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Chapter 20 Cultural and Social Evolution. Figure CO: A lion and her cubs . © George Lamson / ShutterStock , Inc. Overview. Unlike most other animals, humans transfer information from generation to generation through genes and culture Animal Behavior – Ethology – Sociobiology

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Chapter 20 Cultural and Social Evolution

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chapter 20 cultural and social evolution

Chapter 20Cultural andSocial Evolution

Figure CO: A lion and her cubs

© George Lamson/ShutterStock, Inc.

  • Unlike most other animals, humans transfer information from generation to generation through genes and culture
  • Animal Behavior – Ethology – Sociobiology
    • All organisms exhibit behaviors, not just animals
  • Human language abilities
  • Social Darwinism – a discredited social philosophy
  • Biological and cultural evolution interact
    • Eugenics, genetic engineering and cloning
animal behavior
Animal Behavior
  • Animal behavior is the scientific study the behavioral relationships of animals to their physical environment as well as to other organisms, and includes such topics as how animals find and defend resources, avoid predators, choose mates and reproduce, and care for their young
  • The study of animal behavior is concerned with understanding the causes, functions, development, and evolution of behavior
  • The causes of behavior include both the external stimuli that affect behavior, and the internal hormonal and neural mechanisms that control behavior
  • The functions of behavior include its immediate effects on animals and its adaptive value in helping animals to survive or reproduce successfully in a particular environment
animal behavior4
Animal Behavior
  • The development of behavior pertains to the ways in which behavior changes over the lifetime of an animal, and how these changes are affected by both genes and experience.
  • The evolution of behavior relates to the origins of behavior patterns and how these change over generations
  • This discipline was founded by American biologists and psychologists, primarily after WWII, and included considerable emphasis on laboratory experimentation
  • Many behavioral psychologists emphasized the study of learned behaviors
    • Pavlov and his dog studies is the classic example
  • Ethology is the scientific study of animal behavior, and a sub-topic of zoology
  • The modern discipline of ethology begun during the 1930s in Europe and parallel to but rather independent of the Modern Synthesis
  • Ethology is a combination of laboratory and field science, with a strong relation to certain other disciplines — e.g., neuroanatomy, ecology, evolution
  • Ethologists are typically interested in a behavioral process rather than in a particular animal group and often study one type of behavior (e.g. aggression) in a number of unrelated animals — a comparative approach
the nobel prize in physiology or medicine 1973
The Nobel Prize in Physiology or Medicine 1973
  • Karl von Frisch, Konrad Lorenz, and Nikolaas Tinbergen "for their discoveries concerning organization and elicitation of individual and social behavior patterns“
  • A rare prize for evolutionary biologists for the founders of modern Ethology from the Nobel Committee
karl von frisch 1886 1982
Karl von Frisch (1886 - 1982)
  • Austrian entomologist who studied insect communication
  • Made major contributions to the study of honey bees, their ability to communicate to hive mates about food sources with the waggle dance, use of pheromones, and their ability to see in color and in ultravioltet and polarized light.
  • Wrote Dancing Bees, A Biologists Remembers,Animal Architecture, and other works
konrad lorenz 1903 1989
Konrad Lorenz (1903 - 1989)
  • Austrian ornithologist and ethologist
  • Studied instincts and fixed action patterns in birds, and later became interested in human behaviors
  • Wrote many books including King Solomon’s Ring and On Agression
nikolaas tinbergen 1907 1988
Nikolaas Tinbergen (1907 - 1988)
  • Dutch zoologists who studied fish, birds and insects in nature and the laboratory, and later autism
  • A better experimentalist than Lorenz, the theoretician
  • Wrote The Study of Instinct, The Herring Gull’s World, Social Behavior in Animals, Curious Naturalists, etc.



effect ↑

robert hinde 1923
Robert Hinde (1923 - )
  • British zoologist who studied birds, then primates, and later humans
  • Wrote Animal Behaviour: A Synthesis of Ethology and Comparative Psychology (1966), a classic work that helped integrate research in psychology and ethology, Biological Bases of Human Social Behaviour (1974), Individuals, Relationships and Culture (1987), Towards Understanding Relationships (1979), and Why Gods Persist (1999), etc.
desmond morris 1928
Desmond Morris (1928 - )
  • British ethologist, popularizer of science, and surrealist painter.
  • Happy to take controversial positions when advocating for the biological basis of human behaviors
  • Wrote the bestsellers The Naked Ape and The Human Zoo, among nearly eighty volumes
david p barash 1946
David P. Barash (1946 - )
  • American psychologist and sociobiologist
  • Barash has been named one of the country's "101 Most Dangerous Professors," by right-wing writer David Horowitz, because of his advocacy of peace and other progressive causes, as well as his avowed atheism and persistent exploration of evolutionary biology and its application to human behavior
  • Excellent writer and author of more than 25 books

