JAMES HIGHAM talks about primates and primatology; long-term fieldwork in Cayo Santiago, Puerto Rico and Gashaka Gumti National Park in Nigeria; and the ethics and politics of conservation. In September 2017, Hurricane Maria, now considered the strongest storm to hit the Caribbean islands in recorded history, hit Cayo Santiago and its resident rhesus macaques. This conversation begins with the devastating hurricane and opens up to questions about value, human agency, scientific expertise, and the urgent need for interdisciplinary collaboration.
Higham works across the fields of zoology and anthropology. He teaches at New York University Department of Anthropology, where he also leads the Primate Reproductive Ecology and Evolution Group.
To learn more about the coloniality of disaster and the aftershocks of Hurricane Maria in Puerto Rico, read the brilliant Yarimar Bonilla in conversation with Ryan Cecil Jobson in Public Books in May 2020. See also an important collection of texts, Aftershocks of Disaster: Puerto Rico Before and After the Storm, co-edited by Yarimar Bonilla and Marisol LeBrón (Haymarket Books, 2019).
Welcome to the Multispecies Worldbuilding Lab. We are recording in New York City on July 15, 2019. James Higham is an evolutionary biologist and primatologist. He is Associate Professor in Anthropology at New York University. He works with collaborators and students at three field sites:
(1) the Caribbean Primate Research Center at Cayo Santiago in Puerto Rico, (2) the Macaca Nigra Project at the Tangkoko Reserve in Northern Sulawesi in Indonesia, and (3) the Gashaka Gumti National Park in Nigeria.
Thank you for joining us, James. Might we start with an introduction to your research and your work as a scientist who studies primates?
My research sits at the intersection of social biology and social behavior, sensory ecology, perception and communication, and cognition and the brain—and how these interacting aspects of animal biology and evolutionary selection work over time. I’m especially interested in sexual selection as a set of evolutionarily selected mechanisms, and how sexual selection (acting on those interacting aspects of animal biology) produce and maintain diversity and variation over time, both within species and between species.
I’m very interested in why we have the species that we do, why we have so many species, why they look, sound and smell different, what factors have led to that variation and then also why we have so much variation within species. We might expect evolution to act towards selecting for a few types of successful phenotypes within species, but actually lots and lots of variations are produced and maintained over time. One question that I’ve always been interested in is why and how this happens. How so much diversity and so much variation has been produced on our planet. I think one thing that is perhaps underestimated about our own order, the primates, is that it’s fantastically diverse and a lot of diversity has been created in pretty short periods of evolutionary time. That’s interesting because primates are thought to have quite slow life history in the sense that we have very long lives, we have long developmental periods, we don’t tend to have very many offspring relative to, for example, insects or even say birds or fish. Those kinds of life histories are thought to have relatively slow rates of evolutionary change over time, and yet actually primate evolution has been punctuated by lots of rapid radiations in which lots of species have been produced in short periods of time. And that’s something that’s also relevant to our own evolution. So twenty years ago, you might have had people saying that perhaps if we went back 100-200,000 years, there would only have been perhaps two species of Human, namely Homo sapiens and Neanderthals, whereas now we think if we went back 100-200,000 years, maybe there were seven, eight species of Homo within our genus. Even relatively recently, we were probably living alongside lots of other species of Human depending on how you define “human,” whether you mean just members of our genus or whether you mean members of our species specifically. But if we’re using it to mean members of our genus, we were a pretty diverse genus actually until pretty recently. We already have a huge amount of variation and diversity among human populations. Imagine living in a world with many species of human, many different species of human. It’s a remarkable thing to think about!
As a primatologist, as a zoologist, what are your thoughts on the role of humans in relation to other species in this current age of widespread mass extinctions, environmental transformations, overall climate change.
We’re certainly having very transformative effects on the environment in a relatively short period of time. But plenty of radiations of life have completely transformed the environment as well. I mean the vascular plants completely changed the atmospheric composition. The changes that we’ve made to the atmosphere are nothing compared to some groups which have had much bigger effects. And I’m not playing down issues of climate change, which I think are extremely serious and very worrying.
Stephen Jay Gould wrote an article a number of years ago in his book, Eight Little Piggies, in which he talks about perspectives on extinction. And I think it sort of depends on what your perspective is. If your perspective is, this a huge mass extinction and climate change event that’s serious and very threatening to human life on earth. Absolutely. I think it’s very likely that if the earth is still around in say a hundred million years’ time, there will be more species on earth than there are now. There won’t be any humans, but there will be more species on earth than there are now. This is what has always happened. The earth has these big mass extinctions, but overall the trajectory is towards more and more species, and more and more diversification followed by these periodic mass extinctions.
Now, is that any consolation to those species that are trapped in that mass extinction? No. But I think it depends what people are worried about. If they’re worried about life on earth, I would say don’t worry about it. What will happen is we’ll drive ourselves to extinction. The earth, you know, may take a million years to recover, or it may take 10 million years to recover. But ultimately, recover it will. And life will go on. That’s of no consolation to us.
I think it’s a strange situation actually because I think there are a lot of people out there who think, “climate change and pollution and extinctions, who cares about that sort of thing. I don’t care about biodiversity and I don’t care about this. I just care about humans.” Well, actually humans are the only ones that need to worry about this. If you don’t care about life on earth, that’s fine, because life on earth is going to be fine. You should only be concerned about this, in my opinion, if you care about humans and our relatively short-term fate, because this is potentially a huge disaster for us, and we need to try and get ahead of it as quickly as possible.
