2.4 Million Year Old Stone Tools Found in North Africa

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Archaeological excavation at Ain Boucherit, Algeria. Photo by Mathieu Duval.

Mathieu Duval, Griffith University and Mohamed Sahnouni, Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)

When did early humans first arrive in the Mediterranean? New archaeological evidence published December 14 in the journal Science and funded in part by The Leakey Foundation indicates their presence in North Africa at least 2.4 million years ago.

This is about 600,000 years earlier than previously thought.

The results, from the Ain Boucherit site in northeastern Algeria, provide new information on a time window involving the earliest representative of the Homo genus.

These discoveries are the result of excavations and intensive investigations performed under the umbrella of the Ain Hanech project since 1992.

Location of Ain Boucherit and other prehistoric sites mentioned in the text. Right: Zoom in on the vicinity of El Eulma city. Maps from Google map

Located north of El Eulma city, the area was previously well known for providing stone tools and cut-marked bones dated to about 1.8 million years ago (Ain Hanech and El Kherba sites, see map above), which have been until now the oldest occurrences in North Africa.

In 2006 and 2009, new artifacts were found at Ain Boucherit, a few hundred meters from the other sites. They were distributed in two layers below the previous archaeological findings, suggesting an even older human presence in the area.

The new archaeological finds

Excavations of the lower (known as AB-Lw) and upper (AB-Up) archaeological levels yielded more than 250 stone tools and almost 600 fossil remains.

A wide range of animals was identified, including elephants, horses, rhinos, hippos, wild antelopes, pigs, hyenas, and crocodiles. These animals currently occupy a relatively open savanna type habitat with permanent water nearby, suggesting similar conditions in the past.

The stone tool find includes mostly chopping tools and sharp-edged cutting tools used for processing animal carcasses. Those tools are made of limestone and flint that were most likely collected nearby from ancient stream beds.

They are typical of the Oldowan stone tool technology known from East African sites and dated to between 2.6 million and 1.9 million years ago. But the Ain Boucherit find also shows some subtle variations, in particular with the presence of very peculiar tools of a spheroidal shape whose function remains unknown.

Two examples of stone tools from Ain Boucherit. An Oldowan core from which sharp-edged cutting flakes were removed (left). Sharp-edged cutting flake that may be used for butchery activities on the bones (right). Photos by Mohamed Sahnouni.

Some of the fossil bones show very specific marks that could not be of natural origin, but rather the result of intentional activity.

Two types were identified. The first were cutmarks made from sharp-edged flakes, suggesting skinning, evisceration and defleshing activities (pictured below). The second include percussion marks made from a hammerstone, suggesting marrow extractions.

These show the use by early hominins of meat and marrow from animals. This is consistent with other studies from broadly contemporaneous East African sites.

A small bovid bone with stone tool cutmarks. Photo by Isabel Caceres

Dating the site was quite challenging, but the relative positions of AB-Up (within Olduvai event) and AB-Lw (a few meters below Olduvai) allowed us to derive an age of about 1.9 million and 2.4 million years ago, respectively.

The significance of the discovery

This new discovery modifies our understanding of the timing and diffusion of the Oldowan stone tool technology throughout Africa and outside the continent.

By pushing back by about 600,000 years the earliest occurrence of Oldowan tools in North Africa, the age difference with the oldest East African evidence suddenly becomes relatively small.

This indicates at least a somewhat rapid (or, more rapid than previously thought) expansion of this technology from East Africa, although a multiple origin scenario of stone tool manufacture in both East and North Africa might even be possible.

As a consequence, the first settlements of the southern margin of the Mediterranean area now appear to be much older than their northern counterparts.

The oldest evidence from southern Europe does not exceed about 1.4 million years ago (Atapuerca and Orce sites, in Spain), while the hominin fossils found at Dmanisi in Georgia, at the gates of Europe, are dated to 1.8 million years ago.

Who made these tools?

Since no hominin fossils were found at Ain Boucherit, we can only speculate about the possible makers of these Oldowan stone tools.

The hominin fossil record in North Africa is extremely poor, and there is currently no fossil reported in the age range of Ain Boucherit.

