Evolution of Humans Evolution of Humans

Marie ČernáMarie Černá

Time scheme of EvolutionTime scheme of EvolutionPrecambrian eraPrecambrian era

4.6 billionyears ago

4.0 billionyears ago

3.5 billionyears ago

2.5 billionyears ago

1.5 billionyears ago

multicellular eukaryotesunicellular eukaryotes(prokaryotes)

Time scheme of EvolutionTime scheme of Evolution

• Paleozoic era (supercontinent Pangea)• 500 million y. a. – plants, fungi, animals

colonize land (Cambrian period)• Mesozoic era = “Dinosaurs period”• 250 million y. a. – first mammals• Cenozoic era (after extinction of dinosaurs)• 50 million y. a. – majority of mammals• 5 million y. a. – diversion of humans and apes

Time scheme of Human EvolutionTime scheme of Human Evolution

Homo ergaster

Time scheme of Human EvolutionTime scheme of Human Evolution

• 35 million years ago – dawn ape: anthropoid Aegyptopithecus

• 5-7 million years ago - diversion of humans and apes • from the common ancestor• 4 million years ago – ape-man: Australopithecus• 2.4 million years ago – handy man: Homo habilis• 1.9 million years ago – working man: Homo ergaster• 1.8 million years ago – upright man: Homo erectus• 0.5 million years ago – archaic Homo sapiens

0.2-0.03 million years ago – Homo neanderthalensis• 0.2 million years ago – Homo sapiens

Important Characters of Human Evolution

• Size of brainAustralopithecus 400cm3 = Homo sapiens 1 300cm3

• Shape of jawbone - shorter and reduced jawbone

= flat face, chin protrusion, change of dentition

• Upright bearing, bipedal locomotion → skeleton

• Reduced sexual dimorphismhigher weight of male than female: gorilla 2x = human 1,2x

• Changes in social lifemonogamy with long-term pair-bonding – longer care of the young allows better learning and complex behaviour formula

Three Models for the Origin of HumansThree Models for the Origin of Humans• Multiregional model – Modern humans evolved in

many parts of the world from regional descendants of Homo erectus, who dispersed from Africa between 1 and 2 million years ago.

• Monogenesis model (“out of Africa” model) – Only the African descendants of Homo erectus, who dispersed from Africa just 0.1 million years ago, gave rise to all the diverse populations of modern humans. All other regional descendants of Homo erectus, including Neanderthals, became extinct without contributing to the gene pool of modern humanity.

• Intermediate model - Modern humans may be the result of a migration out of Africa as well as some genetic contribution from non-African archaic groups.

Multiregional Model Multiregional Model for the Origin of Humansfor the Origin of Humans

1-2 million years ago

Monogenesis ModelMonogenesis Modelfor the Origin of Humansfor the Origin of Humans

100 000 years ago

Proof for Monogenesis Model:Proof for Monogenesis Model:

• mitochondrial DNA divergence

• greater genetic diversity within African populations

• studies of DNA from the Y chromosome

Three Major Stages of Three Major Stages of Cultural EvolutionCultural Evolution

• The first stage began with nomads who hunted and gathered food on the African grasslands 2 million years ago. They made tools, organized communal activities, and divided labor.

• The second stage came with the development of agriculture in Africa, Eurasia, and the Americas about 10 000 - 15 000 years ago. Along with agriculture came permanent settlements and the first cities.

• The third stage was the Industrial Revolution, which began in the 18th century.– Through all this cultural evolution we have not changed biologically in any

significant way.– Our know-how is stored not in our genes but in the cumulative product of

hundreds of generations of human experience, passed along by parents, teachers, books, and, most recently, by electronic means.

LiteratureLiteratureBiology, eighth edition,

Campbell, Reece

Unit five: The Evolutionary History

of Biological Diversity

Chapter 34: Vertebrates

Concept 34.8: Humans are mammals that have a large brain and bipedal locomotion

Pages 728 – 733