EVOLUTIONARY THEORY

Question 1

define evolution

Answer 1

a change over time

living things: refers change over time in the structure(s) of living things

many scientists before Darwin, especially geologists and embryologists, suspected that evolution occurred and they offered theories about how it might work

Lamarck (1744-1829) popularized the theory of inheritance of acquired characteristics. The theory is mechanistically plausible and it could potentially explain evolution and the existence of purposeful structures. But there was a problem with the theory… acquired characters (generally) aren’t passed on.

Question 2

darwins goals

Answer 2

Darwin liked Lamarck’s theory but thought it was incomplete in scope and possibly incorrect in its mechanism

Darwin wanted to explain:
1. the mechanism of evolutionary change
2. the existence of purposeful structures
3. the origin of species.

clues of this:

-darwins finches
- horse breeding
- more organisms are made than what can survive

Question 3

evolution by natural selection

Answer 3

1. Variability exists (variance)
2. Variability is passed on (heredity)
3. Some variants survive & reproduce better than others (selection)

When all 3 conditions are met, then some variants will increase/decrease in frequency.

The change in frequency of particular variants in a population, due to inheritance and selection, is called “Evolution by Natural Selection”.

Question 4

misunderstandings in evolutionary theory

Answer 4

1. Human Behavior is Genetically Determined. The environment is unimportant

Evolutionary theory presents an interactionist framework: evolved, genetically based adaptations must be triggered by appropriate environmental input.

2. If It’s Evolutionary, We Can’t Change It

Since genes and environment always interact, we can alter the environment if we want to alter the outcome
The better we understand our evolved psychological mechanisms, and how they interact with the environment, the greater our power to create desirable outcomes.

3. Current mechanisms are optimally designed

A. Our current mechanisms represent adaptations to past environments. So if the current environment differs substantially from our previous one, the mechanisms won’t be adaptive or useful any more.

B. All adaptations have costs so not all features can be optimized

C. Natural selection has no foresight so it often doesn’t find the best solution to a selective problem. It usually finds solutions (traits) that are better than other ones currently in the population.

Example of an imperfect adaptation: The design of the vertebrate retina is “inside-out.” Where the optic nerve leaves the eye, there is a hole, which results in a blind spot

In the eyes of some mollusks (squids and octopuses) the retina is in front of the optic nerve, and thus they have no blind spot.

Question 5

sexual selection

Answer 5

Sexual selection was defined by Darwin (1871) as “the advantage which certain individuals have over others of the same sex and species, in exclusive relation to reproduction”

Sexual selection and natural selection both require that the same 3 conditions be met:

Variance, Heredity, and Selection

The difference is that, in sexual selection, variants or traits that increase reproductive success are selected, rather than traits that favor survival.