Fossilized monkey teeth help fill six million year gap in evolution
Researchers have used fossilized teeth found near Lake Turkana in northwest Kenya to identify a new monkey species — a discovery that helps fill a 6-million-year gap in primate evolution.
UNLV geoscientist Terry Spell and former master’s student Dawn Reynoso were part of the international research team that discovered the species that lived 22 million years ago.
Understanding the evolution of Old World monkeys is important because, along with the great apes and humans, they belong to the anthropoid group of primates — primates that resemble humans.
According to Spell, the monkey fossil discovery grew out of a more extensive study of a section of sedimentary rocks in Kenya that contain a large number of different types of fossils, including several hundred mammals and reptile jaws, limbs, and teeth.
Previous studies had documented the early evolution of Old World monkeys using fossils dated at 19 million and 25 million years old, leaving a 6-million-year gap in the earliest record.
However, the new fossil was determined to be 22 million years in age. Isotopic ages on the rocks were obtained in the Nevada Isotope Geochronology Laboratory on the UNLV campus.
“This adds to our understanding of the earliest evolutionary history of Old World monkeys, including changes in their diet with time to include more leaves,” Spell said.
“Monkeys originated at a time in the past when Africa and Arabia were together as an island continent. Plate tectonic motions pushed this landmass into the Eurasian landmass 20 to 24 million years ago, and an exchange of animals and plants occurred.
It is unclear if competition with newly introduced species or changing climate conditions drove changes in diet.”
Scientists named the newly discovered monkey species Alophia (“without lophs”) due to the lack of molar crests on its teeth — a phenomenon that sets them apart from geologically younger monkey fossils.
Old World monkeys are the most successful living superfamily of nonhuman primates with a geographic distribution that is surpassed only by humans.
The group occupies a wide spectrum of land to tree habitats and have a diverse range of diets. They evolved to develop a signature dental feature — having two molar crests — which to this day allows them to process a wide range of food types found in the varying environments of Africa and Asia.
Others involved in the research were scientists from nine U.S. universities and a foreign national museum.
What is the oldest-known archaeological site in the world?
Our human ancestors were roaming Earth as far back as 6 million years ago, but what is the earliest site containing archaeological evidence of their existence?
It turns out, there are two spots — one in Kenya and the other in Ethiopia — that are considered the top candidates for the world’s oldest archaeological sites, according to about a dozen scholars, all with expertise in prehistoric archaeology and anthropology, who spoke with Live Science.
The question of what is the oldest archaeological site in the world is “a topic that has since recently divided the archaeological community,” Yonatan Sahle, a senior lecturer of archaeology at the University of Cape Town in South Africa, told Live Science in an email.
The first site, called Lomekwi 3, holds bones of hominins as well as stone artefacts and is located on a low hill in West Turkana, Kenya. In a study published in 2015 in the journal Nature, researchers reported that, by dating the sediment where the artefacts were found, they estimated the age of the site to be about 3.3 million years.
The finds “mark a new beginning to the known archaeological record,” a team of scientists wrote in the journal article. The tools were likely created by Australopithecus afarensis, a hominin (human ancestors and their relatives) that thrived in the region at the time.
The site is located in a wooded area on a small hill not far from Lake Turkana. It’s possible that Australopithecus afarensis was using the stone artefacts to break open nuts the team wrote in the paper. The number of people who lived at the site at any given time is not clear.
“Lomekwi 3 is the oldest known archaeological site in the world,” Jason Lewis, assistant director of the Turkana Basin Institute and a co-author of the paper, told Live Science in an email.
Jeremy DeSilva, an associate professor of anthropology at Dartmouth College who was not involved in the study, agreed that Lomekwi 3 is the oldest known archaeological site, but he noted that not all scholars agree. “Lomekwi is controversial, and some of our colleagues remain unconvinced of the antiquity of these tools,” DeSilva told Live Science.
Indeed, a number of recent papers “call into question the status of the artefacts at Lomekwi 3, arguing that some of the artefacts were not actually found in a context where the age of the artefacts can be certain,” David Braun, an anthropology professor at The George Washington University, told Live Science. In other words, the artefacts may not date to the same time as the sediment that it was found in.
