1. Human Evolution Another Example of Speciation

2. Classification Hierarchy
Kingdom Phylum Class Order Family Genus Species
Animal Chordate Mammal Primates Hominids Homo sapiens

3. Evolution of Primates mobile limbs
The evolution of primates is characterized by trends towards:
mobile limbs
grasping hands (with opposable thumbs)

4. Primate Hands

5. Evolution of Primates mobile limbs
The evolution of primates is characterized by trends towards:
mobile limbs
grasping hands (with opposable thumbs)
a flattened face
binocular vision
a large, complex brain (for learned behavior)
a reduced reproductive rate

6. How do scientists study human evolution?
Humans evolved from ape-like creatures
THEORY
Humans and apes share many biological features
Humans and apes have a common ancestor
2. There should be fossils with human and ape-like features
1. Humans and apes should share a high percentage of DNA
Observation
HYPOTHESIS
Prediction
Since Charles Darwin’s time, scientists have gathered a huge amount of evidence about human evolution. Using the scientific method they form and test ideas to build theories about human evolution.
Ideas generally start with an observation, from which scientists form a hypothesis. A hypothesis is a testable statement about the world based on observations. From a hypothesis we can make a prediction about what would happen in the hypothesis was true or false, and scientist then gather evidence to test whether their hypothesis is true. If the hypothesis is supported by multiple lines of evidence, it becomes a theory. In science a theory doesn’t mean a guess or a hunch. It means a well-supported explanation for some aspect of the natural world that incorporates facts, laws, observations and testable hypotheses.
In the case of human evolution, Charles Darwin noted that humans and apes share many biological features (click 1). He hypothesized that (click 2) humans and apes share a common ancestor. If this hypothesis is true then (click 3) humans and apes should share a high percentage of their DNA, and (click 4) there should be fossils with humans and ape-like features. Darwin wasn’t able to gather this sort of evidence to test his hypothesis in his time, but many studies since then have tested these predictions (click 5). Both DNA and fossil evidence support the hypothesis of humans and apes sharing a common ancestor, and the idea that humans evolved from ape-like creatures is now an accepted theory.
Measure DNA differences between humans and apes.
Examine fossils from several million years ago.
Gather evidence,
test with experiments

7. Darwin published another book…
In 1871, Darwin wrote “The Descent of Man”
In this book, he proposed that humans evolved in Africa and shared a common ancestor with great apes.

8. Evolutionary trees depict clades
A clade is a group of organisms that includes an ancestor and all descendants of that ancestor.
Think of a clade as a branch on the tree of life.
Since Charles Darwin’s time, scientists have gathered a huge amount of evidence about human evolution. Using the scientific method they form and test ideas to build theories about human evolution.
Ideas generally start with an observation, from which scientists form a hypothesis. A hypothesis is a testable statement about the world based on observations. From a hypothesis we can make a prediction about what would happen in the hypothesis was true or false, and scientist then gather evidence to test whether their hypothesis is true. If the hypothesis is supported by multiple lines of evidence, it becomes a theory. In science a theory doesn’t mean a guess or a hunch. It means a well-supported explanation for some aspect of the natural world that incorporates facts, laws, observations and testable hypotheses.
In the case of human evolution, Charles Darwin noted that humans and apes share many biological features (click 1). He hypothesized that (click 2) humans and apes share a common ancestor. If this hypothesis is true then (click 3) humans and apes should share a high percentage of their DNA, and (click 4) there should be fossils with humans and ape-like features. Darwin wasn’t able to gather this sort of evidence to test his hypothesis in his time, but many studies since then have tested these predictions (click 5). Both DNA and fossil evidence support the hypothesis of humans and apes sharing a common ancestor, and the idea that humans evolved from ape-like creatures is now an accepted theory.

9. Evolutionary trees depict clades
Since Charles Darwin’s time, scientists have gathered a huge amount of evidence about human evolution. Using the scientific method they form and test ideas to build theories about human evolution.
Ideas generally start with an observation, from which scientists form a hypothesis. A hypothesis is a testable statement about the world based on observations. From a hypothesis we can make a prediction about what would happen in the hypothesis was true or false, and scientist then gather evidence to test whether their hypothesis is true. If the hypothesis is supported by multiple lines of evidence, it becomes a theory. In science a theory doesn’t mean a guess or a hunch. It means a well-supported explanation for some aspect of the natural world that incorporates facts, laws, observations and testable hypotheses.
In the case of human evolution, Charles Darwin noted that humans and apes share many biological features (click 1). He hypothesized that (click 2) humans and apes share a common ancestor. If this hypothesis is true then (click 3) humans and apes should share a high percentage of their DNA, and (click 4) there should be fossils with humans and ape-like features. Darwin wasn’t able to gather this sort of evidence to test his hypothesis in his time, but many studies since then have tested these predictions (click 5). Both DNA and fossil evidence support the hypothesis of humans and apes sharing a common ancestor, and the idea that humans evolved from ape-like creatures is now an accepted theory.
= most recent common ancestor

10. Old-World monkeys Gibbon Orangutan Gorilla Chimpanzee Human
We now know, from genetic and fossil evidence, that our closest relative is the chimpanzee.
This does not mean we evolved from chimpanzees, it means that we share a common ancestor.

