Humans are the only creatures that can eat a hot meal while flying, goes the joke of German comedian Loriot. This description by Bernhard-Viktor Christoph-Carl von Bülow (Loriot’s long-winded real name) of the anthropological difference between people and animals may not be a fully comprehensive analysis, but there’s certainly a grain of truth in it – discovering how to make fire and the invention of airplanes are two of the cultural achievements that set humans apart from animals. The matter is nevertheless a bit more complicated than that. Academia today is intensively concerned with examining the question of what makes us human, how we are different from animals (or not), and how the abilities specific to humans may have developed.
Alongside anthropologists, behavioral biologists and veterinary scientists, philosophers, linguists and psychologists are also researching the behavior and abilities of animals in a bid to find out how humans developed intelligence, language and cooperative social behavior. Researchers are looking at a wide variety of very different animal species, from our nearest relatives the apes, to dogs, meerkats and dolphins, songbirds, crows and octopuses. All of them share capabilities with us humans – albeit often in rudimentary form. Scientific research attempts to find out how these capabilities were formed and how they can be explained in evolutionary terms.
But what is driving our curiosity in this field? “We are feeling insecure about our status, our position in nature,” explains philosopher Hans-Johann Glock, whose research examines the question of animals’ spirits. “We humans have always defined our place in the world in terms of being below the higher level of God, but above the lower level of animals.” Secularization has made religious paradigms such as the creation story obsolete, the concept of our relationship to a higher authority has fallen by the wayside, “and what remains is our relationship to animals on the one hand and to robots or artificial intelligence on the other,” says Glock. Science, then, attempts to define the position of humans in this constellation of a world without God. Research into animals can hold a mirror up to our own behavior and give us insights into who we are and how we came to be that way. If we want to find answers to such questions, we can’t avoid looking at both our nearest and our most distant relatives in the animal kingdom. As French nature researcher Etienne de Condillac postulated in his Traité des animaux in the mid-18th century, our interest in animals may actually be due to our need to define what it means to be human.
If we take a closer look at the work being done by UZH researchers, we find that animals have a number of skills that scientists have only recently become aware of. For example, anthropologist Michael Krützen was recently able to demonstrate that dolphins have individual “names” and nurture lifelong friendships with other dolphins; fellow anthropologist Carel van Schaik has shown that orangutans have simple cultural practices; and behavioral biologist Marta Manser has documented how meerkats cooperate and communicate adeptly and intensively.
The assumption that animals only live in the moment, a position even adopted by Nietzsche (known for his fondness for animals), has also been swept aside. “Many experiments have now shown that animals not only have memory, but can also plan for the future,” says Hans-Johann Glock. For example, researchers at the Max Planck Institute in Leipzig were able to teach great apes to use tools to open a container of food. When one day the scientists didn’t leave the tools next to the container and the apes couldn’t open it, they reacted with disappointment and frustration. However, the next time on finding the tools in the right place again, the apes took them with them when they went to sleep.
Crows, observed British cognitive scientist Nicola Clayton, cleverly lay aside stocks of food in different places: They put perishable meal worms in places which they are going to come back to quickly, while they hide peanuts, which keep for a much longer time, in places which they visit less often. Examples such as these show that skills like planning ahead, which we think of as specific to humans, are also present in rudimentary form in some animals.
Current research is therefore bringing humans and animals closer together, which inevitably leads to the question – what actually is the difference between us? For Hans-Johann Glock, there is no one single characteristic that makes us fundamentally different. Rather, he sees it as a combination of three significant factors: Instrumental intelligence – above all the ability to understand cause and effect; cooperation – the way we live together with common values and societal norms; and our sophisticated and flexible language.
“All these abilities can be seen in animals at least in rudimentary form, but we have them to a much greater extent and our having the combination of all three is totally unique,” says Glock. “It’s that mix that sets us apart.” It was this combination that enabled the quantum leap in human evolutionary development, initially biologically, later culturally.
Anthropologists and linguists from UZH are researching the origins of those skills which according to Hans-Johann Glock enabled the evolution of humans: Intelligence, cooperative behavior and language. In addition, anthropologists Caroline Schuppli and Judith Burkart are observing orangutans and Callitrichidae monkeys, and linguist Simon Townsend is observing songbirds and apes, among others.
Caroline Schuppli researches how intelligence is formed by observing orangutans in the jungle. These red giants of the ape world are not particularly social animals – unlike we humans. The mothers even choose to raise their young alone. But when they meet others of their kind and the young apes have the opportunity to learn from them, there is a positive effect: They become more intelligent. “Young apes who learn from others have a much larger repertoire of skills and enjoy a wider range of food,” says the researcher. They know more about their environment and are able to get along better in it.
