Category Archives: Life Histories

Amy Kass

In the Odyssey, the goddess Athena appears to young Telemachos in the form of an old man, Mentor. In this guise, Athena tells Telemachus what he needs to do.

At the University of Chicago, Amy Kass appeared to many of us as a Mentor. But she didn’t tell us what to do. She didn’t give us the answers. Instead, she asked us questions:

“Who is someone you think of as an example of human excellence?”

“Is it better to be a virtuoso, or virtuous?”

“What will be the most important decision that you make in your life?”

She didn’t dispense a particular body of knowledge to students: chemistry, physics, classics, literature, or philosophy. Instead, she served as a guide, helping students learn to read great books, and to think seriously about big questions in their lives.

I first met Amy Kass  the summer after my junior year in high school, when I spent six weeks at the University of Chicago for a Telluride Association Summer Program. Amy and another great teacher, her husband Leon, led the seminar, Science and Society: Knowledge Morals and Power. Eager for more classes like this, I returned to Chicago for college, where I took Human and Being and Citizen with Mrs. Kass. We read Homer (the Iliad), Genesis, Aristotle (The Nicomachean Ethics), Shakespeare (King Lear), Rousseau (Discourse on the Origin of Inequality), Kant (Foundations of the Metaphysics of Morals), Dostoevsky (Crime and Punishment), Luke. We read about examples of human beings: Abraham, Achilleus, the Great Souled Man, Lear, Savage Man, Rational Man, Raskolnikov, Jesus. We talked about what, if anything, was excellent about these men (and looking back, yes, in that class, the exemplary human beings were all men).

Class took place in seminars: twenty or so students gathered around a set of tables arranged in a square. We read and we talked. Mrs. Kass asked questions. She was slender and small, with bright eyes and silvering hair. She leaned forward when she spoke, gesturing with her hand, looking intently at each student. We called each other by last names and titles: Mr., Miss, or Mrs. Everyone had a place at the table, and the value of your ideas didn’t depend on your title or rank. Everyone was treated as an adult, and with respect. She encouraged us to speak our minds, and to disagree with her and one another, but to do so through discussions (“What is right?”), not arguments (“Who is right?”).

Amy Kass at the 1986 Telluride Association Summer Program in Chicago.
Amy Kass at the 1986 Telluride Association Summer Program in Chicago.

Mrs. Kass didn’t lecture. She didn’t tell us her views on things, at least not directly. She asked questions and listened to our answers. She knew our names, she knew who we were, and despite her years of teaching these books to students, she seemed genuinely interested in what we had to say about them. How often does a class of first year college students say something really new or surprising about Homer or Shakespeare? But she never seemed jaded or condescending towards her students. She wasn’t interested in whether we could say something clever or novel; she was interested in our development as readers and thinkers.

She led us through the readings slowly. She asked a student to read a passage, then we discussed what it meant. We might spend an entire class period discussing a few such passages.

Mrs. Kass helped teach us to read.

I didn’t know how to read when I started college. Even by the time I finished college I’m not so sure if I could read; these lessons have taken time to really sink in. Oh, I read lots of books, but I skimmed along the surface, and often didn’t even understand the surface. Too often, reading was something I did at the end of a long day of lectures, labs and problem sets, slouching in a big chair in a bay window of the Regenstein Library, underlining and querying a few puzzling sentences before dozing off.

But in class, we read aloud, we read slowly, and we read for understanding.

Mrs. Kass began a discussion of Book IV of The Iliad by asking, “If I asked you who you were, what would you tell me?”

“I’m a 20th Century American.”

“And how does Homer introduce these men? Who is, say, Echepelos?”

“He’s… um….” searching the page for the name, “Thalysias’s son.”

“And Elephenor?”

Okay, there’s his name a few lines down. “Chalkodon’s son.”

In the world of The Iliad, you weren’t an isolated human being, or an undifferentiated member of a particular society in a particular time. You were someone’s son or daughter.

Then we moved on to the next page, where Antiphos, a son of Priam, killed Leukos, “a brave companion of Odysseus,” as Leukos was dragging off a corpse. Odysseus, “stirred to terrible anger,” struck down Demokoön, a son of Priam.1986-07 Eileen Helen Amy Mike Kim Tricia

Mrs. Kass asked, “Why did Odysseys kill Demokoön, and not Antiphos?”

I hadn’t even thought to wonder about this; my eyes had glazed over in the series of seemingly random, bloody killings on the battlefield.

Mrs. Kass persisted. “Who is Demokoön?”

“He’s Priam’s son. Oh. Odysseus killed his brother.”

Instead of seeking revenge by killing the killer, Odysseus inflicted a more painful, longer lasting wound, by killing the killer’s brother. And so a seemingly unimportant detail was revealed as an illustration of the cruel wisdom of Odysseus.

With Mrs. Kass, we read old books. The most recently written thing we read was Dostoevsky’s 1866 novel; not one of her favorites, and one that must have been chosen by others on the course committee, judging by a comment she made after a class spent discussing this book: “This is my punishment; what was my crime?”

One thing we learn from the standard university curriculum is how wrong people were in the past. Aristotle appears in science textbooks mainly as someone who got things wrong: that a heavier object falls faster than a lighter object; that there are four basic elements; that the sex of human babies is determined by temperature. We learn about Descartes’ error (mind-body dualism) rather than anything he got right. The basic lesson of the textbooks is: people in the past were ignorant. They didn’t know germ theory, or atomic theory, or evolution.

And it’s not just in the remote past that people were ignorant. By the time I reached college, scientific views of the solar system, of dinosaurs, and so many other things had changed dramatically from what I remembered learning as a child. Every year, we know so much more than we did before.

It’s easy – and self-gratifying – to be smug about how smart we are today. We know so much more. We are right about so many things.

Mrs. Kass helped us see that despite how much we know now, we still had much to learn from close reading of Homer, Aristotle and Shakespeare, even if they are Dead White Males, even if they lived before the discovery of quantum physics and the genetic code, even if their views on politics and religion might sometimes seem old fashioned (though perhaps not always so old fashioned as one might expect). She helped us understand the difference between knowledge and wisdom.

Despite all the changes over centuries and millennia, much about the human condition remains the same. We are born, we grow up, we search for a path to follow. We seek love and friendship. We may marry, we may have children. If we live long enough, we grow old. Whether we live long enough or not, we die. Even people admired for excellence have their quirks, weaknesses, and sometimes terrible, fatal flaws.

Universities have plenty of classes that provide answers. But few classes ask questions. And hardly any classes ask questions that are really the most important ones for young people trying to find their way in life.

When Mrs. Kass asked her class, “What is the most important decision you will have to make,” most students answered something to do with their careers. One young man responded: “Who will be the mother of my children?”

The answer sounded old fashioned, and embarrassingly serious. But really, what could be more important?

I wanted answers. I wanted to know. While we were reading Kant, I asked Mrs. Kass what was her foundation for morality. She threw up her hands and laughed. “Standing on one leg?” she asked.

If it were that easy – if you could give an answer to this question, standing on one leg like a circus performer – then we wouldn’t need to spend hours reading, thinking, and discussing these questions. A short lecture on moral foundations would do.

We read about many different kinds of human excellence, but none of these literary examples struck me as vividly as the example of Mrs. Kass herself: intensely smart but never merely clever or showy; respectful, but not afraid to question or disagree; inclusive; courageous; serious yet also wry, funny and good humored; challenging us all to be better.

The last time I saw Mrs. Kass, she was discussing with a young person an assignment for a class on Shakespeare, taught by someone else. The student had developed a particular view of how to interpret a passage, but was worried that her teacher would disagree with this interpretation. Mrs. Kass asked her, “Do you want a good grade? Or do you want to be right?”

Amy Kass died Wednesday, 19 August 2015, less than a month before what would have been her 75th birthday.

I have not known a better teacher.

Irven DeVore

On Tuesday, 23 September, I lectured to my Primate Ecology and Social Behavior class about how methods of measuring behavior have changed since the first pioneering studies in field primatology. As an example of the importance of methodology, I used baboon troop progressions, a controversy starring Irv DeVore. That night, I learned from Greg Laden that Irv had died that same day, a couple of weeks shy of his 80th birthday.

I first met Irv twenty years ago, when I visited Harvard as a prospective graduate student. He sat at the big desk in the corner office of the Peabody Museum, at the top of the stairs. The bathroom outside his office stank of cigarette smoke because that’s one of the few places in the building he could get away with smoking. Irv looked a bit like Colonel Sanders: white hair, mustache and goatee, a tall southern gentleman, wearing a khaki field vest like he had just gotten back from safari and hadn’t had time to change clothes. The books packing the tall bookshelves included classics that Irv had edited: Primate Behavior: Field Studies of Monkeys and Apes (1965), Man the Hunter (1968) and others. From the walls hung artifacts from Africa: bows and arrows, spears, wood carvings.

