Human Evolution

Outline

• Ardi assignment answers

• Misconceptions 2.0

• Human Evolution

• Race

Ardi Answers1) Ardi was discovered in Ethiopia in 1994, 125 bones were uncovered. It

was determined that Ardi was 4.4 million years old, making her 1 million years older then Lucy the previously oldest human ancestor. This discovery has changed common beliefs that humans evolved from chimps. It is now accepted that humans and chimps evolved from a common ancestor about 6-7 million years ago. Ardi does not have many of the traits of African apes which indicate that Ardi and apes had evolved extensively since they last shared a common ancestor.

2) No, humans did not evolve from apes however they do share a common ancestor

3) The most significant find that classified Ardi on the human lineage was that she was bipedal and walked up right.

4) A) She had a projecting muzzle/ face and she was able to climb and grasp trees with her big toe for occasional tree swinging and climbing.

B) She lacks pointed canine teeth, her teeth were more rounded and she lacked knuckle walking ability.

C) She had molar teeth very similar to humans; this indicates that she ate a diet similar to humans.The brain position was similar to humans indicating that she walked up right and had a larger brain then chimps.

5) It was very difficult to put the skeleton together since it was in so many pieces and they were very old. Determining the movement, musculature and anatomical plan took very long time. Putting together all of the information from the scientific communities.

6) They examined volcanic layers above and below Ardi to properly date her.

7) The bones were over 4 million years old and too fragile to test directly

Misconceptions 2.01) Humans came from monkeys

- This is a BIG no-no.- Started when Darwin first

suggested that humans and apes have a common ancestor

- Humans and other ape-like creatures share a common ancestor from millions of years ago

- Species evolved independently

2) Humans did not evolve from anything- We did- The modern human species (Homo

sapiens) changed over time from ancient hominids

Misunderstandings• Humans and chimpanzees are closely related

– Share about 98% of DNA• What does this actually mean?

– Are humans 98% chimpanzee?

• No, we are not. – This 2% difference is huge!– Even one deletion or insertion of nucleotide in a gene can make a huge

difference!– “I would like a mousse for dessert” v.s. “I would like a mouse for dessert”– E.g. A human is a 100 page book. Take out two pages and then scramble

up the rest of the book. The scrambled book is chimpanzee.

• Be careful with stats and numbers– Numbers can be manipulated very easily to show what you want to show

• E.g. played only two basketball games and won both = 100% success

Shared DNA %

• With bananas: about 50%

• With sea slugs: about 70%

• With fruit fly: about 40%

• With lettuce: about 16%

Human Evolution: bio characteristics• What makes humans unique as a species?

– Perform complex reasoning– Incredible ability to learn– Use sophisticated tools– Complex language– Very large brain relative to body size– Walk upright therefore free hands– Ability to imagine

• All other animals can do most of these– BUT the difference is the degree to which the

characteristics evolved in humans

Human Phylogeny

• Humans are primates• Characteristics of primates:

large brains, forward-directed eyes, flexible hands and feet, arms fully rotatable, opposable thumbs, most have tails

• Started with a common ancestor dating back to about 60 million years ago

Hominid Fossil Record• Shows sequence of steps

in the evolution of humans• About 6mya, started

walking upright• First evidence of tools used

dated back to 3.4mya• About 2mya, first members

of genus, Homo, evolved• The first modern humans

evolved by about 100,000 years ago in Africa

Figure 4 on pg. 360

• Hominid brain size increased rapidly about 800,000 to 200,000 years ago

• Footprints dated to 3.6mya showed that human ancestors developed the ability to walk upright before they had large brains

Distribution

• Early hominids evolved and lived in Africa

• Homo erectus population spread across Eurasia

• Homo neanderthalensis distributed across parts of Europe

• Early modern humans spread from Africa to Europe and Asia and eventually reached America

Human Race• Observation:

– Look around the classroom and notice that people have different physical characteristics

• Question: – Who do YOU think you are most closely

related to genetically?– Why?

Human Race

• There are no significant genetic differences between people

• Meaning: the concept of “race” is not biological

• Meaning: someone who is black can be more genetically similar to someone who is white– All depends on the ancestor population’s

movement pattern on Earth long ago

• The term “race” has no biological meaning– It is a social / cultural concept

• This idea that “race” is biological is so ingrained in society today that it is extremely hard to change

• Often, people use skin, hair, and eyes colour to categorize people into “race”

• Genes that govern skin, hair, and eyes are separate and the genes are inherited independently

• The physical differences that we see in people are individual differences/variations

• There are no characteristics, no traits, and no one gene that distinguish all members of a “race” from all members of another

• So then…if “race” has no biological bases, why is there still racism?

Because…

1) Most people believe that race is a biological concept

2) Lack of education

3) Since “race” is not biological at all, someone who is racist really is just:

IGNORANT

Some questions to think about• We all did the following:• E.g. “That person is half white, half black”• Is there meaning to this?• When have we seen a “gray’ person walking

around?• Skin colour and country of birth• E.g. “half black, half Chinese”• What does that even mean?• When is “black” a country or when is

“Chinese” a colour?

• Why do people associate “race” with “country of birth”?

• Does the location of where you were born influence your genes?

• We have to be careful how we use sentences and ideas like that

• Why?• Because as soon as we use them, we are

assuming that the person will behave or act in a certain way

• This prejudgement is very dangerous

• We all know what happens when you assume

Race: The Power of an Illusion

• If you are interested:

Check out the 3-part series called:

RACE – The Power of an Illusion