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  • Writer's pictureArthur Bruso

Not My Monkeys

Updated: Sep 23, 2020

Review of The Third Chimpanzee by Jared Diamond

What is great about science is that it is in constant flux. We are always adding to our accumulated knowledge through study. There is always new information to be found that rewrites what we already know. Adding to our wealth of knowledge about our world and universe can only be helpful to our understanding of life and the processes that shape us all. But that does make it difficult to create an immutable record. By the time of publication – or a few years after - something new is discovered and the printed becomes obsolete. That is the case with The Third Chimpanzee by Jared Diamond.

Two birds: Red-eyed Verio (left) White-eyed Verio (right)
Red-eyed Vireo (left) White-eyed Vireo (right)

The main premise of the book, and what inspired its writing, was the discovery that humans share 98.4% of our genes with chimpanzees. That leaves only 1.6% of our genetic material to give us our unique humanness. Diamond questions how animals such as the birds, the red-eyed vireo and the white-eyed vireo can be placed in in the same genus while having a 2.9% genetic difference between them. Their 2.9% genetic difference is a 1.3% larger difference than the 1.6% between humans and chimpanzees. Diamond advocates in The Third Chimpanzee for chimpanzees to be reclassified and put on the same place in the tree of life as humans. He asserts that it’s our vanity and our imagined superiority, not science, that places us as the only member of the genus Homo. Thus, the title The Third Chimpanzee which encompasses: bonobos, chimpanzees and, Diamond asserts, humans.

Chimpanzee (left) Bonobo (right)
Chimpanzee (left) Bonobo (right) Chimpanzee by Thomas Lersch; Bonobo by Natataek at English Wikivoyage, CC BY-SA 3.0,

The book was published in 1992. In the intervening twenty-eight years science has moved forward and the new information on our own ancestry has been added through new discoveries. By the second chapter, Diamond writes about the evolution of the human family tree, and what he terms “The Great Leap Forward,” (the time when our evolutionary ancestor’s behavior changed from animal to human). During this period Neanderthals lived at the same time as Cro-Magnon man (Cro-Magnon is the designation of hominid that is a physically modern human who existed in Europe before humans developed their first recognizable culture). Diamond states about the possibility of their interbreeding, “If Neanderthal behavior was as relatively rudimentary, and Neanderthal anatomy as distinctive as I suspect, few Cro-Magnons may have wanted to mate with Neanderthals. Similarly, although humans and chimps continue to coexist today, I'm not aware of any matings. While Cro-Magnons and Neanderthals weren't nearly as different, the differences may still have been a mutual turnoff.” Since the time of the publishing of this book, we have discovered this is not true.

By 2005, the reality of human and Neanderthal interbreeding had become evident. By 2013, the DNA sequencing had become complete. The reported result was that all European and East Asian populations share 1.5% - 2.1% of genetic material with Neanderthals. These genes are mostly expressed in hair, skin (thickness and pigmentation) and diseases (lupus, diabetes) of modern people. Additionally, a 2011 study found that another ancestor, the Denisovan people have contributed genetic material to modern Australian Aborigines, Near Oceanians, Polynesians, Fijians, and East Indonesians. So, there is evidence in our genes that some interbreeding between a second ancient hominid had taken place. This situation is also in opposition to Diamond’s statement. While Diamond’s declarations about Neanderthal’s has been proven wrong through the advancement of genetic mapping, this does not make the rest of his book obsolete. His information about human behavior, its origins and how it compares and contrasts with chimpanzees and other animals continues to be relevant.

While still a point of debate, Diamond proposes that the arrival of Cro-Magnon man was the greatest factor in the extinction of Neanderthals. He posits that Cro-Magnon man’s replacement of Neanderthals had to do with the patterns of behavior that occur whenever humans of advanced technology clash with less advanced peoples. They conquer them. Diamond does not write these words. He infers them. Like many scientists, he presents facts that have been derived from research and avoids as much as he can any situation that requires a social or political discussion. Later in the book, he discusses some very controversial topics regarding sexism, world domination and the human behavior that these come from. Even so, he still stays with the scientific facts, allowing the reader to form their own opinion.

