Human Biocultural Evolution and Anthropological Perspectives

Comprehensive vocabulary flashcards covering evolutionary mechanisms, primate taxonomy, hominin paleontology, evolutionary models, human variation, and medical anthropology concepts.

Phylogeny

A diagram of branching evolutionary relationships illustrating how lineages split from common ancestors.

Evolution

The change in allele frequencies within a population across generations.

Mutation

A random evolutionary process that creates new genetic variation and serves as the ultimate source of new alleles.

Natural selection

A non-random evolutionary process whereby heritable traits that improve survival or reproduction become more common, producing adaptation.

Gene flow

The movement of alleles between populations via migration and mating, which makes populations more genetically similar.

Genetic drift

A random change in allele frequencies resulting from chance; it is non-adaptive and strongest in small populations.

Selection vs drift

selection is directional and tied to fitness differences; drift is chance, with no relationship to how well a trait works.

Plasticity

A body's ability to change in response to environmental conditions during an individual's lifetime (e.g., tanning, muscle growth, height responding to nutrition).

Niche construction

The process by which organisms modify their own environments, thereby altering the selection pressures they face (such as through farming or dairying).

Extra-genetic inheritance

Information passed down across generations by means other than DNA, such as learned behavior, culture, and inherited environments.

Why study nonhuman primates

Comparison shows which traits we share through ancestry, helps reconstruct the traits of our common ancestors, and highlights what is actually distinctive about humans.

Homology

An anatomical or biological similarity between organisms due to shared ancestry (e.g., the bone structure of a human arm and a bat wing).

Analogy

A similarity in function between organisms resulting from independent (convergent) evolution rather than shared ancestry (e.g., bat wings and insect wings).

may falsely suggest close relationship

Primate tendencies

• Grasping hands and feet (often with opposable thumbs or big toes)

• Reliance on vision over smell

• Relatively large, complex brains

• Prolonged infant development and dependence

• Social complexity

Strepsirrhines

A primate suborder that includes lemurs, lorises, and galagos

Often nocturnal, greater reliance on smell.

Haplorrhines

A primate suborder comprising tarsiers, monkeys, and apes.

Monkeys

New World monkeys include the ones with prehensile tails (e.g., spider and howler monkeys). Old World monkeys (e.g., baboons, macaques) have tails that are not prehensile.

Apes

no tails. Gibbons, orangutans, gorillas, chimpanzees, bonobos, and humans.

Closest living relatives of humans

chimpanzees and bonobos.

Arboreal

Adapted to living primarily in trees.

Terrestrial

Adapted to living primarily on the ground.

Diurnal

Active primarily during the day.

Nocturnal

Active primarily at night.

Sexual dimorphism

Average physical differences between males and females of a species, such as differences in body size or canine size.

Brachiation

swinging arm over arm through the trees.

Chimpanzees vs bonobos

• Chimpanzees: male-dominated, more frequent aggression, including violence between groups.

• Bonobos: female coalitions are important, sex plays a large role in social bonding and conflict reduction, less lethal aggression.

• Both are equally closely related to us, yet they behave quite differently. So ancestry does not simply determine behavior.

• Neither is a direct model of our ancestors: both have been evolving as long as humans have since our lineages split. They are cousins, not living fossils.

What makes humans unique

• Tool use: chimps make and use tools (e.g., termite fishing, nut cracking).

• Learning and culture: groups of primates show learned local traditions.

• Self-recognition: great apes pass mirror tests.

• Communication: gestures, calls, and (with training) some symbol use.

Distinctive combination of capacities

1. Cumulative learning (building on what earlier generations learned)

2. Symbolic communication (language)

3. Cooperation at large scale

4. Cultural transmission across generations

Relative dating

A dating method that determines whether a specimen is older or younger than another (such as by examining rock layers) without assigning an age in numerical years.

Absolute dating

A dating method that provides an actual age in years, typically using radioactive decay (radiometric methods).

Hominin

A member of the human lineage after the evolutionary split from the chimpanzee and bonobo lineage, including modern humans and our extinct upright-walking relatives.

Earliest hominins roughly 7 million years ago

• 'Missing link' is misleading because the human family is a bushy tree with many branches and many transitional forms, not a single chain with one gap to fill.

Bipedalism

• Anatomical changes: foramen magnum moved forward, under the skull; S-shaped spine; shorter, broader, bowl-shaped pelvis; angled knees and arched feet.

• Sequence: bipedalism appeared before large brains.

• Possible advantages: efficient walking, hands free to carry things, staying cool, seeing over tall grass, feeding posture. No single cause, probably a combination that varied by place and time.

• Pelvis, brain size, and childbirth: a pelvis adapted for walking is narrower, while babies' heads got bigger. This makes birth difficult for humans and is linked to babies being born relatively helpless and to cooperative assistance during birth.

Australopithecus (Three early hominin genera)

approximately 4 million years ago

Small brain, ape sized

Moderately large teeth

Bipedal but retained some climbing features

Paranthropus (Three early hominin genera)

approximately 2.7 million years ago

Small brain

Huge grinding molars, massive jaws and chewing muscles (often with a crest on top of the skull)

Specialized for tough, fibrous foods; a side branch

Homo (Three early hominin genera)

approximately 1.8 million years ago

Larger brain, increasing over time

Smaller teeth and jaws

More extensive tool use

Origin of earliest Australopithecus, Paranthropus, and Homo

Which was the first to disperse beyond origin

Africa

Modern humans first appeared in Africa

Homo erectus was the first to disperse beyond Africa

Biocultural feedback loop

changes in diet (e.g., more meat and cooked food), larger brains, tool use, and social cooperation likely influenced one another. Tools help get higher-quality food, which supports bigger brains, which supports more complex cooperation and culture, and so on.

