Human Origins - Exam 3

What does hominid refer to?

All great apes and humans

What does hominin refer to?

Humans and their ancestors after splitting from chimpanzees

How old is the hominin lineage?

Around 6-7 million years old

What is habitual bipedalism?

Walking upright on two legs as the normal form of locomotion

What are some unique traits of human dentition?

Smaller canines, parabolic arcade, Y-5 molar pattern

What is the material culture in human evolution?

The use and creation of tools and other physical objects

How has brain size changed in human evolution?

Significant increase compared to other primates.

What does “long developmental period“ mean in humans?

Humans grow and mature slowly, with longer childhoods

What is mosaic evolution?

Different traits evolving at different times

What is the human dental formula?

2.1.2.3

Human dental formulas are the same as what?

All Catarrhines

What is the Y-5 molar pattern?

A molar with 5 cusps forming a Y-shape, found in apes and humans

What is the CP3 honing complex in apes?

A system where the upper canine sharpens against the lower third premolar

What happens to the CP3 complex in humans?

It is lost due to canine reduction

How does sexual dimorphism differ in humans?

It is reduced compared to other apes

What does reduced sexual dimorphism suggest?

Less male-male competition and different social behavior

What is a humans dental arcade?

Parabolic

What is a chimps dental arcade?

U-shaped

What anatomical change supports bipedal balance?

Center of gravity aligned over the midline

What is the foramen magnum?

It’s the hole in the skill where the spine connects

How does the foramen magnum differ in humans?

It is underneath the skull

What spinal curvatures help with bipedalism?

Cervical and lumbar curvatures

Why are human lumbar vertebrae larger?

To support more body weight

What is the intermembral index?

Ratio of arm to leg length

What is the intermembral index for chimps?

110%

What is the intermembral index for humans?

70%

How is the human pelvis different?

It is short and broad with rotated ilia for upright walking

What is the valgus angle of the knee?

The inward angle of the femur that keeps feet under the center of gravity

How is the human foot adapted for walking?

Non-opposable big toe, large heel, and foot arches

What muscles are used for chewing?

Temporalis and masseter

What facial bone features are related to chewing in apes?

Sagittal crest and robust zygomatic arches

How does facial prognathism differ in humans?

Humans have less facial projection than apes

What are the social explanations for bipedalism?

Carrying food and provisioning in monogamous relationships

What are the ecological explanations for bipedalism?

Moving efficiently across forests, finding food, spotting predators