One of his most recent books is Natural Selections: selfish altruists, honest liars and other realities of evolution (2007)

george b schaller 1933
George B. Schaller (1933 - )
  • Perhaps the world’s greatest living field biologist and ethologist
  • Preceded Dian Fossey with his 1959 study of the mountain gorilla
  • Since has studied big cats, pandas, African, Tibetan, Brazilian, Chinese and Southeast Asian fauna
  • Helped establish many national parks in Asia
  • Has won many awards and written several dozen books, beginning with The Mountain Gorilla – Ecology and Behavior (1963), and, recently, A Naturalist and Other Beasts: Tales From a Life in the Field (2007)
nature versus nurture
Nature versus Nurture?
  • Animal behavior is best explained by investigating the contributions of both genes and environment
  • Behaviors form a spectrum from innate behaviors which exhibit little variation among members of a species and appear at predictable times in development to learned behaviors which require exposure to various environmental stimuli to develop, usually require trial-and-error repetition to improve their efficiency and exhibit considerable variation among members of a species
  • In all cases, organisms with genes must interact with their environment for behaviors to occur
  • Relatively complex innate, predictable, stereotypical behaviors which are present in individuals, sometimes even from birth, and performed completely without requiring any experience
  • The simplest are muscular and autonomic reflexes such as pupil constriction in bright light or a flexor reflex when the hand touches a hot object
  • More interesting are fixed action patterns, e.g., courtship rituals in many animals, nest building, predator defense behaviors, etc.
filial imprinting
Filial Imprinting
  • Konrad Lorenz himself raised these greylag goslings from first hatching, so it was to him that they imprinted, expressing their innate behavior of following their “parent”
  • Imprinting behaviors usually trigger at critical times in development
  • Now imprinting is used to reintroduce captive-reared birds to life in the wild
biased learning
Biased Learning
  • Biased learning is a restricted form of learning ― the ability to learn and modify behavior from a restricted set of environmental stimuli
  • Lorenz, Tinbergen, and others demonstrated that imprinting and other “innate” behaviors develop from heritable “hard-wired” neurological programs which may still be influenced by biased learning
    • Following behavior in water birds, mate identification in various birds, mating rivals, etc.
sexual imprinting
Sexual Imprinting
  • Male zebra finches select a mate based on the color pattern of the female that rears them, regardless of species
  • On the other hand, their courtship song and dance require some learning
reverse sexual imprinting
Reverse Sexual Imprinting
  • When two people live in close domestic proximity during the first few years in the life of either one, both are desensitized to later close sexual attraction
  • This phenomenon, known as the Westermarck effect, was first described by Finnish anthropologist Edvard Westermarck
  • Documented in biological families, Iraeli kibbutz, Chinese Shim-pua arranged child marriages, and many other cultural setting
genetic sexual attraction
Genetic Sexual Attraction
  • When a brother and sister are brought up separately, never meeting, they may find each other very sexually attractive as adults; first cousins are also often highly attracted
    • Charles Darwin and Emma Westwood were first cousins, but did know each other through their youth
  • This suggests that the Westermarck effect evolved to inhibit inbreeding with its negative genetic consequences
inherited behavior in lovebirds
Inherited Behavior in Lovebirds
  • Experiment
  • Two species of lovebirds were interbred. Female Fischer's lovebirds cut long strips of nesting material, which are carried individually to the nest. Female Peach-faced lovebirds cut short strips and carry several at a time by tucking them into her back feathers.
  • Results
  • Hybrid females cut intermediate length strips and tried, but failed, to transport them by tucking into back feathers. They learned to carry strips in their beaks, but never gave up all tucking behavior.
  • Conclusions
  • Phenotypic differences in the behavior of the two species are based on different genotypes. Innate behavior can be modified by experience. Learned behaviors are typically based upon gene-determined neural systems that are receptive to learning.
genes vs environment bird song
Genes vs. Environment— Bird Song
  • Three calls of the male meadowlark are shown, one set produced by a free-living individual and one produced by a hand-reared male kept isolated from ever hearing the songs of another male. The meadowlark’s genetic program is sufficient to produce normal songs.
genes vs environment bird song23
Genes vs. Environment — Bird Song
  • The free living male chaffinch produces a complex song, but if raised in song isolation, its song is much different. If the chaffinch is exposed to the song of a tree pipit, then the chaffinch song picks up some of this vocal culture. Not only is the chaffinch genetic program insufficient to produce the normal song, but song culture (exposure to the tree pipit) can modify it.
learned behaviors
Learned Behaviors
  • Learning can be defined as a persistent change in behavior that occurs as a result of experience
  • In general, learned behaviors will always be:
    • Nonheritable -- acquired only through observation or experience
    • Extrinsic -- absent in animals raised in isolation from others
    • Permutable -- pattern or sequence may change over time
    • Adaptable -- capable of modification to suit changing conditions
    • Progressive -- subject to improvement or refinement through practice
learned behaviors25
Learned Behaviors
  • Learned behavior is more flexible and often more complex than innate behavior
  • The capacities for most behavioral traits, like so many other adaptations, result from evolutionary selective forces
  • Most behaviors have instinctive and learned components, a spectrum related to the size and complexity of the animal’s nervous system
learned behaviors26
Learned Behaviors
  • Imo, the Japanese Snow Monkey genius (Macaca fuscata) learned to wash yams in sea water and dip a handful of rice and sand in the water to remove the sand grains
  • Caledonian crows learn to modify twigs to probe for grubs
  • Both are traditions that vary among demes

