Human Origins.

Presentation on theme: "Human Origins."— Presentation transcript:

1 Human Origins

2 Common argument against human evolution…
If we evolved from chimpanzees, how are there still chimpanzees!?

3 Human Characteristics
What makes us human? As with all species, humans have a number of evolved characteristics In our own way we have become enormously successful and have come to thrive in many environments

4 What are some human traits?

5 Human Characteristics
What are some of those traits? High-functioning mental facilities Ability to perform complex reasoning Exceptional ability to learn Use and make sophisticated tools Communicate with complex language

6 Human Characteristics
What are some of those traits? Physical characteristics: Large brain relative to body size Hands capable of fine manipulation and coordination Walk upright, allowing hands to use tools

7 What about other species?
Other species have some of these characteristics But we are unique in two regards We have all, not some, of these traits We have evolved these traits to a higher degree than other species

8 Primates Humans are members of the primate family
Primate: A group of mammals with relatively large-brains, forward-facing eyes, and flexible hands

9 Primates Other members of the primate family include gorillas, chimanzees, orangutans, monkeys, gibbons, and lemurs All primates share a common ancestor dating millions years ago

10 Human Phylogeny

11 Human Phylogeny Early on, the prosimians and the anthropods split
Prosimians: A number of relatively small nocturnal members of the primate family, including lemurs Anthropoids: The group of primates including monkeys, apes, and humans

12 Continental Drift Early primates lived in areas that would become Africa, India, and South America 60-70 million years ago, South America was separating from Africa and India This split led to a division in the early ancestors of monkeys

13 Human Phylogeny

14 How are apes different than monkeys?
Do not have a tail Divided into 2 branches: Lesser apes Great Apes All are fairly similar genetically

15 Genetic Similarities All great apes have very similar genetic make-up
Chimpanzees are the closest relatives of humans: 98.8% of DNA is shared (identical) Both differ from gorillas by about 1.6%

16 Planet of the Apes Humans are great apes
Both genetically and physically, we share a lot of similarities with other great apes Does this mean that we descended from apes? No. It is more correct to say that we descended from the same ancestors as modern apes

17 We didn’t evolve from chimpanzees
We didn’t evolve from chimpanzees! We evolved from a common ancestor that also gave rise to chimpanzees!

18 Common Ancestry Our most recent shared ancestor with chimpanzees existed about 6 million years ago Our more recent ancestors form an evolutionary branch known as hominids Hominids: all species descended from the most recent common ancestor of humans and chimpanzees that are on the human side of the lineage

19 Human Phylogeny

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21 The Hominid Fossil Record
Hominid fossils help trace the steps in human evolution Skulls can be measured to determine brain size Leg bones can be examined for evidence of bipedalism

22 A Map of Our Past

23 Bipedalism Bipedalism: The ability to walk upright, on two legs
The Laetoli footprints provide evidence that out ancestors were bipedal 3.6 million years ago

24 Tools Hominid tools have also been discovered in the fossil record
The first evidence of tool use dates to 3.4 million years ago By 2 million years ago, tools were being used by a more recent ancestor, Homo habilis

25 Cooking The first evidence of cooking dates comes from hearths dating back to years ago This would have reduced the chance of disease from eating raw food

26 Evidence for Brain Growth
We see a large increase in brain size from fossils dating between and years ago The proposed most recent ancestor of humans, Homo heidelbergensis arose at this time

27 Homo heidelbergensis Both Homo sapiens and Homo neanderthalensis, or neanderthals, likely descended from this species The first modern humans, Homo sapiens had evolved by about years ago in East Africa

28 The Big Picture The hominid fossil record contains more than 20 species currently Not all are proposed to be ancestors of humans The precise relationships among hominids is still being worked out Each new fossil discovery adds to the story

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30 Neanderthals Homo neanderthalensis Now extinct
Lived at the same time as Homo sapiens until they went extinct Homo sapiens and Homo neanderthalensis show only a 0.15% difference in DNA Why did they go extinct?