From the Field: Chris Gilbert, India

Chris Gilbert is an assistant professor at Hunter College, CUNY. He was awarded a Leakey Foundation Research Grant in fall 2017 for his project entitled “Primate evolution, chronology, and biogeography in the Indian Lower Siwaliks.”

Chris Gilbert searching for fossils at Ramnagar. Photo credit: Biren Patel

We just returned from another successful field season in the Indian Lower Siwaliks surrounding the town of Ramnagar (Jammu and Kashmir State), India. What constitutes a “successful” field season? One during which another fossil ape specimen is found!

Fossil apes have been known from the Ramnagar region since 1922, when the famous fossil collector Barnum Brown from the American Museum of Natural History first found a specimen preserving the anterior portion of a lower jaw. Researchers have been collecting at Ramnagar on and off ever since, but ape specimens remain very rare. Nevertheless, the combined ape fossils from Ramnagar and the classic Lower Siwalik Chinji Formation-level sites on the Potwar Plateau of Pakistan are generally agreed to represent the earliest specimens of the great ape Sivapithecus, a close relative of the living orangutan.

Chris Campisano collecting geological data and field crew collecting fossils at Ramnagar. Photo credit: Chris Gilbert

Unlike the fossil sites on the Potwar Plateau, the sites around Ramangar are not well-dated in terms of geological age. However, answering broad questions in the study of ape and human evolution requires an understanding of time. For example, correlating climatic events with the appearance of key species, calibrating the molecular clock, and evaluating evolutionary scenarios regarding the acquisition of important anatomical traits, all depend on accurate age assessments of the geological deposits containing notable fossil specimens. Thus, the ages of the Ramnagar-area fossil localities are important for two reasons: first, because we have collected specimens representing new ape (and other primate) taxa, making an accurate age assessment crucial for a full understanding of their evolutionary significance; and second, because Ramnagar has been suggested to possibly represent the earliest occurrence of Sivapithecus, which is important due to its widespread use as a calibration point in molecular clock studies.

Confirmation of an earlier geological age for Sivapithecus could potentially push back other divergence dates in the hominoid family tree, including the Asian/African great ape and human/chimpanzee divergence dates.

2018 Ramnagar Field Team (left to right): Biren Patel, Rohit Kumar, Wasim Wazir, Chris Gilbert, Chris Campisano, Shubham Deep, Deepak Choudhary, Premjit Singh, Rajeev Patnaik. Photo Credit: Wasim Wazir

The current project (an international collaboration between Hunter College, CUNY, University of Southern California, Arizona State University, and Panjab University) began in 2010, and from 2010-2015, we documented new Ramnagar area fossil sites, collected vertebrate and invertebrate fossil remains, and began efforts to better document and understand the geology of the region.

Premjit Singh collecting a Sivapithecus specimen! Photo credit: Chris Gilbert

Most notably, we found two primate specimens representing new genera and species: one a new sivaladapid adapoid (Ramadapis sahnii) and one a small-bodied ape (manuscript currently in preparation). Thus, in a few short years, we doubled the known primate taxa at Ramnagar and, more broadly, added to the known primate diversity found in the Lower Siwaliks. However, questions regarding the age of the new Ramnagar primate fossils, along with the age of the previously collected Sivapithecus specimens, still remain.

Field crew collecting fossils at Ramnagar. Photo credit: Wasim Wazir

With generous funding from The Leakey Foundation, our latest field season in 2018 continued efforts to find additional primate specimens and obtain more precise age estimates of the ape-bearing fossil sites at Ramnagar. We revisited known fossil localities as well as discovered new ones, and we collected detailed geological measurements to more accurately document the stratigraphic sequence in the area. We also collected around 20 bags of sediment from our primate-bearing sites (filling up an entire pickup truck flatbed) and sent them back to Panjab University for sieving in the Patnaik lab.

Collection of sediments for sieving in the Patnaik lab. Photo credit: Biren Patel

The sieving operation (already underway) is of high importance, as previous efforts have resulted in the recovery of a small number of tiny fossil rodent teeth. Because many fossil rodent species have well-documented, brief geological time ranges in the Lower Siwaliks, if a few well-preserved specimens of these time-sensitive species can be found within the collected sediments, they can provide a highly accurate and precise time range for the fossil site in question. We are hopeful that our collection efforts will result in additional fossil rodent specimens to help with our age estimates; in combination with a revised stratigraphy, we will then be able to provide much more accurate and precise age estimates for the Ramnagar-area hominoid sites. Finally, as alluded to above, our efforts this past season resulted in the recovery of an additional specimen of the fossil ape Sivapithecus indicus, a nice reward for all our hard work!