As Diamond writes, Neanderthal technology was remarkably sophisticated from the outset compared to the hominids that came before. Still, Neanderthals did not show any innovation or change for the entire span their existence. The tools they made when they first emerged onto the scene, look and were created exactly the same as the tools they crafted when they died out 90,000 years later. This was a distinct disadvantage for them when the Cro-Magnon arrived. The Cro-Magnon were not only mentally able to consistently improve and develop new innovative tools but also began using symbolism and language extensively as a means of communication. These behaviors gave them an intellectual advantage that seems to have accelerated the Neanderthal’s demise.

After Diamond’s examination of our ancestral family tree, he begins to discuss the 1.6% difference, where humans diverge from chimpanzees. He begins investigating what traits and behaviors separate us from not only the chimpanzee but other animals as well. This is also the section of the book where he starts leaving the premise of the chimpanzee comparisons behind and begins an exploration of some major and often socially controversial human behaviors and where they originated from. He begins by listing the major differences humans have that separates them from chimpanzees. They are: human babies must have food brought to them after weaning until they develop the knowledge and muscular coordination to do it themselves; human fathers share in the caring for their offspring; humans have long lives and live to ages that allow important information and experience to be passed along; human females experience menopause; humans prefer sex in private; human females have concealed ovulation. He then examines each item and considers it thoroughly. His lighthearted tone makes reading about penis size or copulation practices, and pigment changes during ovulation less clinical and scientific and more engaging without resorting to eye winking and elbow ribbing. There are reasons for all of these behaviors, even if scientists have not agreed upon a definitive one. Diamond explores what has been theorized about them, then offers the one theory that makes the most sense to him. He tries to decipher how these behaviors give humans an evolutionary advantage and tries to parse out if they are genetically determined or learned behavior (almost always they are a mixture of both).

The author devotes an entire chapter to the concept of adultery. While humans may have evolved a preference for monogamy, (Diamond is not unaware of cultures that deviate from monogamy, but for this chapter, he is concerned with the concept of bonded couples) they are not averse to taking advantage of opportunities to spread their genetic material further afield. He cites a 1940s study, which was suppressed at the time to avoid scandal, found through blood tests that at least 10% of babies are the product of adultery. On mating practices, Diamond compares humans to herring gulls which are monogamous, but often take liberties during their mates’ absence to accept the advances of a neighbor. He chooses herring gulls sexual strategy as an example because their mating behaviors more closely resemble humans than chimpanzees. The chimpanzee’s sexual strategy is to be promiscuous, with several males mating serially with an estrous female. This is one example where chimpanzee behavior is far different than human and cannot be used as a comparison despite our close genetics.

Diamond discusses what he terms animal “game strategy” as it applies to animal and human sexual practices and child rearing, Chimpanzee males have no part or interest in the care of their offspring. Given chimpanzees indiscriminate mating practices it would be impossible for them to determine paternity. But for humans, Diamond proposes that securing paternity is key to seducing human males to participate in child rearing

Socially it has evolved through the realities of the hunter gatherer lifestyle that human males need to participate in the child’s well-being, even if the male role is reduced to providing food for the family. Yet a human male’s effort in reproduction is minimal, while the female’s is great (9 months of pregnancy, plus nursing and rearing which gives the female a greater incentive to get the male involved). Diamond discusses this sexual asymmetry of human mating in detail. But the males’ basic impulse is to spread his genes as wide as possible and avoid the responsibilities of child rearing. Thus, there are at least three plans of human mating strategies that may be used for males to maximize their mating potential.

Game Plan 1 – men should copulate with as many women as possible and leave as many descendants as possible. This plan is only advantageous to the male and negates the females’ needs.