The oldest fossils found in Algeria are dated to about 700,000 years ago. They were found at Tighennif (formerly known as Ternifine, see map above). If their attribution has changed over time (initially Atlanthropus mauritanicus and nowadays Homo erectus or early Homo heidelbergensis depending on the authors), these fossils are too young compared with the Ain Boucherit discoveries to support any kind of connection between the sites.

All the early hominin fossil remains found in the Mediterranean area in association with Oldowan stone tools are significantly younger than Ain Boucherit, by at least 1 million years. The oldest Western European evidence such as the partial mandible found at Atapuerca Sima del Elefante, Spain, and the isolated deciduous tooth from Barranco León, southern Spain, are dated to about 1.2 million and 1.4 million years ago, respectively.

Consequently, the best candidates are most likely to be found in East Africa, despite their geographical distance from North Africa. Several hominins are broadly contemporaneous with Ain Boucherit (a good overview may be found here), including australopithecines and different members of the genus Homo such as Homo habilis, Homo rudolfensis or the undefined early Homo from Ledi-Geraru, Ethiopia.

That said, we cannot rule out the possibility that the stone tools at Ain Boucherit come from another hominin species, belonging or not to the genus Homo, that has not been found yet.

We hope our future excavation at Ain Boucherit will give us the opportunity to identify these stone toolmakers.

Mathieu Duval, ARC Future Fellow, Griffith University and Mohamed Sahnouni, Archéologue et professeur au National Center for Research on Human Evolution (CENIEH), Burgos., Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)

This research was funded in part by The Leakey Foundation.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Grantee Spotlight: Elizabeth Mallott

Elizabeth Mallott is a postdoctoral fellow at Northwestern University. She was awarded a Leakey Foundation Research Grant during our fall 2017 cycle for her project “Response of primate gut microbiome function to increased faunivory.”

Elizabeth Mallott in the lab at Northwestern University.

The gut microbiome – all of the microorganisms living inside an animal’s digestive tract – plays an important role in supporting primate nutrition. The foods that primates eat contain complex molecules, like cellulose, that primates are not able to digest on their own. Luckily, the bacteria in primate guts are able to break down these molecules and turn them into short-chain fatty acids, which are energy sources that primates can access. This relationship is influenced by what foods primates eat, unsurprisingly, and different foods are broken down into different kinds of short-chain fatty acids.

Research to date suggests that low fiber, high fat, high protein diets might shift the gut microbiome away from producing short-chain fatty acids used to power the intestines and towards short chain fatty acids used to fuel more peripheral body tissues, including the brain. Thus, as primates incorporate more animal prey into their diet, their gut microbes might be producing more sources of energy for their brains. However, we do not have the comparative data yet to test this hypothesis.

Woolly monkeys at the Tiputini Biodiversity Station in Yasuní, Ecuador. Photo: Evelyn Pain

My project asks how animal prey consumption has shaped the gut microbiome of primates. I am examining the gut microbial communities of six species of primates at Tiputini Biodiversity Station in Ecuador.

In addition to examining what bacteria are present in the gut microbiome of these species, I will be using metabolomics – a method to identify all of the small molecules present in a sample – to see if there are differences in which short chain fatty acids are being produced. I hope to learn if a more faunivorous diets results in a gut microbiome that both contains different bacterial taxa and is more efficient at producing short-chain fatty acids used by peripheral tissues. Understanding how a shift to a diet that focuses on animal prey influences commensal relationships between nonhuman primates and their gut microbiome will allow us to generate novel hypotheses about how the gut microbiome is helping humans support the energetic requirements of their longer life spans, faster interbirth intervals, and relatively large brains.

Elizabeth Mallott in the field in Costa Rica.

What Teeth Can Tell Us About Ancient Humans and Neanderthals

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Fossilized tooth crowns hold lots of information about past climates and life events. Tanya M Smith, author provided

Tanya M. Smith, Griffith University

Increasing variation in the climate has been implicated as a possible factor in the evolution of our species (Homo sapiens) 300,000 years ago, as well as the more recent demise of our enigmatic evolutionary cousins, the Neanderthals.

But knowing the impact of that change on a year-by-year basis has always been a challenge.

Most prehistoric climate models are derived from large-scale records such as deep-sea cores or terrestrial sediment layers. These methods yield information on the scale of thousands of years, making it impossible to understand how seasonal climate patterns directly impacted ancient humans and their evolutionary kin.

