Darwin and Evolution Philosophy Through the Centuries BRENT SILBY Unlimited (UPT)

Darwin and EvolutionPhilosophy Through the Centuries

BRENT SILBYUnlimited (UPT)

Darwin and Evolution

Young Not so young

The ancient world view

God created the world

Humans are separate from the natural world

The world only existed for about 7000 years. That’s acomfortable timescale that people can understand.

No religious theory ever considered that we are related toanimals. Humans are special, put here by God to look afterplanet Earth.

The current world view

Homosapiens (modern humans) first appeared 100,000 years ago

The Hominid line(the family to which humans belong) split from the apes about5-6 million years ago.

Life originated on Earth approx 3.5 billion years ago

Earth first formed about 4.5 billion years ago

Universe sprang into existence between 10 and 15 billion yearsago

Humans are biologically very similar to other animals. The onlydifference is our mind, which is the result of culture.

Entire human history takes about 1 part in 35000 of the historyof life.

This means if you lined up 35000 dollar coins to represent theentire history of life on Earth. Human history would all becontained in the last coin.

Or, think about driving to Dunedin, each kilometer is 10 million years

All of recorded human history, less than 1 meter

Modern humans appeared about 10 meters that way

Homo heidelbergensis

Neanderthal Human

Split from ancient apes around Yaldhurst/Avonhead cnr

Dinosaurs extinct around Hornby mall

Dinosaurs first appeared around 25 kilometers further, say Rolleston

First multi-celled life forms just beyond Ashburton

First simple cell in center of Dunedin

The Theory of Evolution

Given the evidence, it is reasonable to accept the Theory ofEvolution as true.

Basic idea:• All living things are related by descent

• This is Darwin’s “Descent with Modification” theory

• Natural selection is the cause of evolution.

• Natural selection explains adaptive change.

A rationally convincing, logically sound argument for Evolution:

1. In ideal circumstances (unlimited resources) populations will grow exponentially

2. Resources are limited

3. Because resources are limited, populations tend to remain stable

4. Individuals within a population have unique characteristics

5. An individual’s characteristics are passed on to its offspring (inheritance)

6. Change can occur. This sometimes results in offspring having slightly differentcharacteristics to their parents

7. Given the fact that individuals have varied characteristics, it is reasonable to supposethat some individuals will have characteristics that give them a better success atsurviving and reproducing

8. Given premise 5, it is reasonable to assume that characteristics that enhance anindividual’s survival and reproductive success will be passed on to its offspring. This isnatural selection.

9. Evolution is the result of this process

10. Populations that possess the above characteristics will evolve.

A common objection to Evolution Theory

The probability of humans evolving is so extremely low that it ismore likely that we were created by an intelligent designer.

Response 1

A low probability does not entail impossibility

Response 2

It may seem like a low probability, but consider the time frame involved. This didn’t happen over night.

Response 3

Anti-evolutionists are misguided in their assessment of the odds.

Consider the following experiment:6 students are given a card from a deck of 52 poker cards

[give cards to students][list their values on board]

You work it out like this:52 x 51 x 50 x 49 x 48 x 476 x 5 x 4 x 3 x 2 x 1

= 14658134400 720

= 1 in 20,358,520

What is the probability of this series of cards being delt?

1 in 20,358,520

Incredible, such a low probability and yet we did it.

It is a mistake to look at the end result and then attempt tocalculate the likelihood of that result occurring.

A better approach is to look at the likelihood of each step alongthe way.

For example:Card 1: 1 in 52Card 2: 1 in 51Card 3: 1 in 50Card 4: 1 in 49Card 5: 1 in 48Card 6: 1 in 47

Think about evolution as a 3.5 billion year long list of smallchanges, rather than looking at the end result and trying to lookat the odds of that end result occurring.

Another common objection to Evolution Theory

There is not enough evidence to support the theory

Response: This objection looks at things the wrong way around

It is not the case that Darwin came up with the idea of evolutionthen went out to look for evidence to support it.

Rather, he developed the theory to explain the evidence he sawaround him. Currently his theory is the best way to explain theevidence he found in the world.

It’s like detective work.

We are animals…

98.4% of our DNA is shared with chimpanzees

All of these creatures evolved from a “common ancestor”

“Evolution” in everyday language means“Progressive change”, or “change with a purpose”

This is not true for biological evolution.

