Plavcan Discusses New Species of Monkey
Michael Plavcan: Thanks.
MM: I want to start with the site in Africa, Kanapoi, and what is known as the West Turkana Paleo Project. Can you tell listeners what is the significance of Kanapoi and the West Turkana Paleo Project?
MP: Well, the West Turkana Paleo Project is a collaboration between myself and Carol Ward at the University of Missouri, and Kyalo Manthi who is a director of Earth Sciences of the National Museum of Kenya. Kyalo is the leader of the project. We all three collaborate equally on this, and we’ve had a very successful project running since 2011. Our first place that we worked was at a place called Kanapoi. The project in West Turkana works in the very far northwest of Kenya, which is one of the most important places for finding fossils concerning human evolution. And the deposits are around 4 million years old, and we specifically, at Kanapoi, we’re looking for fossils of a human ancestor called Australopithecus anamensis. Kanapoi is a hot, dry place to the west-southwest of Lake Turkana which is one of the largest brackish lakes in the world. It is the earliest… Australopithecus anamensis, is the earliest of the Australopithecines or the one type of early human ancestor, kind of looked like a chimpanzee that walked on two legs like you and me. It’s a pretty wild thing. It’s clearly related to us. These guys walked on two legs upright just like you and I did pretty much…
MM: 4 million years ago?
MP: 4.2 million years ago, and the site is very well known for that. We’ve worked that site for a number of years, collecting lots and lots of fossils and not only finding the Australopithecus, but also all of the fauna that go along with it. So we’re interested more than in just the human ancestors, but we’re interested in the environment they lived in, all the animals that lived with them, and trying to figure out where it was that these guys lived, that our ancestors lived, the environment that they evolved in, so it’s a really important key to understanding human evolution.
MM: So about Kanapoi, is there something about it geologically? Is that a rift zone? Is there a fault break there or something like that, that causes it to be such a rich site?
MP: Yes, as a matter of fact. All of East Africa, there is a thing called the Rift Valley, and the Rift Valley runs from Ethiopia all the way down east Africa. And it is an area that has, because the tectonic plates have pulled apart and it’s a relatively dry area, the fossil beds have been exposed, and so the place is incredibly rich with fossils. And it’s not just a Kanapoi, but there are many, many localities running down the Rift Valley of various ages. And Kanapoi is, geologically, it is at the edge of an old lake. It was an environment that was sort of marshy and open. So there was sort of a savanna woodland area there, and there was the lake nearby. And it turned out to be a particularly good place to get fossilized if you died.
MM: Mike, what are guenons?
MP: Guenons are monkeys. They are a kind of monkey that lives in Africa. They’re restricted to Africa. There are about 28, 30 species or so depending on how you want to define species, so they’re very, very diverse. They live, most of the species live in the forests in central Africa and coastal west Africa, but there are two, the best-known of these is the vervet monkey. Most people if they saw a vervet monkey would recognize it. In fact they used to be sold as pets in the United States fairly commonly, sometimes called green monkeys. There’s patas monkeys which people have seen probably pictures of too. These are open savanna dwelling animals. They have spread all across Africa, and everywhere you go in Africa you will see not just baboons, but some sort of guenon along with them. So very, very common, but most people here haven’t heard about them.
MM: All right let’s talk about your guenon, Nanopithecus browni. Have I pronounced that correct?
MM: So tell us about what you’re finding, Nanopithecus browni. Who was he or she?
MP: Or it.
MM: Or it, yeah…
MP: Yeah. Nanopithecus is a very small guenon. It actually, the fossil itself comprises two teeth, and which is not a lot, but it’s enough for us to tell what it is. The teeth are diagnostic as a guenon. The amazing thing about this is that the teeth are so tiny. They are minuscule, and if I held them in my hand you’d have to look closely, preferably with a microscope, to see these things. It is the same size, as it turns out, as a living guenon and called the talapoin monkey. So it would probably look similar to it overall, probably weigh about a kilogram, two, two and a half pounds which is the smallest known monkey in the old world that’s alive today so…
MM: Talapoins are still living today?
