Primate and Human Evolution

Primates

Mammals with grasping hands and front facing eyes

Two types of primates

prosimians → “before monkeys”; small, tree-dwelling, nocturnal. eg. lemurs

Anthropoids → “human-like”; all other primates

Hominids

great apes (orangutans, gorillas, humans, chimps)

Hominins (name three)

Hominids closer related to humans. includes:

• Ardipithecus lineage

• Australopithecines

• the genus Homo.

How long ago did humans and chimps have a common ancestor?

6-8 mya.

Sister group to hominins

chimps.

List three of five derived traits in human evolution

• bipedalism

• big brains

• tool use

• reduced jaw muscles

• language and speech-

The earliest hominin

ardipithecus kadabba

Name three advantages of bipedalism

• improved predator detection

• display of warning signals

• more energy efficient for long distance travel

• efficient thermoregulation

was bipedalism used to free hands in order to carry things?

no. this theory was proved incorrect.

Foramen magnum

hole in the skull where the spine connects to the brain

how does the position of the foramen magnum affect posture?

As bipedalism evolved, the foramen magnum moved towards the front of the skull, and stayed centered in order to balance the head on top of the spine.

Human brains have ___x in size over the last 2.5M years

3x (tripled)

Who has the largest brain size relative to body size of any hominin?

Homo sapiens.

Brains have higher energy cost, therefore…

later hominins must have had greater nutritional needs.

why did brains get bigger? (five theories)

Aid in…

• social interaction

• tool use

• language

• responding to changing environment

• allowing for conceptual complexity

Tool use was present in hominids, hominins, or both?

hominins

True or false: Tool use is recorded in four vertabrate species

true

why did we start using tools? (four reasons)

to efficiently…

• collect food and fuel

• build shelter

• cook food

• extract resources

Did jaw muscles increase or decrease as hominins evolved??

decreased. later jaw muscles have a smaller attatchment areas on the skull

why did jaw muscles become reduced?

as hominins learned to cook, food got softer, therefore less chewing was required, and jaw muscles got smaller.

In what species of hominins did langauge and speech develop?

The Homo genus.

Modern vocal tract was only present in..

Homo sapiens

Why did hominins develop language and speech?

For communication.

• community coordination to productively live in larger groups, therefore increasing fitness

• convey danger, food, resources

Who are the ancestors of the genus Homo?

Australopithecines

Name the three early Homos

• H. habilis → the Handy man

• H. ergaster → the Working man

• H. erectus → the Erect man

Name the two recent Homos

• H. Neanderthalensis (neanderthals)

• H. Sapiens

Did neanderthals and homo sapiens interbreed?

Yes. most non-african populations have ~1.5-2.1% neanderthal DNA.

T/F: Most discovered hominins are human ancestors

False. Most hominins existed at the same time as homo sapiens

INCOMPLETE — Why are modern humans the only hominins left?

• cognitive advantage: advanced language, thought, and planning abilities

Where did Homo sapiens originate?

Originated in africa, moved around the world over time.