In terms of evolutionary biology they are “fitter”, says Schuppli: “Apes who can source more and better nutrition with less effort improve their survival and reproductive chances.” What makes the young apes clever is that they learn social behavior by observing others. First they observe their mothers, and then, when they get the chance, they observe other members of their species. The more opportunities they have to learn from others, the greater the range of skills they end up developing. Orangutans are similar to human children in this way – both learn by watching others and then trying out what they have seen.
Caroline Schuppli has made a short film of the ape Lisa with her son Lois, which demonstrates how this learning process works: Lisa picks a stalk off the forest floor, peels it and then eats the tasty and nutrient-rich cambium. Lois watches her carefully – in technical terminology “peering” – then he tries it himself. In this case he hadn’t watched carefully enough how his mum did it, and instead of the soft cambium he tries to eat the hard skin. He’ll soon learn how to do it properly.
“Social learning doesn’t just make the individual young apes more intelligent, but the whole group,” says Caroline Schuppli, referring to the findings from her observation of two ape populations, one on the island of Sumatra and the other on Borneo. The Sumatran orangutans are much more sociable than those in Borneo – the females spend around 55 percent of their time with other apes, while in Borneo they spend only around 15 percent of their time in company. That means the young apes in Sumatra have a lot more opportunities to observe others and are better able to pass on cultural techniques from one generation to the next.
The Sumatran orangutans therefore have a higher cultural level than those in Borneo. This can be seen from the fact that in the Sumatran apes, researchers found 198 different innovations that are passed on socially, while for those in Borneo they found only 116. Also, the Sumatran orangutans use tools while the Bornean ones do not. One prime example of their differences is in how they open a neesia fruit.
This fruit has nutritious seeds hidden inside a very hard football-sized shell protected by razor-sharp needles. Orangutans in Sumatra poke sticks into splits in the shell and loosen the seeds, which they can then tip directly into their mouths. Caroline Schuppli draws far-reaching conclusions from her observations: “Social learning has a certain influence on evolution, because it makes apes cleverer.” Thanks to social learning, an orangutan infant is able to learn 50 skills instead of only five, for example.
With our capacity for social learning, orangutans and humans are alike. But humans are much more sociable and therefore have many more opportunities to watch and learn from others and to pass on knowledge. Zurich anthropologists working with professor emeritus of anthropology Carel van Schaik assume that it is precisely this ability to pass on cultural accomplishments that is the key to the development of the more complex societies based on division of labor in which we humans live.
The other central aspect that has enabled us to develop into the humans we are today is the collective raising of children. That is the groundbreaking hypothesis of UZH anthropologist Judith Burkart. Collective raising of offspring is not something we have in common with the great apes. But Burkart has observed and documented this phenomena in the Callitrichidae family of monkeys.
For her, this is the missing link when explaining human development: “Collective child-rearing is a decisive factor.” Why? Because it forces us to work together, to let our own needs take a back seat – which a chimpanzee would never do, for example – and because it gives us opportunities to learn socially and pass on knowledge. But how did humans develop from being like orangutans to having this mix of curiosity, social learning and collective child-rearing? Caroline Schuppli says: “I think it was environmental factors driving it initially. The natural habitat changed and became more diverse. One strategy of our forebears to cope with this change was to become more exploratory. Those who were more curious had an advantage.”
The ones who were able to find new and better sources of food in this way had the energy to support bigger brains. And if food is plentiful, we have the opportunity – the leisure time – to try out new things. At the same time, better nutrition leads to more socially tolerant behavior and therefore social learning. That becomes evident from the comparison of the Sumatra and the Borneo orangutans. Food is more plentiful on Sumatra, so the apes there have more time to interact with each other and try out new things, and therefore have more opportunities to learn from each other.
We know how this story goes: In the (for now) end, Homo sapiens evolves – the modern human with our complex societies including distribution of labor, institutionalized passing on of knowledge through education, and professionalized development of new knowledge at universities and in industry. It took a while, but considering the age of the earth, the time it took us to go from using tools to open neesia fruit to building supercomputers passed in the blink of an eye.
To invent technical wonders such as the computer, it was necessary not just to have intelligence, tools and cooperation, but also language. Simon Townsend of the Department of Comparative Linguistics researches the evolution of language at the interface of linguistics and biology. For him it is clear: “Animals don’t have a complex language system like humans.” So what is it that makes our language use so unique? The key aspects are the conferral of meaning (semantics) and the structure (syntax), which make it possible to say many different things with a limited set of signs and sounds.