I’m also very concerned about the species that we are losing, of course, because they’re beautiful and precious and important. One can make all kinds of arguments about their utilitarian value to us as seed dispersers and that’s important because we need the forest. They’re the world’s lungs and we need them to protect watersheds and to prevent flooding and to maintain fertile land. They recycle carbon for us. They do all kinds of utilitarian ecosystem services and we don’t value them properly. We use them for timber and for fishing, for game, and for all kinds of things. But I think at some fundamental level they’re also beautiful and interesting and precious. Humans value all kinds of things like that very expensively. You know, if you go to Sotheby’s, you’ll see all kinds of things that are of very little utilitarian value. What is the usefulness of a Monet that is literally just oil on canvas? But we decide that it’s worth $30 million because people like it and they think it’s beautiful and it’s rare. Well, there are all kinds of beautiful, rare species on the earth that are completely irreplaceable. They will never be replaced even when they’re lost. You know, a real question for all of us, which I don’t think we’ve yet really resolved, is whether we are happy to pay for and allow some component of nature to exist for its own sake. Not because we can go to the Great Barrier Reef and think, “wow, this is amazing.” Or we can go and see gorillas at Bwindi Impenetrable National Park in Uganda. Are we happy for them to be there just for their own sake and just to leave them alone?
You know, the mountain gorillas—which have a very small global population, perhaps 750, that’s it—they’re not kept in captivity and they’re only found in a small corner of DRC, Uganda, and Rwanda. Something like probably half of that remaining population has habituated to human observers, either for research or for tourism. Do we need to habituate more groups? Will the groups that are not habituated go extinct because nobody’s going to care about them? Or are we going to allow any of these species to exist without being useful or interesting to us, or for our entertainment? Are we happy to pay and protect them and just leave them alone? It’s not clear to me whether we are actually. We only seem interested in those that we can go and see for tourism or that we can study. Everything else that has been kind of left alone has typically just been allowed to either wither on the vine or has been been deliberately destroyed. I think that’s a fundamental ethical question that humans have to ask ourselves.
I’d love to talk about Cayo Santiago, also known as Monkey Island in Puerto Rico, which is one of your field research stations that was hit very hard by Hurricane Maria in 2017. Can you share with us some of its history and why this Island is particularly significant?
Clarence Ray Carpenter was a forerunner of Primatology within the United States in the 1930s. He studied Howler monkeys in Panama and then he went over to Southeast Asia where he studied Gibbons. Then I think he paid people to trap around 500 rhesus macaques in India and then these were shipped to New York and ended up in Puerto Rico. Some of them were sold. Almost certainly some died on the journey, I would think. In 1938, 409 of these monkeys were released on Cayo Santiago. The descendants of those original 409 rhesus macaques still live on Cayo Santiago today, around eight years later.
Cayo Santiago is a 15-hectare island. It’s actually two islands connected by a narrow isthmus off the East coast of Puerto Rico, about a kilometer off the coast of the town of Punta Santiago. They live there and there are currently about 1,500 to 1,800 animals that are living in about seven naturally formed social groups.
They free range on these two islands. They historically at times have not been studied and have not been provisioned or anything, but today they’re provisioned with commercial monkey chow and when they’re the age of one, they’re trapped. Blood is taken for genotyping, for the genetic pedigree of the population. Also increasingly, to be genomically sequenced, to be studied for functional genetic variation. They are ear-notched and tattooed on the inner thigh and on the chest for identification. And they’re given a tetanus jab at that age. Tetanus wasn’t originally in the population and it was introduced later. Lots of monkeys were dying in a bad way and so they started introducing tetanus inoculation. But otherwise, there’s no medical intervention on the Island and they live freely unless investigators request them to be trapped. Aside from that one trapping when they’re one-year old, they will never be trapped. They’ll just live free-ranging their entire life on the island, until they die.
Carpenter studied them on Cayo Santiago in 1938 and 1939 then left. Of course, war was breaking out in Europe and the monkeys were largely left alone. There were some visits to the island, I believe by the military and by researchers who took some monkeys off the island. But they were largely left alone until the mid-1950s when Stuart Altman heard about them from E.O. Wilson and Ernst Mayer. He went and found Carpenter, spoke to him about where to find this island and how to get there. It was a different era of course in the 1950s than it is now. So he went, camped on Cayo Santiago, and re-introduced tattooing, daily census of everyone on the island, noting the social groups, births, deaths, immigrations, emigrations. He started introducing that in 1956 and then we take the kind of census of the demography and the life history database continuously from about 1958. There were a couple of years when data is quite patchy, when it’s being set up and initialized, and then all of the different procedures are being put into place. So, we tend to go back to about 1958 in terms of the continuous demographic, the life history database.
In the early 1970s, a skeletal collection was started in which individuals that died on the island were macerated—so skeletonized— and then put into a skeletal collection, which currently resides at the University of Puerto Rico Medical Science Campus in Rio Piedras. That skeletal collection continues to the current day. They’ve run out of room actually on that campus to store skeletons. So newer skeletons from animals that have been dying since 2010 are actually coming here [NYU] and are now under long-term loan from the University of Puerto Rico to NYU. Since the 1980s when genotyping became available, there were various small functional genetic studies that were started, and then it was really taken up in earnest in the early 1990s, starting with adult individuals.
