Fishing With Gorillas!

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Gorilla culture and tool use is currently shrouded in relative mystery when compared to our understanding of other great apes.  For example, landmark behavioural studies detailing technological variation and distribution have been published for all great apes except gorillas (e.g., bonobos, chimpanzees, orangutans).

In the major gorilla tool use study I am aware of, gorillas were observed engaging in behaviours that can only reasonably be asserted to be technologically complex.  In one situation a gorilla was observed using a stick as a walking stick to aid in balance when crossing a river.  In another situation a gorilla was observed using shrubs to construct a bridge to cross a river.  Both of these observations demonstrate that gorillas have a very complex understanding of how physical systems work.  Furthermore, it is evidence that gorillas have a well-developed understanding of physical systems that extends beyond the acquisition of food.

In most situations throughout the animal kingdom, tool use is stimulated by an inaccessible and valuable nutritional resource.  This is true for New Caledonian crows, bearded capuchin monkeys, bottlenose dolphins, and most other tool using species.  Tool use that is directed towards non-food related goals is theorized to develop later.  So considering that gorillas have already been observed using tools for non-food related goals, it logically follows that they should have a tool kit that involves tools for procuring food.

Gorilla Doctors Blog is reporting that just such an observation has now been made.  The observation was made by Jean Felix, a medical doctor who was making a routine health check on a population of gorillas in Volcanoes National Park in Rwanda.

He reported that a second ranked silverback gorilla was:

eating ants by reaching his left hand into the ant pile before putting it in his mouth. He ran away at one point – it appeared the ants were biting his arm. Afterwards, juvenile female Lisanga joined him and used a piece of wood to retract the ants from their nest.

This is an interesting observation.  It seems as though a high ranking male was unaware that access to an ant food resource required a tool in order to prevent being attacked.  Considering that this was not an official primatological study, no further data is available that I’m aware of, but the observation raises several questions:

  • Was the juvenile female teaching the silverback?
  • Why was a younger individual aware of a tool that the older individual seemed unaware of?
  • Are female gorillas more adept tool users than males?

I don’t think any primatologists have the answers to these questions at present.  But, as I stated a few months ago, I am really excited to see what future research reveals about gorilla culture and tool use.

What do you think of this observation?  Let Cadell know on Twitter!


The Century of Great Ape Culture

In the past, I have discussed some of the biggest chimpanzee culture discoveries in The Ratchet.  Many of these discoveries were made in the 20th century.  This culminated in 1999 with a behavioural synthesis of 20th century chimpanzee cultural data throughout Africa (Whiten et al. 1999).  This research stimulated other primatologists to test whether cultural behaviour was exhibited within other great ape species.  As a result of this research, the 21st century has been a century of great ape culture discovery.  These discoveries are forcing us to reconceptualize our understanding of the great apes and ourselves.  There is no more question of whether our closest relatives are cultural, the focus has shifted to understanding the evolution and variation of cultural behaviour.

There have been far fewer studies conducted to understand cultural behaviour of bonobos, orangutans, and gorillas vis-à-vis chimpanzees.  Gorilla culture is perhaps the least understood.  Most of our knowledge of gorilla culture comes from a groundbreaking study by primatologists Thomas Breuer, Mireille Ndoundou-Hockemba, and Vicki Fishlock, revealing that gorillas make tools that are partially inspired by ecological problems they face in certain habitats (Breuer et al., 2005).  The team reported two interesting cases of gorilla tool use:

a) An individual utilizing a branch to test water deepness and stabilize herself during a river crossing

b) An individual using a trunk from a small shrub as a bridge to cross a deep swamp

This study shows that we may have a lot more to learn about gorilla culture.  Unfortunately, gorillas are extremely difficult to study in the wild.  There are entire subspecies of gorilla that have never really been observed at all. For researchers, this makes understanding gorilla culture and cultural variation almost impossible.  However, new motion-sensor camera traps are enabling scientists to design research studies that were impossible just a few years ago.  It is possible that future research designed with these camera traps could allow us to learn more about gorilla culture.  The 2005 paper by Breuer et al. (2005) makes me excited for the possibility of such a study.

