Questions and Answers About Alesi

Research findings on ‘Alesi,’ a newly discovered  13 million-year-old fossil ape species, were published this week in the journal Nature, and the story has been carried widely in the press. The research team behind the Nyanzapithecus alesi discovery has collaborated to put together this list of questions and answers.

Q: What is the difference between apes and monkeys, and where do humans fit in?

A:  Apes are typically characterized by the absence of a tail, whereas monkeys do have a tail. Humans evolved from a long extinct ape species, and we share the lack of a tail.

Q: How can you tell Alesi is an ape and not a monkey?

A:  Alesi has teeth like an ape rather than any kind of monkey that ever lived in Africa. In addition, Alesi possesses fully developed bony ear tubes, another feature shared with living apes that is not found in more primitive primates.

Akai Ekes (l) and John Ekusi (middle) watch as Isaiah Nengo (r) lifts the sandstone block with Alesi after six hours of excavation. © Isaiah Nengo

Q: Why is the fossil skull nicknamed ‘Alesi’?

A: It is taken from the new species name Nyanzapithecus alesi, which was suggested by John Ekusi, the discoverer of the fossil, because ‘ales’ means ancestor in the local Turkana language.





Q: How do we know how long ago Alesi was alive?

A: The rock layer from which the fossil derived could be identified. A sample of this rock was found to be 13 million-years-old by our project geologist Craig Feibel and dating specialist Sara Mana, based on measurements of argon isotopes. The time period is known as the Miocene.

Q: What is the Miocene?

A:  The Miocene is the geological age that lasted from approximately 23 to 5 million years ago. Apes emerged during this time period and became widespread in Africa and Eurasia.

Experimental setup at the European Synchrotron Radiation facility, used for the high resolution X-ray scanning of Alesi. The skull is mounted on a rotation stage in front of the detector, and a laser beam is used for accurate alignment. © Paul Tafforeau

Q: How can you see that Alesi was an infant rather than an adult?

A: Alesi still had its baby teeth, and none of the adult teeth had yet erupted. The baby teeth can no longer be seen because they broke off when the skull fossilized, but the roots are still in place. The unerupted adult teeth inside the skull can be seen with X-ray imaging.

Q: How do we know how old Alesi was when she/he died?

A: When teeth grow they leave daily growth lines, just like the rings inside a tree. Using an extremely sensitive form of X-ray imaging, our team member Paul Tafforeau could make these growth lines visible in the unerupted teeth of Alesi. By counting them he could calculate an age of one year and four months.


Q: Do we know if Alesi was a boy or girl?

A:  At present we cannot tell whether Alesi was a boy or girl. In humans and apes the features of the skull that distinguish males from females only appear after a certain age, and Alesi was simply too young to display these.

Alesi, the skull of the new extinct ape species Nyanzapithecus alesi (KNM-NP 59050). © Fred Spoor

Q: What did Alesi look like?

A: Compared with living primates the skull looks most like that of a baby gibbon, for example by having a relatively small snout. We don’t have direct evidence about the rest of the body because no other bones than the skull were found. However, there is one indirect clue. The balance organ inside the skull gives information about the way an animal moved around (see additional question below). In the case of Alesi, it suggests slower, more deliberate movements than the tree swinging of gibbons. Hence, Alesi probably did not have the long arms of gibbons that make this acrobatic behavior possible.

Q: If Alesi looked like a baby gibbon, does this mean that it was an extinct gibbon living in Africa?

A: No. The researchers found that gibbon head shape with a small snout evolved several times in primate evolution. For example, the living leaf-eating monkeys (colobines) look superficially like gibbons as well, despite being distantly related. Gibbon-like features evolved independently each time, and does not demonstrate that animals were related to gibbons.

Q: Why is Alesi a new species?

A: Its molar teeth are very similar in shape to those of other species in the genus Nyanzapithecus, which indicates that Alesi belongs to this group. However, its teeth are much larger, suggesting that it was a larger species than the others.

Q: Do we know how Alesi died?

A: The area where Alesi was discovered was long ago blanketed by thick layers of ash from huge volcanic eruptions. Alesi might have been buried and perished in one such ash fall, but we do not know for sure.

Q: Fossil skulls are regularly found and reported in the press. Why is this one any different?

A: Little is known about the time before the living apes started to evolve, which in Africa was only previously documented by isolated teeth and broken jaw fragments. Alesi is not only the most complete extinct ape skull yet found, but it also comes from this poorly understood time period.

