The Human Journey
Our Distant Ancestors, page 1

Our Distant Ancestors


Who Do We Think We Are?

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“A noisome bacillus whom Our Heavenly Father created because he was disappointed in the monkey.” (Mark Twain)

“A man, woman, or child of the species Homo sapiens, distinguished from other animals by superior mental development, power of articulate speech, and upright stance.” (Oxford Dictionary)

Les Demoiselles d'Avignon
Les Demoiselles d’Avignon by Pablo Picasso

Our view of ourselves changes over the centuries as it reflects changes in contemporary events and our reactions to them. More recently, prior to the First World War, our assessment of human nature was much more positive than it is today. Humanity had transcended previous limitations in art, music, literature and the sciences with innovative contributions such as the works of James Joyce, Picasso’s Les Demoiselles d’Avignon, Stravinsky’s The Rite of Spring, the phonograph and telephone, the airplane and undersea cable which linked the world by telegraph to an unparalleled degree, connecting people all over the world for the first time. We were enlightened, peaceful, creative, and capable of extraordinary feats.

Then came 1914 and the beginning of the First World War – along with these positive scientific inventions, others in the name of “defense” caused unprecedented destruction. In all, 20 million people were wounded and over 16 million died in this “Great War.” After such destruction it is understandable that psychologists and others were compelled to look again at human nature in an attempt to understand who we are and how we became so. The idea then was that our aggressive natures reflected our evolutionary past and that our struggle was against this – in a sense – animal self. Of course, this theory was already to some extent reflected in the Christian idea of original sin: we were born with negative “animal” characteristics, which had to be overcome. Animals in general were “savage” and primates were no exception. Animals had no feelings – they were “other.”

And then the Second World War – where under the initiation and direction of one man a nation was taught to view a community of their own kind as “other.” Six million Jews were annihilated in concentration camps and a total of 70 million or more people died, including many civilians, women and children; and war-related famine deaths in China, Indonesia, Vietnam, the Philippines, India that are often omitted from other compilations of World War II casualties.

Today, thanks to advances in science and technology – studies in animal and primate behavior on the one hand and in psychology and neuroscience on the other – we can at last begin to ascertain what we inherit from our animal and primate past and in what respects we differ; from there we can hopefully begin to understand our unique place and potential as human beings.

Tree of origin of humans and the 4 great apes
“Tree of origin of humans and the four great apes based on DNA comparisons [right]. Data points indicate how many millions of years ago species diverged. Chimpanzees and bonobos form a single genus: Pan. The human lineage diverged from the Pan ancestor about 5.5 million years ago. Some scientists feel that humans, chimpanzees, and bonobos are close enough to form a single genus: Homo. Since bonobos and chimpanzees split from each other after they split from us, about 2.5 million years ago, both are equally close to us. The gorilla diverged earlier, hence it is more distant from us, as is the only Asian great ape, the orangutan.” (Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are, Frans de Waal)

We share genes with all living things – even the banana and the fly! But most relevant to our starting off on this journey is to take a cursory look at the remaining primates closest to us. About five and a half million years ago the human genus split from the ancestor we share with chimps and the lesser known bonobos; we still share all but 1.3% of our DNA with these two primates, who themselves split into separate species about 2 million years ago.

While far more studies have been done on chimps than bonobos, it is important to note that neither one of these apes is genetically closer to us than the other. Chimps have been known to science since the seventeenth century, whereas bonobos have been studied in the wild only since the 1970’s and, because of political unrest, inconsistently at that. Chimps live across Africa in great numbers, whereas bonobos live only in the rain forests on the south bank of the westward streaming Congo River, which permanently separates these more secretive, peaceful apes from the chimpanzee and gorilla populations to the north.   