1992 was when it officially started, and the adult animals were six or seven years old at the time, so we know that the animals were born from 1985 onwards. Then of course there’s been a lot of behavioral studies, because they trapped animals, collected blood samples, and took physiological measures, morphometric measures of the somatic tissues, muscle, body fat, teeth, dental casts. Of course, from the late 1990s onwards, when we acquired the technology, you can also now non-invasively measure lots of physiological components of animal biology via collection of urine and feces, which the animals are just depositing naturally on the island. You can collect those samples and you can measure things like female steroid hormones and track ovulatory cycles, for example. Or you can measure androgens or glucocorticoids. You can measure energy balance. You can measure immune activation and inflammation. Oh, I should also say that the rhesus macaques of Cayo Santiago were very amenable to direct cognitive testing in which you can—without trapping them, without capturing them—go up with clever operators that you set up, put stimuli in front of them, and they’ll engage with the stimulator. We use paradigms that were developed in developmental psychology. So one example is called the “looking time paradigm” in which pre-verbal infants are shown stimuli to test their gaze duration, how long they look at different things when they’re paired together, as measures of their relative interest in particular stimuli. We can at least say—in a counterbalanced experiment with careful controls in which one type of stimulus is consistently being preferred and looked at more over another—we can at least say that pre-verbal infants and monkeys and apes and things that we test discriminate between those two things.
So the value of Cayo Santiago is that we have this incredible scope of data. We can measure them cognitively, we can observe them and look at them behaviorally, we can look at their physiology, we can look at their genomes, we can look at their morphology, we have their skeletons, we have their genetics, and then we know everything about their ancestry going back for decades and decades. And because we have this genetic pedigree database, we can ask questions about the heritability of traits and we can also ask questions about selection on traits. So it’s a fantastic model for evolutionary biology really. I think it’s fair to say that there is no other primate study that has the breadth and also the depth and the longevity of data that Cayo Santiago has to offer.
So what are some features, for example physical, behavioral, social features? What are some features that make this particular group of rhesus macaques very unique and very special for you as a scientist?
The way in which rhesus macaques live is that they live in matriarchal societies, so they’re female-bonded. Females will, on the whole, live their entire lives in the group that they’re born in. Whereas the males will disperse and they will go and live in another group. These are very female-bonded groups. In each group, there’s usually a number of different matrilines, so a mother and her descendant daughters and their descendant offspring and then whole other kind of matrilines. The rhesus on Cayo Santiago, which are similar to populations of Japanese macaques, exhibit something called “youngest ascendancy” in which the youngest daughter always ends up being the highest-ranked female, not the lowest-ranked female. She, each new daughter, assumes a position above all of her older sisters. It could be that rhesus and their closest living relatives—that’s Taiwanese macaques and Japanese macaques and the Mulatta radiation of macaques—they have very despotic, very nepotistic, and hierarchical societies, very steep linear dominance hierarchies in which everyone one punches down. And it could be that in order to protect these infants and these young individuals, mothers have to protect them and come in on their side constantly against their older sisters and things. And so these infants are in a good position in which they can behave pretty boisterously and they’re always going to be strongly protected by their mom. And so they end up being able to push around their older sisters and they end up becoming dominant over them. Some people have suggested it’s artificial actually, and that it’s an artificial effects of food provisioning, in which food provisioning is making some of these populations more aggressive by condensing food spatio-temporally. But I have to say that I personally don’t buy it. I think that there’s plenty of other macaque species that don’t show youngest ascendancy that also live in captivity and are provisioned and they don’t under that circumstances. So at the very least we could say that it’s something that the Mulatta macaques show in response to provisioning and that itself makes them different. So then the males will disperse and they will live most of their lives in groups in which they may not have many relatives. So, some smart people, for example Anja Widdig, who is professor at the Max Planck Institute for Evolutionary Anthropology in Leipzig does a lot of work on kin recognition. She has some evidence that males dispersing into new groups may be able to preferentially associate with relatives even in those groups. So the males have dispersed into those groups and of course they will share sisters in those groups from males who moved between groups and have fathered in multiple groups. They may have half siblings but I think the jury is still a little bit out on that, like how much kin recognition is really going on. And it certainly would then have to be coming through other mechanisms such as phenotypic matching and things where you preferentially associate with individuals that sound a bit like you, smell a bit like you, or something like that. Whereas it’s easy for these females, because they grow up with their sisters and their mom and their aunts surrounded by them all the time since the day they were born. They’ll probably never disperse. That won’t change. At some point, their mom will die, at some point their aunt will die, some of their sisters may die but then they’ll end up having their own daughters and things. And they’re all surrounded by their close female kin. So it’s easy for them to bias behavior towards their kin. Their sisters, of course, may only perhaps be half sisters. They may well have a different father and then they have an interesting mechanism of male dominance acquisition which again, some people have argued is artificial but I don’t think it is, which is that individuals rise in dominance over time. They have a queuing system, males join the new social hierarchy at the bottom and tend to rise over time. Individuals at the top of the hierarchy tend to have been in the group for a long time and individuals at the bottom tend to have just joined. They join peripherally and they queue, and when individuals die or disperse and move to another group, they rise in social status. And what social status really means to a rhesus macaque is, for both males and females, is preferential access to food. And for males, it’s also preferential access to females, but rhesus macaques have relatively low body and canine dimorphism relative to other species of macaque, and relatively large testes volume. And that’s thought to indicate that they’re under reduced direct male-male competition as a selective mechanism. So in a number of other species of macaque for example, that are much more sexually dimorphic, males tend to turn up from outside of the group, they attack the alpha male and if they beat him and depose him, they become the alpha male. They have very strong body and canine size dimorphism. They’re clearly under strong direct male-male competition with lots of fights and associated selection for weaponry, upper body mass, large canines that can be used to fight, large body size. And they tend to hae relatively small testes volume because there’s not a lot of indirect competition in which males are just mating with lots of females and competing indirectly.
And then rhesus are very different in which the body size and canine size dimorphism has been reduced, and the relative testes volume has increased. So relative reduction in direct male-male competition and increase in indirect male-male competition. And concurrently with that, there seems to be an increase in direct female mate choice, in which females are just going and rather than being in a more coercive society, I mean there’s still coercion, but rather than it being a more coercive society like some of the other macaque species are in, because of that reduced body size dimorphism, because dominance is a queuing system rather than being a competitive fighting system, females then will go and choose the males that they prefer and mate—even with low-ranking males—and show stronger direct female mate choice.
