ANTHRO EXAM 2 9-12

Traits that define all hominins

Teeth ( especially canine tooth becomes smaller )

walking ( bipedal )

arboreal ( spending less time in the trees )

increase brain size

Trends in Human Evolution

• Brain size gets larger over time (especially with homo Erectus

• Teeth get smaller over time (especially the canine tooth)

• body size gets larger over time

• face gets flatter overtime

The "big 3" hominin groups

 Australopithecus, Paranthropus, and Homo

Sahelanthropus tchadensis

•Chad (Central Africa)

•Dated: 6-7mya

•Features: Small braincase (cranial capacity: 320-380cm3)

•Huge browridges

Sagittal crest ( pointy part on top of head )

More anterior foramen magnum

Ardipithecus ramidus

Aramis site, NE Ethiopia
• Date: ~ 4-5 mya
• Anterior foramen magnum
• shorter, broader pelvis
• Height – 4 ft
Weight - ~100 lbs
• Little sexual dimorphism
• Opposable toe
• Relatively long arms
• Small cranial capacity (300-350 cc)

Bipedal adaptations

Pelvis - Shorter, broader

foramen magnum- Repositioned farther underneath skull–centered under braincase

Valgus angle - Human femur angled inward

Foot morphology -Big toe enlarged; in line with other toes

Genus Australopithecus

• Adaptive radiation of early hominins
• Lived between 1-4 mya
• Small bodied (64-100 lbs)
• Small brained (340-500 cc)
• Larger teeth (ancestral)
• Thick enamel (ancestral)
• Bipedal adaptations

Australopithecus afarensis

• Hadar, Ethiopia
• A.L. 288-1 – “Lucy”
• Date: ~ 3-4 mya
• Brain size = modern chimp
• Large teeth
• Short, broad pelvis (derived)
• Femur angled toward knee
(derived)
• Big toe in line (derived)
• Arms relatively longer than
humans
• Curved fingers

Genus Paranthropus

Large sagittal cresting
• Postorbital constriction
• Flaring zygomatic arches
• Large, deep mandible
• large teeth (megadont)
• Strong jaw muscle for chewing fibrous diet

Homo habilis

• ~ 2.4 mya
• Reduced facial size
• Moderate-small browridges
• Encephalization – 630 cc
• Paranthropus – 520 cc
• Australopithecines – 442 cc
• Possibly the first hominins to use
stone tools

Homo erectus

• ~ 2 mya, E. Africa
• 1st hominin group found outside of Africa

sexual dimorphism

Brain size- Cranial capacity between 750-1250 cc

Distribution of Homo erectus

• Africa
• Turkana
• Olduvai
• Eurasia
• rep of Georgia
• Indonesia
• Zhoukoudian, China

Homo erectus – Cultural Adaptations

• Technology (Animal butchery / Digging implements)
•Shift to predation ( Vegetarians → Omnivores, Increased ability to disperse, Evidence of butchery)
• Use of fire ( ~ 1.6 mya, Africa)

Homo neanderthalensis

• Cranial capacity *Neandertal average = 1520 cc
Post cranial Characters
• Robust, heavily built
• Barrel-chested
• Shorter limbs for size relative to H. sapiens

Homo sapiens

300,000 years ago
o Emergence in Africa
o Art
o Sophisticated stone tools
o Adaptable to many climates/diets

Comparative Cranial Capacity

Chimpanzee 275-500
Gorilla 350-750
Homo erectus 850-1100
Neandertals 1200-1900
Humans 1200-1800

Encephalization Quotient (EQ)

Encephalization Quotient (EQ)

brain size compared to body size 

Prefrontal cortex 

area of the brain involved in planning, decision making, impulse control.

How is the Human Brain unique?

• Brain size relative to body size (big)
• Timing of brain development (long)
• Proportions of prefrontal cortex (expanded)
• Circuits and regions for language (left side)
• Genes direct neuronal development and connections (more cells, more connections)’

Humans have larger brains that expected given body mass,
compared with other mammals

Human Brain Energy Demands

Adults spend 400 kcal/day on brain metabolism!
• Humans:
• Brain metabolism accounts for 20-25% of BMR
• Non-human primates:
• Brain metabolism accounts for 8-10% of BMR
• Other mammals:
• Brain metabolism accounts for 3-5% of BMR

How do humans adapt to the high energy cost of brain metabolism?