Sahle is one of those archaeologists. “For many of us — myself included — unequivocal evidence for the oldest archaeological occurrences comes in the form of 2.6-million-year-old stone tools from Gona,” which is located by the Kada Gona river in Afar, Ethiopia, Sahle said. The dating results for Lomekwi 3 are contested, he noted, and he has serious doubts that the remains found at that site date back 3.3 million years.
The research at Lomekwi 3 was published relatively recently, whereas research at Gona has been published over several decades and has withstood academic scrutiny, Sahle said. “Inferences made on the chronological and behavioural context of [the] Gona archaeological assemblages derive from decades of research and have, therefore, withstood the test of time,” Sahle said.
The stone tools at Gona may have been made by Australopithecus Garhi, a human ancestor that lived in east Africa around 2.5 million years ago. Fossils of the species have been found near stone tools and they may have been one of the first human ancestors to make sophisticated stone tools Smithsonian’s Human Origins project website notes.
“The Lomekwi claims were not adequately demonstrated when announced, and there has [been] no new evidence provided, despite several well-considered criticisms of the original Nature announcement,” said Tim White, co-director of the Human Evolution Research Center at the University of California, Berkeley. White agrees that Gona has the best unequivocal evidence for being the oldest archaeological site.
On the other hand, some scholars are supportive of the idea that Lomekwi is older than Gona. Rick Potts, director of the Smithsonian’s Human Origins Program, is convinced that Lomekwi 3 “is the oldest site with solid evidence of stone-on-stone percussion,” meaning that it’s the oldest site that has stone artefacts made by human ancestors. He noted that the stone artefacts at Lomekwi 3 appear different from those found at Gona; they are cruder and may not have been used as tools at all. The stone artefacts at Lomekwi 3 “show awkward fracturing of the rocks, including large, thick, irregularly shaped flakes that could have been the accidental byproducts of pounding — for what purpose, no one currently knows,” Potts wrote in an email, noting that people at Lomekwi 3 may not have been creating tools but rather pounding rocks together for unknown reasons. Even if the Lomekwi 3 artefacts weren’t used as tools, they would still be considered artefacts created by humans.
Brian Villmoare, an associate professor of anthropology at the University of Nevada, told Live Science, “I do tend to think that Australopithecus afarensis could have made stone tools,” but he noted that he has not examined the Lomekwi 3 artefacts.
A third candidate?
Braun said that if future fieldwork cannot alleviate concerns about the dating of Lomekwi 3, his second choice for the oldest archaeological site would be Ledi-Geraru in Afar, Ethiopia, which dates back about 2.8 million years.
At Ledi-Geraru, researchers found a partial hominin mandible with teeth, and they dated it by examining the age of the surrounding sediment, they reported in the journal Science in 2015. Sahle expressed doubts about the dating of this site, saying that it may be considerably younger than 2.8 million years and that Gona is the site with the best unequivocal evidence.
Regardless of which of these archaeological sites is the oldest, all of them make the Giza pyramids (which are about 4,500 years old) and Stonehenge (which is roughly 5,000 years old) relatively young by comparison.
Africa’s Oldest Human Grave Found, Toddler Buried With Pillow 78,000 Years Ago
A village in East Africa buried a boy aged around 3 years old 78,000 years ago. Its caretakers dug a shallow pit, curled its small body, and may have rested its head on a pillow before committing the body to the earth.
According to a new study, the discovery of the child’s grave has revealed the earliest recorded traces of early humans burying their dead in Africa.
“It’s beautifully excavated … and there can be no dissension that it’s a burial,” says Paul Pettitt, a palaeolithic archaeologist at Durham University who studies ancient mortuary practices and was not involved with the work. “It shows that the tradition of burying some of the dead … probably arose from a common custom amidst Homo sapiens in Africa.”
Intentional burials are relatively rare in the archaeological record before about 30,000 years ago. Previously, the oldest suspected burials in Africa dated to 74,000 and 68,000 years ago—in South Africa’s Border Cave and in Taramsa, Egypt, respectively. In Eurasia, burials of modern humans and Neanderthals up to 120,000 years old have been found, but those involved peoples who contributed little to humans living today.
The new grave was found in 2013 under the rocky overhang of a cave called Panga ya Saidi along the coastline of southeastern Kenya. Archaeologists and local workers noticed an unusual, pit-shaped undulation of sediment within the walls of one of their trenches.
