PSY 544 Lecture Notes - Lecture 2: Jean-Baptiste Lamarck, Thomas Robert Malthus
• Outline
• Theories of evolution: historical and modern
• Lamarck
• Dari’s Theor of Natural “eletio
• Dari’s Theor of “eual “eletio
o Intra-sexual selection and Inter-sexual selection
• Other sources of genetic change
o Founder effects, genetic bottlenecks
• What did Darwin miss? The modern synthesis.
• The impact of Darwin in other fields
• The impact of Darwin in Psychology
• Evolution before Darwin
• Eolutio just eas hage oer tie. “o he e talk aout eolutio e're talkig
abt change over time
• When we talk about natural selection though, we're talking about a theory of evolution
• Before Darwin, people had speculated that, rather than having remained the same since
the beginning of life, animals had evolved. And before Darwin people were looking at three
sources of evidence that were emerging and starting to push in the direction that maybe
animals had evolved over time and that they weren't always as how we see them today
• Differences between bones of existing animals and fossils – were life forms once
different?
People started digging up fossils and noticing that fossilized bones looked diff
from the bones of animals today, there were no living versions of the animals
whose bones they found
• They started noticing Similarities in bones of existing animals – did one change into
the other?
So differences with animals that don't exist anymore (1st point) and some key
similarities (2nd point) in the bones of the animals giving them the idea that the
maybe the animals are all related and maybe with just a few key changes you
can see how one animal may have become another
This gave them the idea that all existing life might have once been related to
one another because there were strange similarities in the structure of the
embryonic
3. Similarities in embryonic development – are existing life forms all related? Embryos of
fish, turtle, cat, chicken, human and there are certain structures that appear in all of
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them so why are these things similar and is it possible that they were all once related
- all seem to share some features
• Evolution before Darwin
One of the key theories of evolution before Darwin:
• Jean Baptiste Lamarck (1744-1829) his idea of evolution was that there are animals and
through out their lives they use some parts of their bodies more than others and he said
that the more they use their parts of the body, some fluid gets secreted and that part of
the body gets bigger - so it's kind of a use it or lose it idea
• Ex. He said giraffe used to be an animal with a small neck but through out it's life the
giraffe kept stretching it's neck to reach higher (in order to eat trees) and over their
lifespan their necks got bigger
• Use vs. disuse: Use it or lose it for the body.
• He argued that: Acquired changes are passed on to offspring. He argued that giraffe kept
stretching their necks over their life and then when they had kids, those kids were born
with longer necks
• He said, Repeated over generations, this can lead to new species.
• We know this idea is wrong because acquired changes tend not to get passed on to
offspring
It's not the case that if I spend all my lives exercising and making muscles that my kid
will be born with big muscles - the thigs that happe to us do’t eessaril get
passed on
This was a precursor to Darwin's idea
• Darwin’s Theor of Natural Selection
• Charles Darwin (1809-1882)
• A naturalist on HMS Beagle, travelling the world from 1831-36.
• Darwin was a naturalist who was studying animals in the natural env, studied where
animals existed, what types of animals existed in which type of envs and famously went on
a vogue on a ship (HMS Beagle), travelling around the world for 5 years. He travelled
around passing along diff places
• The key inspiration for Darwin were the Galapagos islands - he made a set of observations
at the Galapagos islands triggering him to think about how theory of evolution might
involve species changing over time
• Darwin’s Theor of Natural Selection
• Darwin noticed both similarities and differences in species of Finch across the Galápagos
Islands. Across the islands there were diff birds, Darwin noticed that they have some
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Document Summary
Outline, theories of evolution: historical and modern. Lamarck: dar(cid:449)i(cid:374)"s theor(cid:455) of natural ele(cid:272)tio(cid:374, dar(cid:449)i(cid:374)"s theor(cid:455) of e(cid:454)ual ele(cid:272)tio(cid:374) The modern synthesis: the impact of darwin in other fields, the impact of darwin in psychology, evolution before darwin, e(cid:448)olutio(cid:374) just (cid:373)ea(cid:374)s (cid:862)(cid:272)ha(cid:374)ge o(cid:448)er ti(cid:373)e(cid:863). Embryos of fish, turtle, cat, chicken, human and there are certain structures that appear in all of them so why are these things similar and is it possible that they were all once related. All seem to share some features: evolution before darwin. One of the key theories of evolution before darwin: It"s not the case that if i spend all my lives exercising and making muscles that my kid will be born with big muscles - the thi(cid:374)gs that happe(cid:374) to us do(cid:374)"t (cid:374)e(cid:272)essaril(cid:455) get passed on. Across the islands there were diff birds, darwin noticed that they have some similarities and some differences.