Figure 01: Caledonian crow tool making

© Behavioural Ecology Research Group, University of Oxford

gene environment interactions
Gene/Environment Interactions
  • Behavioral geneticists interested in humans began with twin and adoption studies
  • Linking specific behaviors to specific genes is just beginning to be possible and will rarely be as simple as a one gene-one behavior model
  • Human environment includes:
    • Prenatal experiences
    • Family upbringing and parental and sibling interactions
    • Extended family and peer interactions
    • Societal experiences, interaction with the educational system, media, marketing, religious and political institutions
    • Demographics: gender, age, geography, culture, language, literacy, socio-economic status, etc.
genes vs environment speech
Genes vs. Environment — Speech

Louis Leakey


Jomo Kenyatta


  • Human language comes in a variety of dialects, here represented as A–G.
  • In humans, genes provide a person with the innate ability to speak language(s), but the culture into which the person is born provides the particular language(s) learned
  • The final behavior is an interaction between genes and culture
  • Second language acquisition is easiest when exposure occurs before 12 years of age
key hominid behavioral trends
Key Hominid Behavioral Trends
  • Bipedal locomotion and an eventual habitat shift beyond the tropical forest
  • Altered reproductive strategy: continuous female receptivity and no cues for maximum fertility (ovulation); enlarged female breasts but no vulval swelling; enlarged penis and glans though the testes are medium-sized relative to body size for a primate
  • Prolonged pair bonding - (serial) monogamy
  • Enlarged brain, tool use and tool making
  • More complex social systems and culture
  • Language development
learning society and culture
Learning, Society and Culture
  • Intelligence — and our consequent ability to learn from our own experience or from the experiences of others
  • Cultural transmission of learned behavior eliminates the hazards encountered when an individual must learn by trial and error to cope with environmental variables
what is language for
What is Language for?
  • Language helps us to pass on and develop technologies (how to make better spears)
  • It helps us to coordinate activities (e.g., hunting)
  • We can communicate knowledge about relevant aspects of the environment (e.g., there’s a big herd of buffalo behind the hill where we camped 5 days ago)
what is language for33
What is Language for?
  • Language helps us identify things with names and descriptions.
  • It helps us to express our emotions
  • It helps us remember and utilize the past as well as plan for the future

Could we achieve any of this without language?