In biology, evolution is not progressive. It has no purpose orend goal.

The term “More Evolved” has no meaning in biology. People arenot “More Evolved” than chimps, or dogs, or worms.

All animals are perfectly evolved to suit their environment. Amonkey cannot survive underwater, and a dolphin cannot survivein a tree. But they are perfectly evolved to survive in their ownenvironments.

What is species?

An arbitrary term used to identify different types of animals.It’s a convenient grouping system invented by people.

From an alien point of view, we are all very similar and are allmembers of “biological life on Earth”. They may not see ourlogic in grouping according to species.

An alien may categorize groups of life-form in a totally differentway

Speciation

A common objection to Evolutionary Theory refers to theappearance of new species.

This objection is misguided and ignores evidence. The fossil recordand DNA evidence show that speciation took place.

Furthermore, biologists have observed species divergence in both natural and artificial environments.

People accept that natural selection builds adaptations within aspecies, however they claim that the process will never bringabout a change from one species to another.

“There are lots of different types of dog, but a dog is always a dog. It cannot turn into a cat”

Speciation

The process by which species diverge into new species iscalled “speciation”

Speciation has been observed in the Three-Spined Sticklebackfish

Speciation

Over 10,000 generations, the Stickleback has been observed tolose its pelvic hind fins, gain tougher armor, and lighten in color.

Stickleback’s elsewhere remain the same and can no longerbreed with the new Sticklebacks.

The Stickleback is an example of parapatric speciation, whichmeans the two species are not geographically separated andcan come into contact, yet they have selected mechanisms whichprevent breeding.

Speciation

Artificial Speciation occurs through human intervention

For example, domestic sheep were created through a longprocess of artificial selection.

They no longer produce viable offspring with Ovis Orientalis, a species from which they are descended.

Males Female

Speciation

A gene responsible for speciation was discovered in 2008. Itcauses reproductive isolation, and hybrid sterility between relatedsubspecies.

If humans can make a new sheep species in just a few thousandyears, imagine what nature can do in 3 billion years.

For more examples of observed speciation, please ask for links

Natural selection builds systems that solve adaptive problems

The solutions do not need to be elegant. Rough solutions thatwork can be selected for.

- Example of frogs catching flies

- Example of wasp checking for danger

Solutions to Adaptive Problems

EVOLUTIONARY PSYCHOLOGY

An Evolutionary Explanation of the Human Mind

The mind is an adapted organ, just like any other organ in thebody.

The mind is a collection of thousands of specialized “algorithms”These algorithms are adaptations to the hunter-gathererenvironment where humans first evolved.

We have stone age minds.

The Adapted Mind

Natural selection builds specialized tools. The human mind isa collection of specialized tools. It is not a big all-purpose tool.

The mind contains many specific intelligences, not a “GeneralIntelligence”

• Special intelligences include algorithms for:* Face recognition* Spatial relations* Rigid object mechanics* Distinguishing living from non living things* Tool use* Social interaction* Interpreting expression and understanding emotions* Recognizing family and caring for children* Sexual attraction, friendship* Many many more…

These mind algorithms are like software which were built bynatural selection to solve adaptive problems.

These mental programs evolved as humans evolved in theancient hunter-gatherer environment. Our minds are built fromsoftware designed to solve ancient problems.

Problem:We do not live in the ancient environment anymore. Oursociety and culture has changed faster than evolutionoperates.

The adaptations built by natural selection worked for ourancestors, but they may not be so useful for us anymore.

Some examples…1 Sweet tooth

2 Eating meat

3 Invisible monsters in children’s bedrooms

These adaptations were very useful in the past, but they are nowmaladaptive. They do more harm than good.

3 problems for Evolutionary Psychology

1 Perhaps these are simply “Just so Stories”* Invent an evolutionary explanation for a known behavior. Its easy to do, but hard to test for truth.

2 Inventing adaptations* Psychologists guess what the hunter-gatherer environment was like, then conclude that it would be a benefit to have a certain behavior in that environment. They then conclude that evolution provided us with that behavior (e.g. the female multi-task myth)

3 Cultural explanations* Human brains are flexible devices, and can change in response to culture. Many human abilities are learned. Just because all humans have the behavior, it doesn’t mean it was inherited. It could be culturally learned.

Powerpoint by BRENT SILBY

Produced at UPTChristchurch, New Zealand

www.unlimited.school.nz