David Sadava H. Craig Heller Gordon H. Orians William K. Purves David M. Hillis

Biologia.bluB – Le basi molecolari della vita e

dell’evoluzione

The Evolution of the Human Species

•Who were the first humans?

•When and where did they live?

•What makes us human?

The Evolution of the Human Species

The Evolution of the Human Species - Who were the first humans?

Human appearance on Earth

Domain EukaryotaKingdom AnimaliaPhylum ChordataSubphylum VertebrataClass MammaliaOrder PrimatesSuperfamily HominoideaFamily HominidaeGenus HomoSpecies Homo sapiensSubspecies Homo sapiens sapiens

The Evolution of the Human Species - Who were the first humans?

Human taxonomy

• Digit mobility (grasping and opposability)

• Optical shift

• Bipedalims

• Relative size of the cerebral cortex

• Parental care

The Evolution of the Human Species - Who were the first humans? Primate evolutionary trends

The Evolution of the Human Species - Who were the first humans?

Human species and anthropomorphic apes (gorilla, gibbon, orangutan, chimpanzee) belong to the superfamily of the Hominoidea, primates without tails.

Close relatives

The Evolution of the Human Species - What makes us humans?

The spine meets the skull, balancing the head in a vertical position

The face is straight

The spine meets the skull in the back

The face shows a relative degree of prognation

Quadrupedal gait(knuckle-walking)

Bipedal gait(man is truly vertical)

Opposability of big toe

Non-opposability of big toe

Plantar arch missing

Plantar arch and a more robust calcaneus

Short pelvis allows bipedalism

Femoral shaft angle,(feet directly below the center of gravity)

Femur almost vertical within a horizontal plane

Hominidae characteristics

Different climates in the two areas of the Eastern African Rift Valley are thought to have caused the evolutionary divergence between Hominidae and anthropomorphic apes.pes

The Evolution of the Human Species - Where did the first humans live?

Atlantic ocean

Indian ocean

A common ancestor

• Bipedalism

• Brain size grew larger (genus Homo)

• Reduction of sexual dimorphism (Homo erectus)

The Evolution of the Human Species - Who were the first humans?

Early hominid characteristics

*ratio of the maximum width of the head multiplied by 100 divided by its maximum length

The first members of the genus Homo appeared around 2.5 million years in Africa.

The Evolution of the Human Species - When did the first humans live?

SpeciesDate

(thousand years)

Body weight

(kg)

Mean cranial capacity (cm3)

Cephalic index*

Homo s. sapiens To present 58 1349 5.3

Homo sapiens 35-10 65 1492 5.4

Homo neandertaliensis 75-35 76 1498 4.8

Late Homo erectus 600-400 68 1090 3.8

Early Homo erectus 1800-600 60 885 3.4

Homo habilis 2400-1600 42 631 3.3

Australopithecus africanus 3000-2300 36 470 2.7

Australopithecus afarensis 4000-2800 37 420 2.4

Chimpanzee To present 45 395 2.0

Gorilla To present 105 505 1.7

Homo erectus is generally considered to have been the first species to have expanded beyond Africa, and related fossils are spread over two continents.A nearly complete 1.6-million-year-old skeleton, found near Lake Turkana, Kenya, belonged to an eight-year-old boy.

The Evolution of the Human Species - Who were the first humans?Turkana Boy (Homo erectus)

An international consortium of researchers has sequenced the genome of our closest relative, the Neandertal. Results indicate that Neandertals are slightly more closely related to modern humans outside Africa. The team also identified several genomic regions that appear to have played an important role during human evolution.(Science on May 7, 2010)

The Evolution of the Human Species - Who were the first humans?

Professor Svante Pääbo holding the skull of a Homo neandertaliensis

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Out-of-Africa model Multiregional model

Europe Africa Asia Europe Africa Asia

0.5 million years ago

(present)

(1.8 million years ago)

Modern humans evolved more or less simultaneously in all major regions of the Old World from local archaic humans.

Humans with modern traits left Africa from 50,000 to 60,000 years ago to settle the world

Homo sapiens evolved from Homo erectus in Africa

Interbreeding between people living in Europe, Asia, and Africa (gene flow)

Two possible models

The Evolution of the Human Species - What makes us humans?

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• Worked stone tools

• Evolution of language

• Cave art, burials

• Domestic animals and agriculture

Cultural evolution

The Evolution of the Human Species - What makes us humans?