Could we even think this without language?

speech and symbolic language
Speech and Symbolic Language
  • Chimpanzee, adult. The language of a signing chimp is here translated into the English words
  • Human, 21 months of age. The spoken words are shown
  • Human, 6 months later than (b). The actions or prompts of the interrogators are not included
can animals develop languages
Can Animals Develop Languages?
  • Allen and Beatrice Gardner (1969) ( )
    • Chimpanzee – Washoe learned ASL; 160 word vocabulary
    • Rules of language or Operant conditioning (Nim Chimpsky)?
  • Penny Patterson & Koko (1971) ( )
    • Koko the gorilla; understands 1,000 ASL signs & approx 2,000 spoken English words
  • Irene Peperberg – Alex the African Grey parrot (1975-2007).
    • ( )
    • Could identify fifty different objects and recognize quantities up to six; could distinguish seven colors and five shapes; had a vocabulary of about 150 words (operant conditioning?)
  • Sue Savage-Rumbaugh

( )

    • Bonobo chimpanzee – Kanzi (the Einstein of chimps?)
    • Used symbols that represented language
    • Receptive language – 72% of 660 requests
when did language evolve
When Did Language Evolve?

chimp-human common ancestor

5-8 million years ago


Australopithecus africanus Australopithecus robustus

Australopithecus afarensis

Homo habilis

Homo erectus


gorillas common chimpanzees bonobos ArchaicHomo sapiens sapiens

language gradually evolved
Language Gradually Evolved

We hunt

Many buffalo there


Don’t attack until I say



Let’s take the kill back to the others

Let’s spend the winter here. It’s more sheltered and there are many animals to hunt

Because out language skills got better we survived better. But it all happened slowly and gradually.

I have seen herds of antelope over the hill. I think we should move there.

why is language so interesting
Why Is Language So Interesting?
  • Because everybody knows that only humans talk although other animals may understand a number of words
  • Language makes long-term cumulative cultural evolution possible
  • A novel type of inheritance system with unlimited hereditary potential
what is so special about human language
What Is So SpecialAbout Human Language?
  • Basically, it is the fact that we make sentences using grammar
  • Languages are translatable into one another with good efficiency
  • Some capacity for language acquisition seems to be innate
  • The “Holy Grail” is the emergence of Syntax
    • A system of rules for arranging words into sentences
    • Different rules for different languages
    • A sentence must have a noun phrase and a verb phrase
language defined
Language Defined

Language: symbols that convey meaning, plus rules for combining those symbols so that they can be combined to generate infinite variety of messages

  • 3 - Properties of Language
    • Symbolic: represents objects, actions, events & ideas (ex: car = class of objects that have certain properties)
    • Generative: limited number of symbols can generate infinite array of novel messages (there is always something novel)
    • Structured: infinite variety is structured in a limited number of ways (Rules govern the arrangement of words into phrases and sentences)
gossiping hypothesis
Gossiping Hypothesis
  • 2/3’s of all conversation is about social relationships
    • Both in developed countries and for hunter-gatherers
  • Does this kind of language use have any effect on our fitness?
  • Does it help our survival rate?
  • Does it increase our reproductive success?
substitute for grooming hypothesis
Substitute for Grooming Hypothesis
  • Monkeys and Apes are very social
  • They maintain complex relationships
  • Grooming is their main form of social interaction
increasing group size hypothesis
Increasing Group Size Hypothesis
  • Largest group size for non-human primates is 50-55 (Chimps and Baboons)
  • For modern hunter-gatherers is about 150
  • Primates spend up to 20% of their days grooming
  • Human’s would need to spend 40% of their time to cover such a large group

 Language is ‘vocal grooming’

genetic origin of language
Genetic Origin of Language

  • Early hominids probably began using gestures to communicate intentions within a social setting.
  • FOXP2 gene: Language or Speech gene responsible for major inherited speech disorder (KE family studied)
    • Over 3 generations, half the family afflicted
    • Inability to form intelligible speech
    • Defects in processing words according to rules
    • Caused by a single nucleotide mutation on exon 14 of chromosome 7
    • Very conserved gene – 1 change in 75 million years before the divergence of chimps & humans and 2 in the 6 million years since that divergence
    • Mutation occurred 10,000 – 100,000 years ago and may be critical for the development of modern human speech
evolution of foxp2
Evolution of FOXP2
  • Grey boxes mark single amino acid mutations
  • 0 mutations in 75 million years for chimps
  • 1 for mice
  • 2 for humans in last 6 million years
  • This suggests Neandertals have the same human allele

75 Mya

vocal anatomy
Vocal Anatomy

Figure B02: Views of how adult humans produce three vowel sounds by positioning the tongue

Figure B01A: Upper respiratory system of humans adult

Adapted from Aiello, L., and C. Dean. An Introduction to Human Evolutionary Anatomy. Academic Press, 1990.

