From the Field: Nicole Herzog, Senegal

Nicole Herzog was awarded a Leakey Foundation Research Grant during our spring 2016 cycle for her project entitled “Chimpanzees in fire-altered landscapes:  Investigating foundations for hominin fire exploitation.”

Chimpanzees moving across a burned landscape at Fongoli, Senegal

Dr. Jill Pruetz has been studying the behavior of the wild chimpanzees of Fongoli, Senegal, for 17 years. She has observed chimpanzees hunting with spears; she has looked on as chimpanzee youngsters learn to fish for termites and forage with family. She has also carefully noted other exceptional aspects of the behavior of these savanna-dwelling primates. In 2010, she with colleague Thomas LaDuke reported on the responses of this population to the dry season fire-regime that impacts a large portion of the animals’ home range each year. In that paper, they noted the savvy responses of chimpanzees to fire. The animals seemed able to read the fires, anticipating the direction and speed, and expertly maneuvering around them. They pondered the relevance of this phenomenon in the context of early human evolution and the role fire may have played in shaping our own species.

Following the 2010 publication, Pruetz continued to collect data on the behavior of her subjects in and around burned landscapes. Other important patterns emerged. Chimpanzees appeared to spend more time feeding in burned areas. They also used burn areas for travel. Did the chimpanzee’s knowledge of fire extend beyond the scope of safely navigating away from active fires? Were there other reasons to be fire-savvy?

In 2016, we were awarded a Leakey Foundation grant to explore these questions further. Our aim was to investigate fire at Fongoli, using the behavior of the chimpanzees as a model for aspects of early hominin response to burned landscapes. We sought to collect data on two issues thought to be critical in the reconstruction of human evolutionary history: 1) establishing foraging niches in savanna settings and, 2) the ranging behavior of a savanna-dwelling ape. We established two hypotheses to test during the 2016-2017 field season at Fongoli. The first was that burning will increase encounter rates for certain resources. Second, burned corridors will provide more direct routes to feeding trees; these routes will be used preferentially.

Fire at dusk at Fongoli, Senegal.

Fall 2016 involved rounding up all of the necessary gear to accurately measure encounter rates, paths of travel, and overall burning patterns. GPS trackers, data books, and field gear in hand, we began the project at the onset of the fire season in late November 2016. As the green grasses of the wet season begin to dry, horticulturalists living in the area use fire to clear the land, the trails, and the woodlands. As the heat of the dry season gathers, natural fires are common as well. With the help of dedicated Senegalese field assistants, we began intensively monitoring the occurrence of fires and the behavior of the chimpanzees in and around them. During that first month of study, we recorded nearly 40 small fires. We mapped each fire, recording the date of burning and total area impacted. It was a very exciting time! The smoke from fires could be seen for kilometers, and if you were close enough you could hear the intense sound of the bush ablaze.

One afternoon as we surveyed a burn scar from the previous day’s fires we rounded a bend and caught sight of a flurry of bulky body and long tail leaping out of a bare tree that sat just on the edge of the burn. The blur moved about 10 meters into the wooded area behind, then turned to look back at us. It was a leopard. When we approached the leopard’s tree, we found it to be a perfect lookout over the newly burned plateau. Conveniently, it also looked over a well-worn trail that humans and apes alike use to travel through the area. We decided to stay close, wondering if the leopard or its prey might return. As we waited we heard the familiar calls of vervet monkeys from the nearby ravine. The vervets skirted the edge of the burn that day but never entered the scorched terrain. Several days later we did find them in the burn, just down the trail from where we’d seen the leopard. They appeared to be foraging well outside the ravine on the other side of the plateau. We watched as they ran wildly back across the newly bare expanse back to the safety of the unburned woods. This anecdote begs many other questions about the draw of burned areas for primates and the safety of their use. While burning may be a boon for savanna-dwelling primates, does it make them easy prey for smart predators – conversely could burning be a bust for ambush predators that rely on thick brush and dense vegetation to make their kills?