We talked about baboons. At the time, I was working for Jeanne Altmann, managing data for the Amboseli Baboon Project, and had spent about ten months at Mpala Research Camp in Kenya habituating baboons for a Kenyan PhD student, Philip Muruthi. Irv told me about his own days studying baboons in Kenya.

Starting in 1959, as a student of Sherwood Washburn, Irv studied baboons in Amboseli and Nairobi National Park. At the time, very few people had studied primates in the wild in any detail. This was the same year that George Schaller began his pioneering studies of mountain gorillas, and a year before Jane Goodall began studying chimpanzees at Gombe. As this figure shows, Irv started studying baboons right at the start of an exponential increase in hours devoted to field studies of primates:

Time devoted to field studies of primates (from Altman, 1965)
Time devoted to field studies of primates (from Altman, 1967)







When I first met Irv, I was mostly ignorant of the many disputes in the history of baboon studies. The example I used in class the other day, about baboon troop progressions, was something that I only learned about later. It’s little more than a footnote now in primate studies, and perhaps not worth dwelling on, but is something I keep coming back to, as an example of methodology, an illustration of how science works, and a point of departure for thinking of Irv’s long and influential career.

By the 1950s, anthropologists were beginning to take seriously the idea that humans had evolved in Africa. Raymond Dart had discovered the oldest known hominin fossil, Australopithecus africanus, in South Africa (Dart, 1925). In attempting to reconstruct the likely behavior of Australopithecus, Dart drew on what was then known about baboons, which were the most conspicuous primates living where the fossil had been found:  on the open plains on the edge of the Kalahari Desert. Dart knew that baboons sometimes hunted and ate meat, which he used to support his view of Australopithecus as having made the transition from “fruit-eating, forest-loving apes” to  “the sanguinary pursuits and carnivorous habits of proto-men” (Dart, 1953).

Washburn hit on the idea of studying baboon behavior while at the 1955 Pan-African Conference in Prehistory in Northern Rhodesia, with Raymond Dart and Louis Leakey. Primarily a comparative anatomist, Washburn had dissected many baboons, which were considered vermin and could be shot at will. But at the Victoria Falls Hotel, Washburn began actually watching live baboons, and found their behavior fascinating, and relevant for testing many ideas about human evolution (DeVore, 1992).

Back in his home base at the University of Chicago, Washburn recruited DeVore to study baboons. At the time, Irv was a grad student in cultural anthropology, with no formal training in animal behavior. As a pioneering researcher, though, Irv quickly became the expert on baboon behavior. He and Washburn published their findings widely, in Scientific American, in edited volumes about primate behavior and human evolution, and in a series of educational films and pamphlets.

One of the puzzles in human evolution was how our ancestors could have survived on open plains inhabited by dangerous carnivores such as lions and leopards. DeVore and Washburn saw baboon troop progressions as an adaptation to keeping safe in this hazardous environment:

Illustration of a baboon troop progression from Hall & Devore (1965)
Illustration of a baboon troop progression from Hall & DeVore (1965)

A baboon troop that is in or under trees seems to have no particular organization, but when the troop moves out onto the open plains, a clear order of progression appears. Out in front of the troop move the boldest troop members-the less dominant adult males and the older juvenile males . . . Following them are other members of the troop’s periphery, pregnant and estrus adult females and juveniles. Next, in the center, comes the nucleus of dominant adult males, females with infants, and young juveniles. The rear of the troop is a mirror image of its front, with adults and older juveniles following the nucleus and more adult males at the end. This order of progression is invariably followed when the troop is moving rapidly from one feeding area to another during the day, and to its sleeping trees at dusk . . . (DeVore & Washburn, 1963)

There was a clear adaptive logic to this organization:

The arrangement of the troop members when they are moving insures maximum protection for the infants and juveniles in the center of the troop. An approaching predator would first encounter the adult males on the troop’s periphery, and then the adult males in the center, before it could reach defenseless troop members in the center. (DeVore & Washburn, 1963)

This idea that baboon societies were geometrically organized for protection appealed to people and became widely cited. As late as 1997 or 1998, I found a textbook in an elementary school in rural Uganda that contained a description of baboons that must have been adapted directly from DeVore’s publications. It faithfully replicated claims about the baboon troop progression, illustrated with line drawings of baboons.

Irv soon moved on from baboons to study hunter-gatherers and work in various ways to bring evolutionary theory into the study of human behavior. In the meantime, other researchers began studying baboons, including Stuart and Jeanne Altmann, who began doing fieldwork in Amboseli in 1963, soon after Irv’s pioneering studies there. Stuart was a leader in the newly emerging field of primatology, having studied rhesus macaques on Cayo Santiago and howling monkeys in Panama. As a graduate student of E. O. Wilson at Harvard, Stuart was one of the first researchers to use the term “sociobiology,” which he used to describe his approach to studying rhesus monkeys on Cayo. In his 1962 paper on rhesus monkeys, Stuart lists Irv as one on of the visitors to Cayo, sometime around 1957-58, so Irv must have visited Cayo before his own first trip to Kenya. Irv studied baboons for a few years; the Altmanns worked together for decades, establishing a long-term project that continues to examine many different aspects of baboon behavior and ecology.

In the midst of documenting many aspects of baboon lives, Stuart made a concerted effort to study baboon progressions (Altmann, 1979). This passage from the methods section of his 1979 paper illustrates the meticulous observations he undertook to test the hypothesis that baboon movements represent an orderly geometry:

Baboons in progressions were censused at opportune times during the course of several projects. With experience, we learned to anticipate their route of progression. From a position ahead of and to the side of the anticipated route, we selected a line of sight that was as free as possible of obstructing vegetation. We picked out some small visual marker, such as a rock or the edge of a distant tree, that would clearly fix the line of sight or ‘counting point’. Then, as each individual in turn walked past this imaginary line, its age-sex class was recorded. Whenever two individuals were close together as they passed the counting point, the order was determined ‘horse race style’, i.e. depending on whose nares crossed first. If an individual turned back across the counting point, then crossed it a second time, it was counted as being in its second position. Whenever possible, individual identifications were made. . . .  During many of these censuses, a second observer not only confirmed observations but also continued to observe individuals that were inadequately observed by the primary observer, who remained with eyes fixed on the counting point so as not to miss the next individual. Observations were facilitated by using 7x, 35mm (or 10x, 50 mm) binoculars, propped in position so that the observer could keep continuous watch on the counting point. Data were usually dictated into a portable cassette recorder, thereby eliminating any need to look down to write. (Altmann 1979: 49-50)

Analyzing data recording during many such observations, Stuart found that baboon progressions were essentially random, rather than strictly ordered:

In none of the baboon groups that we have studied is there a fixed progression order, either by individual or by age-sex class. Indeed, we have seen members of virtually every age-sex at every place in the group, including adult females with small, clinging infants in the front and rear of the group. (Altmann, 1979: 51)

So, as it turns out, Irv’s initial hypothesis about the geometry of baboon troop progressions was wrong. Irv would later tell his class of 500 students that he had done it all wrong, that none of the methods he used then would pass muster today. But Irv was one of the first. He was proud of his baboon films, which he said were the  first wildlife films to use synchronized sound (rather than simply adding sound in later). These films served as many students’ first introduction to baboon behavior. He drew attention to baboons and other wild primates as important subjects for understanding human nature and evolution. He inspired and taught generations of students who followed, including many who would become major figures in primate studies, including John Fleagle, Peter Rodman, Sarah Hrdy,  Patricia Whitten, Jim Moore, Barbara Smuts, Karen Strier, and others.

Irv was my co-advisor for my first years in grad school, and though this formal role lasted only a year or two, I learned a great deal from him , especially while serving on the team of Teaching Fellows for his giant lecture course, Science B-29.

While Irv nurtured and inspired primatologists for his entire career, long before I met him he had switched his focus back to humans. Starting in the mid-1960s, he helped launch modern studies of hunter-gatherers, advising Richard Lee and a series of others in studies of the !Kung San, who as a result became the proto-typical hunter-gatherers. The !Kung exhibit on the ground floor of the Peabody Museum beautifully depicted the material culture and lifeways documented by this project, with video interviews describing the rapidly changing conditions of their lives in more recent years.

In the 1970s, Irv embraced and promoted sociobiology, mentoring pioneers in the field including Bob Trivers and Sarah Hrdy. In the 1980s he assisted at the birth  of evolutionary psychology, advising John Tooby and mentoring others who became leaders of this new field.