Biren Patel collecting a giant crocodile tooth. Photo Credit: Chris Gilbert

By our count, between 1922 and 2011, only 17 fossil primate specimens (16 hominoids) were published from Ramnagar, demonstrating the rarity of ape specimens in the area. Through our fieldwork over the past few years, our team and collaborators have now expanded the known primate sample at Ramnagar by ~25%, expanded the known hominoid ape sample by ~20%, and doubled the known diversity of primate taxa along the way. We believe that these results demonstrate the potential of Ramnagar to continue providing a unique window into hominoid, and more broadly, primate diversity and evolutionary history in South Asia. Funding from organizations such as The Leakey Foundation is crucial to paleontological and geological efforts aimed at discovering and dating new fossil ape (and other primate) taxa around the world, and a more complete and well-dated fossil record provides the only direct means by which to fully understand the timing and scope of ape and human evolution. We plan to publish the results of our work at Ramnagar in numerous journal articles over the next few years.

Thank you, again, to the Leakey Foundation for the generous support!

Grantee Spotlight: Benjamin Finkel

Benjamin Finkel is a PhD candidate at the University of Michigan. He was awarded a Leakey Foundation Research Grant during our spring 2018 cycle for his project entitled “Aging apes: Foraging strategies of old chimpanzees at Ngogo, Kibale National Park, Uganda.”

Ben Finkel at Ngogo, Kibale National Park, Uganda. Face masks help prevent humans from transmitting harmful pathogens to the chimpanzees. Researchers also maintain a minimum seven-meter (21 feet) distance. Photo by Caitlin E Lawson.

Humans are especially long-lived animals. Even in the absence of modern medical care, we live longer than any other primate. Explanations for how we evolved our longevity invoke other unique human features like the importance of grandmothers or a coevolution with our intelligence. Yet it turns out that our fellow apes like chimpanzees also tend to live twice as long as other primates like monkeys and lemurs. We recently learned that chimpanzees age more similarly to us than previously thought, reaching over 60 years in the wild. Still, a lot of our understanding of aging comes from studying human societies, which share food extensively and care for the elderly, things that wild apes don’t do. So what does it mean to be an aging ape in the wild, who has to fend and forage for themselves?

Ngogo chimp Bartok (46) yawns, which shows off his wearing teeth including a broken left canine. Photo by Ben Finkel.

This is the big questions guiding my work with wild chimpanzees as I spend a year at Ngogo in Kibale National Park, Uganda, conducting my research as an anthropology PhD candidate at the University of Michigan. I go into the forest daily to observe some of the over 200 chimpanzees across two communities at our study site. I follow adult males ranging from 21 to 53 years old. Every day I grab my binoculars, GPS, and at least one chocolate bar to find and follow these chimps who have been studied pretty much every day for 25 years.

In particular, I think male chimpanzee aging is interesting because males reproduce late in life, have noticeable drops in weight between 30 to 40 years of age (depending on the community), and sometimes become less social. To what elements of aging can we attribute these observations? Because food is a daily requirement, and the ability to acquire nutrients depends on body condition, I am investigating relationships between aging, frailty, and foraging ability. For instance, do old chimpanzees with worn teeth chew less efficiently? Do aging bones and muscles hinder their climbing? If they have a harder time getting enough nutrients, does this explain why we may see older males lose weight and become less social?

Denis (3) plays in front of the current alpha, Jackson (29) and the former alpha, Miles (38). Photo by Ben Finkel.

Answering these questions means that if you came across me in the forest, I might be jotting down the type of fruit I see the chimps eating, counting the number that goes into their mouth, peering through a clinometer to figure out how high up in the tree they’ve climbed, collecting urine for later energetic assay, or keeping track of how many chimps are around throughout the day.

Since most work on aging happens in the lab or with short-lived organisms, I hope that addressing my questions will clarify what it means for a long-lived animal to age in the wild. Moreover, to get an idea of how human lifespans came to be, we have to know more about longevity – and its limits – in our fellow apes.

For more chimps, aging, and forest life, you can follow Ben on twitter @Benjamin_Finkel.

New Species of Early Human Discovered in the Philippines

Callao Cave on Luzon Island, Philippines, where the fossils were discovered. Photo courtesy of Callao Cave Archaeology Project.