When they inspected it, a small bone fell out—and promptly turned to dust. Realizing they had found an extraordinarily delicate fossil, the archaeologists spent the next 4 years painstakingly digging and casting the fragile bones in plaster. Two teeth later analyzed at the National Museums of Kenya unambiguously identified the body as a human child.
The researchers then sent the remains to a lab at the National Center for Research on Human Evolution in Burgos, Spain, for further analysis. Virtually sorting through the layers of bone and dirt using computerized tomography, scientists analyzed the bones.
They couldn’t determine how the child had died, but its position suggested caretakers had deliberately curled it into a fetal position before placing it into a shallow pit, explains the study’s senior author, Michael Petraglia, an archaeologist at the Max Planck Institute for the Science of Human History.
The skeleton’s torqued shoulder indicates it was likely wrapped tightly in a shroudlike material, and the way the skull twisted and bent inside its grave suggests it may have been propped up on some sort of pillow that slowly decayed.
A technique that tells scientists when sediments were last exposed to light revealed the remains were deposited about 78,000 years ago, making this the oldest known human burial site in Africa, the researchers report today in Nature.
Emmanuel Ndiema, an archaeologist at the National Museums and one of the study’s co-authors, named the child Mtoto, after the same word in Swahili. The remains have since been returned to the National Museums.
As complex symbolic behaviours, including jewellery use and ochre pigment painting, are thought to have arisen in Africa, the birthplace of our species, about 125,000 to 100,000 years ago, it’s reasonable to think that human burial may have also emerged there and spread around the world with early migrants from the continent, Petraglia says. It’s not clear though, he says, whether Neanderthals independently began to bury their dead or the roots of burial-related behaviours go back to the common ancestor of humans and Neanderthals.
Nearly half of such ancient burials involve children, Petraglia points out. Dying young may have been seen then, as now, as particularly tragic, prompting the community to commemorate the death. “Here we have a child where the legs are pulled up to the chest, in a small pit—it’s almost like the womb,” Petraglia says.
Julien Riel-Salvatore, an anthropologist at the University of Montreal, agrees that the level of care that went into Mtoto’s burial suggests a child’s death was especially poignant.
“The idea that people would go out of their way to preserve the child’s body, which would slow its decay and protect it from scavengers, reflects the fact that people cared deeply about their children,” he says.
More burials from the region and time period will need to be discovered before researchers can start to puzzle out the significance that burial held to these ancient humans, says Louise Humphrey, an anthropologist at the National History Museum in London. Still, she says, the tenderness of the burial in Panga ya Saidi reveals “an expression of personal loss”—a sorrow that transcends time.
A large cave site was identified by an international interdisciplinary group of scholars operating along the east coast of Africa that documented significant activities of hunter-gatherers and later, Iron Age communities.
Detailed environmental research has demonstrated that human occupations occur in a persistent tropical forest-grassland ecotone, adding new information about the habitats exploited by our species, and indicating that populations sought refuge in a relatively stable environment.
Prior to this cave excavation, little information was available about the last 78,000 years from coastal East Africa, with the majority of archaeological research focused on the Rift Valley and in South Africa.
Humans lived in the humid coastal forest
A large-scale interdisciplinary study, including scientific analyses of archaeological plants, animals, and shells from the cave indicates a broad perseverance of forest and grassland environments.
As the cave environment underwent little variation over time, humans found the site attractive for occupation, even during periods of time when other parts of Africa would have been inhospitable.
This suggests that humans exploited the cave environment and landscape over the long term, relying on plant and animal resources when the wider surrounding landscapes dried.
The ecological setting of Panga ya Saidi is consistent with increasing evidence that Homo sapiens could adapt to a variety of environments as they moved across Africa and Eurasia, suggesting that flexibility may be the hallmark of our species.
Homo sapiens developed a range of survival strategies to live in diverse habitats, including tropical forests, arid zones, coasts, and the cold environments found at higher latitudes.
Technological innovations occur at 67,000 years ago
Carefully prepared stone tool toolkits of the Middle Stone Age occur in deposits dating back to 78,000 years ago, but a distinct shift in technology to the Later Stone Age is shown by the recovery of small artifacts beginning at 67,000 years ago.