As a comparative linguist, SNSF professor Simon Townsend investigates the origins of our unique system of language, its age and how it developed. He does this by documenting and comparing communication in other types of animals. Among the animals he observes are our closest relatives the chimpanzees, as well as birds and meerkats.
“At the moment we don’t know much about how language came about,” says Townsend and then laughs – because that’s only half true. But certainly science has not yet been able to explain how and when human language developed. Some scientists believe that it’s a very young phenomenon that arose around 100,000 years ago, closely linked to the human ability to think abstractly and symbolically, for example as seen in cave paintings.
“I don’t believe that’s true,” says Townsend. “The human language is certainly complex, but we do see forms of pre-language in animals too.” The decisive point for Townsend is that our complex language system consists of simple components, like the combination of words such as “duck and cover!” or prefixes and suffixes which can give words a different meaning (un-do, care-ful). Such forms also exist in animal communication, which for Townsend indicates that language formed through a long evolutionary process and didn’t just one day “spring from the mind of Zeus”, as he puts it.
Townsend and his team research how animals communicate and how their communication can be compared with human language. One current example is the research of postdoc Sabrina Engesser into chestnut-crowned babblers and pied babblers. The chestnut-crowned babbler, a songbird native to Australia, can make different combinations of various acoustic elements (AB or BAB) which on their own are meaningless. The combinations have different meanings.
The South African pied babblers, meanwhile, can combine two calls to make a new one. “The birds have one call which they use to call attention to minor threats, and another call with which they tell group members to come to them, for example to distribute food,” explains Townsend. “If they combine the two calls, it has a new meaning: Great danger, come and help!”
That would be the case, for example, if a snake appeared that might plunder the birds’ nests. When they hear the call, the birds rush to their companion’s aid and work together to chase off the intruder. Engesser has therefore dubbed this call combination the “bullying sequence”. “That’s an example of how animals can come up with new structures with their own meaning using existing sounds,” says Townsend.
The other central aspect of human language is the allocation of meaning. This is done arbitrarily and randomly – for example different languages use quite different words for the same thing, e.g. tree/Baum/arbre. Also, humans are able to separate our communication from our emotional state. “Until recently it was assumed that animals could not do this,” says Townsend. He now knows otherwise.
Townsend got a rare opportunity to observe what happens when two groups of apes meet each other: In 2010, the chimpanzees at Edinburgh Zoo were joined by eight apes from a safari park in Holland. The comparative linguists initially observed that the chimpanzees from Holland liked apples very much and reacted to them with excited grunts, while for their Scottish colleagues apples were nothing special and their reaction was less animated.
Over time, the two groups became well integrated, but their preferences remained the same. However, within three years the incomers had adapted the noise they made when they saw apples to sound less excited. “Even though they were still excited when there were apples on offer, they were able to produce noises that didn’t reflect their excitement,” explains Townsend. In addition, the fact that the apes were capable of reacting to apples using a different sound – indicating the same thing with a new sound – shows that the allocation of meaning is arbitrary.
For Townsend, such examples prove that precursors to and simple basic forms of human language exist in the animal kingdom. “If we can manage to explain these, then we can start to find out how the more complex forms of language arose.” Basically, the evolution of language moves from rudimentary basic forms to ever greater complexity. Complex language is another evolutionary advantage: “Those who are better able to communicate have better chances of survival.” Our complex language and communication skills have enabled us to organize communal living in larger and larger groups and to pass on knowledge – and with complex language comes complex culture.
The origins of our unique development lie, as described above, in the animal kingdom. Many of the abilities that supposedly set humans apart and that have made human culture and society possible can be observed in animals. Current research is demonstrating this to an ever greater extent, despite the fact that many of the biggest questions about how we became human still remain open.
In animals, we often find simple forms of the very behavior and abilities that we think of as uniquely human, such as intelligence, cooperation and language expression. However, only humans have managed to harness the potential of these abilities. For example, our intelligence enables us to plan ahead and to understand complex connections, our capacity for cooperation has enabled us to create large diverse societies, and our language ability ensures the flow of communication without which those societies would not be able to function, as well as the exchange of knowledge and cultural connections.
Above all, however, humans have the ability to reflect on their own nature and to research other animals and their behavior and compare it with their own. That is exactly what researchers at UZH and elsewhere are engaged in – thanks to them, we know more about animals and therefore more and more about ourselves. After all, in the words of Etienne de Condillac: The really interesting question is what it means to be human.