MP: Talapoins are still living, and what’s unusual about Nanopithecus is talapoins are thought to have been dwarfed, that is reduced in body size over time. They are so small, and they have characteristics of a species that is undergone dwarfing. There are certain aspects of what the animal looks like that are very peculiar when they reduce in body size and diagnostic, and this animal has them. So it’s thought to have been dwarfed. Now the living talapoin lives in west-central Africa in thick dense forests and swamps. With guenon, we know very, very little about guenon evolution. We know from genetics that they probably arose sometime around 11 million years ago or so, that they’re very, very diverse today, and apart from a few fossils here and there, there’s one tooth at about 6 million years from Arabia, actually, which we think of in geopolitics is not Africa but environmentally it really is, pretty much the same place. There, most of the fossils that we find are less than 600,000 years old, and most people when they think about the evolution of guenons think well where they are today is where they evolved. And the reason that there’s so many of these things is that the rainforests have dried up and shrunk and separated in populations, and they turn into species. And then the rainforests come together, and there’s this process of shrinking and growing forests that leads to speciation and –
MM: Depending on drought or rain?
MP: Right, depending on glaciations, and yeah, the change in the climate over long term. The talapoin monkeys are living in these swamp forests. And so the logical conclusion is well, there’s something about living in a swamp forest that has made these animals very, very small, and their range is relatively limited. And then we come along, and 4 billion years ago we find that these things are living all the way across Africa on the other side of the continent, and not only that, but they’re living in the same place with human ancestors. Literally we found it feet away from where we were finding hominin fossils. But they’re living in a savanna forest and grassland area which is environmentally pretty much as far away from the swamps and rainforests as you possibly can get in Africa. So it turned out to be a real surprise, not only that we found this dwarfed animal so long ago, but that it was completely out of the range of the living animals, and living in a totally different environment. So I think it’s kind of interesting.
MP: It gets you thinking.
MM: When you say dwarf or dwarfed species, to give us an example of roughly, can you compare it to an animal that people would know?
MP: It’s, oh it’s the size of a cat. You know, it’s about 2 pounds or so. A small cat, you know.
MM: Domestic cat?
MP: Yeah, domestic, a small, domestic cat. Two pounds.
MM: You kind of touched on this already but other than it being a new species, which is interesting in itself, what is the significance of this discovery? What is the, what is the significance of the discovery of Nanopithecus?
MP: Well it turns –
MM: Perhaps, I guess another way of asking is what is significant about where it was discovered?
MP: Well, both where and what it is. The first is that it is, we know so little about guenon evolution that it’s the old… for all intents it’s the oldest thing that we can actually identify of guenons. Guenons are problematic because there’s, they’re beautiful, beautiful animals, just absolutely gorgeous, and if you just glance at one you can tell what species it is from the fur color. But if they give you a bag of bones, you can’t tell one apart from another, so it’s frustrating to try to figure out what is what, in terms of guenon evolution or identifying who’s what. Now this thing we can actually identify, and link it up to a modern species. So this is the first thing that we found this old, that actually indicates that the guenons are there at this time. The second thing is that being far away from where it lives today, it change… it throws up a caution to people who are interested in the evolution of these animals because it’s saying that you can’t just say where they live now, and it is going to be key to understanding their evolution. And this thing is found all the way across Africa, right, on a totally different environment. So if you’re going to talk about hypotheses, about what caused the diversity of modern guenons, just saying that, well they live here, and it must be something to do with this particular forest environment that has to do with their evolution and speciation, well this animal proves that no, you can’t really quite say that with these animals. They used to be spread, at least these talapoins or their ancestors, used to be spread all over Africa in totally different environments, so it’s suggesting that things were a lot more complicated.
MM: Well thank you for coming here today and talking about this new finding, and we look forward to learning more about it in the future.
MM: Thanks a lot.
MP: Thank you.
MM: Music for Short Talks from the Hill was written and performed by local musician Ben Harris. For more information and additional podcasts, visit researchfrontiers.uark.edu, the home of research news at the University of Arkansas.