Figure B01B: Upper respiratory systems of chimpanzee

  • In the chimpanzee and Austrlopithecine, the pharynx is short and the soft palate and epiglottis meet to separate the oral cavity from the pharynx while breathing
  • In the human, the pharynx is longer, the oral cavity is taller, and the tongue is shorter and has more room to change size and shape to form the sounds of speech

Figure B01D: Upper respiratory systems of australopithecine

Figure B01C: Upper respiratory systems of human infant

Adapted from Conroy, G. C., G. B. Weber, H. Seidler, P. V. Tobias, et al., Science 280 (1998): 1730-1731; and Lieberman, P. The Biology and Evolution of Language. Harvard University Press, 1984; and Lieberman, P. Uniquely Human: The Evolution of Speech, Thought, and Selfless Behavior. Harvard University Press, 1991.

vocal anatomy49
Vocal Anatomy

Various investigators have suggested that the Neandertal vocal anatomy is intermediate and, perhaps, less efficient for making the variety of sounds of modern human speech

vocal anatomy50
Vocal Anatomy

The modern human palate is arched which gives greater variety to tongue shapes to articulate speech

humans have a distinct chin
Humans Have a Distinct Chin

The attachment of the tongue behind the chin allows for more varied tongue movements necessary to articulate speech sounds




paranasal sinuses
Paranasal Sinuses

Act as resonating chambers,

giving distinct timbre to

each human voice


Perhaps the most important synapomorphy in all of human evolution!

human society and culture
Human Society and Culture
  • Humans have two hereditary systems:
    • a genetic system, which transfers biological information from biological parent to offspring through the coding properties of DNA
    • a cultural system, which transfers cultural information, ideas from speaker to listener, from writer to reader, from performer to spectator through social interactions coded in language and custom, and embodied in records and traditions
  • Richard Dawkins compared the two in his classic The Selfish Gene (1976) in which he coined the term “meme” for the unit of cultural inheritance or cultural evolution, an idea or concept
human society and culture57
Human Society and Culture
  • The entire tradition of the Liberal Arts is an effort to describe and understand human society and culture
    • Anthropology and Archaeology
    • History and Sociology
    • Languages and Literature and the other Arts
    • Psychology and Philosophy
  • The scientific disciplines went their own way in studying the causes of human behaviors in the first century after Darwin
human society and culture58
Human Society and Culture
  • If we look back to the Victorian era, Darwin’s concept of natural selection both captivated and frightened many of his contemporaries
  • The power of the process of natural selection, the “struggle for existence,” caused many individuals from disciplines outside of the biological sciences to apply Darwinian-type explanations and analogies to other fields of study to help justify their positions in disciplines outside of biology: sociology, politics, ethics, jurisprudence, aesthetics and economics, etc.
the two cultures
The Two Cultures
  • The Two Cultures is the title of an influential 1959 Rede Lecture by British scientist and novelist C. P. Snow
  • Its thesis was that the breakdown of communication between the "two cultures" of modern society — the sciences and the humanities — was a major obstacle to solving the world's problems
social darwinism
Social Darwinism
  • Historians looking back at these efforts to justify social hypotheses by analogy to natural selection term the phenomenon “Social Darwinism”
  • The term was not coined until 1877 by a German and did not become a widespread term for this phenomenon in the English speaking world until after WW II
  • It is generally used to discredit the social hypotheses under discussion
social darwinists
Social Darwinists
  • Herbert Spencer, who coined the term the Struggle for Existence was a sociologist who saw human societies evolving and increasing in complexity
  • Freidrich Nietzsche and Sigmund Freud borrowed concepts to apply to the development of the human psyche
  • Frederich Engels and Karl Marx (co-founders of Marxist communism) saw their theory as evolutionary, “a basis of struggle in history”
    • Karl Marx wrote to Darwin for permission to dedicate his book Das Capital to him, but Darwin declined the "honor“
social darwinists62
Social Darwinists
  • Adolph Hitler and Benito Mussolini relied on Darwinian justifications for their fascism
  • In America, laissez faire capitalists, the Rockefellers and van der Bilts, etc., and author Ayn Rand justified their economic philosophy, in part, by analogy to the “survival of the fittest,” but in their view, to be rich was to be fit
  • This is just the short list of some of the most famous of the Social Darwinists; there are still Social Darwinists today, though they wouldn’t use that term themselves