When I was a graduate student, writing up my thesis, Irv dropped by my office one day, and noticed a copy of Primate Behavior on my shelf. He asked, “What are you doing with that old thing?”

Perhaps it was false modesty, but he seemed genuinely surprised that anyone would consult his old tome. I think he felt keenly that his earliest work had been supplanted by the rapid progress of primatology.

His obituary in the New York Times states:

While true that he never wrote a groundbreaking book that lasted the ravages of time, he was most proud of his students and spent his life nurturing them, mentoring them (as long as that didn’t include actually writing the letter of recommendation) and forcing his wife to edit their theses.

Irv published a number of books and other works, but his  list of publications doesn’t come close to reflecting his intellectual influence.

For evolutionary anthropology, Irv DeVore played a role a little bit like that played by Socrates in Greek philosophy.

As far as we know, Socrates never wrote anything. Instead, Socrates served as a teacher, asking questions, probing minds, encouraging people to question received wisdom.

Socrates never held a university position, or taught students in a formal classroom. Irv was a professor at Harvard and regularly taught a class of 500. However, like Socrates, Irv was most influential in informal settings. In Plato’s dialogues, the main source of information we have about Socrates, we often see Socrates as a guest at dinner parties. Irv seems to have been most at home, and most influential, in the Simian Seminars, the informal meetings that took place a couple of times a month at his home.

By the time I started grad school, the Simian Seminars were mainly the stuff of legend. We saw Irv regularly, as a lecturer, in seminars, and at beer hour (where he complained about the bitter, hoppy microbrews that the grad students favored), but the heyday of the Simian Seminars seems to have been from the 1970s through the early 1990s. Sarah Hrdy writes about them here.

In Plato’s Republic, Socrates discusses philosophy with a gathering of young men. It’s basically a dinner party. The discussion begins with an exchange between Socrates and an old man, Cephalus, who, seeing the end of his life approaching, busies himself with making sacrifices to the gods, to make sure things go well for him in the afterlife. Cephalus is pious and conventional. The conversation really gets going only after Cephalus leaves to make more sacrifices to the gods.

The Simian Seminars seem to have been a place where old Cephalus was not invited: a safe zone from pieties and conventional thinking.

At Simian Seminars almost no idea or topic was too sensitive, too politically incorrect or too bawdy to be off limits. This openness was made possible by an atmosphere of mutual trust, respect, and affection, which was very deliberately cultivated by the DeVores. (Hrdy, 2005)

In The Republic, the main impiety committed by Socrates was to talk about Justice without reference to the gods. As Plato describes in another work, The Apology, in the end Socrates was tried and executed for impiety. Among his crimes: teaching the young that the planets were not gods but were instead made of stone. But while Socrates may have held materialist views in regards to the planets, he still talked frequently of gods, daemons, souls, and an ideal world, arguing that the material world we see around us is a mere shadow of a higher reality.

Irv promoted an even more profound impiety: a serious embrace of evolutionary thinking. Daniel Dennett describes evolution as “the universal acid” (Dennett, 1996). It cuts through everything. Irv saw this and embraced it, and encouraged his students and friends and colleagues to think hard about what an evolutionary understanding of human nature really means.

Unlike Socrates, Irv was never tried for thought crimes, or forced to drink hemlock. But he did attract critics and and controversy. In Primate Visions , Donna Haraway uses DeVore as her main example of “the bad old days” before primatologists took notice of female primates. The schools of thought that Irv championed, sociobiology and evolutionary psychology, have long attracted controversy, and have been criticized by some for having a sexist bias. At least some of this criticism seems to result from people focusing on the titles rather than the contents of books. For example, many people seem to think that Lee and DeVore’s 1968 book Man the Hunter is devoted to celebrating the macho side of human evolution. Those who have read the book, though, will know that the authors actually argued against some widely held male-centered views. For example, Lee and DeVore argued that hunter-gatherer societies are often not organized along lines of male kinship (in contrast to the prevailing view at the time). Although the book’s title emphasized the meat hunted by men, inside the book the authors emphasized the importance of plant foods, which were mainly collected by women.

Because Socrates wrote nothing that survives, we know about him only from what was written by others. His followers, Plato and Xenophon, depict Socrates as a paragon of virtue and intellect; the playwright Aristophanes depicts Socrates as a clown. Similarly, Irv is perhaps better known from the words of his disciples and detractors than from his own work. And while detractors depicted Irv as someone focused on alpha male baboons and hunting men, as a mentor Irv championed both his male and female students. In Plato’s dialogues, only men participated in the philosophical discussions with Socrates. In the 1970s, some 2300 years later, women were still often excluded from important discussions. As Sarah Hrdy describes, though, the Simian Seminars welcomed women from the very beginning:

For many graduate students, these gatherings were the core of an unbelievably heady education. The format was especially important for women students, who in those days would often have been excluded from post-seminar gatherings where men talked out the issues over a beer, somewhere else. (Hrdy, 2005)

Irv was a pioneer. He was not a master of collecting or analyzing large datasets. But he was a great story teller. As a lecturer, he held the attention of hundreds of undergraduates every semester for decades.  Students laughed at his jokes and remembered details of his stories for years to come. He inspired many people to go out and check his stories, to prove him right or wrong. Most importantly, his overall vision of how to answer questions about human nature is, I think, spot on. To understand human nature, we need to take evolutionary theory seriously. We need to approach the world with an open, critical and creative mind. We need to test hypotheses with empirical data, not just philosophical introspection. We need to pay particular attention to the behavior and ecology of our primate cousins, and to people living as hunter-gatherers. Evolutionary principles hold enormous promise for explaining the behavior of people everywhere and everywhen. And in a lifetime devoted to implementing this vision, Irv championed collaborative work, took chances on unconventional students and ideas, and was not afraid to admit when he was wrong.

Irv DeVore at his last lecture, 15 December 2000. (Photo by Randall Collura)
Irv DeVore at his last lecture for Science B-29, 15 December 2000. (Photo by Randall Collura)










Altmann, S. A. (1962). “A field study of the sociobiology of rhesus monkeys, Macaca mulatta.” Ann N Y Acad Sci 102: 338-435.

Altmann, S. A., Ed. (1967). Social Communication among Primates. Midway reprints. Chicago, University of Chicago Press.

Altmann, S. A. (1979). “Baboon progressions: order or chaos? A study of of one-dimensional group geometry.” Animal Behaviour 27: 46-80.

Dart, R. A. (1953). “The predatory transition from ape to man.” International Anthropological and Linguistic Review 1(4): 201-218.

Dennett, D. C. (1996). Darwin’s Dangerous Idea: Evolution and the Meanings of Life. New York, Simon & Schuster.

DeVore, I. and S. L. Washburn (1963). “Baboon ecology and human evolution.” African Ecology and Human Evolution. C. F. Howell and F. Bourlière, Eds.. Chicago, Adline: 335-367.

DeVore, I. and S. L. Washburn (1992). “An interview with Sherwood Washburn.” Current Anthropology 33(4): 411-423.

Hall, K. R. L., & I. DeVore (1965). “Baboon social behavior.” Primate Behavior: Field Studies of Monkeys and Apes. I. DeVore, Ed. New York, London: 53-110.

Haraway, D. J. (1989). Primate Visions: Gender, Race, and Nature in the World of Modern Science. New York, Routledge.

Hrdy, S. B. (2005). “Milestones for Irv DeVore and the Simian Seminar.” Evolutionary Anthropology 14: 90-92.

Lee, R. and I. DeVore, Eds. (1968). Man the Hunter, Aldine Transaction.

Plato (1991). The Republic of Plato, Basic Books. Translated by Allan Bloom.


Family Ties

Anton Johnson was born to a family of farmers in  Ärtemark Parish, Sweden in 1859. With his wife Christina he homesteaded a plot of forested land east of Ely, Minnesota. As I think Garrison Keillor has said of other Scandinavian migrants, they left their homeland, with its dark forests, thin rocky soil, cold weather, and short growing seasons, to find a better country. They traveled thousands of miles across the ocean and halfway across America until they reached Minnesota, where they settled down because it reminded them of home: dark forests, thin rocky soil, cold weather, and short growing seasons.

As it turns out, though, Anton got a job working underground in an iron mine, so it didn’t matter so much that the soils were poor and the weather was cold. This was in the early days of Ely’s rapid growth as a mining boom town. He and Christina had one child, Burt, born in 1890. Just over a year later, while Anton was working in the mine, a massive rock fell on his head and killed him. He was not quite 33 years old.

Christina remarried. Burt grew up, married a Norwegian girl, and had two daughters, who had their own families, whose members dispersed across the continent. I knew Burt as Dadda, my great-grandfather: a thin, straight, dignified old man, with thin white hair, thick, black, arched eyebrows, large ears and a long, thin face, serious but kind.