The miniaturization of stone tools may reflect changes in hunting practices and behaviors. The Panga ya Saidi sequence after 67,000, however, has a mix of technologies, and no radical break of behavior can be detected at any time, arguing against the cognitive or cultural ‘revolutions’ theorized by some archaeologists.
Moreover, no notable break in human occupation occurs during the Toba volcanic super-eruption of 74,000 years ago, supporting views that the so-called ‘volcanic winter’ did not lead to the near-extinction of human populations, though hints of increased occupation intensity from 60,000 years ago suggest that populations were increasing in size.
Earliest symbolic and cultural items found at Panga ya Saidi cave
The deep archaeological sequence of Panga ya Saidi cave has produced a remarkable new cultural record indicative of cultural complexity over the long term.
Among the recovered items are worked and incised bones, ostrich eggshell beads, marine shell beads, and worked ochre. Panga ya Saidi has produced the oldest bead in Kenya, dating to ~65,000 years ago.
At about 33,000 years ago, beads were most commonly made of shells acquired from the coast. While this demonstrates contact with the coast, there is no evidence for the regular exploitation of marine resources for subsistence purposes.
Ostrich eggshell beads become more common after 25,000 years ago, and after 10,000 years ago, there is again a shift to coastal shell use.
In the layers dating to between ~48,000 to 25,000 years ago, carved bone, carved tusk, a decorated bone tube, a small bone point, and modified pieces of ochre were found. Though indicative of behavioral complexity and symbolism, their intermittent appearance in the cave sequence argues against a model for a behavioral or cognitive revolution at any specific point in time.
Project Principal Investigator and Director of the Department of Archaeology at the Max Planck Institute for the Science of Human History Dr. Nicole Boivin states, “The East African coastal hinterland and its forests and have been long considered to be marginal to human evolution so the discovery of Panga ya Saidi cave will certainly change archaeologists’ views and perceptions.”
Group Leader of the Stable Isotopes Lab Dr. Patrick Roberts adds, “Occupation in a tropical forest-grassland environment adds to our knowledge that our species lived in a variety of habitats in Africa.”
“The finds at Panga ya Saidi undermine hypotheses about the use of coasts as a kind of ‘superhighway’ that channeled migrating humans out of Africa, and around the Indian Ocean rim,” observes Professor Michael Petraglia.
1.5-Million-Year-Old Footprints Reveal Human Ancestor Walked Like Us
Homo erectus last walked through the Earth for thousands of years, but our fossil ancestors likely had a few behaviours in common with humans today.
In a new study, researchers have examined a set of 1.5-million-year-old footprints discovered in Kenya, revealing new insight on how they moved and interacted.
The international team discovered that Homo erectus was able to go along in the same manner as modern humans and had human-like social behaviour, using innovative analytical techniques.
Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, along with an international team of scientists, investigated ancient hominin footprints discovered in 2009 near the town of Ileret, Kenya.
The continued efforts since the initial discovery revealed an unprecedented set of trace fossils, consisting of 97 tracks from at least 20 different individuals, all thought to be Homo erectus.
These were found over five distinct sites.
The researchers say the footprints are indistinguishable from those of a modern barefoot human, with similar foot anatomies and mechanics.
‘Our analyses of these footprints provide some of the only direct evidence to support the common assumption that at least one of our fossil relatives at 1.5 million years ago walked in much the same way as we do today,’ says Kevin Hatala, of the Max Planck Institute for Evolutionary Anthropology and The George Washington University.
Habitual bipedal locomotion sets modern humans apart from other primates, and researchers have long debated the question of when this giant first emerged among hominins.
Determining these types of answers are difficult using traditional forms of paleoanthropological data, but the findings in Kenya and the use of new experimental techniques have provided a unique look at the locomotion patterns and social structures of Homo erectus.
The researchers also calculated body mass estimates based on the tracks, allowing them to infer the sexes of multiple individuals.
This revealed that there may have been several adult males at each of the sites, which suggests Homo erectus groups had developed some degree of tolerance and maybe even cooperation.
According to the researchers, this trait also separates modern humans from other primates.
‘It isn’t shocking that we find evidence of mutual tolerance and perhaps cooperation between makes in a hominin that lived 1.5 million years ago,’ says Hatala, ‘especially Homo erectus, but this is our first chance to see what appears to be a direct glimpse of this behavioural dynamic in deep time.’