Thorpe et al., 2007 (bipedalism on flexible branches)

Question 1

Recent paleontological evidence suggests that adaptations for bipedalism arose in an … context. This study revealed a potential adaptive benefit for … bipedalism.`

Answer 1

arboreal, arboreal

Question 2

This study showed that the most arboreal great ape, the orangutan, crosses …, … supporting branches with their 2 hind legs in a straight, fully … position, generally (… of the time) using their arms to grasp branches or vines above them and guide themselves along. This allows them to explore areas of forest they could otherwise not reach, and navigate the arboreal environment more efficiently (in terms of energetic expenditure) when foraging

Answer 2

slender, flexible, extended, 75%

Question 3

They react to branch flexibility in a similar way to humans running springy tracks: by increasing … and … …. All other primates do the opposite.

Answer 3

knee, hip extension

Question 4

Therefore, human bipedalism may be less of an … than previously thought and may have been retained from arboreal great ape ancestors, evolving in a forested environment. Or bipedalism in our ancestors may have began its evolutionary path arborealy and become advantageous and refined terrestrially.

Answer 4

innovation

• our ancestors may not have been knuckle walkers - that may have evolved in chimps and gorillas

Question 5

The mechanics of orangutan bipedalism are…

Answer 5

more similar to those of humans than are those of pains and gorrilines

Question 6

The hand assistance ensures maximum … while the bipedalism allows an unloaded hand to reach out for …, weight transfer or balance.

Answer 6

safety (stability), feeding

Efficient foraging + extended hindlimb allow further reach

Question 7

Hand-assisted locomotor bipedality under these strong selection pressures seems the most likely evolutionary … of …-limbed human walking

Answer 7

precursor, straight

• especially since Africa has been largely forested for significant periods of time during the course of hominin evolution

Question 8

May explain why specimens such as A. afarensis have many features adapted to both terrestrial and arboreal environments - perhaps crossing between or beginning to become more terrestrial whilst retaining foraging or shelter in forests??

Answer 8

Just ideas