It’s an interesting mating system and this is variation above and beyond the kind of variation people usually talk about in mating systems. So when people usually talk about mating system variation, they use it to describe the distribution of matings among males and females. And so if one male is mating with multiple females, you would say that’s a polygynous mating system. If one male and one female are predominantly mating together, you would say that was a monogamous mating system. A polyandrous mating system would be one female mating with multiple males. And all macaques live in a polygynandrous mating system in which multiple males and multiple females mate, and yet above and beyond that mating system variation, there’s all this variation in the strength of relative mechanisms of sexual selection, how males and females are competing with each other and how they’re choosing. So that’s the kind of social and mating system of rhesus macaques.
So Hurricane Maria is considered the worst storm to hit Puerto Rico in nearly a century. What happened when the hurricane swept through Cayo Santiago in September of 2017? Can you tell us about some of the immediate effects as well as maybe some of the long-term effects on the monkeys and their island, from you and your team’s point of view on the ground? You’ve worked with them for a very long time.
So hurricane Maria came through in September of 2017. It came in from the East/Southeast, absolutely huge hurricane and of course hit Cayo Santiago before it hit mainland Puerto Rico because it’s just a kilometer off the coast. Completely trashed the island. Massive deforestation, destroyed every structure on the island completely. There were trucks on the island, there was a backhoe—all of that trashed. The monkeys were pretty much fine as far as we can tell, in that we don’t have much evidence of any immediate direct hurricane mortality. There’s an increase in mortality in the couple of months afterwards in October and November of 2017 especially a spike in October of 2017. In some ways that mirrors what happened in the human population too. We all know that Donald Trump has famously said, not many people that died in the hurricane, quoting only very immediate deaths from things like damage to the ceilings collapsing and vehicles being swept away and things like this. And then ignoring, of course, the huge spike that was seen in the twelve months afterwards in mortality in Puerto Rico, among the human population, in which that spike was several thousand additional deaths. And that can happen with a lot of natural disasters in which individuals dying in the immediate natural disaster itself may or may not be relatively large, but that is not the same as all deaths that can be attributable to the natural disaster itself. So the rhesus is a bit like the human population in that extent. We don’t know of many. Perhaps there were a few. It’s hard to know because in a large population where you have census takers trying to monitor the population, they hadn’t been working for a little while because Hurricane Irma came through right before Hurricane Maria. And when the waves are very choppy, it’s very hard to get out to Cayo Santiago. So the boats had been taken out of the water. Individuals die all the time in a colony of that size. So we don’t have much direct evidence of direct mortality during the storm, but there’s nonetheless spikes afterwards indicating the mortality effects of the storm. And I think as I said, that’s interesting because it kind of, in many ways, mirrors what happened in the human population too.
So there’d been other major hurricanes too over the last 80 years, but Maria was the biggest. Major effects to the island included heavy deforestation, the fact that the dock in Punta Santiago, where we take the boat from, was very heavily destroyed. The concrete dock on Cayo Santiago itself became detached from the island, not because the concrete dock moved, but because there was so much land change on the land side that it no longer connected to the island. It just stuck into the water. The isthmus that connects the two islands is completely submerged. It was several feet under the water, isolating the two islands from each other. All structures were destroyed. Most vegetation was destroyed. There were 40 coco palms on Cayo, now I think there are five, six, something like that. All the mangroves seem to be dead. None of them have come back yet. The West-facing side on both the large island and on the smaller island still has trees. Grass and small shrubs have regrown. We’re seeing succession on the island actually. Because you’ve removed this shade from all these kinds of trees, now you’re getting grasses and shrubs and low-level vegetation, but it has dramatically changed the amount of shade on the island. And of course without all of these trees, the island is eroding and the soil is getting very heavily eroded and washing off very easily without trees to protect it.
It’s changed where the animals are on the island because some of these large exposed areas are now very hot without any tree cover and shade, and so there tends to be fewer animals in those areas. In terms of longer term stuff—what brain development looks like, what life history development looks like, whether individuals are maturing faster or slower, whether they’re going to have shorter life aspects and suits, things like this—the most honest answer is that we don’t know. And it may be many years before we truly see some of these effects. I think that that’s true for the human population of Puerto Rico too. We see the immediate aftermath, what does it look like for five- or six-year olds who had to be evacuated in the middle of the night to a hurricane shelter, who thought they were going to drown because they were floating in their living room higher and higher up towards the ceiling, with the amount of air that was diminishing. I mean that happened to people. People have told me those accounts directly, accounts of being in their homes as they filled with water and trying to get out of the house during the hurricane. I don’t know what the long-term effects of that are on people and maybe we won’t know for many years if we ever do fully know. And similarly, with the rhesus macaques, I think it could be a long time before we really know what the effects look like. And there are two different sort of things: there’s trauma or traumatic effects of the lived experience, and then there’s the aftermath. What’s it like to live in a newly deforested, hotter environment after that? Well, you can say the same for the human population. What was it like to live for six months, nine months with no power, with no clean water for months. In places like Punta Santiago, it was months before they even had clean running water again. I think Punta Santiago got electricity in May of 2018, having lost it in September of 2017…it’s a long time.