Bonobos have been slightly less mysterious than gorillas.  A study by Gottfried Hohmann and Barbara Fruth in 2003 partially uncovered the cultural world of our other most closely related relative.  Hohmann & Fruth were inspired by the “Cultures in chimpanzees” study by Whiten et al. (1999) and wanted to know how many of the cultural variants described in chimpanzees were also present within Lomako’s bonobo population.  By analyzing behavioural data between 1991 and 1998, they revealed that 14 cultural variants in chimpanzees are also present in bonobos.  These include branch drag, leaf sponge, branch clasp, vegetation seat, aimed throw, and the hand clasp (Hohmann & Fruth, 2003).  Although the study sample was considerably smaller than the one used by Whiten et al. (1999), this study raised the possibility that chimpanzees were more culturally complex than their sister species (Tennie, et al., 2009).  If true, the implications of such a discovery would raise some interesting questions about the evolution of culture and the behaviour of our common ancestor with chimpanzees and bonobos.  However, these results could also simply be a product of the fact that there are more chimpanzees that inhabit a wide and diverse number of ecological niches.

Finally the orangutan, the lone Asian great ape, has also provided researchers with impressive evidence of cultural behaviour and variation.  In fact, the geographic variation of cultural traditions among orangutans may most closely parallel those observed in chimpanzees.  In 2003, Carel P. van Schaik and a team of researchers revealed that there was a strong correlation between geographic distance and cultural distance among orangutan populations (van Schaik et al., 2003).  Surprisingly, this correlation may even be stronger than that observed among chimpanzee populations throughout Africa (Tennie et al., 2009).  Also, orangutan tool use has proven to reveal some of the most unique functions in the entire animal kingdom, including autoerotic tool-use, leaf napkin, branch swatter, seed extraction tool-use, sun cover (building a cover for a nest on bright sunny days) and branch scoop (drinking water from a deep tree hole using a leafy branch) (van Schaik et al., 2003).

Of course, all of these data indicate that many 20th century academics were wrong about culture being a defining aspect of our species.  Culture appears to be ubiquitous among the great apes, and widespread throughout the animal kingdom.  There is now evidence for large-scale patterning of culture within and between populations, and entire communities appear to possess suites of cultural behaviours (Whiten et al., 2003).  Furthermore, just like humans, culture allows the great apes to flexibly shape their environment (Breuer et al., 2005), gain access to resources (Sanz & Morgan, 2009), develop subcultures (Boesch, 2003), and share meaning (e.g., Hohmann & Fruth, 2003).

The fact that culture is present in all great apes increases the likelihood that the capacity for culture within our lineage may have been present as late as 14 million years ago (van Schaik et al., 2003).  And studies on some monkey species have suggested that it could have been present as early as 35 million years ago (Visalberghi et al., 2009).  However, despite the fact that modern primatological inquiry has revealed startling similarities between human and great ape culture, more research needs to be done in order to understand the mechanisms that enable novel behaviours to be learned (Hrubesch et al., 2009).

Also, if we are not the only cultural species, what makes us so different?  I have hinted at what primatologists have learned about this perplexing question, and I will be exploring those ideas in great detail in the near future.

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Boesch, C.  2003.  Is culture a golden barrier between human and chimpanzee?  Evolutionary Anthropology, 12: 82-91.

Breuer, T., Ndoundou-Hockemba, M. & Fishlock, V.  2005.  First observation of tool use in wild gorillas.  PLoS ONE, 3: e380.

Hohmann, G. & Fruth, B.  2003.  Culture in bonobos?  Between-species and within-species variation in behaviour.  Current Anthropology, 44: 563-571.

Hrubesch, C., Preuschoft, S., & van Schaik, C.P.  2009.  Skill mastery inhibits adoption of observed alternative solutions among chimpanzees (Pan troglodytes).  Animal Cognition, 12: 209-216.

Sanz, C.M. & Morgan, D.B.  2009.  Flexible and persistent tool-using strategies in honey-gathering by wild chimpanzees.  International Journal of Primatology, 30: 411-427.

Tennie, C., Call, J., & Tomasello, M.  2009.  Ratcheting up the ratchet: on the evolution of cumulative culture.  Philosophical Trasactions of the Royal Society.  364: 2405-2415.

van Schaik, C.P., Ancrenaz, M., Borgen, G., Galdikas, B., Knott, C.D., Singleton, I., Suzuki, A., Utami, S.S., Merrill, M.  2003.  Orangutan cultures and the evolution of material culture.  Science, 299: 102-105.

