An evolutionary perspective on human nature

Chung-I WuChung-I Wu

Department of Ecology and Evolution, Department of Ecology and Evolution, the University of Chicagothe University of Chicago

Chicken first or egg first?

I.I. Nothing in biology makes sense except inNothing in biology makes sense except inlight of evolution. light of evolution.

-Theodosius Dobzhangsky -Theodosius Dobzhangsky

Five examples where an evolutionary Five examples where an evolutionary perspective is essential for perspective is essential for

understanding biologyunderstanding biology

1 Examples from morphology

(1) Gill slit during human embryonic development.

(2) Vertebrate eyes and blind spots

Q: Is biology nothing but very complex chemistry?

History (= evolution) is important for understanding the biology. So is sociology, politics or language.

2. Examples form behavioral studies2. Examples form behavioral studies (1) Phobia (1) Phobia （恐懼感）– （恐懼感）– snakes, spider, snakes, spider,

height, height,

etc. but not gunsetc. but not guns

(2) animal domestication ( horses vs. zebras)(2) animal domestication ( horses vs. zebras)

3. Medical studies – Why do we get sick? 3. Medical studies – Why do we get sick? Why do we age? Why do we age?

(1) diabetes – the thrift genes(1) diabetes – the thrift genes

(2) aging – decrease in performance before death (not in (2) aging – decrease in performance before death (not in salmon or many insects). salmon or many insects).

4. Sex4. Sex(2)(2) Why is there sexual reproduction? Sex – the union of Why is there sexual reproduction? Sex – the union of

an egg and a sperman egg and a sperm

Sexual reproduction

Asexual reproduction

4. Sex 4. Sex （（ more about it)more about it)

（（ 22 ）） Why is sex ratio 1:1?Why is sex ratio 1:1?

（（ 33 ）） The strange sexual behaviors of humans. The strange sexual behaviors of humans.

II The basic concept of evolution

1. Common ancestry (1. Common ancestry ( 共同祖先共同祖先 ))

2. Natural selection 2. Natural selection （自然選擇）（自然選擇）

- Darwin’s contribution (1859) was to unite 1 and 2. - Darwin’s contribution (1859) was to unite 1 and 2.

- Religious opposition to evolution often fails to - Religious opposition to evolution often fails to

distinguish between the two aspects. distinguish between the two aspects.

- Legitimate scientific theories such as mutationism, - Legitimate scientific theories such as mutationism, and neutralism have questioned the supremacy of and neutralism have questioned the supremacy of natural selection. natural selection.

神造萬物神造萬物

(creationism)(creationism)

輪回說輪回說reincarnationreincarnation

III Common ancestry and the origin of human

11. How do we know that human, chimpanzee, . How do we know that human, chimpanzee, gorilla, and orangutan were once of the same gorilla, and orangutan were once of the same stock?stock?

Traditional classic methods

– Morphology, behavior, physiology, and

geographic distribution

New molecular evolutionary methods – DNA and proteins -

Think about hand-scribed versions of bibles before Guttenberg press in Europe.

“In the beginning God created the heavens and the earth.”

Version 1 - In the beginning God created the havens and the earth.

Version 2 - In the beginning God created the havens and the earth.

Version 3 - In the beginning God crated the heavens and the earth.

Version 4 - In the beginning God crated the heavens and the earth.

1 2 3 4 5 6 7 8 91 2 3 4 5 6 7 8 9HumanHuman T C C T T A A A AT C C T T A A A AChimpChimp T T C T A T A A AT T C T A T A A AGorillaGorilla T T A C A A T A AT T A C A A T A AOrang-utanOrang-utan C C A C A A A T AC C A C A A A T A

3,000,000,000 letters

H-C ~1.2% 5 Mys 36,000,000 difs

H-G ~1.5% 6 Mys 45,000,000 difs

H-O ~2.5%, 12 Mys 75,000,000 difs

Human Chimpanzee Gorilla OrangutanHuman Chimpanzee Gorilla Orangutan

H C G OH C G O

WARWAR war ? ? war ? ?

? ? SEX sex sexSEX sex sex

1.1. How different are humans and chimpanzees?How different are humans and chimpanzees?

C.C. Not very different, only 1.2% after all. Not very different, only 1.2% after all. The phenomenon of neoteny (lengthening of the The phenomenon of neoteny (lengthening of the

juvenile period) extends to cranial morphology, juvenile period) extends to cranial morphology, position of magnum forum etc.position of magnum forum etc.

F.F. Very different - 3,000,000,000 x 1.2% = 36,000,000 Very different - 3,000,000,000 x 1.2% = 36,000,000 differences in our genetic codedifferences in our genetic code

V. Natural selection

SummarySummary

(1) Female/male=1 is the result of natural selection; it is also (1) Female/male=1 is the result of natural selection; it is also “unintelligently designed”“unintelligently designed”

(2) Natural selection does not always lead to the benefit of the (2) Natural selection does not always lead to the benefit of the species. It does almost alwasy lead to the benefit of the species. It does almost alwasy lead to the benefit of the genes.genes.

““Chickens are eggs’ way of making more eggs”Chickens are eggs’ way of making more eggs”

The concept of selfish genes “Individuals are genes’ way of making The concept of selfish genes “Individuals are genes’ way of making more genes”more genes”

Conclusion – Conclusion – Humans and human nature are Humans and human nature are the products of evolution, most likely the products of evolution, most likely influenced by natural selection. Humanity, influenced by natural selection. Humanity, social sciences, philosophy and religions social sciences, philosophy and religions would do well to heed this simple logic in would do well to heed this simple logic in the quest to understand ourselves.the quest to understand ourselves.