Large size

Tail-less bodies

Herbivore (plant only diet)

Tool use

Use of fire and cooked food, supporting advanced behaviors like tool-making and social groups.

Migration to colder climates, supporting better heat retention.

Development of fur, supporting better protection from predators.

Reduction in body size, supporting faster movement.

Shift toward eating more meat and cooked plants.

Increase in consumption of raw fibrous plants.

Development of larger molars for chewing tough material.

Adoption of a strictly vegetarian diet.

They caused jaws and teeth to become larger for tougher foods.

They led to smaller jaws and teeth due to softer, energy-dense foods.

They had no effect on jaw and tooth size.

They made jaws and teeth disappear completely.

Cutting meat

Scraping hides

Cracking bones for marrow

Driving in cars

It allowed for better hunting strategies and innovation.

It made them physically stronger than other species.

It reduced their need for tools.

It led to the extinction of other hominids.

It facilitated teaching, storytelling, and passing knowledge across generations.

It made hunting and defense impossible.

It prevented social bonds from forming.

It discouraged group activities.

The oldest skull has a smaller braincase than the most recent skull.

The jaw size decreases in skulls that are more recent.

Hominids likely developed more complex behaviors as brain size increased.

The brow ridge is more prominent in the oldest skull compared to the most recent skull.

Increasing jaw and teeth size

Increasing language skills and culture

Increasing population of hominids

Increasing brain size and bipedalism

There is an inverse relationship between brain size and jaw size. Brain size is increasing as jaw size is decreasing.

There is an inverse relationship between brain size and jaw size in hominids. Brain size is decreasing as jaw size is increasing.

There is a direct relationship between brain size and jaw size in hominids. Brain size is increasing as jaw size is increasing.

There is a direct relationship between brain size and jaw size in hominids. Brain size is decreasing as jaw size is decreasing.

medulla oblongata

pons

brain stem

spinal cord

A

B

C

D

Back of the brain, near the base of the skull

Left side of the brain, near the ear

Front of the brain, just behind the forehead

Top of the brain, near the crown of the head

brain stem

cerebellum

frontal lobe

cerebrum

Cerebrum

Cerebellum

Brain Stem

Cerebrum

Cerebellum

Brain Stem