how we evolved

8/2/2019 How We Evolved

1/52

Hominid EvolutionHow did humans evolve?

What are humans?

Why do we look the way we do?

Were there other types of humans?

Other human-like species?

How old are we?

How do we know?

Noelle Tankard, University of Cambridge, 2012


2/52

We are Homo sapiens...

Animalia Chordata Mammalia Primates Hominidae Homo sapiens

Kingdom Phylum Class Order Family Genus species

We are animals...

We have spinal chords...

We have spinal chords...

We are primates...

We are great apes...


3/52

Primates Hominidae Hominini Homininae Homininae Hominini Homo sapiens

Order Infraorder Superfamily Family Subfamily Tribe Genus species


4/52




5/52



And the rest of ourrelatives?

.. Theyre all extinct!


6/52


7/52

What makes a

humanhuman?


8/52

How close is close?

Genetic divergence tree


9/52

Hominids

Any species more closely related to a human thanto a chimpanzee


10/52

Hominins

Any species more closely related to Homosapiens than to other (extinct) hominids andwho might be an ancestor


11/52

How do we know?

Comparative Anatomy

Ontogeny (development)

GeneticsFossil specimens


12/52

Comparative Anatomy


Genetics

Fossil specimens

Figure from Thomas Huxley's "Evidence of Man's Place in Nature" (1863)


13/52

Comparative Anatomy


Genetics

Fossil specimens


14/52

Comparative Anatomy


Genetics

Fossil specimens


15/52

Comparative Anatomy


Genetics

Fossil specimens


16/52

What is a fossil?

- Preserved organic material plant or animal


17/52

Evolution

- Doesnt change animals:

- each generation has random changes, and the ones that are more usefulhave more kids and pass on those useful traits

- For evolution to happen, have to have threethings:

- Different types of a trait in a population

- Variation must be inheritable

- Some versions of the trait must be more beneficial than others


18/52


19/52

Survival of the fittest

Adaptive selectionSexual selection

Adaptive radiation and diversification

Divergence

- Primitive traits, primitive condition

Speciation

Extinction


20/52

A clade by any other name

- Different populations of organisms who cantbreed with each other (except when theycan)

- No good definition for species

- Living species or fossil species?


21/52

Absolute & Relative Dating

How do we know hold oldsomething is?

- Stratigraphy

- Thermoluminesence for inorganic materials

- Paleomagnetism for rocks & burnt materials

- Radiometrics

- C14 (radiocarbon) for bone & organicmaterial

- Potassium-Argon for fossilized bone &lava


22/52

What can bones tell

us?

- About the individual?

- About the population?

- About the species?

- Age, sex, diseases,

nutrition- Life history, growth

- Diet

- Migration

- and more


23/52

The first primate

???

85 mya estimate from genetic studies(before dinosaurs went extinct!)

Very small


24/52

Darwinius masillae

47 mya

Ida is the most complete fossil primateever found even stomach contentspreserved!

From before divergence of anthropoids

(monkeys & apes) and prosimians


25/52

Aegyptopithecus zeuxis

linking African ape

Small primate, aprox 6kg

35 33 mya

Unknown if its from before or after

hominoids (apes) and cercopithecoids(OldWorld Monkeys) diverged


26/52

Proconsul africu

27 17 mya

First ape? Probably an ancestor of allliving apes

Not a kunckle-walker quadruped, butwalked on the flats of its hands


27/52

The big questions

-W

ho descended from whom?- When did bipedalism evolve?

- Why was it better?

- What came before it?

- Did it happen all at once, to one species or slowly, to several, atdifferent times for different reasons?

- Why big brains? Or why not big brains for everyone?

- Why is our life history so different from other apes?

- Why do we live so long?- Why do we have an extended childhood?

- Why do we have menopause?

- Why do our brains shrink when were old?


28/52

And then came the hominids


29/52

Sahelanthropus tchadensis

7 6 mya

Western Africa (Chad)

2 specimens, discovered in 2002

Hominid hominin or maybe a gorilla ancestor?


30/52

Ardipithecus ramdius

4.4 mya

Ethiopia

Discovered in 1994

W

oodland

Omnivorous


31/52

Kenyanthropus platyops

Timespan: 3.3 3.5 mya

Region: West Turkana, East Africa

Specimens: 2 individuals

Discovered: Leakey 2001

Suggested ancestor to H. rudolfensis but

not to H. sapiens?


32/52

Australopithecines


33/52

Australopithecus afarensis

4.2 3.8 mya

Kenya

Discovered in 1960s


34/52

Australopithecus africanus

3.7 2.8 mya

Discovered in 1934

East Africa

Massive jaws! Nutcracker man


35/52

Australopithecus sediba

1.95 1.78 mya

South Africa

Discovered in 2010

Grassy plains & wooded valleys


36/52

Ardipithecus garhi

2.0 3.0 mya

Ethiopia, East Africa

9 specimens

Discovered in 1999

Lake-side

likely omnivorous


37/52

Paranthropus aethiopicus

2.2 2.8 mya

East Africa

Discovered in 1995

Open savannah & possibly closed areas


38/52

Paranthropus robustus


39/52

And then came the genus Homo


40/52

something in the brain


41/52

or something with our hands?

Stone tools go back 2.5 mya

Mode I basic, big cleavers

Mode II bifaced, handaxes

Mode III small, specific, symmetrical,hafted


42/52

Homo habilis handy man?

First tool makers?

2 1.3 mya

East Africa and maybe Asia?


43/52

Homo erectus the explorer

Africa and China, Indonesia..

1.3 1.8 mya

Definitely had tools but none

in Indonensia?


44/52

Homo floresiensis the hobbit!

Newly discovered dwarf or new species?

Last to go extinct?


45/52

Homo heidelbergensis


46/52

Neanderthals our last cousins


47/52

rope


48/52

Homo sapiens wise man

Evolved in East Africa, 200 - 150 kya

Out of Africa!


49/52

Admixture and interbreeding

Did we mix withNeanderthals?


50/52

Man the Tool-maker?Man the Hunter?

Man the artist?


51/52


52/52

Good websites for more info

http://www.revealingthelink.com/

http://www.talkorigins.org

http://efossils.org/

http://humanorigins.si.edu/

http://www.becominghuman.org/

how we evolved

Documents