Visalberghi, E., Addessi, E., Truppa, V., Spagnoletti, N., Ottoni, E., Izar, P. & Fragaszy, D.  2009.  Selection of effective stone tools by wild bearded capuchin monkeys.  Current Biology, 19: 213-217.

The Real Culture Wars

culture wars

When we think of culture, we tend to think about material products of human civilization and/or variation of traditions, rituals, and beliefs between different human populations. And of course, these are products of human culture. But does culture distinguish humans from all other animals? Are any other animals cultural? These questions have produced a “culture war” within academia that has deep implications for how we imagine what it means to be human.

Surprisingly, our contemporary understanding of culture is quite new. It was developed during the as a way for European intellectuals to describe differences in human behaviour throughout the world (Tomasello, 1994). The term wasn’t necessary in the same way during the pre-modern era because cultural diffusion was largely constrained by geography. As a result, very few people knew, or interacted with, people from vastly different cultural backgrounds.

Either way, throughout modern intellectual history, the term “culture” has been used as a defining characteristic of the human species. But is it? Are there behavioural patterns in animal communities that evolve and are transmitted in analogous ways to human societies?

Clues that we were not the only species to possess culture came from early studies of our closest relatives: chimpanzees. In the 1960s, primatologist Jane Goodall observed chimpanzees at Gombe Stream National Park making and using tools. At that time humans were defined as “man the tool maker.” After she told her mentor, paleoanthropologist Louis Leakey about her discovery, he famously replied:

“Now we have to redefine man, redefine tool, or accept chimpanzee as human.”

— Louis Leakey

Of course, under any taxonomic classification scheme it would be foolish to redefine chimpanzees as humans, so we instead reclassified our species. We were no longer the only species that made and used tools, but did that also mean we were not the only species to possess culture?

As the top evolutionary scientists in the field pondered this question, it became evident that culture was a more complex term than had previously been thought. What was culture exactly? And if our closest relatives made tools, what else could they do?

Researchers without a clear grasp on what it meant to call a non-human cultural, started to refer to chimpanzee behaviour as “pre-cultural” or “proto-cultural.“ However, others were skeptical of this classification and believed they were observing cultural beings.

Here is an example of one such observation from the field notes of primatologist Christophe Boesch (1985):

“Nova inserts her index finger in the soft soil and then sniffs it carefully. She starts removing slowly a layer of the soil so as not to alert the driver ants in their nest. She breaks a small branch of a sapling and cuts it with her teeth to produce a stick about 30 cm long. She starts dipping it quietly up to 2-3 cm into the nest entrance, watching as the ants climb up the tool. Once they have reached about 10 cm up the tool, she rapidly turns the end of the stick upwards into her mouth, hastily chewing the ants, and then dipping further.”

— Christophe Boesch

Boesch was observing the practice of “ant fishing.” He knew that not all chimpanzee populations knew how to fish for ants. This was a population-specific behaviour. Afterwards, he wondered: how do such population specific behaviours appear? And do they represent chimpanzee cultures? (Boesch, 1996).

Primatological inquiry into these questions met resistance within anthropology. But evolutionary biologists were making equally perplexing discoveries in other species. Research on cetaceans like whales, dolphins, and porpoises, as well as birds like sparrows, starlings, and crows, revealed they possessed population-specific vocalizations and feeding behaviours that appeared to be socially transmitted.

These were thought-provoking results, but were these behaviours cultural? Using social transmission as the only criteria for culture allowed biologists like Charles Lumsden and Edward Wilson to conclude that more than 10,000 species, including some bacteria, could be deemed “cultural.”

The culture wars were just starting.

Cultural anthropologists were unconvinced by all these data and reasoning. They insisted that linguistic mediation was the key to achieving culture. They further argued that imitation of other members of a group couldn’t be correlated with culture.

Discussion of animal culture was becoming polarized, and evolutionary anthropologists were stuck in the middle. An understanding of the human condition was at stake.

