5 Human Evolution Flashcards
- Opposable thumbs
- Frontally directed eyes
with binocular vision - Large and convoluted
brains - Complex social
behavior - Earliest primate (prosimian)
arose 65 MYA when
dinosaurs became extinct
The primates (Class Mammalia, Sublass Eutheria, Order Primates)
Suborders of Order Primates:
- Known as Prosimians
- Found in tropical rain forests in Madagascar, Africa and Southeast Asia
- May be polyphyletic, with the tarsiers being a separate group
- Skull has large orbits, reduced brain case, elongated snout, and well
developed olfactory and auditory regions
Suborder Prosimii
Suborders of Order Primates:
- Monkeys and apes (including humans)
- Rely more on sight and less on sense of smell as in prosimians
- Larger brain relative to body size
Suborder Anthropoidea
- Africa and Asia
- Tails are NOT prehensile
- Nostrils face downwards
- Arboreal and ground-
Old World Monkeys
- Central and South America
- Tails are prehensile
- Nostrils face sideways and are wide apart
- All are arboreal
dwelling
New World Monkeys
Apes are capable of ___________
(arm swinging) but not monkeys
BRACHIATION
These primates lack tails
and have forelimbs
longer than their hind
limbs (except humans)
The Great Apes
- Oldest known hominid found (Ethiopia)
- Lived around 4.4 million years ago
- weighed about 110 pounds, had very
long arms and fingers, and possessed
an opposable big toe that would have
helped her grasp branches while
moving through trees
Ardipithecus ramidus (“Ardi”)
Two hypothesis on the origin of humans
Multiregional hypothesis, recent single origin hypothesis
Key Trends in Human Evolution
- Terrestriality
- Coming down from trees - Bipedalism
- Obligately having to walk on two feet - Encephalization
- Increase in brain size relative to body
- Development of language - Civilization
- Complex technology, moral systems, society - Behavior
- Increasingly complex with some key ingredients
Four ingredients of human behaviour
- Abstract thinking
- Concepts free from specific examples - Planning
- Taking steps to achieve a farther goal - Innovation
- Finding alternative solutions - Symbolic behavior
- Making use of images and rituals
High Altitude Genes (EPAS1):
Lowlander Response
– Produce more red blood cells
– Help transport oxygen more efficiently
High Altitude Genes (EPAS1):
- Tibetan highlander response
– Produce less red blood cells
– too many red blood cells = blood too thick
(particularly dangerous for pregnancy)
High Altitude Genes (EPAS1):
When genome was compared to Han Chinese
Region EPAS1 different
High Altitude Genes (EPAS1):
- Split between Tibetans and Han Chinese
– Estimated to be less than 3,000 years ago
– Pretty fast evolution (~100 generations)
- Found in 10% of Americans, 10% of
Africa’s, Tutsi tribe, 50% of Spanish and
French people, and 99% of Chinese - Lactose cannot be digested (lacks lactase)
- Gene that makes lactase is shut down
after weaning
Lactose Intolerance
- Lactose tolerance advantageous in people who have access to
animal milk - Drink milk directly rather than process (e.g. Cheese)
- Provide additional sustenance and, during droughts, a source of
water - Parallel evolution: Europe and Africa
Lactose Tolerance
Wisdom Teeth:
– Advantageous for diet (leaves, roots, raw meat), large jaws that accommodate all 32 teeth
Quadruped
Wisdom Teeth:
– Hands can be used to obtain food; jaws became smaller
Biped
Wisdom Teeth:
– Cook and process food; reliance on third molar decreased
Increased intelligence
Mutation in MYH16 gene produces ___________
smaller jaws
______________ are the consequence of [formation of boundaries between human communities], and boundary formation is perhaps the central and most important element of the evolutionary ecology of culture.
cultures
What leads to diversification of cultures?
- Resources, ecology and environment
- Kinship and reproduction
Outcomes of Forming Cultures
- Biologically-related individuals likely share a culture
– Culture constrains biology (choice of mate and gene transfer) - Regional Diversity
– High levels of geographic isolation
– High gradient in resource availability - Extinction