Game Pan 2 – the male should maximize gains while minimizing losses. The potential costs to the male who cheats on his mate are: detection, injury or death of either partner, desertion, cuckolding or child neglect. This implies that the male should plan his infidelities with the idea of getting the most enjoyment or excitement he can, while trying to avoid any of the mentioned costs (detection, injury, etc.). Again, this is a plan that is only advantageous to the male.

Game Plan 3 – include women in the plan. Plans 1 and 2 are flawed because they ignore the considerations of the woman. Without the cooperation of the female all plans are doomed to fail. Any improvement in game strategy must combine male and female interests.

All of these mating strategies are sexist in nature except Plan 3 which isn’t a plan, but an observation on the limitations of the previous two. Biologically, men seemed determined to abandon their child rearing responsibilities after their role in mating but still want to ensure their paternity. Diamond tries to pass this off as male bias, given that these strategies have been devised by male anthropologists. This is an explanation, but it does not resolve the often cruel and barbaric methods that men in different cultures have taken to control women bodies and women’s freedom of choice in sexual matters as they try to make all sexual strategies advantageous to them.

According to Diamond, men enjoy and desire sex and even when partnered, desire sex with many woman. Women, he suggests, are often emotionally content with one partner and because of the investment necessary in child rearing choose to stay with one partner. This dichotomy of sexual interests sets up a conundrum for men; what is it that would seduce a woman away from the satisfaction and security of their mate? This conundrum has taxed the ingenuity of men throughout human history. Diamond delves into the various ways men historically have tried to exploit a wife’s tendency toward monogamy and keep her secluded from the advances of other men and ensure the paternity of his children. Concurrently and selfishly, men try to convince other partnered women to agree to adultery (or non-committal sex) to increase the probability that they produce as many descendants as possible with as many women as possible. Most adultery laws have been designed to secure a married man’s confidence in the paternity of his children. Extra marital sex by a woman, until recently, was considered an offense against a woman’s husband. The offended husband was entitled to damages, including violent revenge, divorce or refund of the bride price. The modern near symmetry of adultery laws has only come about in the last 180 years and it is still not equitable.

Diamond details the extreme measures men across time and cultures have gone to uphold their confidence in their paternity; from Chinese rulers keeping elaborate records of copulations tattooed on the body of the wife, Mediterranean cultures devising strict codes of honor and shame that limit a woman’s social contact and intellectual opportunities, and even the intrusive violence of female circumcision, to name a few. He brings up the fact that some of these odious behaviors can be found throughout the animal kingdom as instinctive biological strategies to ensure the copulating male’s sperm is the sole fertilizer of the female’s eggs. He describes some of these animal strategies in the service of scientific thoroughness, explaining that while these behaviors may have evolved through natural selection, it would be unconscionably cruel to emulate these behaviors among humans. One common strategy Diamond cites is how several diverse male animal species, (primates, kangaroos, reptiles, rodents and insects) seal the vagina of the female after copulation to ensure their paternity. Science should not be held up as an example to justify these behaviors. In a rare deviation into the political, Diamond makes this statement regarding the biological basis for human males controlling paternity, “We have evolved like other animals, to win at the contest of leaving as many descendants as possible. Much of the legacy of that game strategy is still with us. But we have also chosen to pursue ethical goals, which can conflict with the goals and methods of our reproductive contest. Having that choice among goals represents one of our most radical departures from other animals.”

While mating and child rearing behaviors are important to the continuation of humankind, the author moves on to the evolution of creativity and culture that separates humans from other animals. It is easy to point to the generation of music and dance in the animal kingdom. Many animals, especially birds and insects rely on sound and/or movement to attract a mate or communicate in other ways (bees dance to show where the best nectar is). Diamond asserts that there are also biological sources for language and art. He explains that language and art did not erupt spontaneously when hominids became humans. Instead he believes they both evolved from genetically coded and instinctive animal behaviors which evolved into the human activities they are now. He looks to the present-day animal kingdom to retrace the evolutionary line back to the base behavior that may have been the genesis of these complicated and symbolic activities.