My colleagues and I have found a solution using clues from our own mouths, as we detail in an article in Science Advances. We used teeth to reveal climate records formed during the development of ancient hominins.

In the teeth

Teeth are a really useful indicator of past environments.

This is possible because teeth have biological rhythms and key events get locked inside them. These faithful internal clocks run night and day, year after year, and include daily growth lines and a marked line formed at birth.

Histologists like me carefully saw teeth, remove tiny slices and painstakingly map records of microscopic growth during childhood.

For this new study, we examined the enamel in fossilized teeth from two Neanderthal children (dated to 250,000 years ago) and one modern human child (dated to 5,000 years ago) from an archaeological site in southeastern France known as Payre.

Using the sensitive high-resolution ion microprobe (SHRIMP) at the Australian National University we measured how the oxygen isotope ratios varied on a weekly basis in these ancient teeth.

Our approach is based on the fact that two naturally-occurring atomic variants of oxygen vary in predictable ways.

During prolonged periods of warm weather, surface water is higher in the heavy variant of oxygen. The opposite pattern occurs during cool periods.

When individuals drink from streams or pools of water, values from these sources are recorded in the hard mineral component of forming teeth.

The SHRIMP measurements allowed us to create multiyear paleoenvironmental records from the fossil teeth.

What the teeth reveal

The oxygen records show that the two Neanderthals inhabited cooler and more seasonal periods than the modern human who grew up in the same place more recently.

This is consistent with our basic understanding of ancient climates in France, as 250,000 years ago this region was cooler than it has been over the past 10,000 years, when the unlucky modern human child lived and died.

A 250,000-year-old Neanderthal tooth yields an unprecedented record of the seasons of birth (age 0), nursing (yellow box), illness (red line) and lead exposures (blue lines) over the first 2.8 years of this child’s life. Oxygen isotope values sampled on a weekly basis are shown as a ratio of heavy to light variants.

We’ve already shown that teeth preserve faithful records of milk intake during nursing, proving that orangutan mums are lactation champs – they nurse their infants for eight or more years.

In the current study we were able to pair seasonal cycles during tooth formation with nursing behavior, showing that one Neanderthal child was born in the spring and stopped consuming its mother’s milk 2.5 years later, during the autumn.

Even more surprising is the fact that both Neanderthal children were exposed to lead at least twice during cooler times of the year, likely through consumption of contaminated food and/or water.

First molar tooth from a 250,000-year-old Neanderthal child. Yellow dotted lines indicate the beginning and end of nursing, a red dotted line corresponds to an illness, and blue dotted lines indicate lead exposures.
Tanya Smith and Daniel Green

Lead occurs naturally in several historic mines in this region of France, and this is the oldest known prehistoric exposure to this neurotoxic substance. No level is considered safe for humans or animals, and these exposures occurred during a critical time in the early lives of these Neanderthals.

More teeth needed

These findings raise intriguing questions about Neanderthal behavior that require further study, and youngsters with unworn teeth are especially helpful. Although dozens of young Neanderthals have been unearthed, coaxing teeth from the curators of collections for this kind of semi-destructive study is a tall order.

But the more teeth we are able to examine in such detail, the more information we will gather about the lives of ancient people on a year-by-year basis.

Our approach will also facilitate much-needed tests of theories about the impact of climate change on human technological development, and insight into Neanderthal nursing behavior — a key determinant of population growth and life history.

Previously, my colleagues and I discovered that an eight-year-old Belgian Neanderthal was weaned at 1.2 years of age. This probably was atypical as the nursing signal dropped off rapidly and the individual showed stress in its first molar at this exact time.

We’re not sure if this means that it was separated from its mother or just really sick – but it’s likely that Neanderthals kids nursed for longer when they could.

Our new approach allows scientists to flesh out the lives of ancient children with unprecedented detail, including fine-scaled views of life in Ice Age Europe, through the remarkable tales their teeth tell.The Conversation

Tanya M. Smith, Associate Professor in the Australian Research Centre for Human Evolution, Griffith University

Tanya M. Smith is a Leakey Foundation grantee.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Leakey Foundation Baldwin Fellow Sharmi Sen studies geladas in the Simien Mountains National Park, Ethiopia.

