lecture 4- evolution of humans 1 Flashcards
what is the superfamily for primates and when did it exist?
Eurachonta, 80mya
what two groups did Eurochonta diverge into?when?
- simians
- prosimians
- 50ma
what are the differences in characteristics between prosimians and simians?
-promisians are nocturnal, simians are diurnal
-prosimians have binocular vision, simians have overlapping fields of vision
-promisioans are primarily aboreal
prosimians have grasping fingers and toes, simians (in majority) have opposable thumbs
-simians are far more social
Give simian and prosimians examples
Prosimians: lemurs
Simians: humans, gorillas etc
What are the direct ancestors of monkeys and hominids?
The first simians
what two species underwent different adaptive radiations 40ma from a common ancestor?
the new world monkeys and the old world monkeys
where are the new world and old world monkeys found?
- new world in south America
- old world in africa and asia
what two species does the superfamily hominoidea break into?
- hylobatidea (lesser apes)
- hominidae (greater apes)
What are the characteristics of greater apes?
Large brain relative to body size,flexible behaviour, no tail, high social behaviour
What are the similarities between humans and chimps?
96% of DNA is shared, and 99% of this is coding dna
If the genes aren’t that different between humans and chimps, why are we so different?
The phenotypes (gene expression) are different
What’s the difference between shared and derived characteristics?
Shared characteristics are found in organisms across clandestine (eg. Legs) whereas a derived characteristic is on specific to a certain Clade (eg. Feathers on birds )
What are the derived characteristics of humans?
Bipedalism, large brains capable of language,symbolic though and complicated too use, reduced jawbone, jaw muscles and digestive tract, flat faces
What is the difference in skull between humans and chimps?
Humans have an INFERIROY attached skull, chimps have a POSTERIORLY attached skull
What is the difference in spine shape between humans and chimps?
Chimps have a curved spine whereas humans have an s shaped ones
What is the difference in foremen magnum position between humans and chimps?
In chimps it’s located relatively far back in the skull, in humans it’s located underneath
What is the difference in pelvis shape between humans and chimps?
Long and narrow in chimps, bowl shaped in humans
What is the difference in femur angle between humans and chimps?
Points outward in chimps, inward in humans
How is bipedalism thought to have evolved?
When India and Eurasia collided (approx 10 ma) there was a drastic change in habitats. The environment went from being tree dominated to Savannah dominated, and natural selection acted on hominins leaving those best adapted to walking on the ground remaining.
How did hominin bipedalism evolve?
In a non linear fashion, with many different evolutionary stages demonstrating the ability
When is the approx start of hominin permanent bipedalism? Why?
1.9 million years ago, as they lived in arid environments and two legged motion required less energy than four legs
When did humans start using tools? What was the evidence?
2.5 ma. Marks on animal bones found in Ethiopia
What hominins were found with the first tools? What did this imply?
Australopithecus ghani, suggesting evolution of tool use occurred before the evolution of large brains