In an attempt to break this stalemate, primatologists proposed a “nonarbitrary definition.” (Laland & Hoppit, 2003). This definition sought to incorporate the importance of context; imitation alone was not enough. Also, in order to claim that a behaviour was cultural, researchers first needed to control for ecological and biological determinants of behavioural observations.

In order to apply these ideas to field research, primatologists developed the “method of exclusion.” By using this method, researchers would document behaviours between groups and then infer whether what they were observing was cultural by eliminating any possible ecological and/or genetic cause for its occurrence.

A big breakthrough in this research came in 1999, when several evolutionary scientists from six different long-term chimpanzee field sites compiled their behavioural data and attempted to determine how much cultural variation there was between chimpanzee populations in Africa (Whiten et al., 1999).

Their results were startling. They found 39 different behavioural patterns, including tool usage, grooming and courtship behaviours that appeared to be unconnected to either ecological or biological determinants.

cultural variation

From: Cultures in Chimpanzees

For example, chimpanzees at Budongo, Mahale, and Tai Forest performed rain dances. Chimpanzees at Gombe and Kibale had developed traditions for inspecting wounds and removing parasites (a form of self-medication now termed zoopharmacognosy). Other groups had different feeding traditions; in the west chimps frequently constructed anvils to break open nuts and constructed tools to fish for ants. In the east, they developed different tools to fish for termites. Their was also extreme variation in different social traditions and courtship rituals.

These results indicated that not only were chimpanzees cultural, but the complexity of their culture was without parallel throughout the rest of the animal kingdom. Research over the past decade has validated their results and increased our understanding of cultural variation within our closest relatives. For example, one group of western chimpanzees in Senegal constructs spears to hunt other primates (Pruetz & Bertolani, 2007). The ability to construct spears is taught, and context for the use of the spear is the difference between life and death.

Theorists that accept these discoveries as proof of culture in animals have now moved past the simple cultural dichotomy erected during the culture wars. If chimpanzees and other animals possess complex culture, what makes us so different?

Although research into the question of cultural complexity is still in its infancy, some research believe that the key is the cultural “ratchet effect.” Human culture appears to be characterized by a generational increase in complexity and/or efficiency. These is little evidence that any other animals have ratcheting culture.

Of course, we have been wrong before. If scientists had a chance to studyAustralopithecus africanus or Homo erectus they might have concluded that those species had no ratcheting culture just because of how slow and gradual complexity evolved in their technologies and traditions. For example, Homo erectus tool technology remained remarkably stagnant over a period of one million years. Therefore, future research on generational transmission of culture within and between groups may reveal new insights. Also, there are many chimpanzee populations that have never been studied, and research on other great apes like gorillas, bonobos, and orangutans, has only just begun. As is typical of scientific inquiry, one answer, usually leads to even more interesting and perplexing questions.

The understanding of what culture is, and what separates human culture from animal culture, is one of the most important aspects of our quest to understand the human condition. Exploring these questions is the point of The Ratchet.

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Are Chimpanzees Fair?

Originally posted by Jane Goodall Institute of Canada’s Change Is In You Blog

Humans care about fairness.  I know for me personally, if there are a limited number of resources (e.g., food, shelter), I would feel bad making a decision that gave me more resources at the expense of a close friend or family member.  Of course, that is an anecdotal example of human fairness, but it has been studied scientifically!

Researchers have studied this scientifically by designing “the ultimatum game.”  This game tests whether humans always act in their material self-interest.  In the game, one person must decide how to divide a sum of money and/or resources between two people.  The first person (proposer) makes a proposal, and the second player (responder) either accepts or rejects the proposal.  If the responder rejects the proposal, both players receive nothing.  When human adults play this game, they typically split the resources equally.  This demonstrates that humans are sensitive to fairness.  However, primatologists are still unsure of whether our closest relatives, chimpanzees and bonobos, behave in the same way.

In order to find out, researchers from the University of London decided teach a modified ultimatum game to chimpanzees and bonobos (Kaiser, I. et al., 2012).  Individual apes were exposed to two different food resources: their own, and another individual’s.  In each scenario, one ape had to make a decision of whether to eat their own food, or to eat their own food and steal the other individual’s food.  The team found that neither chimpanzees nor bonobos cared about fairness in this experiment and generally stole a portion of food.  They concluded that “our sense of fairness” must be a derived trait (meaning that it was absent in the human/chimp/bonobo common ancestor).