Yeah. I think some of these kinds of effects that we’re thinking about with environmental disasters like this, we’re seeing more and more of these huge national disasters. And I mean some of it is not related to climate change. Part of it may be related to climate change, things like frequencies of major hurricanes. One thing that I would say it is all related to is that we have a much bigger human population than we’ve historically had. We have much higher population densities. And so there are people everywhere. And so natural disasters that a hundred years ago may have not impacted anyone or impacted only small populations, they’re always having big impacts now because there are people everywhere. So, you know, if you get a tsunami, some of the large tragic tsunamis that there have been over the last 20 years, including in Japan, for example, there has been a lot of mortality in towns that up until relatively recently had much smaller human populations. And so, they would have been less catastrophic for human life, even relatively recently. So I think one thing we should get our heads into is that even if natural disasters of certain types don’t become more frequent, they’re obviously going to be much more catastrophic for human populations because human populations are so much larger now. The population density is so much higher and human distributions are so much wider than they used to.
I would love to know more about the range, the kinds of tools that you use to study and get to know the rhesus macaques. You mentioned your research and your interest in sensory ecologies. Would you describe your tool kit, the interdisciplinary tools and methods that you borrow from other fields, other disciplines, and then combine to study how different organisms sense their environments in order to survive, in order to socialize and reproduce?
I have an enzyme immunoassay lab here at NYU, which uses immunoassays to measure physiological aspects of the animals. We also look at their skeletons. We look at their soft tissues, which we measure. We study them observationally, behaviorally. We study them experimentally, behaviorally, with techniques that we pilfered from comparative and developmental psychology. We use methods from genomics, functional genomics to look at the underlying genetic architecture of traits. We also use genetics to build the pedigree so that we can look at heritability of traits and selection of traits. Yes, we use computational techniques sometimes to model the evolution of particular traits, sometimes to model perception. So, for example, I spoke earlier about the coloration of rhesus macaques—the dark red coloration in their face and on their hind quarters and genitals—we can take digital images of those and because we’ve characterized our camera (so I know the wavelength sensitivities of the short-, medium- and long-wave sensors with an eye camera. And because I know the spectral sensitivities of the short-, medium- and long-wave cones in rhesus macaque eyes, I can computationally map directly from what the camera sees to what rhesus macaque would see in response to the same image and look at what that color variation looks like in a perceptual space that’s defined not by the perceptual space of the camera but by the visual space of the species that I’m interested in. So you would build like a visual space in which you can plot colors within a space that’s defined by the retinal receptor catches that they would have in response to the color based on our understanding of the neurophysiology of rhesus macaque color vision.
That sounds really fascinating. Is that what the term sensory ecology means? Can you define what you mean by this phrase, sensory ecology?
I guess sensory ecology is an understanding of the different kinds of sensory inputs that are available in the environment: the smells and the sounds and the colors and the patterns and for other taxa, the electromagnetic signals, you know, chemical things in the environment. There’s a lot of variation in the types of sensory systems that animals have and the way they’re able to detect things around them and the environment. And then how they detect that, how they integrate it, how they make decisions on where to go, what to eat, how fast to fly, which direction to swim based on those sensory inputs. And I would say that’s really what brains are for. You know, there’s a lot of chat in the primate and broader literature about: is the human brain a social brain or is it an ecological brain? Is it selected for spatial cognition within the environment? Is it selected for social cognition and the ability to outwit other individuals? Is it a Machiavellian brain? And I would say it’s a sensory motor brain. It receives inputs from the environment and then coordinates motor responses.
Brain size in primates, but brain size broadly across vertebrates, is strongly positive-predicted by body size. That should be no surprise. An elephant has a massive brain and a mouse is a tiny brain. But let’s just say that the whole function of a brain was to coordinate something in the social environment. You know, I mean mice are social, so are elephants. It doesn’t seem to me to be that different a task. Thinking four or five minutes ahead of an opponent is actually not that complicated. Computers have been able to beat chess grandmasters for decades, but the computational power that it needs to do that, it’s not that great actually, but it turns out that sensory motor control is extremely computationally demanding. So if you look at the latest Boston Dynamics robot trying to water a plant on a table and it realizes it’s gone too far and it started to pour water on the table and it has to pull it back a little bit, it’s a mess. There’s water all over the table. There’s water on the plant, but there’s water all over the table. That kind of sensory motor control that adjusts to sensory input and changes your motor control actually turns out to be really hard to program and computationally very expensive. So sensory ecology, yeah it’s really about understanding these different kinds of sensory inputs and then, decision-making and the motor control that goes into decision-making.
The interesting thing about primates actually is that we do have this great sensory transition. Taxonomically, the largest distinction we make in the primates is between the strepsirhines and the haplorhines. The strepsirhines all have a wet nose and a rhinarium, and less developed color vision—either at the polymorphic color vision among the diurnal lemurs or they’re monochromatic or they’re dichromatic—versus the haplorhines that have a dry nose and forward-facing eyes. And then among catarrhines—that’s the Afro Eurasian monkeys and apes—uniform trichromatic color vision and good stereoscopic vision and stuff. So we have this huge sensory transition and this big sensory distinction between what the strepsirhines are doing and what the haplorhines are doing is at the heart of primate taxonomy and phylogeny. We make this big split in primate taxonomy between essentially the olfactory-guided rhinarium-possessing species and the dry-nosed. And that’s literally what they mean, right? Haplorine means simple-nosed.
I’d love a quick clarification please. What do you mean by sensory transition?
I guess that would mean that we’ve moved away from the ancestral condition of olfaction into a more derived condition of being more visually oriented. Most mammals are not like that, right? If you think about your dog or a horse or a cat or buffalo or whatever, they still are very olfactorily focused. It’s a derived condition in the monkeys and the apes and including humans to be more visually oriented.
