdashidentify the skull as a unique genus (Kenyanthropus). Others say it is related to another branch of hominins, the australopithecines. Still others maintain it is not a unique species at all, but the deformed skull of a familiar hominin, Australopithecus afarensis.

Stakeholders

Since the Koobi Fora Research Project is attempting to understand human evolution, all of humanity could be affected by the project&rsquos findings.

Paleontologists and paleoanthropologists: Discovering and documenting the evolution of Homo sapiens sapiens, our own species, is one of the great scientific endeavors of the 20th and 21st centuries. Paleoanthropologists are continually searching for clues in the field, as well as reviewing earlier finds with new technology, to understand how H. sapiens sapiens evolved from earlier species.

The project is important because it helps us understand our shared past and may help us realize how our species should proceed into the future.

&ldquoIf you believe as I do that understanding our past is important, then our work is important,&rdquo Leakey says.

&ldquoWe have discovered an enormous number of fossil human ancestors that were unknown before,&rdquo she continues. &ldquoWe have demonstrated that the evolutionary past of humans is much like that of other animals. There were radiation and extinction events. Our part is really no different from other animals in that sense.&rdquo

Archaeologists, geologists, climatologists, and other scientists: How early hominin species interacted with the environment and other species&mdashand each other&mdashis a major focus of the KFRP. Many other projects at the Turkana Basin Institute complement the work of the KFRP in this way. Archaeologists study tools and artifacts, such as fish hooks and pottery. Geologists study how the landmass of Eastern Africa developed, and how it is rifting now. Climatologists study the varied history of the Turkana Basin, following the expanding and receding shores of the ancient lake.

Turkana Basin Region Residents: Meave Leakey notes that the Turkana Basin Institute trains the region&rsquos residents about fossil finding, fossil preparation, fossil reconstruction, and even how to curate fossil exhibits.

&ldquoWe are trying very much to involve and educate the local people,&rdquo Leakey says. &ldquoAnd we are trying also to have the local people assisted by the work that we are doing.&rdquo

Conflict Mitigation

Any conflicting ideas or theories that emerge from the work of the Koobi Fora Research Project are resolved by scientists making more discoveries and conducting more research.

&ldquoThe KFRP has discovered and recovered the majority of the fossil collections, hominin and non-hominin, that are known from the lake basin,&rdquo Leakey says. &ldquoThese are the basis of our knowledge of the fauna and of the evolution of the animals found in East Africa today. We continue to recover, as do others, new fossil discoveries and new information that enable us to test past hypotheses and make new ones. Sometimes we are wrong, but that is the way with science. Answers are built on what we know at any particular time. With new discoveries, past ideas and theories are adjusted and refined.&rdquo

For instance, paleoclimatologists and paleobotanists working with the KFRP have uncovered significant faunal turnover between 5 million and 7 million years ago. The humid jungle habitat slowly gave way to more open environments. Grasslands became more prominent. This environmental change is now posited as one of the primary reasons hominin species became bipedal, or walking upright on two legs.

Leakey cites a past controversy that the work of the KFRP helped resolve. In the mid-20th century, paleoanthropologists debated whether H. sapiens sapiens (modern humans) evolved in Africa or elsewhere.

&ldquoToday,&rdquo Leakey says, &ldquoI don&rsquot think anyone doubts that Homo sapiens evolved from Homo erectus in Africa, and there is much support for this, in particular the genetic evidence. [The debate] led to many people trying to find the evidence for the correct answer.&rdquo

Conservation

Leakey sees a distinct conservation focus in the work of the Koobi Fora Research Project. Paleontologists and other scientists studying ancient habitats appreciate that life is fragile. Climate change has impacted life in the Turkana Basin for millions of years. The area has undergone transformations from a large freshwater lake to swampy wetland to grassy savanna to arid desert. These environmental changes have helped shape the niches of new and familiar species.

&ldquoI think it is important to understand that climates have changed dramatically over time,&rdquo Leakey says. &ldquoThere have been some very major changes, and what is happening now is a major extinction event caused by humans.&rdquo

She notes that although the biggest threat to conservation comes from rising temperatures and sea levels due to the emission of carbon dioxide (CO2) into the atmosphere, it is only part of how human activity is changing the planet. There is also deforestation, overfishing, toxic waste disposal, and the use of non-biodegradable plastics.

