Are the famous, sex-loving bonobos really more peaceful than their chimpanzee relatives?

Juvenile bonobo eating

Bonobos (Pan paniscus) are often referred to as the peaceful apes or the "make love, not war" apes. Previously known as the pygmy chimpanzee, they're thought of as more gentle and peaceful than their closely related cousins, the chimpanzee (Pan troglodytes). These two species are very closely related: 99.6% of their genome is the same.  Many people are aware that chimpanzees hunt other primates. You may even have heard that they will go to war against other chimps, brutally killing members of their own species, wiping out another group of chimpanzees.  With 99.6% of their DNA identical to chimpanzees, do bonobos really deserve this wholesome image?

Bonobos are only found in the Democratic Republic of Congo. They're smaller in body statue than chimpanzees but otherwise they look very much alike. In chimpanzee social systems, the males are dominant over the females. In bonobo groups, its the females who are dominant over males. Females remain in their natal unit and develop strong bonds with other females. Bonobos also play more as adults, engage in sexual activity more, and display less severe aggression than chimpanzees. So far, it looks like bonobos are living up to their reputation as the more peaceful primate.

As we learn more and more about bonobos, at least one of our original ideas about them has been proven wrong. Originally, only chimps were thought to hunt and eat other primates, but this isn't true. Surbeck and Hohmann (2008) published the first account of wild bonobos hunting other monkeys. Both males and females were active in the hunts and red colobus monkeys, black mangabeys, and other primate species were on the dinner menu for bonobos.  Seems like we've busted that myth.

Bonobos sharing food

However, a study compiling over fifty years worth of data on chimpanzees and bonobos seems to suggest that there is quite a difference. Studying 18 communities of chimps versus 4 communities of bonobos, scientists reported 152 killings by chimpanzees compared to just one killing by bonobos (Wilson et al., 2014). It is thought that differences in the brain between these two great apes may be the underlying cause behind the increased violence and aggression seen in chimpanzees. The brain of a bonobo seems to be better adapted to impulse control, perceiving stress in others. Rilling and colleagues (2012)  state that their neurology "...allows them to more strongly represent distress of both self and others compared with chimpanzees. This translates into greater empathy, as well as reduced aggression." The Rilling article is a great read, as it includes not only their findings but also a thorough overview of the behavioral differences between chimpanzees and bonobos.

To summarize, while there may not be much separating these two species in terms of their DNA, how their DNA is expressed does appear quite different. At first, scientists wondered if we simply had less data available to us on bonobos, and that lack of data meant we were missing behaviors in bonobos that are seen in chimps. (The chimpanzee population is far larger than the bonobo population.) As we study them more and more, chimpanzees come out on top in terms of aggressive behaviors.  It's important to remember through that all of these aggressive behaviors don't make up the majority of a chimpanzee's day. It's quite the opposite. Social behaviors make up a small amount of any primate's day. Feeding and resting take top priority. That said, I think the conclusion that bonobos are more peaceful than chimpanzees stands for now.


Food for thought: I think it's most surprising that bonobos will share first with strangers before they share with friends or associate bonobos (Tan and Hare, 2013). This isn't something we see with chimpanzees (and arguably something we don't see in all humans). Why would a bonobo share with a stranger first? How is this an adaptive behavior?

Check out this incredible BBC video explaining the hunting tactics of chimpanzees. (Yes, they really do have tactics.)

Read NOVA's interview with the well-known primatologist, Frans de Waal, about studying bonobos.

Journal articles referenced:
Surbeck, M., & Hohmann, G. (2008). Primate hunting by bonobos at LuiKotale, salonga national park. Current Biology, 18(19), R906-R907. doi:10.1016/j.cub.2008.08.040
Wilson, M. L., Boesch, C., Fruth, B., Furuichi, T., Gilby, I. C., Hashimoto, C., . . . Wrangham, R. W. (2014). Lethal aggression in pan is better explained by adaptive strategies than human impacts. Nature, 513(7518), 414. 
Rilling, J. K., Scholz, J., Preuss, T. M., Glasser, M. F., Errangi, B. K., & Behrens, T. E. (2012). Differences between chimpanzees and bonobos in neural systems supporting social cognition. Social Cognitive and Affective Neuroscience, 7(4), 369-379. doi:10.1093/scan/nsr017
Tan J, Hare B. Bonobos Share with Strangers. PLOS ONE, 2013; 8 (1): e51922 DOI: 10.1371/journal.pone.0051922

Finding new species in 2015-how it happens

Articles like this one from Mother Nature Network, titled 9 newly discovered species, pop up from time to time about new organisms that have been found by scientists. Just recently a previously unknown species of fish was discovered no less than five miles below the ocean's surface. New primate species are even discovered, although finding such large species is very rare.