This August, nearly two dozen of his descendants and their families gathered together for a family reunion in a  cabin in the woods in northern Minnesota. In this group, there are some striking family resemblances. Some of my cousins look so much like their mothers that looking at them I feel I’ve become unstuck in time. There are many things that bind us together as a family, including shared memories of gathering in the north woods from time to time over the years. But I am also struck by how different we all are. We are family, but each person is a distinct individual, with different hopes and dreams, likes and dislikes, quirks and foibles. This is obvious, of course, even among siblings; each baby has its own temperament, and grows up to be a unique person.

Uncle Tim now lives out west, but owns the land that Anton and Christina homesteaded. One day we drove to the Ely area and spent two hours searching the woods for the property. Walking through the woods, slapping mosquitoes and gathering raspberries, it was easy to imagine what it must have looked like when those settlers first arrived.

The winters are cold and long. Grandma talked about how winter lasted seven months. I’ve been ice fishing up there in late April. Then once it warms up in the summer there are the mosquitoes, ticks and leeches. As soon as it gets warm enough to bare any skin there’s a crowd of bloodsuckers waiting to take a bite out of you. But the forests grow a bounty of raspberries and blueberries, and the lakes are full of fish. Loons cry their haunting call on the lakes, eagles fly overhead, and in the forests deer, wolves and bears are abundant.

Those northern Minnesota lakes and woods are almost enough to make me believe in ghosts. They vividly bring to mind memories of people who have passed on: sitting with Dadda at his breakfast nook while he explained the town of Virginia’s residential steam heating system; Nana lying in the nursing home bed with her bright blue eyes and wispy white hair;  Poppa scaling a bass after a long day fishing together; Mom orchestrating everyone in previous reunions, making sure that everyone was included and recognized and fed; and Grandma doing the hokey-pokey. I feel a connection to the land and the people. I can’t help wondering, though: if I stumbled back in time and met Anton and Christina in those woods, would we have much in common? Would we recognize each other as kin?

Kinship and lineage are powerful themes in the stories we tell. For example, in Dan Brown’s The Da Vinci Code, a central premise is that Jesus and Mary Magdalene had a child, thereby founding a lineage that continues unbroken to the present. Supposing for the moment that this were true, would people in this lineage be particularly special? Would they be more Christ-like (or Magdalene-like) than the average person?

From a religious point of view, this might be considered a silly question, of course; those who believe in the divinity of Jesus generally attribute this to Jesus having an extraordinary spirit in an ordinary human body. But in the fictional world of the Da Vinci Code, people devoted their lives to the principle that the lineage of Jesus was extra special, worthy of protection (or persecution). And even within the religious tradition, the writers of the Bible show great interest in lineages, describing in detail the generations connecting Jesus to the line of David, Abraham and Adam.

As an exercise focusing just on genetics and not spiritual matters, how many genes would a modern-day member of this lineage have in common with Jesus (or Mary)? We can estimate this using the coefficient of relatedness, r, defined as the probability that any two individuals share a given gene by common descent. (Most genes that we have are very similar to those of every other person on the planet, differing only in minor details, if at all, but the chance that any two genes are identical by descent is estimated by r.) Each sperm or egg that a person produces contains half of that person’s genome. Therefore each generation results in a halving of genetic relatedness: my daughter has half of my genes (r=0.5), and if she has a daughter, that child will have one fourth of my genes (r=0.25).

Estimating r for lots (n) of generations, assuming no inbreeding, r=1/(2n). Assuming human generation time to be about 25 years, about 80 generations have passed since the time of Jesus. The coefficient of relatedness between Jesus and any living descendants of his would thus be 1 over 1.2X1024, which is a really huge number – on the order of the total number of stars in the observable universe. One divided by such a huge number is effectively zero. The coefficient of relatedness between Jesus or Mary and any living descendant of theirs therefore would be r=0.0000000 (with zeros going on and on and on).

Of course, this is assuming that no inbreeding occurred. If (as is common in royal lineages) efforts were made to ensure marriages among members of the lineage, such as cousins, then r would be higher. But even so, with even a modest amount of marrying outside the lineage, the disruptive effects of sexual reproduction would rapidly erode much of the genetic similarity between the founders of the lineage and their remote descendants. Insofar as anything special about Jesus or Mary Magdalene was contained in the particular combinations of their genes, after a few generations of mixing and matching genes with people from other lineages, the descendants would have no more in common with Jesus or Mary than most other people in that population.

The same goes for any lineage. The “royal blood” of Queen Victoria, for example, is seven generations removed from the youngest heir to the throne, Prince George (r=1/27=0.0078). Thus, from a genetic point of view, Prince George is not particularly similar to Queen Victoria, despite being a relatively recent direct descendant of hers.

This calculation of r, though, doesn’t work for all genes. Some genes are passed down in packages rather than individually. We inherit our mitochondrial genome intact from our mothers. Mitochondrial genomes thus change only slowly, through the accumulation of mutations. In the same way, boys inherit their Y-chromosomes intact from their fathers. Prince George thus has the same Y-chromosome as his paternal grandfather Prince Charles.

Back in 2003, Tatiana Zerjal and colleagues published a paper showing that some 8% of men in Central Asia shared nearly identical versions of the Y-chromosome (Zerjal et al., 2003). Based on mutation rates and geographic patterns, they estimated that the family tree of this lineage originated in Mongolia roughly ~1,000 years ago. The most likely explanation of the wide spread of this chromosome was thus the historically well-attested reproductive success of Genghis Khan and his descendants.

There’s not very much on the Y-chromosome, though; just over 200 genes. Just because a man happens to have inherited a slightly mutated version of Genghis Khan’s Y-chromosome doesn’t mean that he shares anything more in common with Genghis Khan’s personality than any other man on the planet.

Personality and appearance both have strong genetic components, but because of sexual reproduction, similarities between lineage founders and descendants rapidly erode over time. So one might ask: given this erosion in similarity across the generations, why do we care so much about kinship and lineages? And more specifically, if there are only 200 or so functional genes on the Y-chromosome, why do patriarchs invest so much effort in ensuring that their particular Y-chromosome is perpetuated?

I suppose a major part of the answer must be that lineage survival is a pretty good proxy of fitness. If organisms are designed by natural selection to do whatever they can to promote the survival of their lineage, such organisms will leave more descendants, and thus more copies of their genes, than organisms that are indifferent to their lineage. If your lineage goes extinct, you won’t leave any copies of genes in the population. But if your lineage survives for two or three generations, and the number of individuals per generation grows rather than declines, then your genes have a good chance of surviving far into the future. Thus the particular satisfaction and happiness that grandparents and great-grandparents experience in seeing their descendants makes good evolutionary sense.

As for patriarchs, the focus on the patriline is less to do with the Y-chromosome itself, but with the greater potential variance in reproductive success between the sexes. The reproductive success of female mammals is limited by the number of babies they can have, whereas the reproductive success of male mammals is limited by their mating success. A Genghis Kahn or King David thus can have many more offspring than a Börte or Bathsheba.

Anton Johnson had just the one wife, though, rather than a harem, and he had only a single child before his life was cut short by a falling rock. Nonetheless, his lineage has carried on and grown.

The particular combinations of genes that Anton and Christina carried, though, have long since been mixed up with the genes of other lineages from varied parts of the world. That is, of course, the whole point of sexual reproduction. But whether due to genes, family experience, mate choice, or just the basic heritage of humanity, many members of this family do share an enjoyment in being outdoors, tramping around in the woods, and looking at living things.

White pine on Anton and Christina's homestead.
White pine on Anton and Christina’s homestead.

As we searched the woods, my son was the first to find the pipe in the ground that marked the southeast corner of the land that Anton and Christina homesteaded. After finding the corner marking, we could discern a cut line along the eastern boundary of the property: a straight path devoid of trees, brambled over in raspberries. Off the property, much of the land has been logged and is now covered with secondary growth: white-barked birches and poplar, thin trees crowded together, straining for the sky. But the family land has older growth, including a grand old white pine that already must have been a tall tree a century ago.

I don’t know what Anton Johnson was like as a person. If I could wander back to this same land 130 years ago, would I recognize any more kinship with him than with any of the other immigrant miners in the area? All the same, I still very much like the thought of him walking in the shadow of that same white pine, and perhaps admiring the flight of an eagle passing overhead.


Zerjal, T., Y. Xue, G. Bertorelle, R. S. Wells, W. Bao, S. Zhu, R. Qamar, Q. Ayub, A. Mohyuddin, S. Fu, P. Li, N. Yuldasheva, R. Ruzibakiev, J. Xu, Q. Shu, R. Du, H. Yang, M. E. Hurles, E. Robinson, T. Gerelsaikhan, B. Dashnyam, S. Q. Mehdi and C. Tyler-Smith (2003). “The genetic legacy of the Mongols.” American Journal of Human Genetics 72: 717-721.