Communication and Education

The Turkana Basin Institute (TBI) educates the scientific community, local residents, and formal and informal students of evolution about the important discoveries made by the Koobi Fora Research Project. One of the goals of the organization&rsquos community outreach programs is to &ldquofacilitate conservation and awareness on our natural heritage and environment.&rdquo

The Turkana Basin Field School, sponsored by the TBI and the State University of New York-Stony Brook, offers college students the opportunity to spend a semester in the Turkana Basin. There, they engage with research scientists, participate in field work, and take courses such as &ldquoVertebrate Paleontology of the Turkana Basin&rdquo and &ldquoPaleoanthropological Discoveries of the Turkana Basin.&rdquo

The National Geographic film Bones of Turkana also illuminates the work of KFRP, and follows the Leakey family on a recent dig site in the Turkana Basin. Broadcast on PBS, Bones of Turkana may reach an audience of millions.

The work of the KFRP is instrumental to the Prehistory Club of Kenya, run by paleontologist Dr. Fredrick Manthi. The Prehistory Club of Kenya has a mission of educating young people about Kenya&rsquos spectacular prehistoric heritage.

The work of the Koobi Fora Research Project and other paleoanthropological studies in the Turkana Basin will continue for decades to come. New fossils, new research, and new technologies will influence the understanding of human evolution.

&ldquoIs research ever finished?&rdquo Meave Leakey asks. &ldquoDoes research ever get all the conclusions? Does research ever get all the answers? No! There will be finds that make new questions and new things to look at and new ways to discover them.&rdquo


Kenya: The Oil Race Is On in the Cradle of Humanity

Turkana in Kenya’s arid north is the most important place you’ve likely never heard of.

The Turkana people live with drought that causes violent clashes with the neighbouring Pokot tribe over land grazing rights. Image by Guillaume Bonn. Kenya, 2014

A Kenyan Wildlife Service officer with apprehended fish poachers on Lake ­Turkana, Image by Guillaume Bonn. Kenya, 2014

Turkana men carry Kalashnikovs to protect grazing land for camels from Pokot raids. Image by Guillaume Bonn. Kenya, 2014

Joyce Ekunoit, right, runs a hotel in Lokichar town for Tullow Oil employees working on the rig. Image by Guillaume Bonn. Kenya, 2014

Local corruption interferes with public services such as rubbish collection, making the desert a dumping ground. Image by Guillaume Bonn. Kenya, 2014

The skeleton of Turkana Boy, above, on display in Nairobi National Museum. Getty Images.

"Turkana Boy" is one of the most complete early human skeletons ever found. A picture based on facial reconstruction makes him look like a morose Shrek, with almost no forehead, ears that sit in-line with his temples, broad cheeks and mouth. Scientists believe that every person alive today is related to Turkana Boy's community, which lived 1.6m years ago in northern Kenya at the far end of Lake Turkana, where the borders of Kenya and Ethiopia meet.

Despite being one of the world's richest archaeological treasure troves, Turkana County is the poorest in Kenya. Home to the minority Turkana tribe, its land is unproductive - a place where until now few people chose to go. Its 73,000 square kilometres of semi-desert are inhabited by just 880,000 people, according to the most recent census. But that is changing, because the same earth that nurtured human life has fostered another highly-prized commodity: that of oil.

Turkana Boy's skeleton now lives 800km south of where he once roamed the Earth, displayed behind a spot-lit, polished glass cabinet in Nairobi's National Museum.

Johnson Gitonga, an undergraduate whose holiday job is to steer visitors like me around the museum, has a plan to claim his share in Kenya's growing fortunes that will take him to Turkana's place of birth.

"In Nairobi, everything has been earmarked. There's nothing left," he says. "In Turkana, there's space for expansion and in the next ten years, it'll be one of the best counties in the country in terms of investment and development."

A few kilometres up the road from the museum is another flagship building, the shiny-glass West End Towers. At the top of its automated lift shaft lies the head office of Tullow Oil in Kenya.

This Anglo-Irish exploration company catapulted Turkana into the spotlight when the Kenya government announced Tullow had discovered oil there in 2012. Within two years, the company found an estimated 600m barrels and in January, it announced that potential for drilling more than one billion barrels.

In the interests of transparency, Tullow ­voluntarily disclosed that it has paid the Kenyan government nearly $22m last year in fees as stipulated by its production sharing agreement. The Ministry of Energy says that none of that money went directly to Turkana it stayed in Nairobi where it was included in the pot for the national budget.

In Turkana, oil is not the only thing driving change. The world's largest desert lake, Lake Turkana demarcates the county's eastern boundary. Islands made of volcanic craters erupt like giant barnacles from the water's surface. Part of a UNESCO World Heritage Site, they provide breeding grounds for one of the world's largest crocodile populations (although their numbers have been decimated in recent decades) and food for some two million flamingos who fly in each year. North of the lake, Ethiopia is building the continent's largest hydroelectric power project, including the Gilgel Gibe III dam, which many believe could, at best, shrink the lake, at worst, dry it up.

