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2 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Sylvia S. Mader Immagini e concetti della biologia

3 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 B5 - Evolution of Humans

4 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Primates share characteristics The order Primates encompasses prosimians, monkeys, apes and hominids.

5 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

6 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 All primates evolved from a common mammalian ancestor about 65 MYA. Primate evolution

7 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.

8 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.

9 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.

10 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.

11 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.

12 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.

13 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.

14 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The genus Homo The genus Homo evolved about 2 MYA and is characterized by 600 cm 3 brain size, jaws and teeth resembling humans, development of hand abilities.

15 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 cm 3 H. ergaster: evolved in Africa with 1000 cm 3 brain, flat muzzle and prominent nose H. erectus: found both in Africa and Asia H. floresiensis: discovered in 2004, used tools and fire

16 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.

17 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 cm 3 ) facilitated language, social organization and artistic accomplishments.

18 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.

19 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.

20 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.