Planet of the Apes

28 July 2014

The latest Planet of the Apes movie raises interesting many interesting questions, such as: what would it take for other apes to replace humans as the planet’s ruling primates?

Spoiler Alert: if you haven’t seen the movie yet, you might not want to read any further until you have. I try to steer clear of plot details, but if you’re the kind of person who likes to know as little as possible about a movie before seeing it, consider yourself warned.

I grew up watching the original Planet of the Apes movies. I am sure seeing movies of a world ruled by apes fueled my interest in our hairy cousins. It was a rich time for anyone interested in apes. The first movie came out in 1968, the same year that the site where Jane Goodall studied chimpanzees, Gombe, was upgraded from a game reserve to a National Park. We watched films of Jane Goodall and the chimpanzees of Gombe in elementary school. New discoveries about the apes were reported regularly in the glossy pages of National Geographic. Studies of sign-language using apes like Washoe and Koko suggested apes were on the brink of human intelligence. Movies like King Kong and the Planet of the Apes franchise presented apes as both dangerous and fascinating, blurring the boundary between human and animal.

I had a special interest this latest Planet of the Apes movie as I contributed some recordings of chimpanzee vocalizations. As a result my name shows up on the big screen for a few seconds, after Ape Extras but before Editorial Assistant, New Orleans. The Chicago Sun-Times even noticed.

(The name  Michael Wilson also shows up in the credits for the original movie, as writer of the screenplay  — though that was of course somebody else!)

I thought they did a good job with ape vocalizations in the movie. One of my complaints in general about animals in movies is that they make much more noise than animals do in real life. Movie predators, whether lions or dinosaurs, always seem to roar right before attacking their prey – something real predators would never do, as they seek to catch their prey by surprise. Roars are for warning members of your own species to stay away (and/or for attracting mates), not for chasing away your prey!

Chimpanzees can be extremely noisy, but most of the time they are very quiet. So one of my recommendations to the sound editors was to avoid extraneous calls. I was very pleased to see that for many scenes, the apes were indeed fairly quiet.

And when the apes did vocalize, I enjoyed hearing real ape calls, and different calls for each species.  I particularly liked one scene where the apes give a massive round of pant-grunts to Caesar. This is a call that chimpanzees use to show submission, and they used it in the right context for this film.

I liked that the apes mainly used sign language, and that when they did speak, they had rough, breathy voices, much like Viki the chimpanzee did when being trained to say words like “cup” and “up.”

In general, I thought the film did an excellent job building the characters and story. The main ape and human characters are complex, with understandable motives, and aren’t depicted as being either simply good or evil.

I think this might be the best movie yet in the franchise, and well worth seeing.

As an ape ecologist, though, I can’t help thinking about certain things.

For example, Muir Woods seems like a pretty rotten place for apes to live. It has trees, sure, but they are mainly redwoods and other conifers that produce no ape-friendly food. Apes are specialists in ripe fruit, which is in pretty short supply in a redwood forest. According to the Muir Woods website:

“Life in a redwood forest is determined by the low light conditions that restrict growth of plant species producing flowers, nuts, or berries. In addition, coast redwood trees contain an abundance of tannin (or tannic acid), a chemical compound that deters the presence of insects. Taken together, these conditions create an environment that is relatively low in the resources that typically form the base of a food web.”

So while it’s really cool to see apes swinging from the branches of redwoods, that forest is pretty grim habitat for apes. The gorillas might be able to subsist on herbs growing in the understory, but these are largely ferns and not very palatable. The chimps and orangutans would be pretty hungry there. They might use the forest as a temporary refuge, but would quickly move on to more suitable habitat, such as the overgrown gardens and city parks of post-apocalyptic suburbs.

If ordinary chimpanzees, gorillas and orangutans were released into the California wilderness, they would probably go their separate ways. The orangutans would forage alone. The male gorillas would compete over the female gorillas, until each silverback had a small group of females for himself. Each gorilla group would then forage separately. The chimps might start off as a single community but over time they would probably fission into several mutually hostile communities, each defending their own territory. It’s not clear why these different ape species stick together, or why they live in a village instead of sleeping up in the trees like real apes do. But of course these are retrovirus-mutated, hyper-intelligent talking apes, so they behave differently.

The film is surprisingly conservative in depicting ape romantic relationships, in that Caesar at least seems to be in a monogamous marriage with Cornelia. I suppose showing Caesar as a loyal family man makes him more appealing to viewers. However, a normal alpha male chimpanzee would try to monopolize matings with all the fertile females; and these females would try to mate with multiple males, even against the wishes of the alpha male. But perhaps the mutating retrovirus also makes apes monogamous.

But a big question relates to the film’s fundamental premise: what would it take to destroy human civilization, and clear the way for the world to be ruled by another kind of ape? (Or, in this case, a triumvirate of three different ape species.)

As Ruben Bolling points out,the Rise of the Planet Ape is a true story, and we are living it: we are the apes that have taken over the whole planet. But is human domination of the planet inevitable? How hard would humanity have to be hit to make way for other apes?

In this movie, humans are very nearly wiped out by a genetically engineered retrovirus, ALZ-113,  that makes nonhuman apes super intelligent but kills humans. (This has interesting parallels with SIVcpz, a naturally occurring retrovirus, which was transmitted from chimpanzees to humans, probably by people hunting and butchering chimpanzees for food. When contracted by people, the virus is called HIV-1 and causes the disease AIDS, which has killed many millions of people around the world. SIVcpz doesn’t make apes super intelligent, of course, and we have learned that it is also fatal to chimpanzees (Keele et al., 2009)).

According to newscasts in the movie, almost everyone who contracts the virus dies; only 1 in 500 survive. Since the virus is highly contagious and transmitted by sneezing, this leads to a much more devastating result than even the AIDS pandemic.

There are about 7 billion people on the planet today. So if 1 in 500 people died, there would still be 14 million people on the planet. Such a rapid and catastrophic epidemic would have huge impacts on the survivors, though, as food distribution systems and everything else collapsed. Say only 1 in 10 of people who survived the virus would survive the aftermath of collapsing civilization. That would bring the total population of people on the planet down to 1.4 million (which is still four to five times the total number of chimpanzees living on the planet today). This is probably a low figure, given that many people on the planet are subsistence farmers and herders of livestock.  Many people living in rural Africa, for example, would be able to survive the collapse of industrialized civilization, because they mainly live off the land without access to electricity, plumbing or fossil fuels.

In the San Francisco Bay Area, though, most people have no idea how to farm, herd livestock, or live off the land. Collapse would hurt people hard. So starting from a Bay Area population of about 7.44 million, if 1 in 500 die from disease, that leaves around 14,880 survivors. If 90% of those survivors died from starvation and post-apocalyptic fighting and such, then only around 1,488 people would be left in the Bay Area. That seems in line with the number of people crowded into the refuge of San Francisco (though as my wife noticed, the virus seems to have selectively killed all the Asians).

(Though why are they living in the middle of the city? I would think any survivors would mainly live on isolated rural farmsteads, where they can grow their own food, rather than crowding into the city center. How do these people eat? But it does look cool and dystopian to have everyone crowded together in the post-apocalypse city — maybe more so than setting it, say, on the outskirts of post-apocalypse Fresno.)

(Some other quibbles: Ten years post-apocalypse, I’m not sure anyone would still have usable manufactured clothing, eyeglasses or electronics anymore.  Even in my own family, after a year living abroad, with easy access to clothing and other supplies, the clothes we brought with us are ragged, the kids need new eyeglasses, and my son and I both need new shoes. Life post-apocalypse would certainly be much harder on such supplies. Moreover, there would certainly be no birth control or antibiotics. Sexually active women would be pregnant or nursing — which would have huge impacts on society. Weirdly, almost no young  human children, or women with nursing babies, were shown in this film.)


Based on the number of apes living in Muir Woods, they must have been reproducing at a really high rate compared to normal apes. This wiki states that there are 2,000 apes living in the ape village. Now that’s a lot of apes. Currently there are only about 2,000 captive chimpanzees in the United States. The starting population in Muir Woods must have been a lot less than that, since they started with apes escaping from just two captive colonies, and it would be hard for apes from other parts of the country to find out about the Muir Woods population, much less travel there.

Is it realistic to have 2,000 apes in ape village just 10 years after the ape revolution?