So much hope for development. So much investment. But in the scramble for resources the question is: are we ransacking one of the most historic places on earth?

When the Tibetan plateau rose-up some 50m years ago, it started sucking moisture out of East Africa, making the once rain-forested region increasingly dry. Meanwhile, a gash in the Earth's crust beneath East Africa began tearing the continent apart. This gave rise to lakes, volcanoes, a giant valley – known as The East African Rift – and highlands at its sides. Apes who did not wish to move west to stay with the shrinking forest had to adapt to new diversity in order to survive. And it was that ecological imperative that created the species we are today.

Turkana Boy, who was found in Turkana on the floor of the rift valley in 1984, is the poster child for this titanic change on earth. His 1.6 metre (5ft 3in) frame graced the front covers of magazines and was subject to countless works of non-fiction you can even buy your own exact replica for $6,000 from the National Museums of Kenya. After a three-hour drive on axle-breaking tracks, I come to a barely inhabited riverbank on the edge of Nariokotome village, five kilometres west of Lake Turkana. I am standing next to ­Turkana Boy's grave.

The only people here, an elderly couple – Ekiru and Nakwaan Ngikomosoroko – show me around. For the early part of their lives, they were Turkana Boy's unwitting custodians. They lived on top of his final resting place, keeping their goats in corrals made from thorny acacia branches. The goats' skulls litter his empty grave, tokens of the ongoing drought. The only evidence of his excavation is a small open quarry just ten metres wide.

Ekiru and Nakwaan make unlikely tour guides. They are angry. The fossil hunters who came here in 1984 robbed them, they say – but to this day they don't understand of what. Their house is a circular hut overlooking the dry bed of the Nariokotome river. On the rare occasion that rain clouds muster the strength, water flows from here into Lake Turkana, where gigantic crocodiles darken the shallows.

Pictures from the excavation, which took place over a number of seasons, show a tanned and topless 39-year old paleo-anthropologist, Richard Leakey, in safari shorts sitting head down in concentration. Today, Leakey's body is a scrapbook of the battles and triumphs of an extraordinary past – extraordinary enough to entice Angelia Jolie to direct a film, Africa, about his life. Penned by Eric Roth, the man who wrote Forrest Gump, production is expected to start next year.

By his early 20s, Leakey was already on the way to discovering Koobi Fora on the eastern shore of Lake Turkana, the richest and most varied site for early-human remains in the world. In 2005, after careers in anti-poaching and politics – and the loss of both his legs ­– Leakey founded the Turkana Basin Institute, an academic organisation that promotes new discoveries in the remote region. He now divides his time between conserving Africa's natural and cultural heritage, and hatching a plan to see Turkana and its residents benefit from their resources. One day, he hopes, Ekiru and Nakwaan's descendants will speak of their home with pride.

As Leakey and his colleagues came and went from Nariokotome village thirty years ago, excavating a large area in collaboration with the National Museums of Kenya, Ekiru and Nakwaan watched from afar. They recall their fear as "the white men and their helpers," as they saw it, wrapped their spoils with great care and drove them away. Unknown to people in Turkana, specialised "preparators" then worked feverishly behind a cloak of secrecy in Nairobi, to get Turkana Boy ready to meet the world.

The government makes money from the skeleton, selling replicas and charging fees to see it in the capital. But the couple were never offered anything for the find. So they vowed to do things differently next time and made a pact to resist all future excavation on their land.

A few months after Turkana Boy was unveiled in Nairobi, a group of tourists travelled to Nariokotome to visit his grave. They found their passage blocked by an angry young couple. "We tried to obstruct them," Ekiru recalls.

But Ekiru and Nakwaan don't technically own this land. Outside of the urban areas in Turkana, almost no pastoralists hold legal titles to land. Most of it is communal, held in trust for the community by the county government for the people of Turkana. As the race for acquisition and development ramps up, so the need for adjudication and allocation of land becomes critical, for individuals to have some say over what to do with it.

There is still no paved road to Nariokotome village, no secondary school, no water point, no phone signal. But now its inhabitants want Turkana Boy back. They are not alone. The 22-month old Turkana County government, one of 47 established after the 2013 elections according to Kenya's new constitution, is making demands on its national leaders and they believe that the fossil belongs to them. The county governor, Josphat Nanok, said in June that the county needs all of its archaeological finds back to boost local tourism. "The fossil of the Turkana Boy will make more sense when tourists see it in Turkana County," he said.

Peter Lokoel, the deputy governor, added: "For many years the Turkana story has been told by outsiders who do not understand the community and the county."