Open and shut case right?  Perhaps not.

A team of researchers at Yerkes National Primate Center led by primatologists Darby Proctor and Frans de Waal decided to design their own ultimatum game to re-test the hypothesis that our sense of fairness is derived (Procotor & de Waal, 2013).  The study was conducted with six adult chimpanzees and the ultimatum game was much more similar to the human-version of the ultimatum game when compared to the Kaiser et al. study.  The chimpanzees had to choose between coloured tokens that could be exchanged for food rewards.  One token offered equal rewards to both players.  However, a second token would give more resources to the player proposing the deal, at the expense of resources allocated to the second player.  No food reward would be given until both individuals agreed to use one of the two coloured tokens.

So what did the results show?  Chimpanzees behaved in the same way adult humans do.  When a partner’s cooperation was required, they would allocate resources fairly.  So it seems that Kaiser et al. may have prematurely concluded that fairness is a derived behaviour for modern humans.  In retrospect, it shouldn’t be surprising that chimpanzees display empathy and act fairly to one another.  All chimpanzee groups live in highly social groups, and antisocial behaviour would be detrimental to prolonged group cohesion.  In fact, wild behavioural studies have shown that chimpanzees do have a tendency to distribute various foods equally among kin (e.g., Pruetz & Lindshield, 2011).  Western chimpanzees in Senegal have been observed to share plant food, honey, meat, and tools based on elaborate hierarchies that have yet to be fully understood.

In the future more wild behavioural research may need to be conducted to better understand how sharing behaviours function with a chimpanzee community, and how their sense of fairness relates to our human sense of fairness.  So although we do not have all the answers yet, it seems likely that our common ancestor with chimpanzees had a similar sense of fairness in regards to resource allocation.  And we should feel lucky that that is the case because that means our sense of fairness is a deeply ingrained aspect of what it means to be fair.

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Kaiser, I., et al.  2012.  Theft in an ultimatum game: chimpanzees and bonobos are insensitive to unfairness.  Biology Letters, DOI: 10.1098/rsbl.2012.0519

Proctor, D & de Waal, F..  2013.  Gambling and Decision-Making Among Primates: The Primate Gambling Task.  Proceedings of the National Academy of Sciences.

Pruetz, J.D. & Lindshield, S.  2011.  Plant-food and tool transfer among savanna chimpanzees at Fongoli, Senegal.  Primates, DOI: 10.1007/s10329-011-0287-x

Building The Genetic Bridge

Now that scientists have decoded the genome for humans and all great apes, we can now start to identify all of the functional genes that make us different.  One such gene was discovered recently: MIR941-1 (Hu et al. 2012).  This gene encodes human specific microRNA that is not present in our closest relatives, or any other known mammals.  And it may be the start to building a complete understanding of what functionally separates our genetic structure from the rest of the animal kingdom.

What Does It Do?

MIR941-1 regulates cellular differentiation and neurotransmitter signaling.  Specifically, it plays a role in human-specific cognitive functions like language and speech, and it also affects pathways that increase the human lifespan.  What is most interesting is that when there is a problem with the brain region producing miR-941 microRNA, people display “mental retardation, developmental delay, as well as speech and language defects.” (Hu et al., 2012).

Exercise Caution

To clarify, this is not the gene responsible for human intelligence.  In all likelihood there is not one-single gene that gives us the cognitive capacity we enjoy over other animals.  Uncovering the complex genetic relationships and pathways that make us human will be a very long process, and will likely include the discovery of other genes similar to MIR941-1.  But it is still an important discovery because it shows us that scientists now have the data and technology to start “building the genetic bridge” that separates humans from great apes.

All too often, the popular scientific media exaggerates the importance of interesting genetic discoveries, because they want to break a simplistic story of the one gene that makes us special.  FOXP2 was a gene that was described in this way back in 2003.  Jerry Coyne gives a fantastic explanation of how this was done with the discovery of miR-941 on his blog Why Evolution Is True.  A basic rule of thumb would be to never believe any post that claimed there was a very basic Mendelian inheritance pattern between a few genes and our uniqueness.  As evolutionary scientists have discovered over the past few decades, genes that are related to cognitive functioning very rarely display this type of pattern.  More research should reveal other genes that play an important role in our uniqueness from the great apes, but is exciting to know that we have identified one key gene and region of the brain that seems to play a very important role.