With funding from The Leakey Foundation, a new member of the human family has been found in a cave in the Philippines, researchers report today in the journal Nature.

The new species, called Homo luzonensis, is named after Luzon Island, where the more than 50,000-year-old fossils were found during excavations at Callao Cave. This species lived at the same time that the small hominins named Homo floresiensis or “hobbits” lived on the Indonesian island of Flores.

This discovery makes Luzon the third Southeast Asian island to show evidence of unexpectedly ancient human presence.

Photo credit: Callao Cave Archaeology Project.

The researchers uncovered the remains of at least two adults and one juvenile within the same archaeological deposits. Some of the newly discovered fossils share similar features with other species in our genus Homo. “The fossil remains included adult finger and toe bones, as well as teeth. We also recovered a child’s femur. There are some really interesting features – for example, “the teeth are really small,” says lead author Philip Piper from The Australian National University.

In shape and size, some of the fossils match those of corresponding bones from other Homo species.

“The size of the teeth generally, though not always, reflect the overall body-size of a mammal, so we think Homo luzonensis was probably relatively small. Exactly how small we don’t know yet. We would need to find some skeletal elements from which we could measure body-size more precisely,” says Piper.

Professor Philip Piper from the ANU School of Archaeology and Anthropology inspects the cast of a hominin third metatarsal discovered in 2007. The bone is from a new species of hominin.
Photo credit: Lannon Harley, ANU.

“It’s quite incredible, the extremities, that is the hand and feet bones are remarkably Australopithecine-like. The Australopithecines last walked the earth in Africa about 2 million years ago and are considered to be the ancestors of the Homo group, which includes modern humans. So, the question is whether some of these features evolved as adaptations to island life, or whether they are anatomical traits passed down to Homo luzonensis from their ancestors over the preceding 2 million years.”

While there are still plenty of questions around the origins of Homo luzonensis, and their longevity on the island of Luzon, recent excavations near Callao Cave produced evidence of a butchered rhinoceros and stone tools dating to around 700,000 years ago.

“No hominin fossils were recovered, but this does provide a timeframe for a hominin presence on Luzon. Whether it was Homo luzonensis butchering and eating the rhinoceros remains to be seen,” says Piper.

“It makes the whole region really significant. The Philippines is made up of a group of large islands that have been separated long enough to have potentially facilitated archipelago speciation. There is no reason why archaeological research in the Philippines couldn’t discover several species of hominin. It’s probably just a matter of time.”

Homo luzonensis shares some unique skeletal features with the famous Homo floresiensis or ‘the hobbit’, discovered on the island of Flores to the south east of the Philippine archipelago.

In addition, stone tools dating to around 200,000 years ago have been found on the island of Sulawesi, meaning that ancient hominins potentially inhabited many of the large islands of Southeast Asia.

If you are a paleoanthropologist or paleoanthropology student from East or Southeast Asia, please apply for our Baldwin Fellowship funded by the National Geographic Society. Click here for more information.

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We frequently hear from scholars that The Leakey Foundation provides critical seed money at just the right time in a young scientist’s career.

Leakey Foundation grantees Eric Delson and Dagmawit Abebe Getahun at the American Museum of Natural History.

Dr. Eric Delson, five-time Leakey Foundation grant recipient, professor of anthropology at Lehman College-CUNY, and Director of NYCEP (the New York Consortium in Evolutionary Primatology), says, “Scholars who focus on human evolution in their research are lucky indeed to have the support of The Leakey Foundation. Any possibility to increase this generosity would be well rewarded with an improved understanding of our species’ history.”

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Fossil Teeth from Kenya Solve Ancient Monkey Mystery

Sedimentary rocks exposed in the eroded badlands of Nakwai, Kenya, where the remains of a newly discovered ancient species of Old World monkey named Alophia was discovered. The truck and scientists at bottom right of center show the scale of this landscape. Photo copyright John Kappelman, used by permission.

AUSTIN, Texas — The teeth of a new fossil monkey, unearthed in the badlands of northwest Kenya, help fill a 6-million-year void in the fossil record of Old World monkey evolution, according to a study by U.S. and Kenyan scientists published in the Proceedings of the National Academy of Sciences, and funded in part by The Leakey Foundation.