As a precursor to language he discusses how certain primates have limited but particular sounds that have meaning for them. However particular these calls are, they are limited in the scope of their meaning to a particular kind of danger or food. Studies have deciphered them to a point. There are a lot of sounds that primates make that are seemingly understandable between them, but they are apparently unintelligible to humans no matter how much we study them to try and parse out meaning. These casual sounds made among the animals themselves, even if we could translate them, do not constitute language because they do not have the grammatical structure that true languages have. Instead they are sounds that are only a start of communication. Still it is clear that many primates and other animals are able to transfer limited meaning among each other, despite the limitations of their communication.

When trying to find the primary biological source for art, he is less successful. He uses the bowerbird as his example for the beginnings of art in the animal kingdom. For me this is a stretch. An attraction for shiny and colorful things does not compare to the rich intellectual and symbolic communication of art. Many animals show an interest in collecting shiny or colorful things without it being considered a creative statement. There needs to be more of a connection between the action and the intent. While the bower bird does show an instinctual behavior of collecting objects to attract a mate, that has no comparison to the complexity of ideas in art. Like nest building, which can be strikingly complex, it is only an instinctual activity that evolved as a child rearing strategy. Nest building is not a personal expression of the internal life of the bird who longs to be an architect and the bower bird for all of its toil is not an installation artist.

Satin Bowerbird
Satin Bowerbird photo by Luke Shelley

While language and art may be the activities that move humans away from their animal pasts, agriculture has proven to have the greatest impact on human life and history. It has allowed humans to rise above their station as hunter and gatherers and caused the final leap out of Arcadia into the world of toil and strife. Agriculture provided some people with the leisure time to plan construction programs and follow artistic pursuits. But, Diamond dwells mainly on the dark side. He points out that while agriculture was good for a few and allowed for easily gathered nutrition and peace of mind to devise a civilization, it was bad for most people when looked at from a social standpoint.

Hunter-gathering societies spend only about 12 – 19 hours a week in pursuit of food. They spend much of that free time in conversation, music, dance or other creative pursuits. The individuals of hunter-gatherer societies are nearly equitable. Let’s not convince ourselves that the life of the hunter-gatherer was idyllic. They had to keep their population constant, since foraging can only support a limited number of people. And as the hunter-gathering societies are often mobile, children need to be spaced out at 4-year intervals to keep parents from being burdened with children that cannot keep up with the tribe. Any particular landscape can support a limited number of individuals. The number is determined by the resources the particular landscape provides. This number must be maintained, or the future of the entire tribe can be affected. Population control is achieved through infanticide, if other natural methods (death of the elderly, disease, warfare) do not keep the number of people to the minimum. As everyone is equitable, there can be no leisure class and no choice of career. In a hunter gatherer society, everyone needs to work for the survival of the tribe so options for personal growth are limited. Also, deviations from the accepted tribal culture (such as other sexualities) are often not tolerated since they can upset the balance of the tribe.

Early on, people discovered that there were benefits to growing food crops and domesticating animals. Food sources were all in one place, easier to control, more reliable, and in the case of livestock, the dangers and fickleness of the hunt could be avoided. The drawback of agriculture was the intensity of the labor and tediousness of the work. When farming for a clan or family group, the benefits outweighed the drawbacks. When the population of the group grew to a community of several clans, the drawbacks began to outweigh the benefits. At this point in agriculture, the enterprise could be abandoned due to the loss of interest in the people to investing in the labor. Alternatively, an enterprising individual, seizing a leadership opportunity, could motivate the people to continue farming. These motivational leaders became the first rulers and the first layer in the stratification of an agricultural society. Once the leadership determined the commitment of the society to agriculture, the need for foraging is eliminated. This frees up individuals to take on other roles that become necessary for agriculture to flourish. Soon people would be needed to protect the fields and the field workers. There may be a need for protection from raiding tribes or to wage war when it was necessary to expand fields. Craftspeople would be needed to build and make the various tools and constructions needed to contain the livestock and store the harvest. As populations grew because of the increase in food production, shelters would have to be built, towns have to be planned. This gives rise to grander civic programs, such as, building irrigation canals, constructing government buildings, or various other long-term public projects that require cooperation of labor and elaborate planning. Soon the new society contains various classes, with duties that confer status. An entire new complex culture has grown out of the family farm.