One key to the success of humans is demography. We can reproduce much faster than other apes. For example, suppose by coincidence that both the surviving human population in San Francisco, and the chimpanzee population in Muir Woods, started out at about 1,000 individuals. (Gorillas reproduce more quickly than chimpanzees, and orangutans reproduce more slowly, but since in the movie most of the apes are chimps, I’ll focus on them.) In a best case scenario, chimpanzee populations could potentially grow at about 2% per year. (Most wild chimpanzee populations “grow” at about 0% per year, though, because mortality is high and food supplies are limited — which in turn limits fertility and growth.)

Projected populations of humans and chimpanzees post-apocalypse, starting from 1000 individuals in each population.
Projected populations of humans and chimpanzees post-apocalypse, starting from 1000 individuals in each population.

So starting out with 1,000 chimps, in ten years there would be only about 1,221 chimps (if they somehow found food and didn’t suffer high mortality from predation, warfare etc.). Human hunter-gatherers, though, can grow at much faster rates, such as around 4%, even without medical care and with all of the hardships that hunter-gatherers face. At this rate, starting with 1,000 humans, we’d have around 1,492 people by the end of ten years — so about 270 more humans than chimps. And realistically, survivors in California would be farmers, not hunter-gatherers, with potentially even faster population growth. So if Ape Village apes are reproducing like normal chimpanzees, and if the starting population was in the hundreds, a population of 2,000 ten years later is not realistic.

Why can human populations grow so much faster than chimpanzees?

In some ways it is surprising that this can even be possible. After all, humans take longer to reach maturity than chimpanzees. Female chimpanzees have their first birth around age 14 (males reach full size around age 16, but for population growth, it’s females that matter more). Humans hunter-gatherers take longer to mature, with an average age of first birth at 18-20 (Hill & Kaplan 1999). Moreover, even though humans live longer than chimpanzees, human females stop reproducing in their forties — so their reproductive careers are, on average, shorter than those of chimpanzees.

However, once humans do grow up, they can reproduce quickly.  Chimpanzees have an average interval of around 5 years (Jones et al., 2010), whereas hunter-gatherers have an interbirth interval of only 4 years (Hill & Kaplan 1999).

How can women reproduce more quickly than chimpanzees? A big part of the answer must be cooking. Thanks to fire, humans can extract more energy from the environment, by increasing the energy available from food, and by making otherwise unpalatable foods safe to eat (Wrangham et al., 1999). Cooking likely helps children grow faster, by providing soft, energy rich foods from a young age, whereas chimpanzee children continue drinking their mother’s milk for longer, as they gradually add tough, hard adult foods to their diet. This surely has a big impact on human fertility and growth rates.

In the movie, the apes in Ape Village had fires in each house, so maybe they were cooking? That would certainly help them reproduce more quickly.

Another reason human populations can grow so much faster than chimpanzee populations is that humans have much lower mortality than chimpanzees, even in hunter-gatherer populations without access to medicine. Hunter-gatherers regularly live into their 50s, whereas the median age of survival for wild chimpanzees is about 30, and few live into their 40s. What accounts for this difference?

I suspect cooking is probably important for reducing mortality as well.  Cooking and other food extraction and preparation technology likely help people obtain food even in difficult times of the year, whereas chimpanzees in seasonal environments may become weak and more likely to die from diseases. Cooking also must help people live longer by providing soft foods that they can continue to eat into old ages, as their teeth wear down.

So super-intelligent mutant apes potentially *could* take over the world, but only if most of the humans are killed off, and apes learn how to cook.


Works cited:

Jones, J. H., M. L. Wilson, C. M. Murray and A. E. Pusey (2010). “Phenotypic quality influences fertility in Gombe chimpanzees.” Journal of Animal Ecology 79(6): 1262-1269. get pdf

Keele, B. F., J. H. Jones, K. A. Terio, J. D. Estes, R. S. Rudicell, M. L. Wilson, Y. Li, G. H. Learn, T. M. Beasley, J. Schumacher-Stankey, E. E. Wroblewski, A. Mosser, J. Raphael, S. Kamenya, E. V. Lonsdorf, D. A. Travis, T. Mlengeya, M. J. Kinsel, J. G. Else, G. Silvestri, J. Goodall, P. M. Sharp, G. M. Shaw, A. Pusey, E. and B. H. Hahn (2009). “Increased mortality and AIDS-like immunopathology in wild chimpanzees infected with SIVcpz.” Nature 460: 515-519. get pdf

Hill, K. and H. Kaplan (1999). “Life history traits in humans: Theory and empirical studies.” Annual Review of Anthropology 28: 397-430. get pdf

Wrangham, R. W., J. H. Jones, G. Laden, D. Pilbeam and N. Conklin-Brittain (1999). “The raw and the stolen: cooking and the ecology of human origins.” Current Anthropology 40(5): 567-594. get pdf






Frodo (30 June 1976 – 10 November 2013)

Several of my blog posts have featured Frodo, the iconic alpha male chimpanzee of Gombe National Park. Frodo also figures prominently in several of my research papers, given that he has been a major player in aggression at Gombe, both within his own community, and during attacks on the neighbors. I’m sorry to report that Frodo died on Sunday, 10 November 2013. Perhaps fittingly, given Frodo’s aggressive behavior in life, aggression seems to have contributed to his death. Necropsy revealed that he had a scarred scrotum and infected testis, probably due to what seems to have been a canine puncture wound received in August 2013. As ye sow, so shall ye reap. [Edit (23 May 2022): subsequent results from pathology indicated that Frodo died from renal failure, not from infection from his scrotal wound.]

Jane Goodall named Frodo for the noble, humble, diminutive hobbit from the Lord of the Rings, which she had been reading to her son. From a cute little baby chimpanzee, Frodo grew to be a hulking brute, a despotic alpha male, and a fearless hunter of monkeys.

Frodo was born on 30 June 1976, the second of Fifi’s nine offspring. Fifi was a highly successful mother and was for many years the highest-ranking female of Gombe’s Kasekela community. As an infant, Frodo proved mischievous, disrupting Jane Goodall’s efforts to record data on mother-infant relationships by grabbing at her notebooks and binoculars. As he grew older, Frodo developed a habit of throwing rocks, charging at, hitting, and knocking over human researchers and tourists. In 1988, Frodo grabbed and pulled at cartoonist Gary Larson’s arm when he visited Gombe, and the next year Frodo severely beat Goodall herself.

In his prime, Frodo weighed 55 kg (121 lbs), larger and stronger than any of his peers. Frodo rose quickly in the ranks as he matured and won the position of alpha male by overthrowing his brother Freud in October, 1997. Frodo reigned as alpha male for 5 years, until weakened by sickness in December 2002. We knew the game was up for Frodo when he gave submissive pant-grunts to the next alpha male, Sheldon, in January 2003.

As alpha male, Frodo ruled by brute force. Unlike his brother Freud, who frequently groomed lower ranking males in apparent efforts to win their support, Frodo rarely groomed any other males, but instead frequently presented himself to be groomed by them.

Frodo competed vigorously for mating opportunities throughout his life, fathering his first offspring, Zeus, when he was 17, and his last, Samwise, when he was 25. He even forced his attention on his own mother, fathering an infant, Fred, who lived for less than a year before dying in a mange epidemic. Frodo fathered both of Gremlin’s twins, Golden and Glitta, the only wild chimpanzee twins known to have survived to adulthood. Frodo’s son Titan follows in his father’s footsteps by throwing rocks at baboons, chimpanzees and people, and has recently challenged the current alpha male. In total, Frodo fathered eight offspring, more than any other male at Gombe but Wilkie (who fathered 10). Frodo’s offspring were born to six different females: Trezia, Patti, Gremlin, his own mother Fifi, Sparrow and her daughter Sandi.

After being deposed in 2003, Frodo spent months by himself recovering, and when he rejoined the other males he had fallen to low rank. He continued to show keen interest in competing for mates and hunting monkeys, but he mellowed considerably, and in his last years rarely showed any signs of aggression towards people.

Frodo was the first chimpanzee that I saw in Gombe, and I recognized him instantly, with his silvery grey back, the round ruff of silvery hair framing his face, and his large size. Frodo taught me what life is like for most chimpanzees: you must constantly be aware of where the alpha male is, because he might charge any time, and may beat you up. The first time he came charging past me, I wondered why everyone was running away; as a kid I had read George Schaller’s descriptions of gorillas, and how when they charged you must stand your ground, and only people who ran got bitten. I assumed the same must be true for chimps. And sure enough, when I studied chimpanzees for my dissertation research in Kibale Forest, Uganda, the alpha male Imoso would simply veer around me if I got in his way, acting as if that was what he meant to do. But not Frodo. He saw that I wasn’t moving and went straight at me, knocking me into the bushes. He beat on me briefly with his fists, but in a surprisingly gentle way. He could have easily done real damange, but he acted as if his only goal was to show me who was boss. Him.