When Did It Appear?

Future research on this specific gene should also help us understand more about our evolution as a species.  At the moment, we know that the gene appeared very rapidly between 6-1 million years ago.  This is critical because it is the period of human evolution when our ancestors evolved from early stem hominins to ancestral Homo.  Unfortunately, it does not tell us anything about when this critical gene became fixed, and consequently, what species first acquired it.  Understanding this development in more detail may help us to understand a great deal more about the evolution of human language.  Theories in the 1980s and 1990s posited that human language emerged during the Upper Paleolithic, a mere 40,000 years ago (Diamond, 1994; Klein, 1995).  However, more recent anatomical (Nishimura, 2002), cultural (Bar-Yosef, 2002), primatological (Dunbar, 2001), and genetic data (Enard et al., 2002) has revealed that the first modern humans that emerged 200,000 years ago, likely had what we would call modern human language.  The discovery of MIR941-1 could push that date back even further.  If a gene that plays a unique and specific role in enabling human language and speech existed as early as 1 million years ago, it is likely many ancient hominids had more complex language abilities than do contemporary great apes.

Concluding Thoughts…

This discovery is extremely interesting.  It could represent the start of our attempt to understand all of the genes that are functional and unique to our species.  However, genetics is very complicated, and it should not be viewed as the gene that separates us from the great apes.  Future research will need to be conducted to both better understand the significance of the role MIR941-1 has in modern day human populations and our ancestors.  Future research will also be needed to better understand what other genes play a role in our cognitive abilities.  It is an exciting time to study human origins – as I’m sure it always has – and hopefully always will.


Bar-Yosef, O.  2002.  The Upper Paleolithic Revolution.  Annual Review of Anthropology, 31, 363-393.

Diamond, J. (Ed. Campbell, and William Schopf, J.)  1994.  The Evolution of Human Creativity.  InCreative Evolution?! (pp. 75-82).  Los Angeles: Jonas and Barlett Publishers.

Dunbar, R.  2001.  Brains on Two Legs: Group Size and the Evolution of Intelligence.  In Tree of Origin: What Primate Behavior Can Tell Us about Human Social Evolution (173-191).  London: Harvard University Press.

Enard, Przeworski, Fisher, Lai, Wiebe, Kitano, Monaco, and Paabo, S. 2002.  Molecular evolution of FOXP2, a gene involved in speech and language.  Nature, 418, 869-872.

Klein, R.  1995.  Anatomy, Behavior, and Modern Human Origins.   Journal of World Prehistory, 9(2), 167-198.

Hu, H.Y., et al. 2012.  Evolution of the human0-specific microRNA miR941.  Nautre Communications 3, Article number: 1145 doi: 10.1038/ncomms2146

Nishimura, T.  2002.  Comparative morphology of the hyo-laryngeal complex in two steps in the evolution of the descent of the larynx.  Primates, 44, 41-49.

A ‘Great’ Crisis

I have been thinking a great deal about happiness and how we can best study the happiness of our species.  I will likely expound more on this topic in the coming months but a recent study caught my eye that I found quite insightful.  The study was led by psychologist Alexander Weiss, who investigated patterns of well-being in two great ape species: chimpanzees and orangutans (Coles, 2012).  In this study, Weiss and his colleagues wanted to understand if our closest relatives share the same general life pattern of well-being that humans seem to possess.  Social scientists have established that humans experience a U-shaped pattern of well-being.  This means that as a species we tend to experience greatest mental health in youth, become far less happy throughout midlife, and then become happier again in old age (Weiss et al., 2012).  This seems to be a general pattern regardless of various socio-cultural  and economic factors.  The study by Weiss et al. (2012) provide some evidence that this U-shaped well-being curve is an evolved predisposition that we share with our closest relatives.