"Are there no workhouses? Are there no prisons...then let them die and decrease the surplus population.“ — Ebenezer Scrooge

social darwinism63
Social Darwinism
  • Not everyone agreed that biological concepts should be extended to society, even though nature and culture share similar evolutionary mechanisms, especially natural selection
  • Thomas Huxley – Evolution and Ethics (1893)
  • Julian Huxley – Evolutionary Ethics (1943)
  • The naturalistic fallacy described by British philosopher G. E. Moore in his Principia Ethica (1903)
    • Moore stated that a naturalistic fallacy is committed whenever a philosopher attempts to prove a claim about ethics by appealing to a definition of the term "good" in terms of one or more natural properties (such as "pleasant", "more evolved", "desired", etc.)
  • Human traits and human populations could be improved by guiding their evolution through selective breeding
  • First advocated by Darwin’s cousin, Sir Francis Galton in 1883
  • Positive Eugenics: increase the frequency of beneficial alleles
  • Negative Eugenics: decrease the frequency of harmful alleles
  • Initially eugenics was simply proposals to encourage or discourage marriages based on phenotypes
  • Even at the outset, this was impractical and it was difficult to identify superior or inferior phenotypes in an impartial scientific way
  • Originally it was well-meaning, progressive, and based on the good science of the day
  • Idealized for its lofty goals for half a century and supported by many prominent thinkers, it fell into disfavor when abused by the Nazis
  • Simultaneously, advances in genetics, i.e., the Modern Synthesis, showed that harmful alleles cannot be eliminated by controlling breeding, since most harmful alleles exist in phenotypically normal heterozygotes, and that with multigenic and pleiotropic effects, it is difficult to determine which alleles are truly harmful at the population level
  • We may be entering a new age of molecular eugenics thanks to the Human Genome Project
harmful eugenics policies
Harmful Eugenics Policies
  • Restrictions on immigration and marriage
  • Racial segregation, including bans in the United States on marriage between whites and African Americans, was overturned by the Supreme Court in 1967
  • Compulsory sterilization of the “feebleminded,” certain criminals, and others deemed unfit
  • Forced abortions
  • In Germany under the Nazis, genocide of those (especially Jews) regarded as racially inferior and thus a threat to the “purity” of the Aryan race
  • Among many other examples . . .
deleterious alleles
Deleterious Alleles
  • Despite improvements in medical care, alleles that have obvious deleterious effects still affect human populations
  • Some arise as new mutations
  • Some are preserved by heterozygote advantage or hybrid vigor
  • Others are preserved because public health, sanitation, and medical science reduce the effect of natural selection, but add to our genetic load
nature versus nurture69
Nature versus Nurture?
  • This false dichotomy has been debated since before Darwin’s day
  • At times it pitted biologists against psychologists and other social scientists
  • Few biologists ever doubted that it was the combination of genotype and environment interacting that produced the phenotype, whether at the molecular, cellular, organismal, or species level
  • E. O. Wilson, Sociobiology: The New Synthesis, 1975, launched a new field of science which offered a way to solve the contradictions by placing humans, as Darwin had, within the tree of life
    • Animal behavior is shaped by natural selection
    • Human behavior is determined in part by natural and sexual selection, but also by cultural forces which have no equivalent in animal societies
    • Start with the constraints from the genotype and then see how environment can shape development from that foundation
jared diamond 1937
Jared Diamond (1937- )
  • American physiologist, ornithologist, biogeographer and evolutionary biologist
  • Became interested in human cultures and history while studying birds in New Guinea
  • Books include The Third Chimpanzee; Why Is Sex Fun: The Evolution of Human Sexuality; Guns, Germs, and Steel: The Fates of Human Societies; and Collapse: How Societies Choose to Fail or Succeed.
why is sex fun
Why Is Sex Fun?
  • Diamond speculates on the evolutionary forces that shaped the unique aspects of human sexuality:
    • female menopause, males' role in society, having sex in private, and, most unusual of all, having sex for fun instead of for procreation
  • Diamond considers the lengthy period of dependency of human infants, sex for pleasure as the tie that helps bind a mother and a father together, and menopause as an evolutionary advantage that, by ending the childbearing years, allows females to pass wisdom and knowledge on to society and succeeding generations
the third chimpanzee
The Third Chimpanzee
  • Diamond argues that humans are just a third species of chimpanzee but a unique animal due to its capacity for innovation, which caused a great leap forward in hominid evolution
  • After stressing the significance of spoken language, along with art and technology, Diamond focuses on the self-destructive propensities of our species to kill each other (genocide and drug abuse) and to destroy the environment (mass extinctions)
  • He also discusses human sexuality, geographic variability, and ramifications of agriculture (metallurgy, cultivated plants, and domesticated animals)
guns germs and steel
Guns, Germs, And Steel
  • Diamond proposes that the uninterrupted east/west axis of Eurasia produced a wider variety of potential crop plants and large, land-dwelling animals suitable for sedentary food production
  • Agriculture gave rise to food surpluses, which allowed for the specialization of labor, which provided for the emergence of centralized governments and bureaucracies
  • Farming and centralized government created the necessity for writing, providing its possessors a far more accurate way of recording and transmitting data than oral language, which greatly increased the military prowess of Eurasian “generals” by allowing for better intelligence
  • Finally, these farming, centralized societies urbanized
  • Urbanization, combined with the domestication of animals, subjected these denser human populations to diseases, zoonoses from their livestock, diseases to which these populations developed immunities and which would one day kill off and weaken other human populations when introduced around the globe
  • Collapse is a catalog of case studies of the deaths of past civilizations, such as the Mayans and Anasazi, as well as contemporary societies, such as Rwanda during the 1994 genocide
  • In Collapse, Diamond argues that past civilizations collapsed for five reasons: environmental damage, climate change, hostile neighbors, friendly trade partners, and societal responses to environmental problems
the world until yesterday
The World Until Yesterday
  • Diamond looks at the ways we have evolved by comparing practices of traditional societies and modern and industrialized societies
  • Diamond draws on his fieldwork in New Guinea, the Amazon, Kalahari, and other areas to compare the best and most questionable customs and practices of societies past and present
  • Diamond does not idealize traditional societies, with smaller populations and more interest in maintaining group harmony than modern societies organized by governments seeking to maintain order, but he does emphasize troubling trends in declining health and fitness as industrialization has spread to newly developing nations
human control over our own evolution
Human Control Over Our Own Evolution
  • Although our lives have changed immeasurably as a result of our advanced technology, our genetic makeup has not
  • Biological and cultural adaptations operate at different rates
  • A result of improvements in sanitation, diet, and medical practice over the last century and a half, natural selection now exerts relatively little influence on our “fitness”
human control over our own evolution78
Human Control Over Our Own Evolution
  • Less than half the hunter gatherers lived to age 20 so they were unlikely to have more than 3 or 4 offspring and most of those died young too
  • In technologically advanced societies, most live past age 50 and can reach their biological capacity of 12 to 15 offspring unless they choose to limit family size
  • As economic security increases, they tend to do so