Leakey agrees. In his Nairobi office, he slides two sheets of A4 across his desk. Working with the county government, his proposal is to construct the most comprehensive museum of the history of mankind – showing what happened, where it happened – in the desert in Turkana. He plans to include the region's first planetarium, an exhibition with a lifesize Tyrannosaurus rex (traces of which were also found in Turkana), and interactive presentations that transition from early man into the modern world, presenting oil discovery, its recovery, and its uses.

Daniel Libeskind, the architect selected to lead the reconstruction at the World Trade Center site in New York, is on board to design it. So far, Leakey says a single donor has given $10m, but he refuses to be drawn on his or her identity.

After what he's calling the science park, he hopes to see schools and hospitals built to rival those in the capital – not as an oil city, but a development facilitated by oil wealth. The constitution does not currently allow the county government to borrow money, so Leakey is talking about funding the development through a non-profit organisation working in partnership with the national and county governments and the local communities, mobilising grants and concessional loans from a host of partners: private companies with stakes in the region, including oil companies, multilateral and bilateral partners, and private philanthropists.

What the Turkana need, Leakey says, is not more wells or basic primary schools, but a total reversal of the status quo, where select residents in Nairobi get the best and those in Turkana get only enough to survive. In the long run, he also wants Turkana Boy to return home so the Turkana benefit from him rather than, "simply saying 'bye-bye' to their fossils and hearing that they're in Nairobi."

Turkana County is united by one tribe, and one language, bordered by mountain ranges and the lake. Its people are used to isolation and nationhood remains a foreign concept. "We're going to Kenya," the Turkana still say of Kitale, the nearest town south of the county border.

Thirty years after Turkana Boy's remains were removed, Ekiru and Nakwaan believe their land is once more to provide fame and fortune for foreigners, but not for them. The planes started overhead a few years ago - small planes that never land and that fly unusually low. Ekiru has heard it said that there is oil beneath the ground, but he doesn't know what oil is, nor what it is used for. When I point to the plastic beads around his neck and to Nakwaan's flipflops, she squeals in disbelief: "Ei!"

Do they stand to benefit from the oil? The history of hydrocarbons in Africa is not encouraging. Research has shown that a strong democracy with transparency and accountability is necessary to avoid what's become known as "the resource curse."

Kenya already has a notoriously corrupt government. It is in the bottom quartile of Transparency International's Corruption Perceptions Index 2013. Despite a pledge by President Kenyatta to back full disclosure of petroleum agreements, they have not all been made public. (Tullow Oil is in favour of disclosure but will only do so with the government's permission.)

In Turkana, more than 80% of the population are illiterate. In the swathes of ungoverned semi-arid desert, guns are ubiquitous and armed conflict already rife.

The educated few among the Turkana are steeling themselves to take on the national government, oil explorers, neighbouring tribes, and even local government if they must, to ensure that their communities receive fair profit.

A local newspaper, The Turkana Times, was set up in 2013 with the strapline "the arid voice" to report on Turkana from Turkana for the first time. Paralegals and educated local leaders are demanding appropriate legislation and transparency. But if their voices are not heard, and their demands not satisfied – which means more employment, more contracts going to Turkana, and a solution to the insecurity on Turkana's borders where pastoralists engage in reciprocal cattle raids and fight over access to land and waterpoints – then they will be forced to use violence to achieve their goals.

Yet, despite ultimatums by Turkana leaders, and proclamations from those leaders that they are ready to be embraced by Kenya for the first time, the national government still seems keen to denigrate those living in the arid north.

Turkana's largest urban centre is not Lodwar, the county capital and it is not Lokichoggio, the 90s boomtown that was a base for humanitarians and gunrunners during the 20-year-long civil war in Sudan. Nor is it Lokichar, the oil town stealing Lokichoggio's boomtown mantle. It is Kakuma, a blisteringly hot, 6,000-acre refugee camp in the desert that houses 160,000 people, the majority from South Sudan and Somalia. If granted Kenyan citizenship, the refugees would swell Turkana's population by a fifth. Having fled their homes, they live in a haphazard, temporary city under identikit rectangular sheets of galvanised steel that have been handed out by aid groups. It's seen as a place where nothing grows.

In September 2013, Somalia-based militants al-Shabaab attacked the Westgate Mall in Nairobi, the worst terrorist attack on Kenyan soil since the bombing of the US embassy in 1998 by Islamic extremists. Following investigation of the attack, a Kenyan parliamentary committee reported that the terrorists who stormed the shopping centre killing 67 people came primarily from Kakuma refugee camp in Turkana.

The government's response included rounding up some 4,000 refugees, predominantly Somalis, who were living in the capital. Those who could paid bribes to secure their release the police netted thousands of dollars in the process. Others were kept in cages before being removed wholesale – in contravention of international law – to the refugee camps in the neglected north, the same camps that the government had declared breeding grounds for Islamic militancy. There is a real fear that the north of Kenya, with its large and vulnerable refugee population, could provide a new anchor point for militant Islam in Africa.