Q: Does this discovery mean that humans evolved from apes 13 million-years-ago?

A: No. Alesi is from a time when the common ancestor of all living apes and humans was alive in Africa. In contrast, humans themselves diverged from apes much later, sharing a last common ancestor with chimpanzees about 7 million years ago.

Map of Africa and Kenya, showing the location of Napudet, where Alesi was found. © Isaiah Nengo

Q: Among the living apes, humans are least related to orangutans and gibbons, which both live in Asia only. Does this not mean that ape ancestors lived in Asia rather than Africa?

A: Some experts believe that the ancestors of all living apes evolved in Eurasia, while others believe they evolved in Africa first and then spread to Eurasia. Alesi and its direct relatives are all found in Africa and closely related to the living apes, supporting the idea that the living apes evolved in Africa.

Q: How can you see from the inner ear how an animal moved around?

A: The inner ear is not only the place where you perceive sound (sense of hearing) but also where you perceive how your head is moving (sense of balance). This balance organ leaves an impression in the surrounding bone, so that this can be studied even in fossil skulls that are many million years old. Detailed X-ray imaging revealed that Alesi had a balance organ (semicircular canals) that is associated with slower, more deliberate movements, rather than the acrobatic arm swinging of gibbons.

The work was supported by The Leakey Foundation and trustee Gordon Getty, the Foothill-De Anza Foundation, the Fulbright Scholars Program, the National Geographic Society, the European Synchrotron Radiation Facility and the Max Planck Society.


New infant cranium from the African Miocene sheds light on ape evolution.” Nature August 10, 2017. doi:10.1038/nature23456.

Nengo, I., Tafforeau, P., Gilbert, C.C., Fleagle, J.G.., Miller, E.R., Feibel, C., Fox, D., Feinberg, J., Pugh, K.D., Berruyer, C., Mana, S., Engle, Z. and Spoor, F.


Grantee Spotlight: Matt Tocheri

Matt Tocheri is the Canada Research Chair in Human Origins at Lakehead University and a Research Associate in the Smithsonian Institution’s Human Origins Program. He was awarded a Leakey Foundation Research Grant during our fall 2016 cycle for his project entitled “New archaeological excavations at Liang Bua (Flores, Indonesia).”

Liang Bua, a large limestone cave on the Indonesian island of Flores, is an incredible site best known for the discovery in 2003 of the extinct human species Homo floresiensis. Tourists from Indonesia and around the world visit the site almost daily throughout the year on locally-guided tours. In this image, Matt Tocheri and Thomas Sutikna are sitting at the table discussing plans for their excavations in 2012. (Image Credit: Smithsonian Digitization Program Office and the Liang Bua Team)

In 2003 and 2004, archaeologists excavating on the Indonesian island of Flores uncovered a partial human skeleton roughly six meters beneath the present-day surface of a cave called Liang Bua. Their discovery would soon spark intense scientific debates worldwide and attract a level of public interest rarely seen in any scientific discipline. The recovered skull revealed an extremely small, chimpanzee-sized brain (~400 cm3) while the limb bones showed this fully-grown adult would have stood about 1 m tall and had australopith-like body proportions. The remarkable discovery, which made the cover of the journal Nature in October 2004, presented the world with a new member of the human family tree called Homo floresiensis, referred to informally as the “hobbits” of human evolution.

The implications were startling: human biological diversity during the terminal Pleistocene was significantly larger than what it is today. Until relatively recently our species shared this planet with Neandertals and Denisovans as well as this even more distantly related evolutionary cousin that also walked upright, and made and used stone tools. What exactly happened to this branch of our human family tree is still poorly understood, but current evidence shows that they disappear from the Liang Bua stratigraphic sequence around 60–50 thousand years ago.

We cannot physically travel back in time in order to save this lineage of our family tree from extinction, but we can strive to learn as much as possible about when and why they ultimately went extinct, and whether members of our own species, Homo sapiens, played any direct or indirect role in the process. Building knowledge and understanding about Homo floresiensis provides an important and unique perspective on the ramifications of losing diversity—be it biological, cultural, or linguistic—and helps society and individuals make better, more informed arguments for preserving diversity among all species that survive today.