• High quality diet ( protein(14%) fats (33%) and carbs (53%)

Humans have reduced …

gut size and muscle mass

Humans have altricial young with high percentage of fat for brain growth.

Altricial young - need a lot of time to develop, longer parental care ( rely on parents )

The great chain of being 

a hierarchical system that places all matter and life in a divine order

Ethnocentrism

the belief that one's own culture is superior to others, leading to the tendency to judge other cultures by the standards of one's own.

700s – competing ideas

1. Human variation is ancient, permanent, and
divinely ordained
2. Human variation is a product of natural causes

Polygenism

• Doctrine that held that the human races were separate biological species that were descended
from different “Adams”

Monogenism

• Doctrine that held that all human races were the result of a single origin as described in the Scriptures
• Subsequent changes in traits were the
result of different factors such as climates
and modes of living

typology

A method for reducing a spectrum of variation to a smaller set of categories (These categories are based on the assumption that there are “ideal types” that are representative of a certain
group)

Eugenics

• Movement beginning in the late 1800s that sought
to improve the human species and preserve racial
purity through planned human breeding

Impossible to delineate racial groups

Impossible to delineate racial groups using
anthropometric measures because...
• They are influenced by the environment
• They are independently inherited
• They exhibit a clinal distribution pattern

Cline/Clinal Distribution

• A plot or map of the changes in allele, genotype, or
phenotype frequencies over a geographic area

Franz Boas (1858-1942)

• Considered the “Father of American Anthropology”
• Engaged in all four subfields of anthropology

What We Know Today

• Races cannot be defined based
on the incidence of certain
genes
• There is greater genetic
diversity within groups than
between major geographical
divisions
• Race is socially constructed and
not biologically determined

Race

idea created by Western Europeans during global exploration to explain differences among people. used to justify colonization, conquest, enslavement, and social hierarchies by grouping individuals. culturally and socially constructed concept passed down over time

Ethnicity

concept similar to race that groups people by common origins or backgrounds, typically referring to social, cultural, religious, linguistic, and other affiliations, . sometimes linked to perceived biological markers, often expressed through cultural features such as dress, language, religion, and social organization.

Population

• A community of individuals where mates are usually found.

what we know today

Races cannot be defined based on
the incidence of certain genes
• Race is socially constructed and
not biologically determined
• There is greater genetic diversity
within groups than between major
geographical divisions
• Only ~0.1% of human DNA varies
between individuals

Genetic diversity outside of Africa

is a subset of what exists within the content due to founder effect and genetic drift (Because Homo sapiens evolved in Africa and stayed in Africa over 100,000 years, most human genetic diversity evolved there)

3 Main Critiques of Race as Genetically Determined Category

1. Human genetic variation is clinal
2. Most human genetic variation is discordant
• Meaning, the traits we use to distinguish race are independently inherited and have no value for predicting other aspects of biology
3. Human genetic variation is widely shared across the species, with little variation occurring between racially defined groups

Genetic determinism

is the belief that genes alone—or far more than anything else—determine traits like behavior and personality, and that environmental or life factors matter very little.

Tuskegee Study of Untreated Syphilis

Started in 1932 by US Public Health Service working
with Tuskegee Institute

Recruited a total of 600 African American male sharecroppers in Macon County, AL
399 had syphilis and 201 did not

Men were told they were being treated for “bad blood”
They never received a diagnosis or treatment
1940s: penicillin became standard treatment
• But participants never received it

Only 74 participants with syphilis survived

Epidemiological evidence of US racial inequalities in morbidity and mortality

• Morbidity = the rate of a disease in a population
• Mortality = the proportion of deaths in a population

Race and the Embodiment of Social Inequality

some researchers claim that racial health differences are mostly caused by genetics. This belief—racial-genetic determinism—assumes that genes, not social inequality, explain why different racial groups have different health outcomes.

timeline

Sahelanthropus

ardipithecus

australopithecus

homo habilis

homo erectus

h heidelbergenisis

neanderthals

homo Sapiens