PSYC 3100 – Week 3
Lecture 5 – September 24
(Finishing Chapter 2)
- Does natural selection work at the level of the organism? Or does it work at the level of the gene? Are we selecting for the
species or the group?
- Eventually, there will be enough change in a species so that you will end up with 2 groups of animals who are reproductively
isolated – start with common ancestor but will continue to grow and change eventually to produce 2 sub-species
o E.g. Humans and apes – have a common ancestor, continue to breed, we become reproductively isolated – now 2
- Humans and other creatures will breed far more than the planet will offer resources to it – competition, populations grow
exponentially, and most resources stay the same or grow arithmetically – PROBLEM!
- Thomas Malthus (1798) – resources can‟t keep all individuals satisfied. What to do? Only 2 possibilities for more shelter, more
o Moral restraint (keep it in your pants)
o We need war, famine, disease – it‟s tragic, but absolutely necessary to cull the population of otherwise irresponsible
o Classist, highly educated up-scale guy who thought it was the lower-class that was breeding irresponsibly, thought
natural disasters were well aimed because they were at lower class people
Today you hear “wrong people doing all the breeding”, that is a 2012 version of Thomas Malthus
o Lower class are less responsible than upper class
o Malthus did not see the way the media viewed breeding rate, network news will feature a story on a couple with 12 kids,
they cute-ify – don‟t have the resources to look after all 12 children, maybe 2 of them – by showing their kids, they are
showing that irresponsible breeding is cute
- Sexual selection
- Not every trait is adaptation – some are EXAPTATIONS – now enhance fitness but were not built for their current role
o E.g. feathers – built for warmth, not for flying originally Lecture 6 – September 26
Chapter 3 - Genetics
- Shocking that Darwin got as far as he did as he knew DIDDLY-SQUAT about genetics
o Knew mutations were around, but didn‟t know where they came from – didn‟t understand variation
Key terms and issues (Should be able to speak/write a few sentences about each of the following terms/concepts)!!
- Watson & Crick (1953)
o 1953, founded Double Helix of DNA. Won Nobel Prize
o Genes have particular spot on particular chromosome (of which there are 23 pairs)
o 50/50 chance of getting gene from Mother/Father
o Genes shape phenotype
- Alleles – alt alleles (T vs. t)
o Genes – can be 2 different forms in one area
o Why are there alternate alleles? In some cases there are no alternate alleles, but in others alternate alleles exist (e.g.
o Mutations are basis of variation
o Come into being because body screws up, they are „copying errors‟ – in order to pass on gene it has to be copied.
o Pose no advantage, and get selected out before they get going – but once in a while the body may enjoy the mutation