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Unformatted text preview: BIOL 164 Genetics, Evolution, & Society
I. Genetic Mechanisms II. The Big Picture III. A World with Humans in It The unity of life & the necessity of evolution by natural selection Dr. Joseph S. Walsh Hogan 6-110A 6- "Nothing in biology makes sense except in the light of evolution." evolution." - Theodosius Dobzhansky ~~~~~~~~~~~~~~~~~~~~~~~~~ The genetic code is universal Life uses only L-amino acids LHomology of anatomical traits The fossil record The origins of diversity Only one of two possible `identical' identical' stereoisomers of any amino acid (e.g., alanine) is alanine) found in nature. Both (top kind is L-alanine, bottom alanine, is D-alanine) are D- alanine) produced in the lab in a 50:50 mix. The peptide bond between amino acids in proteins forms here, with loss of water. In a mix of L- & D-amino acids, one could not L- Dpredict where the important, reactive functional groups (R's) would be! (R' The functional groups are always on "opposite sides" during protein assembly. sides" That only L-amino acids are used argues for La single origin of all of living things. things. 1 Homology of forelimb bones in mammals The geological record documents the evolution of life for over half a billion years. "Nothing in biology makes sense except in the light of evolution." evolution." - Theodosius Dobzhansky ~~~~~~~~~~~~~~~~~~~~~~~~~ The origins of diversity: Genes, species, & ecological communities display enormous diversity, and are functionally matched ("adapted") to one (" adapted" another and their environments. Evolution by natural selection is the organizing principle of biology. Charles Darwin defined evolution as, "descent with modification". modification" DARWIN's 4 OBSERVATIONS: DARWIN' Organisms overproduce offspring. Population sizes are relatively stable. There is variation in proficiency at tasks demanded by environment. That variation is heritable. LEAD TO 1 NECESSARY CONCLUSION: Evolution by natural selection must occur. A deer population growing at 10% ... N1 = N0 + rN0
This population does not grow: 100, 110, 120, 130, 140, 150, 160, 170 This population grows: 100, 110, 121, 133, 146, 161, 176, 194 2 dN dt N dN dt N K Time Time Time Time When N1 = N0 + rN0, and dN/dt = rN, rN, population grows geometrically... geometrically... but the deer population cannot grow forever! Growth slows when dN/dt = rN(K-N) , rN(KK as carrying capacity (K) is approached. Earth-tone Earthincreases in every generation. Earth piglet Ice piglet Single advantageous mutant (earth-tone) (earth- And, yet Dr. Eugenie Scott had to found the National Center for Science Education because evolution is repeatedly attacked... attacked... Aug 1999 Kansas BoE voted to remove evolution from state stand'zd testing! stand' Dover, PA tried to require science teachers to teach "intelligent design"! design" And, the stickers... 3 Wisdom traditions & science have radically different modes of knowledge acquisition ... Which notion is more offensive to science: a levitating yogi, or a Loch Ness monster? ... one makes leaps of faith, the other follows trains of logic. Wisdom texts do not worry about violating scientific principles because it is not what they are trying to explain to people. Fortunately, they all have in common strong advocacy of the Golden Rule: "Do unto others as you would have others do unto you." you." - Various authors Science is an unending loop of inductive & deductive reasoning. Erecting and testing hypotheses is at its core. Hypotheses that repeatedly defy falsification attain the exalted status of "theory". theory" Evolution generates ultimate explanations; genetics and molecular biology generate proximate explanations. "Nothing in biology makes sense except in the light of evolution." evolution." - Theodosius Dobzhansky ~~~~~~~~~~~~~~~~~~~~~~~~~ The origins of diversity: Genes, species, & ecological communities... communities... But what is the fate of biological diversity? "There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five slowtwentyyears, and at this rate, in less than a thousand years, there would literally not be standing-room standingfor his progeny." - Darwin, On the Origin of progeny." Species by Natural Selection, 1859 Selection, 4 ...
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This note was uploaded on 04/18/2008 for the course BIOL_SCI 164 taught by Professor Walsh during the Spring '08 term at Northwestern.
- Spring '08