Importance of homo erectrus

• Body form more like ours (modern body proportions, long legs)

• Larger brain than earlier hominins

• First hominin to spread widely beyond Africa (into Asia and beyond)

• More advanced technology and evidence associated with fire use

Oldowan

 earliest; simple flaked stones; early Homo

Acheulian

handaxes; Homo erectus.

Mousterian

more refined flake tools; Neanderthals.

Archaeological evidence

stone tools, fire, hunting, shelters, burials.

It is much less certain about meaning. An intentional burial doesn't by itself tell us what people believed about death.

Archaic humans, neanderthals, denisovans (NOT timeline)

Archaic: later Homo groups existing roughly $500{,}000\text{--}300{,}000\text{ years ago}$ that are neither Homo erectus nor modern Homo sapiens.

Neanderthals and Denisovans lived alongside and interbred with modern humans

Multiple coexisting populations undermine the idea of a simple linear progression to modern humans.

Timeline orientation questions

-7mya & 2-4 mya & ~300,000 years ago

~7 mya: the earliest hominins.

2-4 mya: Australopithecus, with early Homo and Paranthropus appearing toward the end of that window.

~300,000 years ago: modern humans, archaic Homo, and early Neanderthals existed in overlapping periods.

A new group appearing did not mean earlier ones vanished. Groups coexisted.

Neanderthals (race and power)

evidence about their biology and behavior (tools, burials, care for others, possible symbolic practices) raises questions about their social relationships and capacities.

Recent African Origins

A model of modern human origins stating that modern humans evolved in Africa and subsequently dispersed to other regions, replacing existing archaic populations.

Multiregional Evolution

A model of modern human origins stating that modern humans evolved from earlier Homo populations across several geographic regions connected by gene flow.

Multiple dispersals

several waves out of Africa, with interaction and interbreeding with archaic groups along the way.

Svante Pääbo and ancient DNA / Pääbo's argument

showed that Neanderthals and modern humans interbred, so many living people carry Neanderthal DNA (and some carry Denisovan DNA). This overturned the view of Neanderthals as a totally separate dead end.

genetics blurs sharp lines between 'us' and 'them,' challenging assumptions about human uniqueness and biological race. But genetics alone can't tell us what it means to be human. That also involves culture, meaning, and history.

NOVA clips

historical assumptions about race and who counts as 'human' shaped how scientists interpreted Neanderthals (e.g., portraying them as primitive or brutish). Scientific debates reflect the social and historical circumstances in which they happen.

mtDNA comparison (Race: The Power of an Illusion, Episode 1)

students expected people of the same 'race' to be most similar, but the genetic evidence did not match those expectations. Genetic similarity didn't follow racial lines.

Central distinction

race is not a meaningful biological division of humanity, but racial classifications have real social consequences (e.g., in housing, health, wealth, and treatment by institutions).

Cline

A gradual, continuous change in the expression of a biological trait or allele frequency across a geographic gradient.

(also genetic variation occurs within populations in todays human biodiversity)

Hair documentary

hair forms are diverse and can be understood in relation to adaptation to environment (e.g., climate and sun). The diversity shows the limits of racial categories.

ABO blood types

frequencies vary geographically but don't correspond to conventional racial categories. (No need to memorize frequencies.)

Balanced polymorphism

An evolutionary equilibrium where two or more alleles are maintained in a population by natural selection because the heterozygote possesses a selective advantage in a specific environment (e.g., sickle-cell allele in malaria-endemic regions).

Evolved variation vs socially produced difference

discrimination, nutrition, stress, and unequal access to resources can affect bodies. These differences come from social conditions, not from separate biological races.

Embodiment

The biocultural process whereby social experiences, inequalities, and conditions become biologically incorporated into human bodies.

Disease

The biomedical, clinical perspective and practitioner's diagnosis of a biological condition or pathology.

Illness

A patient's subjective lived experience, perception, and personal understanding of suffering or a medical condition.

Sick role

The culturally defined expectations regarding how an ill person should behave (e.g., resting, seeking care, being exempted from normal duties), the access to which is mediated by social and economic circumstances.

Medical authority & Explanatory model

Medical practitioners hold social authority

person's understanding of a condition's causes, course, and treatment. Patients and practitioners can have different models of the same condition.

Medicalization

The process through which a condition or category of human suffering emerges at a specific historical moment and is classified and treated as a medical disorder (e.g., Allan Young's work on PTSD).

Classification & Reification

Treating an abstract, socially constructed, or human-made category as if it were a naturally occurring, fixed, objective reality.

Healing as biocultural

clinical, symbolic, and social-support processes, plus the placebo effect. Healing involves more than a treatment's direct biochemical action.

Paul Farmer and global health

social, political, and economic conditions shape who gets sick and what happens to them. Medical anthropology contributes by showing how inequality drives health problems.