The location of Flores within Indonesia (a), the location of Liang Bua on Flores (b), and the site plan of main areas excavated in previous years (2001–2004 in red and 2007–2014 in blue) with the targeted area for our current project, funded by The Leakey Foundation, shown in yellow (c) (modified from Sutikna et al., 2016 Nature). Roman numerals denote the Sector names designated by The National Research Centre for Archaeology in Indonesia. The remaining cave floor sediments are shaded white, while the areas shaded brown are exposed rocks, stalagmites and other surfaces covered in speleothems. The image inset at bottom left shows ~12 m2 of the exposed upper surface of the ~20–24 ka-old flowstone that caps the sediments targeted for excavation this year. Our research will begin by removing this flowstone and then continuing in 10-cm intervals while following the stratigraphic units as defined from our previous excavations in this area (see Morley et al., 2017 Journal of Archaeological Science). (Image Credit: the Liang Bua Team)

The stratigraphic sequence at Liang Bua does not end abruptly at 60–50 thousand years ago. A recently excavated 1 x 4 m test trench within the middle rear part of the cave led to the identification of deposits dated to between 46 and 24 thousand years ago that directly overly 60–50-thousand-year-old sediments. Our project, generously funded by The Leakey Foundation, will significantly extend these earlier excavations over a ~12 m2 area in this part of the cave. This offers an unprecedented opportunity to test whether Homo floresiensis and other associated endemic fauna (e.g., pygmy Stegodon) survived after ~50 thousand years ago. At the same time, our project has strong potential to reveal important new knowledge about the arrival, morphology, and behavior of the earliest modern human populations to reach Flores, as well as how this prehistoric dispersal may relate to the successful colonization of Island Southeast Asia and Australia ~50 thousand years ago by the ancestors of living Australomelanesian populations.

The Liang Bua Team in 2016. A majority of our team members are from the villages of Teras, Bere, and Golo Manuk that immediately surround Liang Bua. Many of our local team members have worked at the Liang Bua excavations since 2001 while some even worked for excavations conducted between 1978 and 1989. These local people are incredibly experienced and have considerable archaeological skills and knowledge. Our archaeological research at Liang Bua is a source of great pride among people living in this area and on Flores more broadly. Matt Tocheri is in the top row at far right and Thomas Sutikna (project co-PI), from the University of Wollongong, Australia, is at the far left of the second row from the top. (Image Credit: the Liang Bua Team)


New 13 million-year-old infant skull sheds light on ape ancestry

The Leakey Foundation is proud to have funded the discovery of the most complete Miocene ape skull in the fossil record. The Foundation has awarded a total of 29 research grants to the international research team led by Isaiah Nengo.

Alesi after attached sandstone rock was partially removed at the Turkana Basin Institute, near Lodwar, Kenya. Photo © Isaiah Nengo Photo by Christopher Kiarie.

The discovery in Kenya of a remarkably complete fossil ape skull reveals what the common ancestor of all living apes and humans may have looked like. The find, announced in the scientific journal Nature on August 10th, belongs to an infant that lived about 13 million years ago. The research was done by an international team led by Leakey Foundation grantee Isaiah Nengo of Stony Brook University-affiliated Turkana Basin Institute and De Anza College, U.S.A.

Among living primates, humans are most closely related to the apes, including chimpanzees, gorillas, orangutans and gibbons. Our common ancestor with chimpanzees lived in Africa 6 to 7 million years ago, and many spectacular fossil finds have revealed how humans evolved since then.

In contrast, little is known about the evolution of the common ancestors of living apes and humans before 10 million years ago. Relevant fossils are scarce, consisting mostly of isolated teeth and partial jaw bones. It has therefore been difficult to find answers to two fundamental questions: Did the common ancestor of living apes and humans originate in Africa, and what did these early ancestors look like?


Alesi, the skull of the new extinct ape species Nyanzapithecus alesi (KNM-NP 59050). Photo © Fred Spoor

Now these questions can be more fully addressed because the newly discovered ape fossil, nicknamed Alesi by its discoverers, and known by its museum number KNM-NP 59050, comes from a critical time period in the African past. In 2014, it was spotted by Kenyan fossil hunter John Ekusi in 13 million year-old rock layers in the Napudet area, west of Lake Turkana in northern Kenya. “The Napudet locality offers us a rare glimpse of an African landscape 13 million years ago,” says Craig S. Feibel of Rutgers University-New Brunswick. “A nearby volcano buried the forest where the baby ape lived, preserving the fossil and countless trees. It also provided us with the critical volcanic minerals by which we were able to date the fossil.”

