Lecture 8 Flashcards
(28 cards)
K-T Extinction
○ 65.5 million years ago ○ Global extinction event ○ Third most severe ○ Responsible for eliminating 80% ○ Changed climate
○ “Milankovic Cycles”
■ according to Milutin Milankovic, theorized tilting in earth’s orbit cause climatic cycles
■ Greater the tilt= greater the contrast between summer and winter
■ Main effect is change the contrast between seasons
Solar System
■ Surface of earth at equator moves 460 meters per second
■ Moves around sun in circular orbit
■ Speed of 30 kilometers per second
Galaxies
■ Moves at speed of 1,000 kilometers per second
● Glacial-interglacial cycles
○ 4 fairly regular glacial-interglacial cycles during past 450,000 years
○ Interglacial cycles shorter
○ Glacial cycles are longer
○ Earth drops into new glacial period by jagged cooling events, followed by faster abrupt temperature swings
Encephalization Quotient
■ Formula allowing comparison of brain sizes of different species while holding body size constant
■ Trends in Encephalization quotient have gone up over time
Socialization Theories
● Group social interaction is more cognitively complex than most other types of behaviour
● Has resulted in complex socialization/hyper-cooperation
Development of language
● Has developed hunting techniques, teaching techniques
● Allows individuals to more accurately and directly express their desires and intentions
● Advantages
○ Can discuss things not present
○ Talked about past/future
○ Address abstract concepts
○ Store information collectively
○ Broca’s area and Wernicke’s area
■ Dr.Paul Broca responsible for speech production
● Language capacity
■ Dr. Karl Wernicke responsible for speech comprehension
Theories on Bipedalism: Tool Use (traditional theory)
■ Consider importance of throwing in hominin adaptations
■ Dexterity of human hand, how important this is to us
Theories on Bipedalism: Thermoregulation (regulating core body temperature)
■ It was thought forests shrank and were replaced by open savannah around same time that bipedalism developed among early hominns
Theories on Bipedalism: Efficiency of Locomotion
■ Large quadrupedal predators
● Sprinting- decent energy use/most efficient
● Jogging- least amount of energy use/least efficient
● Walking- less energy use/ not as efficient
● Stationary- medium energy use/ somewhat efficient
■ Humans evolved to be joggers
Theories on Bipedalism: Survival and Subsistence (energy usage)
● Great Rift Valley of East Africa
■ Creation and disappearance of lakes/streams during hominin evolution
○ Shift to bipedality partly in response to climatic changes
○ Molecular evidence suggests late Miocene apes as first hominization
○ Late Miocene sees increased climate change and colder climates
● Forests to savannas; savannas to forests (changing environments)
Reduced hair cover: tied to development of sweating
■ Very effective thermoregulation system in hot, dry climates
Reduced hair cover: Sweat glands
■ Mammal Two types: sebaceous (secrete oil), eccrine (secrete ‘sweat’-h20)
■ Humans have many more eccrine glands; more effective cooling system than other mammals
Reduced hair cover: thermoregulation
■ “Hyper-efficient thermoregulation physiology is likely tied to hominins moving from forests to living in open environments and development of modern body proportions” - Nina Jablonski
■ Works better with tall, narrow body shape
Reduced hair cover: increased exposure of bare skin to sun resulted in
■ Increased melanin production
■ = darker skin tone
hunting/meat-eating: The Hunting Hypothesis
■ Anatomical/physiological changes:
● Reduction in Canine size
○ Response to increased role that tools took on: “tools used for hunting/butchering replaced big canines”
Hunting/meat eating: increased hominin body size
○ Especially with homo ergaster/erectus
○ Larger body made hominins more effective at hunting larger prey species
Hunting/meat eating: Behavioural changes
● Division of labour based on sex:
○ “Men hunted and women had babies”
● Food sharing
○ Hunters brought their kill back to the camp for sharing among the group
Females depended on males for food supply, explains 2 notable physiological traits
● Constant sexual reception among human females
○ Human females are not necessarily only receptive to sex around time of ovulation
● Concealed ovulation
○ Unlike non-human primates, among modern human females
Changing views on importance of hunting/meat-eating
■ Past primatologists noted eat greens
■ 60’s/70s research among hunters ate berries
■ Scavenged meat from lions
Archaeological evidence of meat eating
■ Meat has been important for at least 2 million years
■ Bones of butchered animals with cut marks from stone tools, lying next to stone tools
■ And bone chemistry analysis
Meat eating: Digestive System
■ Humans: Omnivores
■ Our digestive system is more similar to carnivores than herbivores
■ Digestive system short compared to body length
■ Relatively short small intestine
■ Our digestive system very similar to chimps & bonobos