Thank you for explaining! How about we turn to your work, your long-term field studies with primates at your other research site, the Gashaka Gumti National Park in Eastern Nigeria. It’s been really fascinating to learn about sensory ecologies, but we also know that you have a very great deal to say about political ecology and conservation projects that have to deal with very complicated sociopolitical conditions because they come out of very difficult histories. So what’s it like to work as a biologist in Nigeria over many years and over many sociopolitical turnovers.
Nigeria is a country that I’ve worked in since 2003 when I did my PhD fieldwork there, a country that has had a lot of instability over the last 60-70 years since Independence. I work at a few different places in Nigeria, but the field site that I mainly work at is called Gashaka Gumti National Park, which is in the East of Nigeria on the Cameroon border. It’s a real biodiversity hotspot, lots of species and primates, including the largest remaining populations, we think, of one of the four chimpanzee subspecies, Pan troglodytes ellioti. There are four chimpanzee subspecies: the central African subspecies, Pan troglodytes troglodytes, which is the common chimpanzee. Then there’s the Eastern chimpanzee, the one that Jane Goodall has studied, Pan troglodytes schweinfurthii. Then West Africa, Pan troglodytes verus which is the West African chimp. And then there’s a chimpanzee subspecies that we think is distinct to basically Southwest Cameroon and Southeast Nigeria around the Gulf of Guinea. And there’s a lot of endemism actually within that region, both in primate species but also in biodiversity generally. There’s two large rivers—the Sanaga river in Cameroon and the Niger Benue Complex in Nigeria—that seem to provide strong geographic boundaries and therefore produce a kind of reproductive isolation. Combined with very high rainfall and interesting typography, lots of mountain ranges on that ridge where the border of Cameroon and Nigeria is. And so there’s a lot of diversity there. There was a project set up in 1999 called the Gashaka Primate Project which ran for many years. But at the moment that has been suspended. There are some issues of instability within Nigeria, because of the actions of Boko Haram in the Northeast of Nigeria that’s caused displacement of people further South, including into the park.
There’s always been a very interesting political ecology there, in which you have people living with subsistence farms and with cattle—both on the edge of the park and within the park, in so-called enclaves of the park, which were set up when it was founded in the 1990s. And then there’s some kind of semi-nomadic movement within some of those populations. So there are people that have cows that live up on the plateau within the park that keep them up there during the wet season because there are no tsetse flies, so there’s no sleeping sickness being transmitted to the cattle. And then when the wet season ends and the tsetse fly numbers reduce, they bring the cattle down to graze on these long grasses that have grown during the wet season.
And then there’s also an annual migration of fully nomadic Fulani who move around with their cattle in Niger. They’re in Niger and Chad, when Nigeria and Cameroon are going through their wet seasons, where it’s much drier further North and there’s no tsetse flies for the cattle. And then as those wet seasons fade, they bring them down into Cameroon and then sweep through Nigeria across the border and then back up to Niger—to graze on those long grasses that have grown during the wet season—during the dry season when there are far fewer tsetse flies that are a risk to their cattle.
You’ve got a very interesting scenario where literally all of these nomadic Fulani are coming through the national park, just moving through the national park with thousands, tens of thousands of cattle. And that always causes trouble, not just for the national park. It causes a lot of local political and cultural instability because people turn up with a thousand cows and they get into people’s farms. And this has a complicated history, in that region in which local traditional rulers, such as the Lambda of Gashaka is of Fulani heritage. And then you’ve got that layered over a number of other historical ethnic groups that live in the area, combined with the fact that you also have a lot of Hausa traders moving through Central West and West Africa.
So it’s a very complicated sociopolitical environment in which to try and be a stakeholder who’s interested in environmental preservation. So at the moment, I’m hoping to get back out there soon actually to try and reestablish some of those primate projects that we had running in the national park. So we’ll see how that goes. There are a number of other interested stakeholders who are trying to show renewed interest and get renewed focus back on Gashaka.
Central West and Central Africa have always been more difficult to work in than some parts of East Africa and Southern Africa. There’s been a lot of political instability in some countries. So projects that were run by John Oates, who’s now a retired professor of primate conservation at Hunter College and the CUNY Graduate Center. He had projects in countries like Sierra Leone and Liberia. And of course these were successful for more than a decade and then civil war broke out. And it’s very hard to maintain these kinds of environmentally focused long-term committed conservation projects, in the face of quite overwhelming factors such as civil war in the country that you’re trying to operate in. And those kinds of human, you know, we were talking earlier about humans and our overwhelming ability to change the environment and things. Sometimes these long-term projects can get very overwhelmed by relatively short-term changes within the anthropogenic environment and sociocultural factors. It’s clearly not really safe to operate these kinds of projects under some circumstances where you have rival militia active in your field site and that’s happened a number of primatologists. But it’s a very real thing that a lot of primatologists have to deal with. And some countries have much more stability and are much more positive towards the environment than others. You know, Costa Rica is a fantastic example of a country that’s had a lot of stability and a lot of environmental proactive policies that has been increased in the forestry and the degree of forest cover in the country over the last 34 years. So things like that matter, you know, human socioeconomic factors often overwhelm the biology in conservation. It’s a real question, I think. When I lecture about this, I say to the undergrads, you know, it’s a real question. If you’re interested in this stuff, if you’re interested in conservation, it’s a question of what kind of training your best getting—because it’s probably not biology. You know what we need within the conservation movement is land rights lawyers and people who understand development economics, people who understand political ecology, a very diverse set of people need to be engaged with conservation for it to succeed because the biology is something. But actually it often can be overwhelmed by some of these other kinds of factors. And the only people there might be a conservation biologist, a zoologist, a primatologist. And so they often end up trying to get involved in scenarios where that’s not really their training or their background. The same with community development and outreach and conservation education and all the kinds of things that you hope an integrated conservation program within a so-called developing country, a lower income country might hope to offer. Everything from kind of associated conservation and protection and research of the animals to educational outreach in schools to some community development and working with communities and stuff. You might hope for all of those things, and usually the people doing it are biologists who may not be very well trained in those things, and may make missteps and may make things worse in community development where they have no training. You know, it’s not their area of expertise.
