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05-30-2010, 11:19 PM | #11 (permalink) | |
thirsty ears
Join Date: Sep 2009
Location: Boulder
Posts: 742
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Quote:
don't expect dramatic change so fast. 40K years is nothing at all on an evolutionary timescale. but also remember that we humans have a tendency to resist change by adapting our environment to suit us, rather than vice versa. individuals born with sub-optimal traits are nursed and cared for rather than being left to die. disease rarely takes its toll on the week. etc etc. we've kind of put a wrench in the gears of the system. but no matter, wait till a global disaster comes around and then see who's strong enough to survive in the post-apocalyptic world. it will take a lot more than ruthless inefficiency and a fat wallet
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05-31-2010, 01:57 AM | #12 (permalink) | ||
Juicious Maximus III
Join Date: Nov 2008
Location: Scabb Island
Posts: 6,525
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Quote:
"Random" mating - which means mates are chosen at random. You don't choose a mate based on favourable characteristics that make them attractive (assortative mating) and you don't do inbreeding. Infinite population size (no genetic drift) - Basically, it has to be infinitely huge because then stochastic effects like rock slides killing off some germans here f.ex won't have much impact on the common human genome. No natural selection - Nothing in the social, biotic, abiotic, whatever environment that makes one trait more favourable than another. No gene flow - No input of alleles from different populations that may disturb the equilibrium. No mutations - Mutations will create new alleles and if these increase in the population, that violates the HW equilibrium criteria. In a population that satisfy all these criteria, the new generation should have the same genes (alleles) in the same proportions as their parent generation. This means that although the population may create different individuals, the genome as a whole doesn't change much - it contains the same varieties of genes at the same frequencies. As I wrote, this is not attainable. For example mutations do happen whether we like it or not and we do have sexual preferences. There are also a range of selection pressures, but they vary very much with where you are. Some places in the world, malaria can f.ex be a real selection pressure which favours some mutations. Where I am, it is not. Whether or not there is gene flow is a question of definition because you then have to define the human population or populations that gene flow can occur between, so that's relative. Also, depending on how you see it, you could argue that the human population size is huge So sometimes, large populations of organisms may "approach" what looks like a HW equilibrium. Depending on how you define a human population - f.ex if you only look at Norway or some other western country, you could probably find that we do as well. However, it's never quite attainable and at any rate, it's only temporary. Some stronger selection pressures are bound to come along soon enough. edit : Quote:
http://en.wikipedia.org/wiki/Sickle-cell_disease In other words, which mutations are beneficial or not may simply depend on the environment you're in and environments change over time.
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05-31-2010, 04:29 AM | #13 (permalink) | |
Account Disabled
Join Date: Mar 2007
Location: VAN
Posts: 2,530
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05-31-2010, 04:35 AM | #14 (permalink) |
Juicious Maximus III
Join Date: Nov 2008
Location: Scabb Island
Posts: 6,525
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^That (duga's post) is indeed a statement and I think you should always be a bit careful when making statements. At least ask yourself "how do I know this is true?"!
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05-31-2010, 04:41 AM | #15 (permalink) |
thirsty ears
Join Date: Sep 2009
Location: Boulder
Posts: 742
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haha thanks a lot tore, you just rendered my entire discipline (anthropology) useless with one little post
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05-31-2010, 07:02 AM | #16 (permalink) |
killedmyraindog
Join Date: Aug 2004
Location: Boston, Massachusetts
Posts: 11,172
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Mine does. I was using this cream and it was gone for awhile. Other day my evolution started acting up and my foot went polydactyl.
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05-31-2010, 05:29 PM | #19 (permalink) |
Juicious Maximus III
Join Date: Nov 2008
Location: Scabb Island
Posts: 6,525
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How do you know it plays a greater part now than it did say .. 20 000 years ago?
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05-31-2010, 05:50 PM | #20 (permalink) |
The Music Guru.
Join Date: Jun 2009
Location: Beyond the Wall
Posts: 4,858
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If you mean that people can possibly select the sex of their child due to things like the "test tube" baby or artificial insemination, then sure. But in regards to natural conception, there's no such thing as selecting the gender of the child. You get what you get.
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