PSYA01H3 Lecture Notes - Lecture 11: Horse Breeding, Selective Breeding, Natural Selection
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Psychology Lecture 11 (Chapter 3)
Slide 1: Debate about nature (genetics) vs nurture (environmental/real life influence to your behavior)
Evolution, like geologic evolution had been a talk during Darwin’s days- you can see the history and the
changes in the strata of the rocks. Darwin used that idea when looking at life forms.
He collected new species (endemic, distinct species that can only be found on the island), but eventually
he started wondering about the reason for their traits.
We could have traits because it helped in adaptation, but also because they don’t harm us. Ex: males
have nipples, but they did not lose that feature in the centuries because it did not have a negative point
to it (ie. It did not harm the man, or gave a disadvantage in attracting the opposite sex for mating).
Evolution occurred over centuries in terms of times, and considers natural selection. An analogy is
‘survival of the fittest’ in which ‘fit’ means you’re able to survive in the environment you live in.
Ex. If the only habitable place is a high place, people that can reach that place would be more fit,
because they can survive in that environment.
Ex: in the past, being big and strong is an asset in surviving in a past where you had to hunt and fight
other beasts. Because of this, females are attracted to big and strong even today, but in the past that
was attractive because a big and strong man meant they could be better protected, they had better
access to food, and the offspring can become big and strong. Females were considered attractive, even
on a global scale, who had a specific waist size, because those females would be able to bear children
better in the past. Today, the hip-to-waist ratio is irrelevant with our medical advantages, but they are
still considered the primary attractive figures. These features are irrelevant today, but they had an
impact in the past, it’s just that evolution has not changed those up yet. Today, the environment is
different (you could say that people with a lot of money would be more attractive)
Slide 2: Darwin noticed that certain species were in certain islands, and had features that matched
where they were on the island. Ex: birds had strong beaks in a place with thick nuts.
Artificial selection: horse breeding, dog breeding; these were breeding that were done by people to
create animals of interest. People knew that the traits are inherited from the parents, but not why. This
selection showed Darwin that features can be passed down, but it was done by humans. Maybe the
same gist happens in nature, but the animals choose the mates themselves.
Darwin started publishing his theories after Wallace started running into the same ones. They compiled
their publications, but at the end it is recognized as Darwin’s theories after Wallace announced that
Darwin established it first.
Slide 3: Evolution is gradual- this means that evolution can occur through generations. Ie. Cockroaches
evolved fast, because they have short lifespans, thus had many generations during a short lifespan.
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