On 26 October 2013, thousands of angry Turkana, politicians among their ranks, stormed two of Tullow's drill sites. The protestors believed that the government and the oil company were not giving them enough benefits. Across the county, Tullow's staff were evacuated and its operations shut down for almost two weeks.

What a national government should provide and what a private company should provide is hard to assess. Tullow is considered to be one of the most responsible oil explorers in Africa. Even the campaign group Global Witness refers to it as "squeaky clean".

"We consult every single day on absolutely everything that we can," says Tullow's social performance manager, Andy Demetriou, an engaging British man who grew up in Kenya. "But it's just never enough."

Analysis by data journalist Eva Constantaras suggests that their efforts are indeed not enough. Funded by the European Journalism Centre, she analysed a leaked database of sub-contractors' employees, confirmed as genuine by Tullow Oil, showing that top management positions are held almost exclusively by foreigners, sub-contractors hire Kenyans from elsewhere and some firms hired by Tullow employ no Turkana at all.

A key problem for both the community and the oil companies is that Kenya lacks the legislation to provide operational frameworks, something that is putting off prospective investors. Kenya's long-awaited revision of the Petroleum (Exploration and Development) Act is still under review. The act is expected to increase the obligation of oil companies towards local communities, and to increase government profits. Another key piece of legislation the Turkana hope will be passed is the Community Land Bill, which expressly provides for, "the recognition, protection, management and administration of community land."

After decades of political isolation, violent conflicts with neighbouring tribes, an increasingly deleterious reliance on food-aid, and perennial drought, Turkana and its people are frazzled. But, if you look beyond the wornout land and the pastoralists' daily battles to survive, there are signs of growth.

The county got its first new tarmac road in decades this year, 2.3km of progress. For the government in Nairobi, hydrocarbons present a tremendous opportunity to reduce its reliance on foreign aid and achieve ambitious development goals set for 2030. East of the lake, a giant windfarm that will power millions of homes is catalysing another new road. If the scientists tap into a vast underground aquifer, the arid parts of Turkana may one day yield crops.

Managing expectations and entitlement will not be easy. Richard Leakey has commissioned an obelisk that will be erected at Turkana Boy's excavation site on a small area of protected land, with backing from the county government, as part of Kenya's national heritage. Simple seating will surround it, and a sign in Turkana, Kiswahili and English will explain its purpose.

It should be up by the end of the year. Tullow is improving the main road that runs close to Nariokotome, and Ekiru and Nakwaan will put up a small curio stall, to sell their handicraft.

Standing on top of the excavation site looking at where Turkana Boy once was, I relay news of the statue to the couple. Ekiru frowns. "We need good food and water to live well. After taking the fossil from us, they come and use money from that fossil to put a monument up? I'm not sure we'll be ready to accept that."

TURKANA BOY, OUR HUMAN ANCESTOR

Thirty years ago, the promise of shade and water lured Richard Leakey, then director of the National Museums of Kenya, and a team of fossil hunters to camp by the Nariokotome River while they explored west of Lake Turkana.

On a typically hot day in late July, world-renowned Kenyan fossil hunter Kamoya Kimeu was taking a stroll when he happened upon the holy grail of ­fossil-hunting: what looked like a piece of early-human skull bone lurking in the pebbly ground. The fossil hunters suspected it would turn out to be an isolated piece, but in the coming weeks and months, scepticism turned to ecstasy.

They had discovered not just one, or even a handful, but 150 fragments of early human bone, with teeth to boot. It was a miracle that Turkana Boy's skeleton survived. Our ancient ancestors didn't bury their dead, and if they were not killed by a predator, a scavenger usually got to them before sediment could preserve them. Scientists believe Turkana Boy fell into a swamp and floated face-down for a while, before being trampled by passing beasts, then embedded in mud where fossilisation took place.

He had died a sickly child aged between nine and twelve with a spinal deformity and an infection in his jaw.

Paleoanthropology has a cloak and dagger reputation: significant new fossils are often kept under wraps for years, their secrets poured over by just a select few competition b etween teams of researchers is ferocious. Researchers must accept that they can't study certain fossils because they can't access them. Sometimes, people who take the trouble to find fossils don't want to let anyone else see them, in case they steal the glory by publishing findings first. Also, governments restrict replication of fossils on the basis that it would reduce the income from foreign researchers coming to study them. Turkana Boy, however, was unveiled quite quickly, in 1985, to media and scientific acclaim.