Newly identified Rana kauffeldi Photo credit: Brian Curry

Wait, how is that we're still discovering completely new animals?  Scientists estimate that there are millions, yes millions, of species we still don't know about. While some of these unknown species are reptiles or rodents, most of them are less charismatic. Many species of insect have yet to be identified and many bacteria and plants are unknown too.

New species are often discovered when scientists look at the genome of one species only to find out that one species is really two or more separate species. For example, Bornean and Sumatran orangutans were once thought to be one species. No attention was given to breeding Bornean orangutans only with Bornean orangutans, and many zoos now have hybrid orangs because of this. It was through genetic analysis that we discovered that each island held its own, distinct species.

Some of the time scientists do discover completely new species that are unheard of to science. This usually happens in far-away and poorly studied areas of the globe. Scientists talk to locals in remote areas and hear about a species that doesn't match descriptions of known species. Behavior, anatomy, reproduction, and even vocalizations are all examined when determining if something is a new species. Scientists hunt around in the jungle, struggle to obtain a photograph or grab a sample specimen, and ideally consult with as many other experts as possible to make sure that this is in fact a new, distinct species. It's important to compare a possible new species with existing species to ensure that there are enough differences to satisfy calling something an entirely new species.

Classification of Saimiri oerstedii

A species is a group of organisms that are similar and capable of interbreeding. (To learn more about what the term species means in biology, check out this great page and this one from Berkley.) A species is given a Latin binomial name. Examples of Latin binomial names you might be familiar with include Homo sapiens for humans, Pan troglodytes for chimpanzees, and Drosophila melanogaster for the common fruit fly. When we discover new organisms, it is the taxonomists who study those organisms and decide how they should be named. Taxonomy is the branch of science that includes the classification, identification, and description of organisms. You can see the classification for a species of squirrel monkey to the right. Taxonomy may sound a little boring, but classifying animals isn't always black and white. There's currently a debate about the classification of capuchin monkeys that you can read more about in this article.

So the next time you click on a link about the ten most interesting species discovered in 2014, you understand how it is species are found, how it's determined that those species are distinct, and how they are named.

Food for thought: What do you think is the best way to determine if a species is separate or distinct from another? Would you rely on genetics? Or look at the behaviors of the animal? Is whether or not the two populations coexist in the wild important? There are many things to consider!


News stories about recently discovered species:

Head to LiveScience to read about a species of monkey first spotted in 2007.
Read about a coughing frog species that was recently discovered or
five new bird species discovered in 2014.

The importance of wildlife corridors in conservation

As habitats become more and more fragmented, wildlife corridors are of increasing importance. A wildlife corridor is a straightforward concept: it connects two habitats that have been disconnected,

Fragments in the Amazon, Photo from Google Earth

usually through human activity of some sort.

Ideally, if we wanted to save a species, we would conserve as much of that species' habitat as possible. It's a no brainer. The reality is often different. Continuous stretches of rainforest would be wonderful, but sometimes only parts of an area can be protected. Maybe the government decides that a highway is crucial to connect an outlying town to nearby cities and a forest is interrupted and cut in two pieces. Or maybe parts of a savanna are sold off as farmland, disrupting continuous forests and instead making patches of forest. Either way, the landscape changes and life has to cope.

Dispersal of plants and animals is challenging when that plant or animal has to cross a stretch of non-habitat. A bird can cover that highway or palm oil plantation by flight, but a howler monkey or a sloth is going to have a much harder time crossing that space, missing breeding opportunities, foraging opportunities, dispersal opportunities and unable to move into new habitat if needed.

