Transcript Presentazione di PowerPoint

1
Sylvia S. Mader
Immagini e
concetti
della biologia
2
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
B5 - Evolution of
Humans
3
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Primates share characteristics
The order Primates encompasses prosimians, monkeys,
apes and hominids.
4
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Primates share characteristics
All primates are adapted to live in the trees and show the
following features:
•Prehensile limbs
•Binocular vision
•Large complex brain
•Reduced reproductive rate
5
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Primate
evolution
All primates evolved
from a common
mammalian ancestor
about 65 MYA.
6
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Primate evolution
The fossil Proconsul, 15 MYA, is the junction point
between hominoids (apes and hominids) and
monkeys.
7
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hominids
Hominids include humans and several extinct
species characterized by an upright posture
and a larger brain.
The split between hominids and apes
occurred about 7 MYA.
8
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hominids
Humans and chimpanzees are genetically close and have
many common traits but also distinctive features as spine
position, pelvis size, bone length and toe.
9
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Hominids
Early hominids include Sahelanthropus tchadensis (7
MYA) and Ardipithecus ramidus (4.5 MYA), both extinct.
Later hominids evolved from Australopithecines.
10
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Australopithecus
Australopithecines had a small brain and lived in
Africa from 4 MYA to 1 MYA and could be a direct
ancestor to humans.
Lucy is classified as Australopithecus
afarensis, one of the several species
of australopithecines that lived in East
Africa about 4.2 to 2.7 MYA.
11
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Australopithecus
Two types of australopithecines got adapted to different
environments: robust (A. robustus) and gracile (A.
africanus). Both types lived in South and East Africa.
12
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The genus Homo
The genus Homo originated from australopithecines
when a high rate of fetal brain growth developed.
Brain growth is linked to infantile helplessness, parental
cares and inability of the parents to climb trees.
13
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The genus Homo
The genus Homo evolved about 2 MYA and is
characterized by 600 cm3 brain size, jaws and teeth
resembling humans, development of hand abilities.
14
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The genus Homo
The genus Homo includes:
•H. habilis and H. rudolfensis: omnivores with a
brain size of 800 cm3
•H. ergaster: evolved in Africa with 1000 cm3 brain,
flat muzzle and prominent nose
•H. erectus: found both in Africa and Asia
•H. floresiensis: discovered in 2004, used tools and
fire
15
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Homo: the biocultural evolution
With Homo, natural selection is based on cultural
achievements.
H. habilis used simple stone tools; H. erectus made tools
with wood and bones, gathered plants and used fire.
Hunting encouraged the development of culture and
language.
16
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Homo sapiens
H. neanderthalensis was adapted to cold climates. They
lived in Europe and the Near East, had built shelters,
stone tools, fire places and burial ceremonies.
The Cro-Magnons (H. sapiens) entered Asia and
Europe from Africa, and made advanced stone tools.
Their developed brain (1590 cm3) facilitated language,
social organization and artistic accomplishments.
17
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Homo sapiens evolutionary models
Three evolutionary hypotheses:
1.Multiregional model - modern humans evolved in
Africa, Asia and Europe independently.
2.African model - modern humans evolved in Africa and
replaced archaic humans in Asia and Europe.
3.Assimilation model - modern humans evolved in Africa,
migrated to Asia and Europe and interbred with archaic
humans in those regions.
18
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Homo sapiens and agriculture
Agriculture and breeding originated in the Near East, Far
East, Central and South America about the same period
(4500 years ago).
Conditions favoring agriculture: climate warming, crop
knowledge, increased population, ability in irrigation and
seed storage.
19
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Homo sapiens today
Today’s humans belong to one specie with different
ethnicities. Humans have a wide geographic distribution
with evident phenotypic and genotypic variations.
All ethnicities are evolved from a common ancestor dated
back about 1 MYA.
20
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012