Homo ergaster

Click to enlarge image Toggle Caption

Homo ergaster was the first of our ancestors to look more like modern humans. These people were generally tall and slender and may also have been relatively hairless. Not everyone accepts this species name, some still prefer to use the term African Homo erectus.

Background to discovery

The core group within this species lived between 1.5 and 1.9 million years ago although some classifications include additional individuals that extends their range to between about 700,000 and 2 million years ago.

Important fossil discoveries

Homo ergaster was first proposed as a new species in 1975 after scientists re-examined a fossil jaw previously identified as Homo habilis. Colin Groves and Vratislav Mazák noticed some unique features about this jaw that made it different to our other human ancestors. These same features were later recognised in a group of fossils that had initially been thought to be early forms of Homo erectus from Africa. All these fossils have now been reclassified as Homo ergaster. New fossil discoveries have since been made and this species is now represented by fossils from males and females as well as adults and juveniles.

  • ‘Turkana Boy’ KNM-WT 15000 – skeleton discovered in 1984 by Kamoya Kimeu in Nariokotome, West Turkana, Kenya. The Turkana Boy or ‘Nariokotome Boy’ as he is sometimes called, lived about 1.5 million years ago. He was about 8 to 10 years of age when he died but was already 1.6 metres tall and may have reached 1.85 metres as an adult. Almost 90% of his skeleton was recovered and has provided valuable information on this species’ body size, proportions and development. The Turkana Boy had a tall, slender body adapted for striding out across the extensive savannah plains. He also had a more human-like face with a nose that projected outwards and a larger braincase.
  • SK 847 – a partial skull discovered in 1969 in Swartkrans, South Africa by Ronald Clark. This skull was found in a cave with many fossils from another species, Paranthropus robustus. Stone tools and burned bones were also found at this site. The tool maker was probably Homo ergaster. Fire may have been used here about 1.5 million years ago by Homo ergaster, although the burned bones may have resulted from a natural fire rather than from a controlled man-made fire.
  • KNM-ER 3733 – skull discovered in 1975 by Bernard Ngeneo and Richard Leakey in Koobi Fora, East Turkana, Kenya. This is the skull of an adult female. Females had less robust features compared with males such as ‘Turkana Boy’.
  • KNM-ER 992 – a lower jaw discovered in 1971 by Bernard Ngeneo in Koobi Fora, East Turkana, Kenya. This lower jaw is the ‘type specimen’ or official representative of this species. It was first classified as Homo habilis, but was reclassified as Homo ergaster in 1975 because it showed advanced features such as a lightly built jaw and relatively small premolar and molar teeth.
  • KNM-ER 42700 - A 1.5-million-year-old skull of a young adult discovered in Ileret in Kenya in 2000 (described in 2007). The skull has a very small brain of about 691cc, the smallest for any Homo ergaster. This indicates that this species came in a variety of sizes, with males being much larger than females, which was unexpected for this species. It also shows features that had previously only been found in Asian Homo erectus, such as the ridge on the frontal and parietal skull bones. This mix of traits blurs the distinction between Asian Homo erectus and African Homo ergaster and has caused some experts to rethink whether these should be separate species.
  • BSN49/P27 – a female pelvis from Gona, Afar in Ethiopia, dated to 1.8 million years old. The size of this pelvis suggest the female was quite short at only about 130cm in height, much smaller than has been estimated for females prior to this discovery. The size and shape also indicate the female could have given birth to a young with a brain 30-50% the size of an adult’s. This suggests that the growth rate of the brain in the womb was similar to that of a modern human but slowed down in the first few years of life to a rate intermediate between modern humans and living chimpanzees.
  • Various fossils found in Eurasia at Dmanisi in the Republic of Georgia may belong to Homo ergaster. These Dmanisi fossils are significant because they currently represent the earliest evidence for the emergence of early humans from Africa into Eurasia 1.75 million years ago. Key specimens include: Skull D2700 (discovered in 2001) with a brain size of 600 cc Skull D2280 (discovered in 1999) with a brain szie of 780 cc and features similar to Homo ergaster specimens KNM-WT 15000 and KNM-ER 3733 and Skull D2282 (discovered in 1999) with a brain size of about 650 cc and features similar to KNM-WT 15000 and KNM-ER 3733.
  • Fossil footprints from Ileret, Kenya, dated to 1.5 million years ago. These are the oldest known evidence of an essentially modern human-like foot anatomy and differ from the Laetoli footprints left by australopithecines 3.6 million years ago. The size and shape suggest that they were made by Homo ergaster, which also makes them the oldest surviving footprints made by a human species.

What the name means

Homo, is a Latin word meaning ‘human’ or ‘man’. It is the same genus or group name as the one given to modern humans, which indicates the close relationship between this species and our own.