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Baboons and the Link Between Social Status and Health

DURHAM, N.C. — A growing body of evidence shows that those at the bottom of the socioeconomic ladder are more likely to die prematurely than those at the top. The pattern isn’t unique to humans – across many social animals, the lower an individual’s social status, the worse its health.

Baboon in Amboseli, Kenya. Photo by Amanda Lea

That’s probably proof that these gaps aren’t fully explained by risk factors commonly attributed to humans, such as smoking, drinking or access to medical care, says Leakey Foundation grantee Jenny Tung, associate professor of evolutionary anthropology at Duke University.

What’s trickier to determine is what causes what: Does the stress of low status make you sick? Or is it the other way around: does being sickly make it harder to get ahead and stay there?

New research by Tung,  Amanda Lea (also a Leakey Foundation grantee) and colleagues suggests the answer depends, in part, on how the pecking order comes to be. The findings come from a study of 61 wild baboons in Kenya, where females ‘inherit’ their status, but males must fight their way to the top.

Having a high-ranking mom practically guarantees success later in life for baboon females, whereas males have to rely on their size, strength and battle skills to jockey for position and earn their place.

A study in wild baboons suggests the link between status and health depends on whether an individual has to fight for status, like these males, or it’s given to them. Photo by Elizabeth Archie, University of Notre Dame.

In a paper published December 11 in Proceedings of the National Academy of Sciences, the researchers found strong links between status and how genes turn on and off in baboon males, but not females.

To be sure, status is linked to health and quality of life in both sexes: High-ranking females enjoy better access to resources like food and grooming than their low-ranking counterparts. And males who rise to the top and stay there generally have better mating success than those that don’t.

But when the researchers analyzed the animals’ immune cells for differences in gene activity, they identified more than 2,200 genes whose activity varied with status in males, but only 25 status-linked genes in females.

Genes related to inflammation were more active in high- than low-ranking males. But previous research in humans and macaque monkeys found the opposite pattern in females, whose status isn’t determined by fighting ability.

The best explanation, Lea said, is that the molecular signature of social status may depend in part on gender, but also on what it takes to climb the social ladder — family connections in the case of females, but strength in the case of males.

The research suggests that differences in immune gene expression may arise before male rank is established, and that a male’s eventual place in the hierarchy is a consequence of variation in gene expression, not a cause.

Males with more active immune genes may have an edge as they fight their way to the top, said Lea, currently a postdoctoral fellow at Princeton and the study’s first author. The results are consistent with previous studies of Amboseli baboons showing that high-ranking males recover more quickly from illness and injury than other males.

For females, it may be that factors other than rank and status are more important for immune function, the authors say. It’s not that low-ranking females don’t experience the stress and strain of subordination, but thanks to a social support network of close kin, they may be better equipped to cope.

“Low-ranking females can buffer themselves in other ways, such as by cultivating strong social bonds with kin,” Lea said.

Social status and immune health are interconnected, Tung said. “But increasing evidence suggests that the nature of that relationship depends on whether an individual is male or female, and whether they have to fight for status or it’s given to them.”

Other authors of this study include Mercy Akinyi, Ruth Nyakundi, Peter Mareri, Fred Nyundo and Thomas Kariuki of the Institute of Primate Research in Kenya; Susan Alberts of Duke, and Elizabeth Archie of the University of Notre Dame.

This research was supported by the National Science Foundation (NSF IOS 1456832, BCS-1455808), the National Institutes of Health (R01AG053330, R01HD088558, P01AG031719, R21-AG049936), The Leakey Foundation, the Triangle Center for Evolutionary Medicine, and the North Carolina Biotechnology Center (2016-IDG-1013).

CITATION: “Dominance Rank-Associated Gene Expression is Widespread, Sex-Specific, and a Precursor to High Social Status in Wild Male Baboons,” Amanda Lea, Mercy Akinyi, Ruth Nyakundi, Peter Mareri, Fred Nyundo, Thomas Kariuki, Susan Alberts, Elizabeth Archie, Jenny Tung. Proceedings of the National Academy of Sciences, December 11, 2018. https://doi.org/10.1073/pnas.1811967115