The fossil is the skull of an infant, and it is the most complete extinct ape skull known in the fossil record. Many of the most informative parts of the skull are preserved inside the fossil, and to make these visible the team used an extremely sensitive form of 3D X-ray imaging at the synchrotron facility in Grenoble, France. “We were able to reveal the brain cavity, the inner ears and the unerupted adult teeth with their daily record of growth lines,” says Paul Tafforeau of the European Synchrotron Radiation Facility. “The quality of our images was so good that we could establish from the teeth that the infant was about 1 year and 4 months old when it died.”

3D animation of the Alesi skull computed from the ESRF microtomographic data. It shows first the skull in solid 3D rendering, then transparent surface rendering is used to show the endocast shape (light blue), the internal ears (green) and the permanent teeth germs (grey and brown). © Paul Tafforeau / ESRF

The unerupted adult teeth inside the infant ape’s skull also indicate that the specimen belonged to a new species, Nyanzapithecus alesi. The species name is taken from the Turkana word for ancestor “ales.” “Until now, all Nyanzapithecus species were only known from teeth and it was an open question whether or not they were even apes,” notes John Fleagle of Stony Brook University.  “Importantly, the cranium has fully developed bony ear tubes, an important feature linking it with living apes,” adds Ellen Miller of Wake Forest University.

Alesi’s skull is about the size of a lemon, and with its notably small snout it looks most like a baby gibbon. “This gives the initial impression that it is an extinct gibbon,” observes Chris Gilbert of Hunter College, New York. “However, our analyses show that this appearance is not exclusively found in gibbons, and it evolved multiple times among extinct apes, monkeys, and their relatives.”

That the new species was certainly not gibbon-like in the way it behaved could be shown from the balance organ inside the inner ears. “Gibbons are well known for their fast and acrobatic behavior in trees,” says Fred Spoor of University College London and the Max Planck Institute of Evolutionary Anthropology, “but the inner ears of Alesi show that it would have had a much more cautious way of moving around.”

“Nyanzapithecus alesi was part of a group of primates that existed in Africa for over 10 million years,” concludes lead author Isaiah Nengo. “What the discovery of Alesi shows is that this group was close to the origin of living apes and humans and that this origin was African.”

Akai Ekes and John Ekusi watch as Isaiah Nengo lifts the sandstone block with Alesi after six hours of excavation. Photo © Isaiah Nengo.

The work was supported by The Leakey Foundation and trustee Gordon Getty, the Foothill-De Anza Foundation, the Fulbright Scholars Program, the National Geographic Society, the European Synchrotron Radiation Facility and the Max Planck Society.

Your support made this discovery possible. Support the next big discovery! Your donation will be doubled.


Nengo, I., Tafforeau, P., Gilbert, C.C., Fleagle, J.G.., Miller, E.R., Feibel, C., Fox, D., Feinberg, J., Pugh, K.D., Berruyer, C., Mana, S., Engle, Z. and Spoor, F. New infant cranium from the African Miocene sheds light on ape evolution. Nature 10 August 2017. doi:10.1038/nature23456.

Video about the discovery of a 13 million-year-old fossil ape skull. Produced by Scott Bjelland, Turkana Basin Institute. Images used with permission.

From the Field: Kathryn McGrath

Kathryn McGrath was awarded a Leakey Foundation Research Grant in our spring 2016 cycle for her project entitled “Understanding stress-related enamel defects in wild mountain gorillas.” Click here to read a short summary of her work. Here she updates us on her progress. 

A female chimpanzee canine thin section.

I received a Leakey Foundation Research Grant one year ago, and since then, I’ve traveled around Europe to collect data for my dissertation, analyzed much of it, presented at five (!) conferences (and was accepted to present at two more), and got one award. I actually had to bring my own microscope to image great ape canine thin sections, which was more complicated than I had initially hoped, though not quite as tricky as that time I brought an X-ray gun as a carry-on.

Teeth grow in incremental layers, and just like trees, they can be counted and measured to learn about the rate and duration of their growth. I chose canines for my dissertation because they take the longest to form in great apes (think male gorilla fangs), and thus provide a nice, long window into the early life of the animals to which they belonged.

The first chapter of my dissertation focuses on what information we can glean from the outside of great ape canines, because most teeth can’t realistically be cut in half to learn about how they grew. Luckily, unlike trees, most of the growth rings in teeth are also visible from the outer surface, and they appear as horizontal waves around the tooth. When normal growth is disrupted by events like injury or illness, more pronounced grooves are formed, like the one pictured here.

A male mountain gorilla’s lower canine (left), and a digital elevation model of a defect (right).

