Misconceptions + Acceptance Flashcards
Terminology - ‘Natural Selection’
Invented by Herbert Spencer
- Problems with definition of
Fitness
- Fitness applied to societies
Brought about the idea of helping the weak makes society weaker
What is Social Darwinism?
Applied the idea of survival of the fittest to societies
- Some individuals are better than others
- Free competition helps ensure only the most capable survive and rise to the top
Social Darwinism and Eugenics
If government helps the weak, they survive, pass on their characteristics, and society is thereby weakened
- Eugenics = control the development of the
human race through organized breeding
programs
Issues with using the term Natural Selection + where it comes from
- Derived from analogy with artificial selection
- Semantic problem - implies purpose/direction
Darwin preferred=> Natural Preservation
Can use => Differential survival
Evolution + Fears around religion
- Theory that explains diversity and change in organisms was not explained by god but by evolution
- Fears this would lead to abolition of God, loss of free will / purpose
However, some saw it as strengthening of religion
Misconception - Evolution results in increase in complexity
- Leads to better adapted animals
- Fitness depends on environment, complexity/more features may not work
- e.g whales and snakes lost their legs => less complex => but better adapted
Misconception - All adaptation are advantageous
Genes can affect many characters – pleiotropy
- A single gene influences multiple phenotypic traits
- As long as overall fitness is increased, neutral or negative
adaptations can occur
Negative characteristics may be selected (controlled by same genes) for, if overall, there is net benefit
Antagonistic pleiotropy
Adaptation isn’t positive throughout an organism’s lifespan
- In youth, testosterone is positive;
increases reproductive fitness - In later life, there are negative
effects: increased prostate
cancer
Misconception - Natural Selection is the only mechanism
- Role of chance - founder effect
- Genetic drift - small populations
What use is half an eye? - Argument that initial stages of organ development is useless
From complexity argument
- initial stages of development of eyes was still advantageous - light-sensitive cell
Misconception - Age of the Earth
- Initially thought was too young for how gradual process of evolution
- But now thought to be older than first estimated from the bible
Misconceptions about the Fossil Record
- Darwin predicted gradual change in fossil record
- Punctuation seen as gaps which would be filled
- Point of stasis could be due to punctuated equilibrium - was no reason for change as environment was same for a while
Examples of traditional fossils
- Ichthyostega- emergence of legs
- Archaeopteryx- early evolution of birds
- Pakicetus, Ambulocetus, Indocetus, Protocetus- land
to water transition (whale)
Are sudden large changes possible
Homeotic genes (Hox genes)
- specify the anterior-posterior axis and segment identity during early development of animals.
- Homeotic mutations give big changes
Mutation causes structural changes => may cause an advantage
- Basic instructions are the same
- Changes in timing can have large effects
- Fundamental blueprint is the same
Misconception - The Mechanism of Evolution - Darwin’s Scheme
Darwin’s scheme – blending
- Any beneficial variation diluted out
- Negates effect of natural selection
- Change is more gradual
