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the miller-urey experiment (1950s)
they mixed gases thought to be present on primitive earth
methane (CH4)
ammonia (NH4)
water (H2O)
hydrogen (H2)
the mixture was sparked to create lightning
the results were amino acids, the building blocks of protein
what gases were used in the miller-urey experiment?
methane (CH4)
ammonia (NH4)
water (H2O)
hydrogen (H2)
who was lamarck and his beliefs?
the first scientist to propose a system of evolution
noticed that fossils became more complex in more recent rock strata
believed that there was an internal drive towards the complex
each species came from less complex ones
believed evolution was based on 2 principles
acquired characteristics with example?
organs/structures became stronger/weaker with use/disuse & are passed onto offspring
ex: long necks of giraffes
universal creative force definition?
an unconscious striving in the lower creatures to become more complex & more human
what did hutton & lyell conclude?
the earth was very old & had changed its form slowly over time due to natural processes
what did lyell do?
he dated the ages of rocks by using fossils embedded in the stone as time indicators
who was erasmus darwin?
charles darwin’s grandpa
suggested that competition between individuals could change species
what did malthus do & believe?
observed that in nature, organisms produce more offspring than survive
observed that human pop. can’t keep growing indefinitely
if the birth rate exceeds the death rate, humans would eventually run out of living space
famine, disease & war prevented endless pop. growth
competition → survival of the fittest
charles darwin’s hypothesis?
he hypothesized that if the earth changed slowly over time, then the environmental pressures on different species would also change
these emerging changes would then force the species or perish
darwin’s 6 points
like begets like & more are produced than survive (overproduction)
there is a struggle to survive w/ available resources (competition)
variations exist among the population (variation)
variations can be favourable & may offer a selective advantage (adaptation)
those best suited to their environment survive (natural selection)
w/ enough accumulated differences, a new species may arise (speciation)
what is evolution?
a change in the allele frequency in a pop. over time
who’s wallace?
developed similar ideas on evolution & natural selection at the same time as darwin
