Body Trends

Question 1

Big Toe Trend?

Answer 1

Humans: Absent with hallux aligned with the other toes
Provides efficient toe-initiated push off for propulsion

Chimps: Present
Divergent hallux allows grasping during tree climbing

Question 2

Longitudinal arches in foot trend?

Answer 2

Humans: Present
Can push off the ground with toes

Chimps: Absent
Walks flat-footed however this is not the dominant method of locomotion

Question 3

Robustness of heel bone trend?

Answer 3

Human: Larger and stronger
Forces of heel strike are absorbed by heel bone and balance while standing

Chimps: Reduced
Dense bone and point of attachment for ligaments and muscles

Question 4

Orientation of Foreman magnum trend?

Answer 4

Humans: Central - bipedal
Chimps: Horizontal - quadrupedal

Question 5

Spine shape trend?

Answer 5

Humans: S-shaped
The position of the COM is above the feet to absorb shock and provide flexibility

Chimps: C-shaped
Weight of abdomen well supported on a c-shaped spine (arched) while on 4 limbs.

Question 6

Rib cage shape trend?

Answer 6

Humans: Barrel shape
Allows the arms to be swung from side to side during bipedal locomotion, assist with balance and the suspension of internal organs.

Chimps: Cone Shape
Contains the relatively large gut (vegetation diet) and allows branchiation due to movement around the shoulder.

Question 7

Shape of pelvis trend?

Answer 7

(Like entire hip)
Human: Shorter, broader, bowl shaped
Is vertically broader, shorter and curves forward to support internal organs while standing upright. Allows the attachment of muscles horizontally to achieve a non-swaying gait.

Chimps: Narrower, Flatter, more elongated
Has points of attachment for muscles and ligaments but is shaped so that balancing on one leg is difficult. Results in sway.

Question 8

Angle of femur trend?

Answer 8

Humans: Angled inward at knee, valgus angle
Place feet directly under the COM as knee joints are closer to the mid-line than the hips

Chimps: Parallel Femur 90 degrees
Knees directly under the hip giving stability when walking quadrupedal but poor stability when bipedal.

Question 9

Size of femoral trend?

Answer 9

(Attached femur to hip)
Humans: Larger
Increased ability to tolerate weight transfer and better stability when bipedal

Chimps: Smaller
Weight spread across all four limbs when walking quadruped-ally or not at all when branchiating.

Question 10

Length of femur trend?

Answer 10

Human: Longer
A more efficient human locomotion

Chimps: Shorter
Shorter stride