HUMAN EVOLUTION. Where did we come from?

HUMAN EVOLUTION Where did we come from? www.christs.cam.ac.uk/darwin200

Darwin & Human evolution Darwin was very aware of the implications his theory had for humans. He saw monkeys during the Beagle voyage but saw his first Ape at London Zoo.

Darwin & Human evolution Darwin was very aware of the implications his theory had for humans. He saw monkeys during the Beagle voyage but saw his first Ape at London Zoo. Darwin first saw Jenny the Orang-utan in 1838; He recognized human-like qualities in her

Darwin & Human evolution Darwin was very aware of the implications his theory had for humans. He saw monkeys during the Beagle voyage but saw his first Ape at London Zoo. Darwin first saw Jenny the Orang-utan in 1838; He recognized human-like qualities in her Even Queen Victoria recognized the similarities: frightful and painfully and disagreeably human.

Darwin & Human evolution But the only mention of human evolution in On the Origin of Species (1859) was: Light will be thrown on the origin of man and his history Darwin left people to figure it out the implications of his work themselves

Darwin & Human evolution He later dealt with the topic more thoroughly in The Descent of Man (1871) comparisons between apes & humans reveal their shared ancestry Darwin also showed all human races were one species (which was debated at the time) Also outlined his theory of sexual selection

Human classification sapiens Homo Hominidae Primates Mammalia Chordata Animalia Eukaryota

Human classification Characteristic features: sapiens Homo Hominidae Primates Mammalia Chordata Animalia Eukaryota thinking man Man: bipedal The apes; no tails, larger bodies Large brains, stereoscopic vision Have mammary glands Develop dorsal nerve cord Multicellular, heterotrophic, no cell walls Cells with membrane bound nucleus

What are the main characteristics of primates? Humans are primates. Primates are distinguished from other mammals by: greater reliance on vision than smell shortened snout grasping hands & feet nails instead of claws large brains relative to body size

What are the main characteristics of primates? Humans are primates. Primates are distinguished from other mammals by: greater reliance on vision than smell shortened snout grasping hands & feet nails instead of claws large brains relative to body size Primates evolved 70-80 million years ago. There are about 600 living species. 25% are endangered!

The primate family tree You are here Gorilla Mandrill Woolly monkey Tariser Slow Loris Ring tailed lemur

The Apes Humans Homo Orang-utan Pongo Chimpanzees Pan Gibbons Hylobatidae Gorillas Gorilla Who is more closely related to who?

The Apes HUMAN EVOLUTION

The Apes HUMAN EVOLUTION

The Apes HUMAN EVOLUTION

The Apes Which is more closely related to chimpanzees: humans or gorillas?

The Apes Which is more closely related to chimpanzees: HUMANS! This grouping is supported by anatomical and DNA evidence

How do humans and chimpanzees differ?

How do humans and chimpanzees differ? Brain size Body hair Face length Locomotion

How do humans and chimpanzees differ? Brain size Body hair Face length Locomotion Brain size 1300-1400g 400g Body hair not much quite a bit Face length shorter longer Locomotion bipedal knuckle walking

The human fossil record is quite good about 20 species are recognised. The chimpanzee fossil record is very poor. HUMAN EVOLUTION How did these difference evolve? Evidence from fossils Lots of hominid (human ancestor) fossils virtually no chimpanzee fossils 5-7 million years ago

The human fossil record HUMAN EVOLUTION Paleo-anthropologists don t always agree on the proposed relationships among the early human ancestors But we can recognize general trends

The human fossil record HUMAN EVOLUTION There was not a directed, gradual progression but instead a mosaic pattern

The human fossil record HUMAN EVOLUTION Increase in brain size Evolution Bipedalism Reduction in face more gradual

The human fossil record HUMAN EVOLUTION

The human fossil record HUMAN EVOLUTION Bipedalism Reduction in face more gradual Increase in brain size

Modern humans evolved in Africa HUMAN EVOLUTION Darwin predicted this long before man s African origins were established: In each great region of the world the living mammals are closely related to the extinct species of the same region. It is therefore probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man s nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere. -Darwin (1871) The Descent of Man

Modern humans evolved in Africa HUMAN EVOLUTION The oldest known fossils of anatomically modern humans were found in Ethiopia from about 150,000 years ago

Modern humans evolved in Africa HUMAN EVOLUTION The oldest known fossils of anatomically modern humans were found in Ethiopia from about 150,000 years ago Most scientists agree Homo sapiens evolved in Africa and migrated out from this single origin

Modern humans evolved in Africa HUMAN EVOLUTION Most scientists agree Homo sapiens evolved in Africa and migrated out from this single origin This is supported by genetic and phenotypic evidence. The diversity of both decrease with over-land distance from Africa. This is what would be expected if humans evolved once and their range expanded, going through a series of population bottlenecks

What does the DNA evidence say? Scientists have now sequenced the genome of a: Human Chimpanzee Gorilla Orang-utan Gibbon Macaque (an old world monkey) Marmoset (a new world monkey) and a type of galago and a lemur As well as many other mammals! The DNA evidence confirms the relationships between humans, primates and other mammals. They show how similar we are, genetically, to chimpanzees: an estimated 96-98% of our DNA sequence is identical to chimpanzees (but that s still millions of differences!)

What does the DNA evidence say? By comparing the DNA sequences biologists can see which regions of the genome have changed rapidly since the human-chimpanzee split. These studies highlight genes involved in: immunity & defence evolving to tackle new diseases as humans spread digestion evolving as human diets changed in different environments brain development potentially having roles in the expansion of the human brain

What does the DNA evidence say? By comparing the DNA sequences biologists can see which regions of the genome have changed rapidly since the human-chimpanzee split. These studies highlight genes involved in: immunity & defence evolving to tackle new diseases as humans spread digestion evolving as human diets changed in different environments brain development potentially having roles in the expansion of the human brain BUT There is still a lot about the genetic basis of human evolution to understand. Linking genetic changes to the evolution of human traits is a challenging task!

CONCLUSIONS: HUMAN EVOLUTION humans belong to a group of mammals called primates our closest living relative is the chimpanzee, our evolutionary paths separated 5-7 million years ago the human fossil record is quite good and reveals how and when human traits evolved modern humans evolved in Africa and migrated around the world DNA evidence supports these conclusions and is beginning to reveal changes in genes important to human evolution For further information visit: www.christs.cam.ac.uk/darwin200