These grooves or defects are fairly well-understood in humans because researchers have easier access to health records and other information about the way we live, but opportunities to study their causes in great apes are rare. We know that great ape canines usually have defects, but only recently have researchers begun to measure their shape using sophisticated imaging techniques, like the one used here. I scanned defects in a number of great ape species, created digital elevation models (pictured), and extracted coordinates to compare their depths. Some researchers have proposed that depth is related to the severity of the insult that caused the defect, like a life-threatening illness as opposed to a minor cold, while others have suggested that defect depth has more to do with the way each species grows their teeth. Different rates of enamel growth are hypothesized to correspond to different geometries in the underlying tissue, which might lead to discernible variation in defect depth between species.

In our study, we found that mountain gorillas, the fast-growing, leaf-eating gorillas, have shallower defects than other great apes, including closely-related western lowland gorillas. We think that this mostly has to do with the way that mountain gorillas grow their teeth, although future studies incorporating health and behavioral records from when individual gorillas were alive will assess what kinds of life events might correspond to these defects. We want to know, for example, whether social stress corresponds to defects in the developing teeth of a gorilla, or if they are more commonly associated with physical injuries and illness.

A surprising result of this study is that the deepest defect in the sample belonged to a western lowland gorilla named Haloko who was born in the wild and captured to live in a zoo when she was around 2-3 years old. Based on previous studies of western lowland gorilla canine development, we think that this major defect, which is about ten times deeper than the typical defect in her species, might correspond to her capture from the wild. We can’t be sure of the timing because we aren’t able to create thin sections from her teeth, which is the only way to reliably count the growth increments, but I hope to follow up on this story in my postdoctoral research by studying other great apes that were captured from the wild as infants to see if they have similarly marked defects in their teeth.

Haloko, courtesy of the Smithsonian’s National Zoological Park (left), and a replica of her lower canine with a major defect that might correspond to her capture from the wild (right).

What I’ve learned so far is that the processes behind dental defect formation are super complicated. On the one hand, there are clear species differences in defect depth, and preliminary data from associated thin sections suggest that this has a lot to do with the way these different animals grow their teeth. On the other hand, examples like Haloko with very traumatic histories and corresponding deep defects imply that the severity of the growth disruption might also have something to do with depth. Even though there is still a lot to learn from our closest living relatives in terms of what these defects mean, this study provides an important caveat for researchers interested in studying dental defects in our fossil ancestors. We should be careful when interpreting defect “severity” without measuring a number of teeth from the same species first. A defect that might appear shallow in one specimen might actually represent the species-typical pattern, as in mountain gorillas.

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The most meaningful part of my work as a Leakey grantee is sharing my passion for teeth with kids. At the most recent American Association of Physical Anthropologists meeting in New Orleans, I participated in Education Committee-organized outreach sessions with AP Biology students at a local high school. We talked about chimpanzee behavior, the scientific method, the latest fossil finds from South Africa, and of course, gorilla teeth.

AAPA morning outreach team: John Mitani, Caitlin Schrein, the author, and John Mead

There was a special moment when I walked around the room holding a replica of a chimpanzee canine that came from the Tulane University collections, right in their backyard. This animal has remarkably deep defects all along its canines, representing some kind of repeated growth disruptions throughout early life. In my day-to-day routine, when I’m struggling to find the motivation to power through excel spreadsheets and scientific papers, I think back to those moments when at least a few kids in the classroom seemed to really appreciate what I’m doing, and I feel recharged.

Male chimpanzee canine with repeated defects.

This story is far from over, and I still have about one year left before I become Dr. McGrath, but I would like to express my deepest gratitude to The Leakey Foundation for their support of not only my research, but also my outreach and science communication. Every bit of evidence suggests that we need to prioritize sharing our science, and the Leakey Foundation is doing just that.

I’d also like to thank Sireen El Zaatari for hosting me at Universität Tübingen; Marcia Ponce de León, Christopher Dean, Wendy Dirks, Donald J. Reid, Kristofer Helgen and Darrin Lunde for access to specimens; Arnaud Martin for access to equipment; the Mountain Gorilla Skeletal Project and partners including Dian Fossey Gorilla Fund International, the Rwanda Development Board, and the Gorilla Doctors; Briana Pobiner from the AAPA Education Committee; my interns, dissertation committee, and coauthors; the National Science Foundation; George Washington University and my advisor, Shannon McFarlin, for everything.

