I'm posting the first one on Evolution and Natural Selection. It's all about natural selection but it's a very strange kind of natural selection. The organisms are parthenogenic and each individual is genetically programed to have a certain probability of reproducing. One type has a 50% probability of reproducing and another type has only a 25% probability of reproducing. These probabilities seem to be independent of any competition between them. Each successful individual produces four offspring. After some time the number of one type remains constant (25% probability) but the number of the other type (50% probability) doubles with each generation. This is natural selection according to Ross Firestone.
"Naturally," I was disappointed that natural selection was the only mechanism mentioned. There's nothing about random genetic drift in this video and nothing about the stochastic nature of natural selection. But my face lit up when I saw that there was another video on "Alternative Selection: Learn about driving forces of evolution other than natural selection." This could almost make up for screwing up the description of natural selection.
Alas, the second video is even worse. The "alternatives" are group selection and artificial selection. It gets even more worse. The example of group selection is the grandmother hypothesis. According to Ross Firestone, the fact that grandmothers help their grandchildren survive is group selection.
The video on "Bottlenecks and the environment" is also quite interesting. I didn't know that that the peppered moth story is an example of a bottleneck. Did you?
I think these videos are horrible—so horrible, in fact, that the Khan Academy should take them down. What do you think?
Are you wondering why a 2nd year med student feels so confident that he knows enough about evolution to teach it to pre-med students? Me too.
The organisms are parthenogenic...
ReplyDeleteParthenogenesis is actually "Step 2". Ross Firestone begins by telling the viewers how the long-legged guy escapes the bear and finds a long-legged mate (what if he should find a short-legged one?), and they have long-legged children "because the trait is genetic" (what about dominance?). Then Firestone looks at the problem "again but more deeply", which means forgetting about sexual reproduction entirely. It's a total mess.
They are just kids teaching kids. They know nothing about evolution except what they memorized from a few books. They know nothing about how to critize it and defeat it as a option for biological complexity and diversity in the universe.
ReplyDeleteKids becoming doctors are useless to investigation of the very complicated concepts of biology.
I suspect, just suspect but don't know, that the reason for this kid winning is because of a establishment desire to defend evolution from the attacks its been getting.
I'm suspicious they are all in on this need to confirm evolutions truth and this sways votes.
Population changes has nothing to do with the claims of evolution about everything. Its minor events in species. its no more then saying rich guys get the better looking girls and make better looking kids. Fine but its the extrapolation from this to explain bugs becoming buffalos.
And Bobby's poetry could not be missing.
DeleteWe are eagerly waiting for a YouTube presentation by Robert Byers: Just So Stories Rewritten: How the Kangaroo Got His Pouch (Not always was the Kangaroo as now we do behold him...). Featuring also a short talk by Ken Ham, Esq., and clips from The Ark Vision.
Delete@Robert Byers:
DeleteFind the odd-one-out: Sheep, Rabbit, Cow, Kangaroo, Tyrannosaurus Rex, Buffalo, Giraffe, Zebra.
Giraffe, you say? You're dead right. All the other are/were grass eaters.
Correct, Robert? That's your newest theory (fully researched no doubt).
When does the paper come out? How have you backed up your assertion - on Uncommondescent - that T Rex ate grass?
Roberto,
DeleteI think you've polished up the act as much as is possible and you won't get a tougher audience than the folks here, so I'd say it's time to take your show on the road.
I'd suggest the stand-up comedy circuit, I'm pretty sure you'll have the creotard/idiot niche to your self.
"Are you wondering why a 2nd year med student feels so confident that he knows enough about evolution to teach it to pre-med students?"
ReplyDeleteNo, because I have met med students before. /snark
You joke, but I concur. I was in an anatomy/cell bio program in a medical school. I took several classes alongside medical students - in fact we took the same first year classes they did, and we took those classes with them (we then went back to our department and had additional lectures that the medical students did not). Bunch of egomaniacs - I'd say about 70% of them felt that they were head and shoulders above not just non-medical students, but above their instructors as well.
