Salmonella enterica<\/em> in this case) and gave it a particular gene.\u00a0 Now this gene gave the bacteria a weak ability to survive without the amino acids histidine and tryptophan.\u00a0 The gene basically produced an enzyme that could (again, weakly) catalyze the production of both amino acids.<\/p>\nThis was determined to be the case by placing the bacteria in a medium that lacked both histidine and tryptophan and then seeing if they were able to survive, grow, and reproduce.\u00a0 Which the bacteria did.\u00a0 Averaging about 5 hours between cell divisions.\u00a0 However, if they placed some histidine in the growth medium, then the cell division time dropped to 2.6 hours.\u00a0 If there was tryptophan and no histidine, the cells divided every 2.9 hours.\u00a0 If both amino acids were present, the cell doubling time dropped to 1.5 hours.<\/p>\n
So, the strains that were in the no histidine\/no tryptophan growth medium were stressed.\u00a0 They could survive and grow, but they weren’t good at it (as shown by the increased reproduction time).<\/p>\n
I’ve tried to think of way to say this that was both cool and not anthropomorphic, but I couldn’t think of one.\u00a0 So, let’s just say that evolution happened.\u00a0 Evolution is always happening.\u00a0 Genes mutate, populations grow, compete, die out, etc. based on those genes.\u00a0 Well, in the case of this lab experiment, the end result was that evolution not only produced genes that were good at producing histidine and tryptophan, it also resulted in bacterial species with multiple genes.<\/p>\n
The gene was duplicated.\u00a0 That’s simply it, their was a mutation whose result was two copies of the same gene.\u00a0 Now, things really get interesting.\u00a0 Most of the time, if you have two genes producing a catalyst, then you get more catalyst.\u00a0 That happened, but you also have the ability to radically mutate one of the copies of the gene without harming the organism.<\/p>\n
And that’s the real benefit to gene duplication events.\u00a0 Because a mutation that would kill the bacteria could happen in one gene, but the other gene is still there, still functional and the organism lives.\u00a0 But again, selection takes over and there are many cases of what I call “potentiating mutations”.\u00a0 These mutations may be neutral or even harmful, but they are required for a future mutation that results in massive increases in functionality.<\/p>\n
So, after 3000 generations of bacteria (that’s about two years) what were the results?\u00a0 Oh this is really good.\u00a0 You’re gonna love this.<\/p>\n
There wasn’t one population with two genes.<\/p>\n
There were over 32 unique populations with different types of genes.\u00a0 Some of them had two genes, one that did histidine production and one that did tryptophan production.\u00a0 Some of them had a single gene that did both really well.\u00a0 And there wasn’t just one version of each of the three.\u00a0 There were over 11 unique alleles for these genes present in the various lineages and populations.<\/p>\n
In two years (roughly, that’s an estimate from the 3000 generations and the average generation time), there was\u00a0 a massive divergence in the bacterial populations.\u00a0 Some of the versions of the gene had a 20-fold improvement in catalytic activity.<\/p>\n
Thus, the creationists are wrong.\u00a0 We all knew it, but now there’s another tool in the arsenal against their arguments.<\/p>\n
I’d like to add something.\u00a0 Many creationists will come up with this pathetically stupid argument.<\/p>\n
All this experiment shows is that intelligently designed experiments result in changes consistent with Intelligent Design.<\/p><\/blockquote>\n
Well, no.\u00a0 It doesn’t show that at all.\u00a0 Yes, experiments are intelligently designed.\u00a0 They must be.\u00a0 The entire goal of an experiment is to reduce the variables down to one variable that is controlled by the experimenters and one variable that is controlled by that variable.\u00a0 This allows the determination if the controlled variable (also called “independent” or “manipulated” variable) is directly responsible for changes in the other variable (called the “dependent” or “responding” variable).<\/p>\n
What the Intelligent Design proponents are saying with this argument is that the experimenter<\/strong> is a variable within the experiment.\u00a0 This is not the case.\u00a0 Just like an intelligently designed roulette wheel still produces random numbers, experiments produce results that often confound the researchers. The whole point is to remove humans from the equation and only observe what happens to X when Y changes.\u00a0 Ideally, the researcher does nothing more than design the experiment and start it.\u00a0 No more human input or influence until the end of the experiment.\u00a0 Humans create all kinds of terrible errors in things.<\/p>\nIf we knew the results of the experiment (i.e. the “front-loading” argument), then there would be no point in doing the experiment.\u00a0 And casino game engineers would all be mufti-billionaires.<\/p>\n
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\n[1]\u00a0 Nachman, M. W. and S. L. Crowell. 2000. Estimate of the mutation rate per nucleotide in humans. Genetics<\/em> 156(1): 297-304.<\/p>\n","protected":false},"excerpt":{"rendered":"For a long time, creationists have insisted that evolution can’t add information to a genome.\u00a0 In general, they never defined…<\/p>\n","protected":false},"author":27,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24,8,6],"tags":[939,938,126,125,25],"class_list":["post-191","post","type-post","status-publish","format-standard","hentry","category-creationism","category-evolution","category-science","tag-creationism","tag-evolution","tag-experiments","tag-gene-duplication","tag-intellignet-design"],"_links":{"self":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/posts\/191","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/users\/27"}],"replies":[{"embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/comments?post=191"}],"version-history":[{"count":0,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/posts\/191\/revisions"}],"wp:attachment":[{"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/media?parent=191"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/categories?post=191"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/skepticink.com\/smilodonsretreat\/wp-json\/wp\/v2\/tags?post=191"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}