My next day in the forest, I was extremely wary of Frodo. I managed to avoid him for most of the morning. However, during a hunt, someone else ended up with the carcass of a redtail monkey, and Frodo was angry. He charged around, displaying. He charged past a whole line of researchers to get to me, where he knocked me into the bushes yet again.

That was the last time that Frodo bothered me, though. He seemed to accept that I was part of the gang of people that followed him and his community all around the forest, and that I sufficiently acknowledged his magnificence.

Frodo resting on the trail in June, 2009.
Frodo resting on the trail in June, 2009.

Frodo was one of several F-family chimpanzees that rose to high status. Most of Fifi’s offspring that survived to maturity rose to high ranks, with three of them becoming alpha male: Frodo’s older brother Freud, Frodo himself, and the current alpha male, Ferdinand. Fifi’s daughter Flossi is one of the highest ranking females in the Mitumba community. Frodo is survived by four sons (Zeus, Titan, Tarzan, and Sindbad), three daughters (Golden, Glitta, and Samwise), his brothers Freud, Faustino, and Ferdinand, sisters Fanni, Flossi, Flirt at least two grandchildren, and numerous nephews and nieces.

Frodo grooming his daughter Glitter (June 2012).
Frodo grooming his daughter Glitter (June 2012).

Researchers and filmmakers followed Frodo throughout his life, making him one of the most thoroughly documented wild chimpanzees in history. Numerous books and scientific articles described Frodo’s success as a hunter, fighter, and alpha male. Frodo first appeared in films as an infant in People of the Forest: The Chimps of Gombe (1991, Discovery Channel). Frodo knocks presenter Charlotte Uhlenbroeck off her feet in The New Chimpanzees (1995, National Geographic). The films Fifi’s Boys (1996, BBC) and Chimpanzee Diary (1997, BBC) depict Frodo’s rising power and rivalry with Freud. Frodo dominated the giant screen feature Jane Goodall’s Wild Chimpanzees (2002, Imax), filmed at the peak of his powers. More recently, Frodo was featured in The Dark Side of Chimpanzees (2004, BBC), Return to Gombe (2004, Discovery Channel) and Chimpanzee Family Fortunes (BBC, 2006).

Gombe just won’t feel the same with Frodo gone.

Causes of Death in Chimpanzees

As George Carlin says, “It’s inevitable when you buy the pet. You’re supposed to know it in the pet shop. It’s going to end badly. You’re purchasing a small tragedy.”

The same goes for studying animal behavior. Anyone who spends enough time in the field, getting to know the lives of animals, will also witness their deaths. In a new paper, “Pathologic lesions in chimpanzees (Pan troglodytes schweinfurthii) from Gombe National Park, Tanzania, 2004-2010,” we report on some of the things we’ve learned from chimpanzees who have died. This paper, led by Karen Terio at the University of Illinois, involved a large team of field researchers, veterinarians, and pathologists.

I started studying chimpanzees because I was interested in how they lived. But in studying their lives, I’ve seen many of their lives come to an end. In this way, studying chimpanzees is a bit like being an Elf in J. R. R. Tolkien’s Middle Earth. In Tolkien’s world, the Elves live for centuries, dying only if they encounter some mishap, such as being slain in battle. In a single life, an Elf such as Elrond watches sadly as generations of mortal men come and go. In a similar manner the generations of chimpanzees, though long by the standards of typical mammals, pass more quickly than those of our own species. Jane Goodall, who has been watching chimpanzees at Gombe since 1960, has seen entire generations come and go. Chimpanzees that Jane saw as newborn babies have grown old and died, and their children, grandchildren, and now great-grandchildren have been born. I’ve only been working at Gombe since 2001, but this is still long enough that many of the chimpanzees I’ve gotten to know there have since passed on: Fifi, Goblin, Vincent, Ebony, Andromeda, Patti, Ebony, Sherehe, Shangaa, Echo, Yolanda, Malaika, Kris, and others.

I knew each of the 11 chimpanzees we describe in this new paper, except for a stillborn baby. I was involved in various ways with documenting the ends of their lives, such as taking observations during their final days, helping with the recovery of their bodies after death, examining the bodies immediately after death, organizing and participating in the necropsies, burying the bodies and recovering their skeletons from their graves, after they had been buried for at least a year. My student Claire Kirchhoff examined these skeletons for evidence of trauma.

Determining the cause of death is important for many reasons, including understanding chimpanzee life histories and identifying threats to their conservation. Because my research focuses on aggression, it’s especially important for me to know the cause of death. Did they die from aggression, or some other cause? In each case, it’s important to document carefully the relevant evidence.

Graucho Marx said, “Outside of a dog, a book is man’s best friend. Inside of a dog, it’s too dark to read.”

I’ve never tried reading inside a dog, but I’ve ended up sending more time looking at the insides of chimpanzees than I ever expected. If I had known what the future held for me, I would have taken some proper anatomy courses. But fortunately at Gombe, we’ve benefited from a wide range of expertise, including the Health Monitoring Project led by Elizabeth Lonsdorf and Dominic Travis, and the virology study led by Beatrice Hahn. We’ve been able to store chimpanzee bodies in large freezers until we can assemble teams of experts to conduct necropsies. We send tissue samples to pathologists and molecular virologists to gain a finer grained understanding of the causes of death.

I study violence in chimpanzees, not because I like violence (I don’t), but because it plays such an important role in the lives of chimpanzees – and as one of the two species most closely related to humans, chimpanzee violence can help us understand violence in our own species. Chimpanzee violence caused 36% of deaths in this study – more than any other factor. Andromeda and Patti were killed during intergroup attacks. Vincent was killed by members of his own community. Ebony – found dead with a broken neck and puncture wounds – almost certainly killed by chimpanzees, and likely one or more of the males of his own community.

One of the humbling things about research is that often, even with all the expertise we can muster, there is much that we will never know for sure. One such case involves the adult female Echo, who became a long-term resident at Kasekela at about the same time that I did.  I caught my first glimpse of Echo during one of my first days in the field as Director of Field Research at Gombe, back in January 2004. While we were watching a large group of chimpanzees feeding in the trees above a steep valley, videographer Bill Wallauer pointed out a new immigrant female chimpanzee with a pretty face and an asymmetric, bumpy sexual swelling. Bill recognized her from pictures he had taken in 1999, and thought she might be a female seen during an intergroup encounter in 2003. We named her Echo because she seemed to keep bouncing back. Unusually, Echo had immigrated together with her juvenile daughter, who we named Eowyn, after the heroic shieldmaiden from Tolkien’s Lord of the Rings.

Eowyn inflicting fatal trauma on the Witch-King of Angmar

Usually, females only move from one community to another as adolescents, before they have children. Infants of immigrants face a high risk of being killed by the resident males, as nursing infants fathered by other males represent both genetic competition and an unwelcome form of contraception. But Echo chose a good time to immigrate: her daughter Eowyn was weaned, and Echo had a full sexual swelling. The Kasekela males left Eowyn alone, and Echo quickly conceived a daughter, Emela.

Genetic analysis of fecal samples confirmed that Echo used to live in the Kalande community. Her departure from Kalande showed just how bad the decline of that community had gotten. Usually, once females have settled into a community and have started having babies, they stay there for life. But females seem to prefer living in a community with multiple males, which may be important both to protect them from intergroup aggression and to provide them with some good options for mates. Echo left when the number of adult males in Kalande dropped to one.

We also learned that Echo was infected with SIVcpz, the virus that is the immediate precursor of HIV-1, which causes AIDS in humans. Four of the 11 chimpanzees in the new study were infected with this virus. Until recently, it was widely assumed that SIVcpz was harmless in chimpanzees. We learned from studying Gombe chimpanzees, though, that infection with this disease greatly increases mortality risk. Two of the chimpanzees in this study died from AIDS-like symptoms.

Echo and Emela

I particularly remember Echo from a day in March 2006. In the late afternoon, the chimpanzees climbed high into a hill above Kasekela valley, into an open woodland. They climbed into the short, stunted trees to feed, rest and groom. Echo climbed rested on a low limb and groomed with Tubi, Bahati and her son Baroza. All seemed peaceful and happy. Echo had immigrated successfully, settled into Kasekela, had a daughter, and made friends.

But this was not to last.

Paralyzed "Patina"

In November 2006, which happened to be my last month of being based full time at Gombe, field assistants monitoring the Kalande community reported that one of their females, Patina, was sick. Together with vet Iddi Lipende, I traveled down to Kalande to investigate. We found a female chimpanzee lying in a dry streambed, her legs apparently paralyzed. She looked at us fearfully. She was too weak even to shoo away the flies that gathered at the wounds she had inflicted on herself, dragging her broken body along the stones of the dry streambed. She died within a few days.