Figure B03: Survival curves for populations of hunter-gatherers versus citizens of a modern industrialized society

Adapted from May, R. M., Nature 327 (1987): 15-17

cultural evolution outpaces biological evolution
Cultural EvolutionOutpaces Biological Evolution
  • One measure of how change continues to affect us is the time it takes to double our collective knowledge
  • Human minds have become agents of a novel selection mechanism by consciously choosing among alternatives because of their consequences (rational decision making)
clones and cloning
Clones and Cloning
  • A clone is an organism descended from and genetically identical to another organism
    • All offspring produced by asexual means

Figure 04: Nucleus in pipette

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Dolly (1996 –2003) was a female domestic sheep, and the first mammal to be cloned from an adult somatic cell, using the process of nuclear transfer

reproductive technology and eugenics
Reproductive Technology and Eugenics
  • So, if almost everyone now survives to have children, and if our children can be protected from natural selection so that they too will have children, will natural selection continue to operate on humans?
  • Yes, but at a reduced rate

Figure 03A: Doctor retrieving eggs from ovary using vaginal ultrasound

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Figure 03B: Illustration of a 12 cell embryo within membrane

Figure 02: Ultrasound

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©Joe Mercier/

supreme court critical of patents on human genes
Supreme Court Criticalof Patents on Human Genes
  • The Supreme Court justices said on Monday, April 15, 2013, they were highly skeptical of the idea that a company or a scientist can hold a patent on human genes and prevent others from testing or using them
  • Several justices said patents should not be given for “products of nature,” whether they are plant leaves that cure a disease or tiny parts of the human body