11. Our Family Tree
We know through genetic evidence that our closest living relatives are chimpanzees
We did not evolve from chimpanzees, we share a common ancestor

12. Allan Wilson proved apes and humans diverged only 6 million years ago
One of the first to use genetics to prove relatedness

13. 6 million yrs ago, the great ape line gave rise to hominids
Hominids are modern humans and our ancestors and closest relatives (after our lineage split from chimps)
Hominids are bipedal, have opposable thumbs and displayed a remarkable increase in brain size

14. Hominid Lineage

15. Hominid Family Tree

16. 5 Main Genera of Hominids
Ardipithecus
Australopithecus
Paranthropus
Kenyanthropus
Homo

17. We are still not exactly sure when the first bipedal hominids evolved, but an amazing discovery in 1974 proved that hominids were bipedal a lot earlier than previously believed.

18. Lucy: Australopithecus afarensis
Discovered in Ethiopia in 1974.
Dated at 3.2 million years old!
40% of her skeleton was found.
Only 3.5 feet tall.
Bipedal for certain She walked upright.
How did she get her name?
Was one of the oldest and most complete hominid fossils found.

19. Lucy: Australopithecus afarensis
Her scientific name is Australopithecus afarensis, a distant ancestor to us, Homo sapiens.
Was one of the oldest and most complete hominid fossils found.
Died out when climate changed. Wet woodlands shrank as dry plains grew, providing environment for Paranthropus and Homo to expand

20. An even more impressive fossil was found in 1978, but there were no bones to it at all.
Laetoli Footprints
3.6 million years old
Older than Lucy
Showed these hominids walked together… awh
This discovery proved that there were bipedal hominids even earlier than Lucy.

21. Paranthropus
Coexisted and lived in the same geographical area as Homo species
This gave evidence that there is no single human lineage, but rather a complex family tree with many branches and many different lineages.
In same plains environment as Homo erectus, but Homo erectus had more varied diet and more evolutionary success
P. Boisei and H. ergaster

22. Kenyanthropus In 2001, a new genus was discovered
It has ear structure like a chimp, yet facial features resembling those in the genus Homo
The fossil record is constantly changing, as will the human evolutionary tree

23. Evolution of Early Homo
It is important to note that there were several other species in the genus Homo that came before Homo sapiens (modern humans)
Homo habilis
Earliest fossil discovered sofar (2.3 mya)
Means “handy man”
Used tools

24. Homo habilis was the first to use stone tools
Homo habilis was more recognisably human than the Australopithecines – he had a smaller jaw, larger brain and ate meat. Eating meat may have driven development of larger brains.

25. Homo erectus 1.3 - .3 mya “Upright human” Left Africa for Asia
Were hunters with stone axes and used fires for cooking/warmth

26. Homo heidelbergensis Modern humans most recent common ancestor
Controlled fire
First species to hunt large animals
First species to build shelters- creating simple dwellings from rock and wood

27. Homo neanderthalensis
Not an ancestor of modern humans
Existed 200,000-28,000 years ago
Coexisted with Homo sapiens
Used tools, controlled fire
Lived in shelters, wore clothing
Skilled hunters and gatherers
Buried their dead, demonstrated culture?
Disappeared as Homo sapiens rose in great numbers

28. Finally…Homo sapiens
The earliest anatomically modern Homo sapiens fossil date to only 170,000 years ago in Africa
By 170,000 years ago, there were hominids (Homo erectus) living in Europe, Africa, and Asia.
So where and when did modern humans evolve?
Two Different Hypotheses: Worksheet

30. Multiregional Hypothesis
Homo erectus left Africa 2 million years ago
We evolved from Homo erectus separately in Europe, Africa and Asia.
This emergence was not restricted to any one area, but occurred throughout all the geographic areas.
Single, continuous human spp.
Sapiens evolved from erectus around the world

31. Out of Africa Hypothesis
Modern Homo sapiens evolved in Africa and migrated out recently 100,000 years ago
Colonized the world, displacing and causing the extinction of Homo erectus and Neanderthals.
All modern humans have similar mitochondrial DNA, meaning we all came from a small group in Africa a fairly short time ago. If we were part of a large population 1 million years ago, we should have mutational differences in the DNA

32. So which theory?! Until the 1980s, the first hypothesis was favored.
Rebecca Cann and Allan Wilson showed that modern humans originated in Africa, evolving recently from a small ancestral population.
Cann and Wilson showed that we can all trace our DNA back to one woman who lived in Africa around 200,000 years ago.

33. Out of Africa Mitochondrial DNA
DNA is present inside the nucleus of every cell of our body, but mitochondria also contains its own separate DNA
Mitochondrial DNA is only found in eggs and does not mix with DNA from the sperm
changes in mitochondrial DNA can easily be traced.

34. Mitochondrial DNA traces the female line
Imagine these dots represent a population in Africa living 200,000 years ago - each one of the dots a female person. Some mitochondrial types get passed down to the next generation (click 1). Occasionally there is a mutation, or spelling mistake in the DNA (click 2). Usually this is not harmful, so it gets passed down to the next generation (click 3). Some mitochondrial lineages die out over time (click 4), and gradually one lineage will replace all the others (clicks 5-9).
The spelling mistakes in the DNA happen at a fairly constant rate over time, so by counting the number of changes in the DNA between two different people we can work out how much time has passed since those people shared a common ancestor. The more DNA differences between two people, the less closely related they are likely to be.
Allan Wilson and Rebecca Cann studied mitochondrial DNA sequences of people from around the world, and found that they could all be traced back to one common mitochondrial sequence that existed in Africa about 200,000 years ago. This means that all humans alive today are ultimately descended from one common female ancestor, who we call “Mitochondrial Eve”. Mitochondrial Eve was not the only women alive 200,000 years ago – she was part of a population that would have contained many other women with other mitochondrial DNA sequences. However, over time these other lineages died out one by one, and by chance one lineage replaces all the others.

35. Ted Talks