SBI3U

HUMAN EVOLUTION

3 Physical Characteristics

1. very large brain to body ratio2. hands are capable of fine manipulation

and coordination3. walk upright (bipedal), hands are free to use tools

Ability to perform complex reasoning, exceptional ability to learn, make use of sophisticated tools and communicate using complex language.

Why are humans so successful?

Hominoids

Hominids

• Humans did not evolve FROM apes• Rather, we share a COMMON ANCESTOR

Misconceptions

• Humans and chimpanzees share 98.8% of their DNA

• The most recent common ancestor we share with chimps lived in Africa more than 6 million years ago

Humans closest living relative

• Hominids are all species descended from the most recent common ancestor of chimpanzees and humans that are on the human side of the lineage

Hominids

• The sequence of steps in the evolution of humans

The Hominid Fossil Record

The Hominid Fossil Record

• Between 6 and 7 million years ago a human ancestor was walking upright occasionally

• First evidence of stone tool use by Australopithecus afarensis date to 3.4 million years ago

• The first members of our own genus, Homo habilis evolved 2 million years ago

• Homo habilis, the handy man, built stone axes and large cutting tools

• Hunting tools allowed hominids to increase the amount of meat in their diet, providing a rich source of protein and fat

• By this time, hominid brains were significantly larger than the chimpanzee-sized brains of australopithecines

The Hominid Fossil Record

• Hominid brain size increased relatively rapidly from about 800 000 years ago to 200 000 years ago– Homo neanderthalensis and Homo sapiens evolved

during this time• The first modern humans had evolved by about

100 000 years ago in East Africa

The Hominid Fossil Record

Out of Africa

• All early hominids evolved and lived in Africa

• The first species to spread beyond Africa was Homo erectus, about 1.9 million years ago, and survived throughout Eurasia until at least 100 000 years ago

• 500 000 to 300 000 years ago Homo neanderthalensis left Africa and populated parts of Europe

• After the earliest humans evolved they began to spread out of Africa into Eurasia and eventually reached the Americas

Out of Africa

• Humans and chimpanzees are so similar genetically, but are dramatically different culturally

• Human culture is so rich and diverse: – Over 6000 languages– Countless artistic endeavors in music, dance and fine

arts– Admire and cherish the talents of others– Societies have different rituals, customs and beliefs

Cultural Evolution

• Our ancestors lived as hunter-gatherers for 300 000 generations

• In the last 1000 generations or less humans have domesticated plants and animals, developed agriculture and begun to live in large population centres

• Only during the last 10 generations has our population skyrocketed

Cultural Evolution

• Genetic comparisons conclusively show that, from a biological perspective, ‘races’ do not exist

• Traits we associate with races, mostly skin colour, are visibly obvious but genetically minimal.

• More diversity within ‘races’ than there is between ‘races’

Human Races