The social lives of chimps are complex. They are patriarchal, ambitious, excitable and violent. A male hierarchy with one “alpha” male at the top typifies the chimp community, though lower-ranking males often form coalitions to topple the reigning alpha male. These coalitions are the basis of their political struggles. Like us, they are more likely to help those who have helped them. Chimps band in aggressive groups to hunt down others often in bloody, brutal and fatal conflict. Perhaps in part to justify the violence of our recent history, our human story has been most closely compared to the hierarchical and murderous behavior of chimps which seems to have inspired the view of humans as aggressive by nature. The implication is that aggression is predominant in our makeup and there’s little we can do about it. But is this true?

As de Waal suggests in his book Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are, the influence of our inherited behavior on our own history would likely have been far different if the situation had been reversed and what we knew about ourselves and our inherited background came primarily from bonobos rather than chimps. Our understanding of the influence of inherited characteristics would then have revolved less around violence, warfare and male dominance, and instead emphasize empathy, caring, sexuality, peace, cooperation and, perhaps, even a matriarchal society. As he says:

“Compared with the male-centered chimpanzee, the female-centered, erotic, and peaceable bonobo offers a fresh way of thinking about human ancestry. Its behavior is hardly consistent with the popular image of our forefathers as bearded cavemen dragging women around by their hair. Not that things were necessarily the other way around, but it is good to be clear on what we know and don’t know. Behavior doesn’t fossilize. This is why speculations about human prehistory are often based on what we know about other primates. Their behavior indicates the range of behavior our ancestors may have shown. And the more we learn about bonobos, the more this range expands.”

With the help of modern studies in DNA, it is possible to establish links which indicate that some of our behavior at least comes from our last common ancestor. We share a particular piece of DNA with bonobos that is involved in affiliation and bonding and is non-existent in chimps. Researchers at Yerkes Primate Center (Emory University) found that bonobos’ brains possessed more gray matter in areas that usually play an active role in identifying distress in social contexts, sensing distress in others and feeling anxiety. They also have larger connections between the brain’s amygdala and anterior cingulate cortex, suggesting a more emotional spin on resolving conflicts, and a better ability to control impulses than chimpanzees.

Faces of a bonobo and chimp
Bonobo (left) & chimpanzee (right),
for a more detailed comparison see National Geographic.

Bonobo society is matriarchal, egalitarian and peaceful by nature: female bonobos form strong bonds with weak hierarchical tendencies; they rely on female coalitions to dominate the males in their group. While male bonobos are stronger individuals than females – up to five times stronger than the average human male – they do not form the male alliances that are observed in chimp groups, but stay by their moms who do form alliances with other females and control the show. Sisterhood is power and female solidarity relies on an extensive network of alliances to assert collective dominance. Although males and females collaborate in obtaining food mostly by foraging, bonobo females decide how food is shared among a group, and they and their young feed first. Bonobos’ food-rich habitat probably contributed to their social structure: since food is near at hand, they are able to stay together as a group and consequently create lifelong bonds. Gorillas and chimps cohabit in areas where food is sparser, so females have to go looking for food on their own.

Chimpanzee sex is for reproduction and males might kill another’s offspring as they compete for sexual favors from a potential mate. They need to know that their offspring survives and no one else’s. Bonobos are sensitive creatures and much of their frequent sexual activity is related to maintaining peace. They use sex to avoid violence – it’s hard to have sex and remain angry with your partner! Often casual and quick, sex, homosexual or heterosexual, is used for bonding, greeting, to settle arguments and for comfort. And, of course, by having multiple partners bonobos avoid infanticide – no one has any idea who their father is!

Bonobos have a more upright skeleton, longer legs, and narrower shoulders than chimpanzees, and because of this, they have the ability to walk bipedally more easily and for longer amounts of time than chimpanzees. Their skeletal anatomy is not dissimilar to Australopithecus, an early ancestor of humans. Their faces are flatter with a higher forehead than those of chimps, and their long black hair parts in the middle.

