Evolution and Hominin Basics

What role does the ilium/gluteal muscles play in bipedality?

• Provide propulsion during running.

• Stabilize trunk while walking upright.

• Facilitate knee flexion during movement.

• Support the weight of the upper body.

When and where did Homo sapiens originate?

• ~300 kya, Africa.

• ~200 kya, Asia.

• ~400 kya, Europe.

• ~150 kya, Australia.

What is the difference between occasional, habitual, and obligate bipeds?

• Occasional = always bipedal; habitual = sometimes bipedal; obligate = rarely bipedal.

• Occasional = sometimes bipedal; habitual = regular use; obligate = fully committed.

• Occasional = never bipedal; habitual = sometimes bipedal; obligate = always bipedal.

• Occasional = fully committed; habitual = sometimes bipedal; obligate = regular use.

Morphology of Paranthropus (e.g., P. boisei, P. robustus)?

• Robust jaws, large molars, sagittal crest, zygomatic arches, small brain (~500–550cc)

• Long limbs and small teeth

• Flat face with large nasal cavity

• High forehead and large brain (~800–900cc)

What are brow ridges?

• Bone ridges above the eye sockets; reduced in modern humans.

• Soft tissue structures that protect the eyes.

• Muscle attachments for facial expressions.

• Cartilage structures that support the nose.

Dates and locations of Paranthropus species?

• ~2.7–1.2 mya; East & South Africa.

• ~3.5–2.0 mya; West Africa.

• ~1.5–0.5 mya; Central Africa.

• ~4.0–3.0 mya; North Africa.

Tools or behavior of A. africanus?

• Used advanced stone tools

• No formal tools; possibly used bones/sticks.

• Created complex shelters

• Engaged in cooperative hunting

How does climate change influence evolution?

• Alters habitats and food sources, prompting adaptation or extinction.

• Increases the speed of genetic mutations in all species.

• Reduces the overall biodiversity of ecosystems without affecting species.

• Has no significant impact on the process of evolution.

Prognathic vs. orthognathic faces?

• Prognathic = flat face (derived); orthognathic = protruding jaw (ancestral)

• Prognathic = protruding jaw (ancestral); orthognathic = flat face (derived)

• Prognathic = square jaw; orthognathic = round jaw

• Prognathic = narrow face; orthognathic = wide face

What does melanin do?

• Pigment that protects skin from UV radiation damage.

• Substance that causes skin to wrinkle.

• Hormone that regulates body temperature.

• Vitamin that enhances skin color.