In the study, 508 captive great apes of varying age ranges were rated based on their ‘happiness’.  However, happiness is notoriously difficult to study.  Many social scientists are still struggling to understand how to study happiness in humans.  Researchers decided that the best way to study happiness in apes was to survey the people who knew them best: their keepers.  In the survey happiness was rated using four criteria (Callaway, 2012):

1. The animals overall mood

2. How much pleasure they got out of socializing

3. Their success in achieving goals such as obtaining food and objects they desire

4. How happy the keeper would be if s/he were that animal for a week

The results of this survey indicated that individuals in their late 20s to mid-30s were significantly less happy than individuals younger and older (Weiss et al. 2012).  These results mirror the U-shaped happiness curve found in humans and raises some interesting questions about the evolutionary pressures that would have selected for these patterns.

Admittedly, the study is intensely anthropomorphic.  As primatologist Frans de Waal suggested, it would have been nice to see a harder measure of ape happiness (e.g., stress hormone levels) (Callaway, 2012).  Furthermore, I do think future studies should incorporate a more sophisticated methodology over a longer period of time before we can conclude with certainty that great apes experience a U-shaped well-being curve.  However, I think this study does give us some insight into our own happiness because it is relatively easy for keepers to gauge the mood of the apes they know so well and because the data had such strong conclusions.  So, if you trust the methodology what does this tell us about the evolutionary pressures that produced it?  Do these results mean that we are all destined to experience a mid-life crisis to some degree, regardless of socio-economic status and/or our own personal perception of age-appropriate achievement?

I believe that if a U-shaped curve is something we share with our closest relatives then it has probably been present for tens of millions of years throughout ape evolution and potentially primate evolution.  It is plausible to suggest that the main pressure for this U-shaped curve would be the need for increased adaptability during mid-life.  Generally speaking, young and old individuals are under less pressure to accumulate resources for survival and do not have the added burden of needing to increase biological fitness.  Perhaps being discontent increases the likelihood that an individual will put extra effort into acquiring more resources or finding a new/better mate.  It would make sense that there would be a strong selection pressure for this throughout our evolution because resources were so scarce and difficult to acquire.  Discontented middle-aged individuals would likely be able to out compete (and out survive) those middle-aged individuals that were content.

Either way, future research regarding great ape happiness needs to be conducted before we can be sure that the U-shaped curve is something they share with humans.  If future data indicate it is true, our only chance of minimizing the bottom of the U-shaped curve may be to genetically reprogram ourselves.


Callaway, E.  2012.  Great ape go through mid-life crisis.  Nature.  Accessed November 21, 2012.

Coles, J.  2012.  Great apes may have ‘mid-life crisis’, a study suggests.  BBC Nature.  Accessed November 21, 2012.

Weiss, A. et al.  2012.  Evidence for a mid-life crisis in great apes consistent with the U-shaped in human well-being.  Proceedings of the National Academy of Sciences.  doi: 10.1073/pnas.1212592109

Communicating with Bonobos

On November 6, 2012, the world lost one of the most linguistically accomplished non-humans on the planet.  Her name was Panbanisha and she was a bonobo (Pan paniscus).  Panbanisha grew up in aHomo sapiens/Pan paniscus hybrid culture at the Language Research Center (LRC) in Georgia (Armstrong & Botzler, 2003).  Her entire life was a language experiment that taught us a great deal about the behavioural continuum separating humans from our closest living relatives.

When Panbanisha was born, language research with bonobos had already commenced with studies on Kanzi.  However, researchers knew more experiments needed to be conducted.  They wanted to understand how a young bonobo would develop linguistically with a linguistically competent bonobo present (i.e., Kanzi) and they wanted to see how bonobo and chimpanzee linguistic development differed (Armstrong & Botzler, 2003).  In order to test bonobo/chimpanzee linguistic difference they raised Panbanisha with a chimpanzee named Panzee.

When research started, Kanzi had already learned 256 symbols using a lexigram.  Therefore, Panbanisha and Panzee were exposed to complex communications from the very first weeks of life.  As a result, they acquired language much quicker than did Kanzi (e.g., Krasnegor et al., 1991).  The effects of Panbanisha’s early exposure to language seemed to have a significant effect on her subsequent development.  Both Panbanisha and Panzee understood and used words through direct linguistic training and also through passively listening to human-human conversation.  Their competency was best displayed in a series of tests to see how well they could understand unique sentences.  At the age of 7.5, Kanzi, Panbanisha and Panzee could respond correctly ~75% of the time to unique sentences that required more than a yes or no response.  In comparison, an intelligent two-year-old child can accomplish the same task with a ~65% success rate (Hillix & Rumbaugh, 2003).  However, PET scans revealed that both Panbanisha and Panzee had superior information-processing skills when compared to Kanzi, which increased their ability to process verbal material.  This demonstrated that rearing may be a more powerful variable than species (e.g., bonobo/chimpanzee) when it comes to comprehending and using language (Armstrong & Botzler, 2003).

