PSY252 Lecture 2 January 17, 2014
Darwin’s dangerous idea: cont’d
- Reproductive advantage of certain features
- Development of complex organs (eyes, heart, etc.) there has to be a designer.
o Creationist’s argument: how can complex organs evolve?
o Complex organs like the eye are designed in a bad way, with many mistakes.
o All evolution does is it modifies existing genotypes & phenotypes, carry the
mistakes of the past, works from an existing genome
o Ex. Unnecessary features we carry in our body: appendix, tail bones, etc.
- Survival is not the point, reproduction is.
o It doesn’t matter if a gazelle is fast but if it doesn’t mate, that gene that made that
gazelle fast and allowed it to survive 200 years will not be passed on.
o Fitness, number of genetic copies you make of your own genome – reproduction,
copies will spread and survive in the population
o Survival to reproduce
- Natural selection: forces of nature select which organism will survive
o Adapt to changing environments
o better suited to the local environment
o will not move a particular species to betterment, only allows individuals to adapt
to their local environment
o no predetermined directional change
- Can you see natural selection at work?
o Bacteria becoming more resistant to antibiotics
o Reproduce rapidly, one a minute a new generation arrives
o Viruses: produce new generations in seconds, evolution is amazingly fast, new
mutations can be seen under microscope
- Evolution of HIV the virus that causes AIDS
o Virus keeps adapting o 19 HIV drugs
o HIV replicates at an alarming rate
During reproduction DNA replicates
• Replication: two strands of DNA separate and two copies are
made of the original
• During the process some