Human Evolution

LESSON # 26

The PrimatesA species of mammals gave rise to the order of mammals called primates.

Important Characteristics of Primates

1- Large front-facing eyes that allow for binocular vision (which enhances depth perception).2- Limbs that have an opposable first digit, like our thumb, which makes grasping possible.

3- Tree dwelling existence.

The lemur of Madagascar is a modern-day descendent of the earliest primates

-Large front-facing eyes

-Opposable first digit

-Tree dwelling existence

There are about 230 species of primates living today (there are 4,600 species of mammals).

There are 60,000 species of mollusks and 750,000 species of insects.

Ape: Any tailless primate with a humanlike appearance.Ape means a member of the family Hominidae other than humans (gorilla, chimpanzees, and orangutan).

Member of the Family Hominidae

Orangutan

Gorilla

Chimpanzee

Human

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hominidae

Subfamily: Homininae

Genus: Homo

Species: H. sapiens

Trinomial nameHomo sapiens sapiens

Scientific Classification of Humans

Common primate ancestor

This branching probably occurred between 6 and 7 million years ago.

The common primate ancestor is unknown. It was an ape-like creature whose closest living relatives are humans, chimpanzees, gorillas and orangutans.

It gave rise to both the chimpanzee family tree and the human family tree.

7 million yearsCommon

primate ancestor

All the species in the figure are members of the taxonomic family of Hominidae (family of man-like primates).

Every member of the Hominidae family is referred to as a Hominin including human beings.

Every species in this tree is extinct, except for the Homo sapiens.

For perhaps 70% of the time hominins lived and died solely in Africa. The hominin fossils found outside Africa date only 1.75 Mya.

There is no doubt that the Australopithecus afarensis species was bipedal.

Australopithecus afarensis is the most famous hominin ever found. She was called “Lucy” and lived 3.18 Mya.

Lucy

-Pelvis of a biped- Long arms- Short legs- Feet that were built for

grasping

- Smaller brain

Lucy is an Australopithecus afarensis, probably the first bipedal hominin.

A reconstruction of Australopithecus afarensis, a human ancestor that had developed bipedalism, but which lacked the large brain of modern humans.

(Lucy)

A. afarensis probably gave rise to the A. africanus

Homo habilis (“handy man”) is the first Homo that had tool-making abilities.

Homo ergaster. The most dramatic changes: height of 2 meters, brain 30% larger than H. habilis (more than half of the size of modern H. sapiens brain).

This member of the species Homo ergaster was tall and had a much larger brain capacity than the earlier hominin "Lucy." His remains, dating from 1.6 million years ago, were found near Kenya's Lake Turkana.

In the remarkably complete skeleton of "Turkana Boy," we can see the evolution of hominins to a form more like our own.

(Lucy)

Homo heidelbergensis gave rise to the Homo sapiens and the Homo neanderthalensis.

The Neanderthals1- The first extinct hominins to be discovered, in 1856 in Germany’s Neander Valley.

2- It is the best known of the extinct hominins because they left many traces of themselves behind.

Homo neanderthalensis

They used nothing but stone for their relatively primitive tools. They lived Europe and elsewhere in a period running from about 200,000 years ago to 27,000 years ago.

H. neanderthalensis probably became extinct because they could not compete with a newer, cleverer species that had move to their territory: the Homo sapiens.

The H. neanderthalensis is the “caveman”.

Neanderthal family

A Hominin Family Tree

Present

H. habilis

K. rudolfensis

Kenyanthropusplatyops

H. mauritanicus

H. neanderthalensis

H. erectus

P. boiseiP. robustus

H. floresiensis

H. heidelbergensis

H. cepranensis

H. sapiens

Au. africanus Paranthropusaethiopicus

ancestral primate

Homoergaster

Sahelanthropustchadensis

Ardipithecuskadabba

Ar. ramidus

Orrorintugenensis

Australopithecusanamensis

Au. afarensis

Au. garhi

Au. bahrelghazali

1

2

3

4

5

6

7

recent

Plei

stoc

ene

Plio

cene

Mill

ions

of y

ears

ago

mon

keys

oran

guta

ns

goril

las

chim

ps

hom

inin

s

Common primate ancestor

Australopithecus anamensis

Australopithecus afarensis (Lucy)

Australopithecus africanus

Homo habilis

Homo ergaster

Homo sapiens

Homo heidelbergensis

Homo mauritanicus

Common primate ancestor

A. afarensisA. africanus

H. habilis

H. ergasterH. heidelbergensis

H. sapiensCranial capacity (the volume of the skull) has increased in hominins over time

4 3 2 1 Present

1400

1200

1000

800

600

400

200

Earliest fossil record (millions of years ago)

Cranial capacity (cubic centim

eters)

1- We come from Africa as direct descendents of the Homo heidelbergensis species. 2- The first appearance of modern human beings has been dated between 100,000 and 200,000 years ago (best estimate 130,000 years ago). More scientists believe that the essence of what set modern human apart from other species is symbolic thinking.

This piece of ochre, found in South Africa, has been dated to 77,000 years ago. The researchers who discovered it believe it represents the world's oldest known work of art.

Symbolic Thinking: The ability to design tools before they make them, the ability to plan for the future, the ability to represent three-dimensional animals on a two dimensional surface (art).