Primate Tales: The Story of Moth, a White-Faced Capuchin

Primate Tales is a new blog series that explores the lives of individual apes and monkeys at research sites supported by The Leakey Foundation. The first installment of our Primate Tales series is the story of Moth, a male capuchin monkey that lives in Costa Rica. He is one of the monkeys studied by Leakey Foundation grantee Susan Perry as part of the Lomas Barbudal Monkey Project. These capuchins have become one of the most intensively studied wild monkey populations in the world.

By Susan Perry, Lomas Barbudal Monkey Project in Costa Rica


Moth is a male white-faced capuchin monkey. Photo: Susan Perry

Moth with his daughter Hildegard von Bingen and granddaughter Vision. Photo credit: Jamin Shih

Moth was born into Rambo’s group in 1992. The circumstances of his birth were somewhat unusual, as he is one of very few individuals born into this population who was not sired by the alpha male. Moth was sired by Doble, the closest ally of the alpha male Pablo. Moth has always been an unusually large and greedy male.  He was always skilled at rough and tumble play and (later) at fighting. He is one of the two largest males in the history of the project.

When he was 7 years old, his mother (Keeda) left Rambo’s group with the rest of her matriline to form their own group (Splinter group). Moth chose to remain in his father’s group, where there were more young males to play with, but he no longer had any close matrilineal kin in the group. As we know from our long-term study, Moth’s decision was typical: Males of this species exhibit unusually strong loyalty to their fathers and also generally prefer to stay with male playmates rather than with their mothers during a fission.

Moth began leaving the group to visit neighboring groups when he was ten years old. He mainly did this in the company of his two closest playmates, Newman and Tranquilo. When he was 11 years old he successfully invaded the neighboring Abby’s group and became alpha male for a few weeks. As soon as he successfully invaded with the help of his ally Tranquilo, he turned on Tranquilo, evicting from the group. He killed the infant of one of the females there, and the group evicted him. (Perhaps he would have fared better had he retained his ally!)

Moth cuddles up with female Mombassa and her infant Yankee. Photo credit: Jamin Shih

Moth returned to his natal group and stayed there for the remainder of his life. This is where his odd circumstances of birth were of assistance to him. His own father left the group around this time, never to return, so he was no longer co-residing with either of his parents. Pablo (the alpha male of that group) had many adult daughters (and even granddaughters) because he had been alpha male for ~17 years. There is strong father-daughter inbreeding avoidance in capuchins, so Pablo couldn’t mate with his own female descendants. This meant that Moth, who was less related to these females than any other natal male, could breed while remaining in his natal group; he conceived seven offspring while living in Rambo’s group as a subordinate natal male. Moth, with his superior fighting skills, was effective in helping Pablo defend the group from would-be invaders.  They had what seemed to be almost a co-alpha arrangement in which the elderly Pablo (now in his late 20’s) contributed the political expertise and Moth (who was always more interested in eating than in socializing) contributed physical formidability.  They co-resided comfortably until 2008, when Moth fought Pablo and wounded him. Pablo stepped down as alpha male then and stopped siring offspring. Moth permitted Pablo to remain in the group as a subordinate male till his death nearly 2 years later, enabling Pablo to care for his children and grandchildren.

Moth naps with immigrant male Bentley. Photo credit: Jamin Shih

Moth permitted various other pairs of co-migrants to immigrate to his group and never seemed particularly concerned about these arrivals (which is unusual for an alpha male). The only time any of these migrants launched an attack on Moth was when he was handicapped for a while by breaking his leg. Two subordinate males took turns at being alpha male during the early stages of this injury, but Moth soon regained alpha status, ruling from the ground until his leg had fully healed. His many fans took to playing and socializing on the ground during his healing phase, so that they could be with him.

Rambo’s group fared well under Moth’s rule until 2014-15, when there was a major drought (caused by El Niño). Many members of the group died (apparently of hunger) during this time, bringing the group down in size from 23 to 10 members during the latter half of 2015. Moth, surprisingly, was one of the members who vanished despite his extreme skill in finding food. We don’t know what the cause of his death was, and in theory, he could have just migrated to a different group outside the study area. But he has not been seen in the past year, and it is rare for males to abandon their own offspring, so we think we can fairly safely conclude that this memorable male has completed his lifespan.

The Lomas Barbudal Monkey Project was founded in 1990 by Leakey Foundation grantee Susan Perry with the help of Joseph Manson and Julie Gros-Louis for the purpose of studying social intelligence in the white-faced capuchin, Cebus capucinus, and this population has been studied almost continuously ever since.

The Leakey Foundation is proud to support this and other long term primate research sites around the world. You can help support long term research by making a donation today!