DeleteThe Khan Academy seems serious and has an infrastructure for making excellent educational material, but it needs assistance in quality control. If these videos are any indication, confusion is currently its primary product.
ReplyDeleteThe evolution videos are good technically, but, as Larry strongly implies, are scientific failures. The one on “Bottlenecks and the Environment,” besides erroneously projecting industrial melanism as a bottleneck event (I've never, never seen that tried before), makes the following red-herring, no brainer, teleology accommodating statement (at 1:10): “the more traits in the gene pool, the more likely the species will survive.” This makes it sound like variability is “for” the survival of the species and that variability is “good” for its own sake. Counter examples is easy to imagine: the non-survival of populations derived from the crossing of individuals with diverse congenital defects or hybridized plant ecotypes that evolved to live under extremely specialized conditions (I do not know if either has ever be done). Either of these strategies to increase variability would be unlikely to promote “the survival of the species”.
At 2:40 there is a confusion between ‘stress’ and ‘catastrophe’ (the latter best applies), but this is somewhat corrected at 4:25 when terms ‘cataclysm’ and ‘huge stress’ are used.
I don’t have the nerve to view the other videos, so will take Larry’s word on them. Biologists residing near the Khan Academy should extend a hand of help to these well meaning people.
I just watched the video on natural selection. Ignoring the intended audience for the moment, it did convey the essence of change in a population caused by differential survival. By ignoring the complications of sexual reproduction and the genetic basis of the trait, longer legs, it got to the heart of the matter. In fact, I think it pretty accurately represents the state of knowledge of most college students after their intro biology course. Whether this is sufficient to pass the MCAT I don't know. It certainly isn't sufficient for a more than rudimentary understanding of evolution. In fairness, I didn't look at all the evolution videos. Perhaps, taken together, they might do a better, more comprehensive job.
ReplyDeleteYou weren't paying attention. The essence of natural selection is, indeed, differential survival. In a mixed population of individuals with long legs and short legs the ones with long legs are more likely to survive than the ones with short legs. Eventually the allele for long legs will become fixed in the population and the allele for short legs will be eliminated.
DeleteThe essence of natural selection is competition for limited resources. Usually this means a relatively constant population size.
In the example shown, the short legs get away form the bear 25% of the time and that isn't affected by how many long legs there are in the population. The long legs escape 50% of the time no matter what the proportion of short legs in the population.
Each survivor produces four offspring so the total number of short legs in the population remains constant over, say, twenty generations. Meanwhile the population of long legs has increased one million times but 50% of them are still eaten by the bears. Presumably, the bear population has also increased by the same amount.
It's true that the frequency of the short leg allele in the population has decreased and the frequency of the long leg allele has increased but it's not a very realistic example of natural selection.
It would be better to say that 75% of the population is killed by bears every generation. If you have long legs you are more likely to be among the survivors than if you have short legs. Thus, over time, the proportion of survivors with long legs increases at the expense of survivors with short legs until eventually the entire population consists of long-legged individuals and the size of the population remains constant.
I think it pretty accurately represents the state of knowledge of most college students after their intro biology course.
DeleteThat's very sad. I expect every student to know about alleles, population size, probabilities, mutation, recombination, homozygous vs heterogygous, Hardy-Weinberg, population genetics, random genetic drift, speciation, and fitness (and more). If this is the state of knowledge expected of university science students in America then things are far worse than I thought.
The Khan Academy approach to teaching is an attractive one. But Khan does not have a monopoly. With Camtasia Studio software it is not difficult for contributors to this blog to prepare videos that may compete effectively with those the AAMC has solicited from the Khan Academy. My modest efforts in this respect were posted two years ago but have attracted little interest.
DeleteIf this is the state of knowledge expected of university science students in America then things are far worse than I thought.
DeleteI didn't say expected -- I said that it was what most college students remember after their intro course. I agree that it is sad. (I'm talking about non-majors, but even majors have inadequacies in their understanding, especially if their only exposure to population genetics/evolution is their intro course.)
. . . population regulation, balanced polymorphisms, character displacement, life-history theory . . . I agree with Larry.
ReplyDelete