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Philosophy Through the Centuries

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Presentation on theme: "Philosophy Through the Centuries"— Presentation transcript:

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

2 Darwin and Evolution Young Not so young

3 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 a comfortable timescale that people can understand. No religious theory ever considered that we are related to animals. Humans are special, put here by God to look after planet Earth.

4 The current world view Universe sprang into existence between 10 and 15 billion years ago Earth first formed about 4.5 billion years ago Life originated on Earth approx 3.5 billion years ago The Hominid line (the family to which humans belong) split from the apes about 5-6 million years ago. Homosapiens (modern humans) first appeared 100,000 years ago Humans are biologically very similar to other animals. The only difference is our mind, which is the result of culture.

5 Entire human history takes about 1 part in 35000 of the history of life.
This means if you lined up dollar coins to represent the entire history of life on Earth. Human history would all be contained 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

6 Modern humans appeared about 10 meters that way
Homo heidelbergensis Human Neanderthal

7 Split from ancient apes around Yaldhurst/Avonhead cnr

8 Dinosaurs extinct around Hornby mall

9 Dinosaurs first appeared around 25 kilometers further, say Rolleston

10 First multi-celled life forms just beyond Ashburton

11 First simple cell in center of Dunedin

12 The Theory of Evolution
Given the evidence, it is reasonable to accept the Theory of Evolution 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.

13 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 different characteristics to their parents 7. Given the fact that individuals have varied characteristics, it is reasonable to suppose that some individuals will have characteristics that give them a better success at surviving and reproducing 8. Given premise 5, it is reasonable to assume that characteristics that enhance an individual’s survival and reproductive success will be passed on to its offspring. This is natural selection. 9. Evolution is the result of this process 10. Populations that possess the above characteristics will evolve.

14 A common objection to Evolution Theory
The probability of humans evolving is so extremely low that it is more 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.

15 Anti-evolutionists are misguided in their assessment of the odds.
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] What is the probability of this series of cards being delt? You work it out like this: 52 x 51 x 50 x 49 x 48 x 47 6 x 5 x 4 x 3 x 2 x 1 = 720 = 1 in 20,358,520

16 1 in 20,358,520 Incredible, such a low probability and yet we did it.

17 It is a mistake to look at the end result and then attempt to calculate the likelihood of that result occurring. A better approach is to look at the likelihood of each step along the way. For example: Card 1: 1 in 52 Card 2: 1 in 51 Card 3: 1 in 50 Card 4: 1 in 49 Card 5: 1 in 48 Card 6: 1 in 47

18 Think about evolution as a 3
Think about evolution as a 3.5 billion year long list of small changes, rather than looking at the end result and trying to look at the odds of that end result occurring.

19 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 evolution then went out to look for evidence to support it. Rather, he developed the theory to explain the evidence he saw around him. Currently his theory is the best way to explain the evidence he found in the world. It’s like detective work.

20 We are animals… 98.4% of our DNA is shared with chimpanzees All of these creatures evolved from a “common ancestor”

21 “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 or end goal. The term “More Evolved” has no meaning in biology. People are not “More Evolved” than chimps, or dogs, or worms. All animals are perfectly evolved to suit their environment. A monkey cannot survive underwater, and a dolphin cannot survive in a tree. But they are perfectly evolved to survive in their own environments.

22 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 all members of “biological life on Earth”. They may not see our logic in grouping according to species. An alien may categorize groups of life-form in a totally different way

23 Speciation A common objection to Evolutionary Theory refers to the appearance of new species. People accept that natural selection builds adaptations within a species, however they claim that the process will never bring about 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” This objection is misguided and ignores evidence. The fossil record and DNA evidence show that speciation took place. Furthermore, biologists have observed species divergence in both natural and artificial environments.

24 Speciation The process by which species diverge into new species is called “speciation” Speciation has been observed in the Three-Spined Stickleback fish

25 Speciation Over 10,000 generations, the Stickleback has been observed to lose its pelvic hind fins, gain tougher armor, and lighten in color. Stickleback’s elsewhere remain the same and can no longer breed with the new Sticklebacks. The Stickleback is an example of parapatric speciation, which means the two species are not geographically separated and can come into contact, yet they have selected mechanisms which prevent breeding.

26 Artificial Speciation occurs through human intervention
For example, domestic sheep were created through a long process of artificial selection. They no longer produce viable offspring with Ovis Orientalis, a species from which they are descended. Males Female

27 Speciation If humans can make a new sheep species in just a few thousand years, imagine what nature can do in 3 billion years. A gene responsible for speciation was discovered in It causes reproductive isolation, and hybrid sterility between related subspecies. For more examples of observed speciation, please ask for links

28 Solutions to Adaptive Problems
Natural selection builds systems that solve adaptive problems The solutions do not need to be elegant. Rough solutions that work can be selected for. - Example of frogs catching flies - Example of wasp checking for danger

29 EVOLUTIONARY PSYCHOLOGY
An Evolutionary Explanation of the Human Mind The mind is an adapted organ, just like any other organ in the body. The mind is a collection of thousands of specialized “algorithms” These algorithms are adaptations to the hunter-gatherer environment where humans first evolved. We have stone age minds.

30 Special intelligences include algorithms for: * Face recognition
The Adapted Mind Natural selection builds specialized tools. The human mind is a collection of specialized tools. It is not a big all-purpose tool. The mind contains many specific intelligences, not a “General Intelligence” 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…

31 These mind algorithms are like software which were built by natural selection to solve adaptive problems. These mental programs evolved as humans evolved in the ancient hunter-gatherer environment. Our minds are built from software designed to solve ancient problems. Problem: We do not live in the ancient environment anymore. Our society and culture has changed faster than evolution operates. The adaptations built by natural selection worked for our ancestors, but they may not be so useful for us anymore.

32 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 now maladaptive. They do more harm than good.

33 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.

34 Powerpoint by BRENT SILBY
Produced at UPT Christchurch, New Zealand


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