anatomy unit 6 - human evolution

8/6/2019 Anatomy Unit 6 - Human Evolution

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Anatomy & Physiology Unit 6:

Human Evolution


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Classification Hierarchy

Kingdom AnimalPhylum Chordate

Class MammalOrder Primates

Family HominidsGenus Homo

Species Sapiens


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Evolution of Primates

The evolution of primates is characterizedby trends towards:

mobile limbs

grasping hands (with opposable thumbs)

a flattened face

binocular vision

a large, complex brain (for learned behavior)

a reduced reproductive rate


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Mobile Limbs

Most primates have flat nails as well assensitive pads on the undersides of fingers

and toes.

Many also have both an opposable bigtoe and thumb.

Mobile limbs and clawless opposable digits

allow primates to freely grasp and releasetree limbs.


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Primate Hands


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Binocular Vision

Stereoscopic vision and resultant depthperception allows primates to make

accurate judgments about distance and

position of adjoining tree limbs.


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Evolution of Primates

Prosimians were the first type of primate todiverge from the ancestral primate line.

Surviving anthropoids are classified intothree superfamilies.

New World monkeys

Old World monkeys

Hominoids


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Hominoid Evolution

Proconsulis believed ancestral to hominids.


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Evolution of Hominids

Phylogenetic tree indicates humans aremost closely related to African apes.

Last common ancestor appears to havelived about 5-7 million years ago (mya)

Genetic changes used as a molecular

clock to measure relatedness ofdifferent groups.


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Hominids

To be a hominid, a fossil must have ananatomy suitable for standing erect and

walking on two feet.

Bipedalism

Human anatomy differs from that of an

ape largely because humans arebipedal while apes are quadrupedal.


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Australopithecines

It is possible that one of theaustralopithecines that evolved and

diversified in Africa 4 mya is a direct

ancestor of humans. Southern Africa

Australopithecus africanus

Eastern AfricaAustralopithecus afarensis (Lucy)


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A reconstruction ofLucys skeleton

Lucy is ~ 3.5-million-years-old

Australopithecus

afarensis adaptations in Lucys hip, leg

and foot allowed a fully

bipedal means of locomotion

Lucy


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Preserved in volcanicash in Tanzania

Discovered in 1978

Proved hominids

were bipedalwalkers at least 3.5million years ago

Most scientists think

the footprints weremade by A.afarensis, whosefossils are foundnearby

Hominid Footprints


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Landscape with A. afarensis

Re-creationof a Pliocene

landscape

showing

members ofA.Afarensis

gathering

and eating

various fruits

and seeds


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Evolution of Early Homo

Homo habilis, dated between 2.0 an 1.9mya, may be ancestral to modern humans.

Skulls suggest portions of the brainassociated with speech were enlarged.

Ability to speak may have led to hunting

cooperatively and the advent of culture.


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Human Evolution


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A reconstruction

of the skull of

Homo erectus

a widely

distributedspecies

whose remains

have been found

in Africa, Europe,India, China, and

Indonesia

Skull ofHomo erectus


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Homo erectus

Homo erectus and like fossils are found inAfrica, Asia, and Europe and are dated

between 1.9 and 0.3 mya.

Larger brain and flatter face than Homohabilis.

Much taller than previous hominids.

Believed to have first appeared in Africaand then migrated into Asia and Europe.

First hominid to use fire.


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Homo erectus Using Tools

Re-creation of a Pleistocene setting in

which Homo erectus use fire & stone tools


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Evolution of Modern Humans

Most researchers believe Homo sapiensevolved from Homo erectus.

Multiregional Continuity Hypothesis

Similar evolution occurred in manydifferent places.

Out-of-Africa Hypothesis

H. sapiens evolved from H. erectus onlyin Africa, and thereafter migrated to

Europe.


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Evolution of Modern Humans


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Neanderthals

Neanderthal (H. neanderthalensis)skeletons were first discovered in

Germanys Neander Valley.

Skeletons date back 200,000 years.Massive brow ridges with protruding

nose, jaws, and teeth.

Heavily muscled.Culturally advanced.

Manufactured variety of tools.


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ReconstructedNeanderthalskull

characterized

by prominent heavy

brow ridges and week chin


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Burial Ceremony in a Cave

Neanderthals lived in caves and had

ritual burials, such as this depictionfrom ShanidarCave, Iraq


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Neanderthals(190,000 27,000 yrs ago)

Flaked stonesthat fit in woodhandles.

Buried their deadwith spices andbedding.

Built sturdy huts.

Made flutes!

A flute formed from a femur & 4 remaining holes.


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Cro-Magnons Homo sapiens

Oldest fossils to be designated H. sapiens.

Modern humans who entered Asia and

Europe from Africa 100,000 years ago.

Made advanced stone tools.

Accomplished hunters.

Hunted cooperatively.

First to have complex language?


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Cro-Magnons were very skilled cave painters

Painting of a horse from a cave in France

Painting From a Cave in France


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Homo FloresiensisHomo Floresiensis

(hobbits)(hobbits)

- one meter high

- lived in Flores12,000 yrs ago

- Upright posture

- 380 cc cranialsize (like a chimp)


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The shapes & sizesof hominid headscan be seen toevolve with time.


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Australopithecus vs. Modern

Australopithecus, 4-3 myrs ago Modern human

Chimpanzee


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Cranial Comparisons

NeanderthalHomo Erectus Homo Sapiens


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With the appearance ofC

ro-Magnons, human evolution has become almost

entirely cultural rather than biological

Humans have spread throughout the world by devising means to deal with a broad

range of environmental conditions

Cultural Evolution


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Homo Sapiens100,000 yrs ago

Art: Cave Paintings, Venuses

Lascaux (17,000 yrs old)

Oldest paintings: Chauvet (32,000 yrs old)

Peche Merle (15,000 yrs old)


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anatomy unit 6 - human evolution

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