Fire at dusk at Fongoli, Senegal.

The Fongoli dry season lasts from November to April. As the dry-season months went on, we observed more burning. By the beginning of May we had recorded over 100 individual fires across the 85 km2 area that makes up the home range of the savanna-chimpanzees. These fires impacted no less than 75% of the total range. In conjunction with fire maps, we also recorded over 100 individual chimpanzee daily routes. These routes track the paths of travel that individual subjects embark on and typically span an entire day’s movements.

In May the rains came to Fongoli, and it is now nearly time for the dry season to begin again. The amount of data we were able to collect during this year of field-work is extraordinary, if not a little daunting. Now that field work is wrapped up for this project – though ongoing behavioral data collection is carried out all year at Fongoili – we’ve begun the process of sorting and organizing our maps and tracks, notes on feeding and fire related behavior. We will spend the next year analyzing all of this data for patterns that can help shed light on the ways fire impacts these animals. We hope to learn more about how they have learned to adapt, and even take advantage of, the force of fire. We have no doubt this information will provide answers to our hypotheses and will shed light on the role of fire in human evolution.

Nicole Herzog in a recent burn, showing height of grasses pre-fire ~6-7 feet tall at Fongoli, Senegal.

Chimp Females Who Leave Home Postpone Parenthood

Imani the chimpanzee, a newcomer to her group, lounges with her son at Gombe National Park in Tanzania. Photo by Ian Gilby, Arizona State University.

DURHAM, N.C. — New moms need social support, and mother chimpanzees are no exception. So much so that female chimps that lack supportive friends and family wait longer to start having babies, according to researchers who have combed through the records of Jane Goodall’s famous Gombe chimpanzees.

Wild chimpanzee females in western Tanzania who leave home or are orphaned take roughly three years longer to start a family.

The researchers analyzed more than 50 years’ worth of daily records for 36 female chimps born in Gombe National Park. Stored in the Jane Goodall Institute Research Center at Duke University, the records are part of a larger database containing close observations of hundreds of wild chimpanzees, going all the way back to Goodall’s first field notes from the early 1960s.

Some female chimpanzees stay with the group they were born into their entire lives. Others pull up their roots and move to a new group when they reach adolescence, presumably to avoid inbreeding.

The average age of first-time moms varies a lot, the researchers found. Females that stay home deliver their first infant around age 13. For migrants, it’s 16.

Several factors may contribute to the delay, the researchers said. Like all newcomers, they get pushed around, mostly by resident females. Having left their family and friends behind, they must jostle for position in the pecking order of a new and unfamiliar group.

“It’s a tough integration period,” said Kara Walker, postdoctoral associate in the department of evolutionary anthropology at Duke.

In contrast, stay-at-home females benefit from better support. Females also started reproducing earlier if their own mothers were around while they were growing up, particularly if their moms were high-ranking — in part because females with high-ranking moms get better access to food.

Their head start on motherhood means these early bloomers have the potential to produce more offspring over their lifetimes, said Anne Pusey, James B. Duke professor of evolutionary anthropology and director of the Jane Goodall Research Institute Center at Duke.

“This really raises the question of why some females stay and others go,” Pusey said.

The results also suggest that a lengthy journey from childhood to adulthood — long thought to be unique to the human branch of the primate family tree — may have deeper roots than previously thought.

“This suggests that chimpanzees are, developmentally, much more similar to humans than was previously believed,” says Christopher Walker, assistant professor of anatomy at NC State University.

The study appears online Nov. 20 in the Journal of Human Evolution.

This research was supported by the Jane Goodall Institute, the National Science Foundation (DBS-9021946, SBR-9319909, BCS-0452315, IOS-LTREB-1052693, DGE-1106401), the National Institutes of Health (R01 AI 058715) and grants from the Leakey Foundation and Margot Marsh Foundation.