So when we work ecologically, we start to engage with, or we have to very often pay really close attention to many kinds of spatial and temporal relationships that form between species or between species and their environments. Ecologies don’t always work within, you know, our very human scales of place and time. Can you talk a bit about how different scales of place and time might become visible or significant as you’ve worked with many different species at your research sites in Nigeria?
In terms of things like conservation and protection, I think there are issues in which the best protected areas in some national parks are research stations and the areas around them because there’s people in the forest every day, and so they may be avoided by hunters and things. And that’s definitely true at Gashaka, at my field site in Nigeria where the Kwano area where we have our field station, the animals are by far the most abundant of anywhere in the national park because people have been there all the time, providing a kind of on-the-ground presence.
There are questions of course, of what kind of scale those kinds of projects can provide protection on. Are we just going to end up with a little island around our research station with forests full of animals, and then if you walk five kilometers in any direction, it’s a depauperate wasteland in which the trees have been logged and the animals have all been hunted out.
The temporal dimension to that is, you know, again to come back to John Oates’ projects, he felt they were going really well and they were going really well for 10 years, 15 years, something like that. And it’s just a blink of an eye, and you can lose it all within weeks, in the face of civil war or something like that in which militia move into the park and need to eat. And they have machine guns and automatic weapons and they can just shoot everything out of the trees. You can think for a long period of time, things are going quite well and still lose it all very quickly.
It’s not clear what sustainable hunting rates might look like for some of these primates because the life histories are so slow, the replacement rate is so low that any kind of population reduction will take hundreds, thousands of years before the populations are back up. These kinds of issues of spatial, temporal dimension outside of conservation also matter a lot in terms of shaping species biology. The distribution of food in space matters a lot and the kinds of things that individual species eat. So folivores, for example, eat leaves and they tend to have relatively small home ranges. They wake up in the morning in small groups, there’s leaves in their tree, there’s leaves on the tree next to them. They don’t have to go very far. They eat then they don’t get much energy from that. They tend to be quite lethargic, so they have large stomachs, small brains, they don’t need to go very far. They don’t tend to be very social. In contrast, frugivores, fruit-eating specialists, tend to have much larger home range sizes because you need to encompass multiple different fruit stands, which tends to be patchy in forests in their spatial distribution. They wake up, they have to range-travel to some fruit trees. When you get there, what tends to determine whether you can stay in that tree or whether you get pushed out by another group is group size. So you get selection for larger group sizes. Of course, fruit as we know is extremely easy to digest and you get lots of energy, lots more energy from it. So they tend to have much smaller guts, larger brains, complex environments, larger group sizes. They tend to be then much more active because they’re getting a lot of energy from their diets. And so there’s whole different kinds of species biology and variation that’s linked to things like spatiotemporal factors in the environment at its base. Like what are you eating? Where is that found? How is it found? How seasonal is the rainfall? So then how seasonal is biomass production and plant production? How patchy is your food in the environment? What are you eating? Lots of primates also eat insects. Well they can be randomly dispersed in the environment. They can be clumped. If they’re eating termites and ants in these giant nests, they can be clumped spatially, things like these huge cicada emergencies in which you get hundreds of thousands, millions of cicadas emerging at once and then it’s a free-for-all in the forest and there’s cicada everywhere. So there’s all these kinds of issues of spatiotemporal variation in the environment that structure species biology and then all kinds of spatiotemporal issues that determine your ability to study them. Stability at field sites, your conservation issues, what they look like. So I think there’s multiple different ways in which we can talk about spatiotemporal effects on what we do, what we study, and how we do it.
As our conversation comes to a close, I’d love to talk about possible futures for protecting biodiversity, for conservation movements, for teaching students, at undergraduate or graduate levels, or even perhaps mobilizing various groups. So what kinds of actions would you like to see? What kinds of actions do you engage in or advocate for, as a biologist and researcher of course, but also as a professor, as a colleague, and maybe just as a regular human being—what would you like to see?
Well, I think that the single most important thing is that we get good multinational agreements in place with proper frameworks for their evaluation and implementation. There’s obviously debates within the United States and elsewhere about what roles of government should be in things. I would say the central roles of government are to understand what broad public issues are that can’t very easily be addressed by individuals and to implement policies that incentivize certain kinds of behaviors, discourage other kinds of behaviors towards better kinds of collective outcomes. Obviously there’s many people in the United States at least that don’t agree that that’s the job of government is. I think that the kinds of issues that we’re dealing with and the scale that we’re dealing with require very, very large strong solutions that have to be governmentally led. Business will be business. It will try and maximize profits. You know, regulation is much derided by certain components of certain societies, but all regulation is important. Things are regulated all the time. I don’t want to get too political but it seems that there’s a certain kind of disingenuous framing of this, in which we cannot apparently have government intervention or international frameworks for things like climate change or healthcare or something like that. But we can have them for subsidizing oil or for subsidizing the corn industry or large agriculture. That’s fine. That’s not a government handout, right? It doesn’t matter how much the corn industry gets every year. That’s definitely, definitely, definitely not a government handout. But the idea that we could spend that amount of money on some collective public policy issues such as trying to cover healthcare because it’s way more efficient to have healthcare collectively covered than it is to have individuals seeking their own mandates is apparently a government handout. What we need is strong intergovernmental, multinational frameworks to solve these problems because they’re not restricted to a specific country.