In the following months, analysis of genetic samples found something puzzling: new fecal samples continued to come in from a female who was an exact genetic match for Patina. Apparently it wasn’t Patina who lay dying in that streambed – it was someone else. Given that the Kalande chimpanzees aren’t habituated, a case of mistaken identity was not so surprising. But the puzzle remained: who was the female who died?

Around this time, Echo’s daughter Eowyn showed up in Kasekela without her mother – something unusual for such a young chimpanzee. And genetic analysis of the tissue from the dead female found that she was, in fact, Echo. She had gone back to her home community of Kalande and died there. In her weakened state, she looked so different that none of us had recognized her. Her infant Emela had disappeared and must have died as well.

The necropsy found that Echo had a broken spine, but we don’t know how she broke it. She didn’t have the other injuries typical of a chimp attack – no canine puncture wounds, missing fingers or toes – so it seems unlikely that chimpanzees had killed her. Did she fall from a tree? If so, why? Was she chased by other chimps? Or did she just have bad luck? We will never know.


Here are the publications where we report some of the findings discussed here:

Keele, B. F., J. H. Jones, K. A. Terio, J. D. Estes, R. S. Rudicell, M. L. Wilson, Y. Li, G. H. Learn, T. M. Beasley, J. Schumacher-Stankey, E. E. Wroblewski, A. Mosser, J. Raphael, S. Kamenya, E. V. Lonsdorf, D. A. Travis, T. Mlengeya, M. J. Kinsel, J. G. Else, G. Silvestri, J. Goodall, P. M. Sharp, G. M. Shaw, A. Pusey, E. and B. H. Hahn (2009). “Increased mortality and AIDS-like immunopathology in wild chimpanzees infected with SIVcpz.” Nature 460: 515-519.

Rudicell, R. S., J. H. Jones, E. E. Wroblewski, L. G. H., Y. Li, J. Robertson, E. Greengrass, F. Grossmann, S. Kamenya, L. Pintea, D. C. Mjungu, E. V. Lonsdorf, A. Mosser, C. Lehman, D. A. Collins, B. F. Keele, J. Goodall, B. H. Hahn, A. E. Pusey and M. L. Wilson (2010). “Impact of Simian Immunodeficiency Virus Infection on chimpanzee population dynamics.” PLoS Pathogens 6(9): e1001116.

Terio, K. A., M. J. Kinsel, J. Raphael, T. Mlengeya, I. Lipende, C. Kirchhoff, B. Gilagiza, M. L. Wilson, S. Kamenya, J. D. Estes, B. F. Keele, R. S. Rudicell, W. Liu, S. Patton, D. A. Collins, B. H. Hahn, D. A. Travis and E. V. Lonsdorf (2011). “Pathological lesions in chimpanzees (Pan troglodytes schweinfurthii) from Gombe National Park, Tanzania, 2004-2010.” Journal of Zoo and Wildlife Medicine 42(4): 597-607.


After starting this blog in August, I hardly blogged at all during the semester. Partly this was because with my teaching and other duties, I had little time to spare for blogging. And in what spare time I did have, I wasn’t thinking about blog topics. I was thinking about my Mom, who was fighting what turned out to be a losing battle with leukemia.

Years ago, as the stem cells in Mom’s bone marrow were going about their usual business of dividing to make cells that would in turn give rise to new blood cells, one of them made a mistake. A deletion occurred on Chromosome 9. That cell divided and gave rise to a whole lineage of cells with the same deletion. Over time, some other cells in that lineage arose with additional genetic errors that prevented them from making proper blood cells. Instead, they produced millions and millions of daughter cells that filled up Mom’s marrow with useless cells, crowding out the good cells.

Mom only became aware that there was a problem a couple of years ago, when she was diagnosed with Myelodysplastic Syndrome (MDS), which often develops into leukemia. And in Mom’s case it did. In March, on her birthday, she was diagnosed with Acute Myeloid Leukemia (AML) and soon started her first round of chemotherapy.

Mom faced all of this with remarkable courage. In the hospital, she joked, made light conversation, took photos of all her visitors, and kept her good humor through all of the indignities of hospital life – the flimsy gowns, the lack of privacy, the constant parade of people coming into the room to do this or that, the increasing need for other people to help with basic bodily functions. Mom accepted all of this gracefully. Though she did not like revealing her birth year to other people, in the hospital many times a day she cheerfully gave her name and birthdate to hospital staff, as required when receiving new medications or blood transfusions. She always liked to look her best. When the chemo caused her hair to fall out, she wore wigs and hats – but mainly to make her visitors comfortable. Over Skype, she asked us if we wanted to see the bald head, and showed us when we said yes, seeming entirely cheerful and matter-of-fact about the loss of the hair that she had been so careful to keep just so over the years.

As a family, we tried to learn as much as we could about Mom’s condition and treatments. Dad bought and diligently read a medical textbook on hematology. This information was interesting enough, and helped us understand what Mom was going through, but we never found what we were looking for: some hidden nugget that would help Mom live. And the scientific literature was far from comforting. Studies of AML (such as here and here) found that for most patients, even with the best treatments available, life expectancy was a matter of months rather than years, especially if they were older, had a background of MDS, and had multiple detectable genetic changes in their chromosomes.

I’m not sure what I imagined chemotherapy would be like, but the actuality was both more peaceful and more awful than I had expected. For the most part, it involved just waiting in the hospital room, attached to a rack full of IV bags dripping an array of different fluids, including saline solution, blood, plasma, and chemotherapy drugs, into a PICC line – a tube inserted into the arm that directed the incoming fluids right to the heart. At first, it hardly seemed like Mom was really sick. She was just like she always was, except confined to a hospital room and attached to an IV drip. But gradually the chemo did its job and took its toll, and Mom got sicker and sicker.

One of the chemotherapy agents that Mom received was Cytarabine. This is chemically nearly identical to cytosine, one of the four bases that make up DNA. It is similar enough that it gets incorporated into new DNA, but different enough that that new DNA doesn’t work properly, and the new cells die as a result. So all the rapidly dividing tissues – cancer cells, but also hair, skin, and the intestinal lining – suffer as a result, resulting in all the usual chemotherapy side effects.

Another chemo drug Mom had was Daunorubicin – a ruby colored compound isolated in the 1950s from soil-living fungus in Italy and named for a pre-Roman tribe, the Dauni. The bright ruby color of this drug made it look especially potent and menacing when it was injected. Daunorubicin molecules are just the right shape to slip in between successive base pairs in DNA strands, unwinding the DNA a bit and interfering with replication. Again, this wreaks havoc, not just on cancer cells, but also on all healthy tissues that rely on rapid cell division.

Mom endured two rounds of chemo, achieved remission, and came home, where before long, life almost seemed back to normal. She cooked dinners, played bridge, went to church, and even traveled across the country to see her newest grandchild. It started to seem that Mom was healthy and out of danger.

However, while the chemo had killed a lot of cells, it hadn’t completely wiped out the mutant stem cells. Instead, the few surviving mutant cells continued to replicate, acquiring new mutations on the way. By September, the leukemia was back, and just before Thanksgiving, it took Mom away from us.

The chemo took a terrible toll, but without it, what happened in November would have happened in March. Thanks to the chemo, Mom had a summer at home, visits from her children and grandkids, and time to say goodbye.

Mom wanted to live, but during what turned out to be her final hospital stay, she talked of how the quality of life, and the prospects for improving it, diminish. In one of our last conversations, she told me, “I had hoped to live long enough to see how things turned out for everyone. But then, even if we lived to be over 100, we would still want more.”

Mom was one of the very best people I have ever known, and it seems terribly unfair that she should be taken from us so soon. It’s hard to believe that such a vibrant person, so full of love and caring and thoughtfulness, the keeper of so many family memories and traditions, should be undone by the information copying errors of the tiny, mindless cellular machinery of her own body.

Around the time Mom got sick, my computer crashed. The Genius at the Apple Store said it was a problem with the logic board, and that there was really nothing to be done, since the repairs would cost about as much as a new computer, and that in a computer of such advanced age (nearly five years old!), more problems would soon be arising. Luckily I had my data backed up, and almost all the files on my old computer are now on my new computer. But Mom is gone. There’s no backing her up.

Religious minded people will be tempted to provide reassurance that Mom is in Heaven. That’s certainly what Mom believed, and if such a place exists, then surely she is there. But my own inclination is to think that we are material beings, and that our lives begin and end on earth. This materialist view provides its own comforts. “No Hell below us – above us, only sky.” There is no one to blame for the loss of loved ones: it just happens. But whatever one believes about the metaphysical, Mom left behind a great big hole here on earth.