18. Our Origins Flashcards
How many living species is the hominid genus comprised of ?
8
When did humans leave Africa? (according to oppenheimer)
Approx 72,000 years ago
Where did humans first spread after Africa?
Around the Indian ocean toward Australasia
What is phylogeography?
Studying human genetic differences to track the paths humans have taken
What is the ‘Beachcomber route’?
A proposed dispersal route suggesting humans used a coastal route to spread
During what range of times did Neanderthals live? And where?
250,000-40,000 Years ago
When did Neanderthals and Humans interbreed?
60,000-40,000 years ago
What examples of species are included in the category of LHVs?
ground sloths, giant kangaroo, moa, woolly mammoths, straight tusked elephants, steppe rhino, woolly rhino, giant deer etc etc
What environmental hazard was subdued by the presence of LHVs and why?
Forest fires, as LHVs cropped vegetation and maintained large open spaces
When did LHVs go extinct?
In a megafaunal extinction when human’s arrived
What are the two broad possibilities for LHV extinction? Which one is likely?
Human effect or environmental change
- Human effect most likely.
Why is it harder to be definite about reasons for LHV extinction on continents than on oceanic islands?
On continents it’s harder to disentangle the effects of humans from the effects of climate change at the time
Why does Africa have such a different distribution of animal sizes to any other continent?
Africa is where humans evolved so its likely that since LHVs evolved alongside humans, they were able to coexist
What are 3 bioanachronisms from the era of LHVs?
Un-distributed fruits, defensive trees, and wet tundra regions
Explain how undistributed fruits are a hangover from LHVs?
Trees in regions that used to have LHVs sometimes produce fruits where seeds would have been distributed by LHVs but now rot in place under the trees
What are some examples of undistributed fruits due to lack of LHVs?
Papaya, avocado
How do plants with defence mechanisms relate to now extinct LHVs?
Some trees/plants have defence mechanisms that are unnecessary in relation to current animals but theoretically would’ve protected the plants from extinct LHVs
Give two examples of extinct animals that plants still have defence mechanisms for.
Some trees have ‘wire plant syndrome which could have protected against giant ground sloths - which are predicted to have gripped tree trunks while feeding.
Some ground shrubs have protection against now extinct large birds.
What sort of conditions did LHVs maintain in tundra reasons and how?
Plaid-like vegetation patterns
- more mixed diets promoted greater diversity within local flora
What effect did plaid like vegetation patterns have on water in tundra regions?
The greater diversity returned water to the atmosphere more effectively.
Which species subject to the island rule have greater extinction risks, giants or dwarfs?
Those that underwent gigantism
Do species that underwent changes in line with the island rule have greater or lower extinction risks than those that don’t?
Greater, specifically ones whose mass have changed by 4-10 times