The discovery of 22-million-year-old fossilized monkey teeth – described as belonging to a new species, Alophia metios – fills a void between a previously discovered 19-million-year-old fossil tooth in Uganda and a 25-million-year-old fossil tooth found in Tanzania. The finding also sheds light on how their diet may have changed the course of their evolution.

A fossil mandible of the newly discovered ancient Old World monkey named Alophia. Photo copyright John Kappelman, used by permission.

“For a group as highly successful as the monkeys of Africa and Asia, it would seem that scientists would have already figured out their evolutionary history,” said the study’s corresponding author John Kappelman, an anthropology and geology professor at The University of Texas at Austin. “Although the isolated tooth from Tanzania is important for documenting the earliest occurrence of monkeys, the next 6 million years of the group’s existence are one big blank. This new monkey importantly reveals what happened during the group’s later evolution.”

Since the time interval from 19 to 25 million years ago is represented by a small number of African fossil sites, the team targeted the famous fossil-rich region of West Turkana to try to fill in that blank.

“Today, this region is very arid,” said Benson Kyongo, a collections manager at the National Museums of Kenya. “But millions of years ago, it was a forest and woodland landscape crisscrossed by rivers and streams. These ancient monkeys were living the good life.”

While in the field, the team uncovered hundreds of mammal and reptile jaws, limbs and teeth ranging from 21 million to more than 24 million years old, including remains of early elephants. The newly discovered monkey teeth are more primitive than geologically younger monkey fossils, lacking what researchers referred to as “lophs,” or a pair of molar crests, thus earning the new species its name, Alophia, meaning “without lophs.”

“These teeth are so primitive that when we first showed them to other scientists, they told us, “Oh no, that isn’t a monkey. It’s a pig,” said Ellen Miller, an anthropology professor at Wake Forest University. “But because of other dental features, we are able to convince them that yes, it is, in fact, a monkey.”

The success of Old World monkeys appears to be closely tied to their unique dentition, researchers said. Today, the configuration of cusps and lophs on the molar teeth enable them to process the wide range of plant and animal foods encountered in the diverse environments of Africa and Asia.

“You can think of the modern-day monkey molar as the uber food processor, able to slice, dice, mince and crush all sorts of foods,” said Mercedes Gutierrez, an anatomy professor at the University of Minnesota.

“How and when this unique dentition evolved is one of the unanswered questions in primate evolution,” said James Rossie, an anthropology professor at Stony Brook University. The researchers speculated that Alophia‘s primitive dentition was adapted to a diet that consisted of hard fruits, seeds and nuts, and not leaves, which are more efficiently processed by the more evolved dentition of fossil monkeys dating from after 19 million years ago.

“It is usually assumed that the trait responsible for a group’s success evolved when the group originated, but Alophia shows us this is not the case for Old World monkeys,” said Samuel Muteti, a researcher at the National Museums of Kenya. “Instead, the characteristic dentition of modern monkeys evolved long after the group first appeared.”

The researchers hypothesized that the inclusion of leaves in the diet is what later drove monkey dental evolution.

Monkeys originated at a time when Africa and Arabia were joined as an island continent, with its animals evolving in isolation until docking with Eurasia sometime between 20 million and 24 million years ago. It was only after docking that the mammals today typically considered “African” – antelope, pigs, lions, rhinos, etc. – made their entry onto the continent. So, researchers asked: Could this event and possible competition between the residents and the newly arrived Eurasian species have driven monkeys to exploit leaves, or did changing climates serve to make leaves a more attractive menu entrée?

Scientists collecting rock samples for dating the sediments at nakwai, Kenya where the newly discovered ancient old World monkey named Alophia was discovered. The fossil monkey is dated to 22 million years in age.

“The way to test between these hypotheses is to collect more fossils,” Kappelman said. “Establishing when, exactly, the Eurasian fauna entered Afro-Arabia remains one of the most important questions in paleontology, and West Turkana is one of the only places we know of to find that answer.”

The team intends to be back in the field later this year.

“Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty”
D. Tab Rasmussen, Anthony R. Friscia, Mercedes Gutierrez, John Kappelman, Ellen R. Miller, Samuel Muteti, Dawn Reynoso, James B. Rossie, Terry L. Spell, Neil J. Tabor, Elizabeth Gierlowski-Kordesch, Bonnie F. Jacobs, Benson Kyongo, Mathew Macharwas, Francis Muchemi
Proceedings of the National Academy of Sciences Mar 2019, 201815423; DOI: 10.1073/pnas.1815423116