A troop of monkeys may survive just fine in parcel X of forest, but imagine there's a drought. They're starving, visibly losing body weight, mothers losing infants, and they need to feed from a patch of trees that they wouldn't normally eat from because the leaves provide such low nutrition but now they have no choice. Let's say that patch of typically undesirable trees in what is now parcel Y.  Parcel Y is separated from the monkey's forest by a rice field. Can our troop of staving monkeys cross the rice field safely to get to that much needed resource? A juvenile jaguar reaches sexual maturity and needs to find a mate so that he can breed and increase his fitness, or the number of offspring an individual produces that survive to sexual maturity. The only available mates in this jaguar's forest are close relatives. If the jaguar breeds with a close relative, inbreeding may become a problem. Inbreeding over time decreases the genetic diversity of a species, making the species more susceptible to disease and genetic defects. These are just two examples of animals that do better with continuous habitat or with patches of habitat that they can cross. If that jaguar can't cross into another patch of forest to mate with a non-relative, he may never produce any offspring. If those monkeys can't cross the rice field, their population numbers will likely decrease even further and the troop won't be around for very long.

This bridge allows wildlife to safely cross above the highway

Wildlife corridors are created to solve these problems. Corridors may be designed specifically with a particular species in mind or more broadly to conserve multiple species. They may be reconstructed to look like the two habitats they're connecting or they may be more artificial. The Jaguar Corridor Initiative seeks to use farmland and other human modified areas as corridors where, while humans may use and own these lands, the jaguars can cross safely. Wildlife corridors allow species to move between fragments that they otherwise may struggle or fail to reach and they are proven to increase plant biodiversity. They're monitored to better understand if those corridors are actually being used. To check out more about the latest in corridor science, be sure to visit Conservation Corridor.

 Food for thought: what might be some of the challenges or barriers be to creating these wildlife corridors?

True or false: an animal or plant only has to cope with a patchy habitat if humans have been involved.



Answer: false. Patches are created by rivers, by mountains and in other natural ways. Patches of habitat are not always man-made.

Citizen science-What it is and how almost anyone can get involved

Watch birds in your own yard with Cornell

Citizen science is a type of scientific research where part or all of the project is done by amateur
scientists. It's a great way to get involved with research, broaden your knowledge, and make a difference. Practically anyone can get involved with a project these days if you have internet access: school children, busy professionals, retirees, stay-at-home parents, undergraduates looking for experience, or anyone else with an interest in nature. You don't have to be an expert, and you'll learn along the way. There are projects you can participate in without ever leaving your house and projects where you definitely get to go far from home!

Take for example what I would argue is one of the most well-known citizen projects: The Cornell Ornithology's FeederWatch . Count the birds you see at your feeder from November to April for FeederWatch and your data will be used by researchers at Cornell to track species distribution and abundance. More than 20,000 people from across North America participate in FeederWatch and the project has been around for decades. Another citizen science project out of Cornell is NestWatch. With NestWatch, participants record any nests they find and monitor the birds in those nests. Scientists then use this data to study reproductive success. Cornell has quite a few options if you're looking to get involved and watch birds.

Keep track of pollinators for The Sunflower Project

If birds aren't your thing, help scientists keep track of pollinators with The Sunflower Project. You'll pick a spot in your yard or in a public place, record the common name or species of the plant, and watch for pollinators for at least five minutes (if you sit for 10 minutes and don't see any pollinators, that's still data). If you're really a go-getter, you can use their resources to learn to identify different pollinators, which will help The Sunflower Project out even more. Given that many pollinator population numbers are in decline, projects like this are more important than ever.

Looking to head further from home? Away from your backyard? Then a great organization with multiple project options is Earthwatch Institute. There are opportunities specifically for families, teens, or you can join an expedition on your own. You can study caterpillars and climate change in Costa Rica for nine days, lions and their prey in Kenya for two weeks, Darwin's finches in the Galapagos, or choose something more local, such as wetlands in South Carolina. These expeditions aren't cheap, but this is an excellent institution. No unorganized field trips, unanswered emails or phone calls when you have questions, or leaders with little experience or who are poor teachers. Earthwatch was founded in 1971 and is respected in the scientific world. You'll learn a lot and it will look great on your resume.

For more opportunities, check out SciStarter, a website where you can search for projects based on topic or on location/time (projects at night, projects at home, entirely online, and so forth).