The word ergaster is based on a Greek word meaning ‘work’, so the name Homo ergaster means ‘workman’. This name was used because large stone tools were found near some of its fossils.

Distribution

Fossils of this species have been found in Africa and Eurasia. Important sites include regions around Lake Turkana and Lake Victoria, Koobi Fora, Nariokotome, Olorgesailie, Swartkrans and Dmanisi, Georgia.

Relationships with other species

Some people do not recognise Homo ergaster as a species and instead classify these fossils as Homo erectus. Those who do accept Homo ergaster consider this species to be the common ancestor of two groups of humans that took different evolutionary paths. One of these groups was Homo erectus, the other group ultimately became our own species Homo sapiens.

Some fossils including the ‘type specimen’ (a jaw known as KNM-ER 992) were formerly classified as Homo habilis.

Finds from Dmanisi in Georgia are currently attributed by most scientists to this species, although new finds led to the suggestion in 2002 that these belong in a new species, Homo georgicus. However, this is not widely accepted.

More recently, skull KNM-ER 42700, dating to 1.5 million years old and discovered in Ileret in Kenya in 2000 (but described in 2007), blurs the distinction between Asian Homo erectus and African Homo ergaster. It shows features that had previously only been found in Asian Homo erectus specimens, such as the ridge on the frontal and parietal skull bones. This mix of traits caused some experts to rethink the whether these should be separate species.

Key physical features

This species’ tall, long-legged body, with a flatter face, a projecting nose and a somewhat expanded brain was well along the evolutionary path leading to modern humans but it still possessed a number of intermediate features.

  • the body is usually considered to be tall and slender with long legs which may have been an adaptation to maximise cooling of the body in a hot, dry environment. However, a pelvis found in 2000 suggests that females at least were broad-hipped and short.
  • females grew to about 160 centimetres in height whereas males reached about 180 centimetres in height.
  • the body may have been relatively hairless as a way of improving body cooling by sweating.
  • ribcage was like that of modern humans in being barrel-shaped rather than cone-shaped as in earlier species. Along with changes to the shoulders, chest and waist, this new body shape improved the body’s balance and made it possible to run.
  • average brain size was approximately 860 cubic centimetres and made up about 1.6% of their body weight
  • had developed a more human-like shape including a higher, more domed cranium or braincase. Unlike modern humans, the cranium had a moderate post-orbital constriction (indents behind the eye sockets). This feature is linked to brain size. As our ancestors’ brains expanded, their skulls became fuller and more rounded with increasingly smaller post-orbital constrictions.
  • face projected outward but to a smaller degree than in earlier ancestors
  • distinct double-arched brow ridge lay above the eyes and a relatively distinct groove was located between the brow ridge and forehead
  • nose was human-like for the first time. It now projected outward whereas earlier species had flat noses
  • jaw was shorter and more lightly built than those of earlier species, resulting in a flatter, shorter face
  • like earlier species, the front of the lower jaw sloped backward and did not form a pointed chin like that of modern humans
  • arrangement of the teeth within the jaws was intermediate between that of apes and modern humans in that the side rows of teeth were much further apart at the back of the jaw than at the front
  • canine teeth were modern in form, being short and blunt like those of modern humans
  • premolar and molar teeth were smaller and more human-like than those of earlier species.
  • pelvis was shaped like that of a modern human and was relatively narrow compared with species such as Australopithecus afarensis.This probably allowed more efficient movement on two legs.
  • a female pelvis specimen indicates that at least some females had quite broad-hipped bodies rather than the tall narrow body suggested by the Turkana Boy skeleton. This pelvis shares some features with A.afarensis.
  • body was vertically aligned above the pelvis.
  • vertebrae from the neck region of the backbone show that the spinal cord was thinner than in modern humans. This may indicate that this species had limited speech abilities due to the lack of nerves needed for the complex control of breathing while speaking.
  • unlike earlier species, the legs were much longer than the arms, so the limb proportions were similar to those of modern humans
  • tree climbing adaptations of earlier species had been lost and had given way to a long-legged striding walk that was an efficient way to move about and made it easier to travel longer distances
  • an ability to run on two legs is suggested by a variety of limb features as well as changes to the shoulders, chest and waist that enabled the body to stay balanced during prolonged running

Lifestyle

Culture and technology

The technology of Homo ergaster became more advanced with the production of new kinds of stone tools. Other aspects of their behaviour also showed some significant changes, including the possible use of fire and increased levels of physical activity.

Tools

Large stone tools including hand axes, cleavers and picks (classified as Mode 2 technology) were manufactured. To make these tools, large stone flakes were produced and these were then shaped on two sides to produce sharp edges. This improved technology created more durable tools that maintained their sharpness longer than earlier types of tools. Microscopic examination has shown their tools were mainly used on meat, bone, animal hides and wood.