CITATION: “Maturation is Prolonged and Variable in Female Chimpanzees,” Kara K. Walker, Christopher S. Walker, Jane Goodall and Anne E. Pusey. Journal of Human Evolution, Nov. 20, 2017. https://doi.org/10.1016/j.jhevol.2017.10.010.

Grantee Spotlight: David Samson

David Samson is from the University of Toronto, Mississauga. He was awarded a Leakey Foundation Research Grant during our spring cycle for his project entitled “What drives sleep flexibility? A comparative investigation of circumpolar and equatorial hunter-gatherers.” 

David Samson (L)

Humans are a remarkable species. We live in large social networks, persist in inhospitable places, fashion complex tools, and communicate using language. While we exhibit many morphological and behavioral differences to other primates – our cognitive capacity likely played a crucial role in our success.

My research investigates the biology, ecology, and evolution of primate sleep. I believe the effects of sleep on our lineage were profound. For example, in humans, sleep is critical for immune strength, working memory, attention, decision-making, and visual-motor performance, yet how sleep affects such processes remains unknown for most non-human primates.

To investigate this research question, I use pioneering, non-invasive technology to study human and non-human primates with a broad phylogenetic scope. In addition, I engage with the emerging field of evolutionary medicine by using my findings to understand human sleep disorders within an evolutionary framework. The ultimate goal of my research is to further our understanding of human evolution.

Scientists Discover New Orangutan Species

 

The newly discovered species of orangutan, Pongo tapanuliensis. Photo: Maxime Aliaga

Funded in part by The Leakey Foundation

Scientists have long recognized six living species of great ape aside from humans: Sumatran and Bornean orangutans, eastern and western gorillas, chimpanzees, and bonobos. But researchers reporting in Current Biology on November 2 have now made it seven, based on a collection of evidence showing that an isolated population of orangutans living in Sumatra is actually its own unique species. They’ve named the new species the Tapanuli orangutan (Pongo tapanuliensis).

Unfortunately, the researchers say, there are only about 800 Tapanuli orangutans left. Those that remain are under threat from loss of lowland habitat and hunting, which makes this newly discovered species among the most threatened great ape species in the world.

“It isn’t an everyday event that we find a new species of great ape, so indeed the discovery is very exciting,” said Michael Krutzen of the University of Zurich in Switzerland, senior author of the study.

The Leakey Foundation is proud to have supported this research. Donate today and help fund the next big discovery.

“Great apes are among the best-studied species in the world,” added Erik Meijaard of the Australian National University. “If after 200 years of serious biological research we can still find new species in this group, what does it tell us about all the other stuff that we are overlooking: hidden species, unknown ecological relationships, critical thresholds we shouldn’t cross? Humans are conducting a vast global experiment, but we have near-zero understanding of what impacts this really has, and how it could ultimately undermine our own survival.”

The newly discovered species of orangutan, Pongo tapanuliensis. Photo: Andrew Walmsley

The new orangutan species lives in the Batang Toru area in North Sumatra, Indonesia. While there had been rumors, no one was sure that this population of orangutans existed until 1997. They live south of what had been the known range for Sumatran orangutans.

Earlier studies suggested that the group differed from other orangutans behaviorally and at the genetic level, but it wasn’t clear that those differences were enough to support its designation as a new species. The breakthrough came in 2013, when the research team including Meijaard got access to a skeleton belonging to a Batang Toru orangutan killed in a human-animal conflict. Careful studies of the animal revealed consistent differences in its skull and teeth.

A sophisticated analysis of 37 orangutan genomes now shows that the deepest split in the evolutionary history of living orangutans occurred more than three million years ago, between the Batang Toru population and Bornean orangutans to the north of Lake Toba. Bornean and Sumatran orangutans separated only much later, less than 700,000 years ago. Behavioral and ecological evidence lends further support for the notion that the orangutans living in Batang Toru are a separate species, the researchers said.

Skull of Pongo tapanuliensis. Photo: Nater et al.