At the fundamental level we, in common with all creatures, seek the greatest possible genetic representation in the next generation: survival of ourselves is paramount for all species, and individuals strive to perpetuate their own genetic heritage to that end. Our abilities, societies and cultures reflect the same basic goal: survival. It’s not surprising that we share elements of these with our nearest relatives, but some characteristics we share are less well known:

1. Self-recognition – Joshua Plotnik, a graduate student in psychology at Emory University in Atlanta, Georgia, recently observed this ability in elephants; it has also been observed in dolphins and apes: gorillas, orangutans, chimpanzees and bonobos all show this ability. According to Plotnik, mirror self-recognition is a trait only known among animals that are thought to lead highly complex social lives, which may require a sense of self-awareness and the display of emotions like empathy. “Recognition of the self may allow you to take yourself out of the picture and see yourself as separate from others,” he explains. Like us, these animals recognize similarities between themselves and others, can tell one individual from another, recognizing friend from foe. Chimpanzees can remember a face for over a decade.  However, unlike us, fMRI data suggests that apes do not engage in self-reflection or introspective contemplation, and have no conceptual sense of self.

Self-Recognition in Apes.

2. Group behavior – So many different animal species survive as groups: from bees to fish, from birds to dogs, from elephants to apes, to ourselves. Quite obviously there is safety in numbers. Most primates, including humans, but excluding orangutans, spend their lives in large social groups or communities. To survive as a group each species has evolved its own strategies and we’ve mentioned some of these with regard to bonobos and chimps.

As de Waal points out: “One can’t reap the benefits of group life without contributing to it. Every social animal strikes its own balance between the two. Some are relatively nasty, others relatively nice. But even the harshest societies, such as those of baboons and macaques, limit internal strife. People often imagine that in nature weakness automatically means elimination – a principle hyped as the ‘law of the jungle’ – but in reality social animals enjoy considerable tolerance and support. Otherwise, what would be the point of living together?” (Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are, Frans de Waal)

Apes and humans are born immature – humans are born with only 25% of our brain developed, apes with 50% – so although apes remain immature for a much shorter time than we do, the early environment of apes and ourselves is crucial for development. The more brain development that takes place in the world, the more adaptive the animal is.  Like us, but to a more limited extent, apes are able to adapt to different environments, live in different areas and conditions, and develop different strategies for survival.  Like us, they are acutely aware of their social environment: they ponder the options in front of them and decide what to do dependent on the circumstances.

Both chimps and bonobos form bonds, first between mother and child, but primates also form friendships within the community, which they express in grooming, traveling together, and defending each other. Cooperation and sharing are vital for group survival, so it is not surprising that many animals including wolves, whales and primates all display these qualities. For example, any chimp that finds food first owns it, no matter what his or her rank is in the hierarchy, and that ownership is respected by all group members. But sharing with family and friends is important: no one in the group goes without. Young captive bonobos have been found to prefer sharing their food to eating alone, and, unlike human toddlers, will do so even with complete strangers. “We found that the test subjects preferred to voluntarily open the recipient’s door to allow them to share highly desirable food that they could have easily eaten alone – with no signs of aggression, frustration, or change in the speed or rate of sharing across trials,” explains Dr. Brian Hare of Duke University. “This stable sharing pattern was particularly striking since in other, non-sharing contexts, bonobos are averse to food loss and adjust to minimize such losses.”

Behavior towards those outside the group varies with circumstances in both our own and ape communities. Aloofness towards outsiders is often seen in non-human primate communities, probably because it helps to keep limited local food resources within the group. Chimp groups live within territories which have distinct boundaries patrolled by male groups. Chimpanzee raids include violence against neighbors and even killing. But when chimpanzees from different troops come together, there is often an exciting, friendly encounter, which lasts several hours, after which time some of the adult females are likely to switch groups seemingly in order to find different mates. Maintaining peace is important and each species follows its own reconciliation protocol. “Golden monkeys do it with hand-holding, chimpanzees with a kiss on the mouth, bonobos with sex, and tonkean macaques with clasping and lipsmacking.” (de Waal)

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