Agriculture also brings about other inequalities. Food distribution often is canted toward the ruling class. Kings and other elites usually get the most and the best of the crop. A diet heavy in plant carbohydrates cause tooth decay, anemia, tuberculosis and other degenerative diseases. Agricultural societies trade varied sources of nutrition for a single food source. Once the crops are established in the culture as the sole food source, the threat of starvation is greater should the crops fail. In the end agriculture brought greater social inequality; an increase in negative long-term health issues; crowded living conditions, which encourage the spread of disease; and the threat of famine through the dependence of monoculture. The reader can tell from the tone of the author, that he is not a fan of farming. It is also telling that agriculture, once invented, was not immediately taken up and spread across tribes as a wonder to acquire. It took centuries for it to become adopted by the peoples throughout the Eurasian continents. It often had to be forced upon the people by ambitious rulers who saw the accumulation of power in its adoption.

By the final section of the book, Diamond begins to get into the human problems that plague us today. I want to stress that The Third Chimpanzee was published in 1992. The concerns of historical colonialism, institutional racism and the exposing of the truth of European “heroes” were not perceived as crucial issues at the time. Instead the major concerns were the war in Iraq, A.I.D.S. and the launching of the world wide web. However, Diamond gives an historical overview of why the people from the European continent came to dominate the world. It begins with luck. Europe and the Middle East, by happenstance had the animals (the wild ancestors of cows, pigs, sheep, goats and horses) with the right temperament and size for domestication. They had the correct plants (the wild ancestors of wheat, barley, oats, rice, rye as well as a host of now common fruits that would flourish and could be improved under cultivation). The Eurasian continent had a geographical advantage because it was situated west to east in basically the same temperate climate zone which allowed for easier distribution and cultivation of the food plants and animals across the continent where they could be grown and nurtured without much modification. This allowed for agriculture to spread more easily. Devoting less time to finding food freed some people to do other things: develop written language, build cities and create trade and technology from the new ideas that free time allowed some people to think up. Most people would be enslaved to the land.

Unfortunately, fate was not with the continents of the New World, Australia or the Pacific Islands. These lands did not have the right animals that could be domesticated. The animals here were either too independent, too skittish or too small to be useful. The plants were also problematic, except new world corn, which adapted easily to the varying growing conditions encountered in the New World but did not contain the nutrition that the Old World grains did. The geography of the New World was against the easy distribution of food crops. The north/south axis of the continents covered many disparate terrains and climate zones that were incompatible with food plants and animals from different locations. These chance situations prevented easy distribution of technology and ideas which kept the New World civilizations from developing in the manner of Europe. As a result, most of the New World did not develop the advances of technology or political power that Eurasia enjoyed.

It was chance that set the dominance of Europe. China was headed along with Europe to share in the bounty of technology and exploration and conquest, but by the 15th century, its rulers decided to isolate themselves from the rest of the world to stave off what they considered the barbaric influences of Europe. That left Europe to set out with its curiosity and its explorations to see what was on the other side of the ocean and claim it for its own, because when more technologically advanced people encounter less advanced societies, they conquer them.

The Third Chimpanzee is an enlightening account about good and bad human behavior and where those behaviors could have originated. Many of the things humans do and consider unique to themselves have their roots in the instinctual behaviors of the animal kingdom. Understanding the origin of such behaviors as culture and conquest demystifies them. They may even have a genetic basis, but not so much that we cannot learn to abrogate them. The book sets out to prove that we are not above animals but are animals ourselves only with a bigger brain that gives us bigger ideas. We share 98.4% of our genes with chimpanzees, but the tiny 1.6% of difference between us makes us much more dangerous.

Arthur Bruso © 2020

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