Conversation with Panbanisha also revealed that she connected deep meaning to the words she was using.  Here is an excerpt from a conversation she had with one of her trainers in the early 2000s (Hillix & Rumbaugh, 2003):

Panbanisha: Milk, Sugar

Liz: No, Panbanisha, I’d get in a lot of trouble if I gave you milk with sugar.

Panbanisha: Give milk, sugar.

Liz: No, Panbanisha, I’d get in so much trouble.  Here’s some milk.

Panbanisha: Milk, sugar.  Secret.

Panbanisha’s understanding of the word, “secret,” provides evidence of incredibly complex thought.  Still there were obvious limitations.  Geoffrey Pullum, a linguist at the University of California stated, “I do not believe that there has ever been an example anywhere of a nonhuman expressing an opinion or asking a question.  It would be wonderful if animals could say things about the world, as opposed to just signaling a direct emotional state or need.  But they just don’t” (Raffaele, 2006).  Furthermore, neither Panbanisha nor Panzee developed the ability to communicate using human-like sounds.  ThePan vocal tract is different than the human vocal tract because they lack a descended larynx.  The human larynx descends shortly after infancy allowing us to make a seemingly infinite number of vocalizations (Hillix & Rumbaugh, 2003).  However, the Pan vocal tract does permit for the production of more sounds than they do produce, which could mean that both chimpanzees and bonobos lack the neural connections necessary to fine-tune the vocal apparatus and produce human-like sounds and language (Hillix & Rumbaugh, 2003).

Despite this, Panbanisha showed us that bonobos can and do participate in meaningful discourse interactions with humans (Benson et al, 2004).  She communicated her emotions, feelings and developed strong linguistic bonds with three species (i.e., chimpanzees, bonobos and humans).  She also learned how to make and use stone tools, which also sheds light on the mental capacities necessary for complex tool construction.

Did Panbanisha prove that nonhumans can use language?  This research may have shown us that this question is too simplistic.  There is clearly a linguistic continuum.  There are several aspects of human language that Panbanisha never displayed.  However, she was able to understand English sentences and respond meaningfully to them.  She could not express ideas or opinions, but she could express her feelings and desires.  She could not use language vocally, but she could master language symbolically.  This research also showed that when it comes to language, early development is crucial.  Without exposure to language at an early age maximal linguistic potential can never fully develop.

Whether Panbanisha used language is also subject to definitions.  If language is any means of communication between two entities, then clearly she was quite advanced on the continuum of linguistic competency.  If language means creating meaningful units from meaningless units and combining them according to certain rules and then turning those units into meaningful phrases and sentences, then Panbanisha did not break the language barrier, and no other nonhuman ever has either (Hillix & Rumbaugh, 2003).

Panbanisha’s life taught us a great deal, not only about what separates our species, but also what makes us unique.  Although she died too young (26), she leaves behind one surviving offspring (Nyota) at The Great Ape Trust in Des Moines, Iowa (The Stone Age Institute, 2012).  Future research into the origins of language, language acquisition and interspecies vocal communication will continue to build on what we were able to learn from her accomplishments.

Panbanisha lexigram Panbanisha (Pan paniscus) (November 17, 1985 – November 6, 2012)


Armstrong & Botzler.  2003.  The Animal Ethics Reader.  Routledge.

Benson et al.  2004.  Mind and brain in apes: a mathodology for phonemic analysis of vocalizations of language competent bonobos.  Language Sciences, vol. 24, 543-660.

Hillix & Rumbaugh.  2003.  Animal Bodies, Human Minds: Ape, Dolphin and Parrot Language Skills.  Springer.

Krasnegor, et al.  1991.  Biological and behavioural determinants of language development.

Raffaele, P.  2012.  Speaking Bonobo.  Smithsonian Magazine.

The Stone Age Institute.  In Memorium – Panbanisha: 1985-2012.