Mode 2 technology includes straight-edged cleavers, pointed picks and hand axes. These tools are often called Acheulean stone tools after St Acheul in France where similar tools were first discovered during the 1800s. These tools were suitable for heavy duty work including processing bones for marrow, butchering large mammals and woodworking. This new technology was developed by Homo ergaster in Africa and was an improvement on the very simple stone choppers (Mode 1 technology) that earlier ancestors such as Homo habilis had been using for about one million years. Later, Homo heidelbergensis continued to use this technology in Africa and they also took this technology with them when they spread into Eurasia. One of the richest Acheulean stone tool sites in Africa is Olorgesailie, Kenya. Dating shows these tools were made over 700,000 years ago and they may even be up to 900,000 years old.

Fire may have been used as long as 1.5 million years ago for cooking and warmth but whether this was a controlled use of fire is not certain. Charcoal, burnt earth, and charred bones found associated with Homo ergaster fossils may have resulted from naturally occurring fires rather than from intentionally lit and controlled fires.

Recent reports (Current Anthropology vol 52, 4, August 2011) of discoveries in Wonderwerk Cave, South Africa, suggest controlled use of fire may have been occuring by 1.7 million years ago. Stratified deposits contain burnt stones, charred-calcined bones and traces of ash that indicate repeated burning events. The discoverers conclude that the fire-makers, most likely Homo ergaster, regularly gathered around the fire to prepare and cook food and also for social reasons.

Social behaviour

None of the Homo ergaster skeletons that have been found so far were deliberately buried. There is evidence however, that they did care for living members of their group who were sick or injured, but they did not seem to be concerned with their welfare after death.

It is probable that these people lived in social groups based on family bonds. A comparison with groups of primates living today suggests that these humans were moving away from a dominant-male social structure. Their developmental rates show that they took longer to mature to adulthood than modern apes, but not as long as modern humans. This feature suggests that Homo ergaster had an extended childhood period in which to complete development to maturity.

Environment and diet

About 1.8 million years ago, the climate over most of Africa became drier and more seasonal with extensive savannahs. Homo ergaster was the first human species to take advantage of these more arid and open environments.

This species’ narrower pelvis and rib cage suggests that they had a smaller gut than earlier species such as Australopithecus afarensis. The development of a smaller gut and a bigger brain required more nourishing food and this suggests that they may have included more meat in their diets.

In the dry savannah environment, plant tubers would probably have been an important part of the diet. These tough vegetables may have been processed using their improved technology as their smaller molar teeth imply that they ate foods that required less chewing.


Stonecraft as soul craft

2.56 – 2.43 million years ago

Until recently the earliest known stone tools dated back to the Oldowan, 2.6 million years ago, although recently stone tools going back 700,000 years earlier were reported. Stone tool use may be a lot older than we thought.

We now know that tool making is not uniquely human. (For tool use in dinosaurs, check out this post, from early April.) But Oldowan tools – including choppers (below), pounders, and scrapers — go beyond anything chimpanzees, or other animals, do. Kanzi, a bonobo (pygmy chimpanzee, who was also taught to communicate with an artificial set of symbols) learned to use sharp stone flakes for cutting, but never mastered the art of striking a stone core at the proper angle to produce useful sharp flakes. Apparently australopithecines (or maybe early Homo or Kenyanthropus) had taken a step further by 2.6 million years ago (or earlier).

Early evolutionary theory developed in tandem with the Industrial Revolution and included an appreciation for the importance of manual labor. Darwin, in The Descent of Man, argued for the central role of toolmaking in human evolution, and, not surprisingly, the same point was echoed by Friedrich Engels in 1876, in his unfinished essay “The Part Played by Labor in the Transition from Ape to Man.” Engels was pushing back against the attitude in most traditional stratified societies that manual labor is low class, while symbolic labor (and/or wielding weapons) is high class.

For example the fingernails on this Chinese scholar advertised that he didn’t work with his hands.

Nowadays, a common complaint about the post-industrial economy is that so much education and employment revolves around pushing symbols around that manual labor is relatively devalued. The recent book Shopcraft as Soulcraft: An Inquiry into the Value of Work is a statement of this lament. Maybe today is a good time to celebrate the part played by labor in the transition from ape to man — by making something, or mending something.

I’m working now on a raised wooden garden planter. I’ve got the boards screwed together and stained, and I’m trying to figure out what kind of liner to use. But if food is more your thing, the next post will suggest a recipe.


Watch the video: Want to Meet Your Ancestors? National Geographic (November 2021).