3.6 Human Evolution - Ape VS Human Features

Nuchal Crest in Apes

Large to prevent head from drooping & for the attachment of large neck muscles.

Nuchal Crest in Humans

Small to balance the skull & for efficient bipedalism.

Saggital Crest in Apes

Large for attachment of strong chewing muscles.

Saggital Crest in Humans

Lack of sagittal crest as less chewing is required in their diet, so no need for big muscles.

Zygomatic Arch in Apes

Large zygomatic arch to allow for more space for large jaw muscles to pass through.

Zygomatic Arch in Humans

Small zygomatic arch as less jaw muscles are needed for chewing.

Brow Ridges in Apes

Large brow ridge due to the tremendous strain put on their cranium by their jaw muscles & to balance out powerful forces of chewing.

Brow Ridges in Humans

Smaller as less chewing is required.

Foramen magnum in Apes

Positioned towards the back of the skull due to quadrapedalism - posture is not fully upright.

Foramen magnum in Humans

Positioned under the centre of the skull to balance the skull.

Spine in Apes

C-shaped. Promotes quadrapedal locomotion.

Spine in Humans

S-shaped. Provides support and balance & supports upright walking.

Pelvis in Apes

Narrow & elongated to allow for attachment of gluteus medius muscles & the pelvis to tilt during 4-legged walking.

Pelvis in Humans

Curved & Broad (bowl-shaped) to support organs above & transfer body weight over to the legs for bipedalism.

Legs in Apes

Shorter than arms.

Legs in Humans

Longer than arms for better efficiency on land.

Ribcage in Apes

Barrel-shaped to help with quadrapedal movement & because organs do not need to be centered above pelvis.

Ribcage in Humans

Broad, narrow & flattened front to back for balance & centre of gravity.

Feet in Apes

Curved digits & opposable big toe to allow for grabbing; useful in trees.

Feet in Humans

Arched foot + big toe in line with other toes for better weight transfer & efficiency in walking.

Hands in Apes

Long curved fingers & short semi opposable thumb, good for tree climbing.

Hands in Humans

Smaller fingers & fully opposable thumb, allows for better hand & finger control, precision grip for using tools.