“The Batang Toru orangutans appear to be direct descendants of the initial orangutans that had migrated from mainland Asia, and thus constitute the oldest evolutionary line within the genus Pongo,” said Alexander Nater, also of the Unversity of Zurich. “The Batang Toru population was connected to populations to the north until 10,000 or 20,000 years ago, after which it became isolated.”

The findings mean that there are now 800 fewer Sumatran orangutans than previously thought. The Tapanuli orangutans are also severely threatened by hunting and the proposed development of a hydroelectric dam that would flood large parts of their best habitat if implemented. That’s especially discouraging given that previous analyses suggest a mortality rate of less than one percent per year would still be enough to drive the Tapanuli orangutans extinct.

“If even 8 out of 800 animals per annum were killed or otherwise removed from the population, the species might be doomed,” the scientists caution.

The researchers say the most important thing now is to work with organizations already in the area and Indonesian government authorities to urge support for more effective conservation measures to protect the Batang Toru area. They also want to learn more about the relationship of the Tapanuli orangutan to now-extinct orangutan populations that used to live in other parts of Sumatra.


This work was financially supported by the University of Zurich, the Swiss National Science Foundation, The Leakey Foundation, the A.H. Schultz Foundation, the UZH Research Priority Program ”Evolution in Action,” the Arcus Foundation, Australian National University, an ANU Vice Chancellor Travel Grant, Australia Awards Scholarship-DFAT, an ERC Starting Grant, EMBO, Fundacio Zoo Barcelona, the Julius-Klaus Foundation, MINECO/FEDER, the Gates Cambridge Trust, and the Department of Anthropology at the University of Zurich.

Current Biology, Nater et al.: “Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species” http://www.cell.com/current-biology/fulltext/S0960-9822(17)31245-9 DOI: 10.1016/j.cub.2017.09.047

Grantee Spotlight: Carrie Miller

Carrie Miller is a PhD candidate from the University of Minnesota. She was awarded a Leakey Foundation Research Grant during our spring 2017 cycle for her project entitled “Does paternity certainty elicit protection and support of offspring by male gelada monkeys?”

Carrie Miller with a gelada monkey in Ethiopia

Recent studies suggest humans underwent an intermediate stage of polygyny within a multi-level society, similar to multi-level societies observed in gelada monkeys (Theropithecus gelada) or hamadryas baboons (Papio hamadryas). Gelada males employ a range of reproductive strategies and may practice multiple strategies over the course of their life. Leader-males invest heavily in mating effort by defending and maintaining stable breeding bonds with ‘harem’ females in their one-male unit (OMU). Because, the gelada OMU typically has just one breeding male, leader-males should have high paternity certainty. The resulting high paternity certainty makes infanticide a logical strategy for new males taking over an OMU. The multi-level social structure also results in frequent encounters with rival males in all-male bachelor groups seeking to acquire an OMU of their own. However, deposed leader-males often stay on as subordinate follower-males, perhaps to protect their offspring from infanticide following the take-over by a new male. These combined features of gelada societies suggest that males, especially recently deposed leader-males, may benefit by shifting their investment to parenting effort. However, male-immature interactions have not yet been studied in detail in geladas or other primates with multi-level societies.

Guassa Gelada Research Project field site

My project seeks to examine the role multi-level social systems of geladas, which exhibit high paternity certainty and high infanticide risk, may have played in promoting paternal care in the absence of provisioning. I will examine variation in male-immature interactions and long-term paternal effects on immatures through behavioral data collection with gelada monkeys at Guassa, Ethiopia. I will also assign paternity for immatures in the Guassa study population through genetic analysis of fecal samples.

By studying gelada male reproductive strategies and male-immature interactions we can better understand the variation in paternal care and male reproductive strategies observed across human societies. In addition, by studying these questions in a species with a multi-level social system, we will begin to understand the significant role multi-level systems played in the evolution of similar social traits in humans.

Guassa geladas

Riff Raff (infant) and Rafiki (mother)