And I think it’s why a lot of people within the environmental movement are so dismayed at the United States’ decision to pull out of the Paris Accords. We’ve been here before. There’s been many big multinational agreements that have either never been ratified, never been implemented. Those kinds of agreements are necessary to incentivize business and to incentivize people into more sensible decision making that takes more medium- and longer-term perspectives into account. It’s especially difficult when we get to the point where scientific knowledge and expertise are under attack. There seems to be an attack on our expertise at the moment. For example, I come from the U.K. where we’ve recently, obviously, been in a complete mess after the Brexit referendum. Michael Gove, who is one of the leading politicians behind the Leave Campaign, when he was asked multiple times by journalists, “British business is saying this would be terrible for our economy, so why do you think people should vote for it?” And he said multiple times, “I think the British people are tired of experts and their expert opinions.” And so, we have this very direct attack on expertise and expertise is extremely important. We rely on expertise all the time. We rely on the science of doctors and surgeons to help us make healthcare decisions and to ensure that we’re in good health. We need to rely on climate scientists. We need to rely on conservation biologists, when they come and say, there’s an environmental catastrophe and actually this is going to impact your economies and your societies. It already is impacting us very heavily globally. The five-year drought that preceded the Syrian civil war was a major factor in the emergence of the Syrian Civil War, which has been an absolutely horrific war. There was a huge amount of pressure on arable land in Syria leading up to that outbreak that was being caused by, you know, the worst drought that the country has seen in recorded memory. So, you know, we are seeing the facts all over, and it’s all very well and good saying, Oh well it might be expensive to deal with. Well, how expensive has the Syrian Civil War been for everybody, including the United States? And even the experts, you know, like the Department of Defense that comes out and says, climate change is a serious military and serious threat to the United States. You know, they’re happy to come out and say that. But again, that kind of expertise is just not currently being valued. You know, when even the military, the Department of Defense is coming out and saying, actually, climate change is a real problem for us, and it’s causing all kinds of military issues globally and instability that’s costing us huge amounts of money to have to deal with.
So, what I would say is that people need to listen to experts across different components of their life, not only in the ones where they’re used to listening to experts, or they’re more comfortable listening to experts. Nobody would get on a plane and start challenging the pilot. We need to put our faith in expertise. We need to try and strengthen our political and civil structures that are under attack and that people are trying to undermine. We need to vote and try and support policies that can deal with these issues.
Now that all said, individuals can still make a difference in the conservation movement and the environmental movement. Individuals have made a lot of difference. The scale of that and the scale of the problems that people have to tackle, these are individual questions for people. Like what is your commitment? What are you able to do? What is your area of expertise? What do you have to offer? And there are other, I think, complicated issues for say someone like me going to a country like Nigeria and I don’t particularly feel it’s my right to go to a country like that and say, Hey guys, you have to stop doing this, and we have to focus on this, and stuff. It’s a kind of environmental neocolonialism. I’m not Nigerian, so my own focus has more been, I have trained a number of Nigerians. One of my former students is now the dean of students at a university in Jalinga, the capital of Taraba state. And another one of my former students just finished his PhD in botany at the University of Lagos. My own strategy is to invest in capacity, in people. You know, what happens in a country like Nigeria with its environment is a decision for Nigerians. I try and help with training and advice and support, financial support, because that is something that we can offer. For example, I was just describing a former student of mine, Mar, who’s now a dean in Jalingo. When he was an undergrad, he had to sell fuel on the side of the road to fund his studies and stuff. And I was getting grants and money and helping support him and provided him with a monthly stipend throughout his masters, which he did alongside me. And then our projects funded him through his PhD. Nigeria is a country that doesn’t have a lot of capacity in things like wildlife biology and environmental biology conservation. We can make those individual investments and then hope and trust that the Nigerians will take on the baton and have to pick this stuff up. But it is complicated and it’s very layered and it’s part of the reason that I don’t have more of an active kind of low income country conservation program. I do what I can.
I would like to restart my research program in Nigeria, involve a lot of Nigerian students, and try and get that area secure, operating, working nicely on a research front. I think that has its own conservation benefits regardless of whether the research projects themselves are specifically conservation-oriented. Just having people in there everyday working, having an active station in the forest—and I think that the data bear this out—is actually one of the best predictors of whether habitat and wildlife get protected in these kinds of environments. They are very complicated scenarios. A number of grave missteps have been made even by conservation NGOs in which, you know, deforestation and wildlife loss has been accelerated by the action of conservation projects, not decelerated. Some of the community development projects that have happened in Nigeria for example, have created net migration into the park because they’re the only village around that has a health center and that has a school and stuff. People have moved there and that has massively increased the human population within the national park. That’s happened in Cross River, for example. And I’m not saying that it was wrong for people to do that, but it was complicated. Often there’s a lot of unforeseen consequences. And so I’ve personally restricted a lot of my own investment into things where I can’t see many downsides, such as I can’t see many downsides to training young Nigerian wildlife biologists, like, what’s the worst that I’m going to do? So things like that I’ve tried to focus on, where I can see possible tangible benefits and increasingly a kind of capacity and awareness—without me being able to foresee that there are too many potential ways in which this could go disastrously wrong. And my own involvement isn’t just gonna make things worse!
James, thank you so much for your time.
And thanks to you, listeners of our Multispecies Worldbuilding Lab.
This episode was produced by Josh Allen, Ben Montoya, Hannah Tardie, Felicity Cain, Aleah Papes, Alex Guillen, Dan Hodnett, Wanda Acosta, and Elaine Gan. Special thanks to the Green Grants program of New York University’s Office of Sustainability and NYU’s Center for Experimental Humanities and Social Engagement.
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