Haldane's Dilemma: a new review (Evolution)

by David Turell , Thursday, August 05, 2021, 21:45 (995 days ago) @ David Turell

His issue is the time limits involved so chance beneficial mutations can do their completed changes for a Newly fully working species. Review the last article if needed. In this case the author forgets the need for chance mutations over time and says death is needed to kills off those without the new chance beneficial mutation:

https://nautil.us/issue/104/harmony/why-do-we-have-to-die

"For this new mutation to climb in frequency from 1 in 100,000 to 2 in 100,000, the individual who carries it must produce not one but two offspring. But the population, we’ve said, is held steady, by some limited resource, at 100,000 individuals. So for one extra individual bearing the new mutation to enter the population, one extra individual who does not bear the new mutation must die, making room for improvement, so to speak. More generally, one extra death is required for each incremental increase in the beneficial mutation’s prevalence. For the new mutation to increase by 1 percent in our population of 100,000, 1,000 extra deaths must occur. For the new mutation to be shared by the whole population—for it to go to fixation, as evolutionary biologists would put it—100,000 extra deaths must occur. Thus, the dues of evolution are paid in the currency of death.

"We ought to add some nuance. For each incremental increase in the frequency of the beneficial mutation, it’s not technically a death that’s called for, but only the failure of one individual to survive and reproduce. Maybe someone just doesn’t get to have her allotted offspring. The point is only that the parent’s genetic lineage must come to an end. But in nature, that usually means mortality for either the prospective parent or the offspring. A reasonable shorthand is, well, just death.

***

"Using our toy model just a moment ago, we reasoned that the number of extra deaths, spread over the entire history of the evolutionary change, would be about equal to the population size in any single generation (our 100,000). In his model of diploids with semi-dominant mutations, Haldane found that the number was more like 30 times the population size in any single generation.

***

"Recall that, in Haldane’s improvement to our toy model, pushing a new mutation from a single copy to predominance and finally to fixation required 30 times as many “extra” or “useful” deaths as there were individuals in the population during a single generation. So that means the minimal number of useful deaths required to transform the chimp-human ancestor into a bona fide Homo sapiens would be 100,000 (that’s the number of selected mutations) times 50,000 (that’s the population size) times 30 (Haldane’s factor). That gives us an answer of 150 billion useful deaths.

"Hmmm. That’s a really big number. How many deaths altogether, useful or not, were there along the lineage from the chimp-human ancestor to modern humans? Based on our estimate of the population size (which we just used), the average generation time (which we can make a pretty good guess at), and the total time since chimps and humans split (a number that comes from both archaeology and genetics), we can do another simple calculation to estimate the total number of deaths. I just worked it out, and it comes to ... 17.5 billion.

"Oops. How can the number of useful or extra deaths that natural selection needs to evolve a human from its ancestor be larger than the total number of deaths that have taken place? Well, it can’t. So what’s the explanation?

"In large part, it’s sex. Say a certain man has a beneficial mutation. And say a certain woman has one of her own, only it’s different: It confers a different advantage, and it’s located somewhere else in the genome. And say, finally, this man and this woman get together and have kids. One of those kids might get both beneficial mutations, while another kid might get neither. When the doubly lucky kid survives and reproduces, while the doubly unlucky kid doesn’t, a single death becomes doubly useful: It pays for the simultaneous rise in frequency of two beneficial mutations.

"You can repeat the argument for parents who have two mutations, three, and so on. Thanks to sex, a single death can push many beneficial mutations toward their ultimate fixation. We can conclude, therefore, that although the price of life is death, sex improves the exchange rate.

***

"And yet, though Darwin may have found no ultimate vindication for death in the creation of beautiful living things, he would continue to find profound joy in such beauty. In sexual selection, he discovered the origin of life’s most extravagant displays. He attributed a great deal of importance to that process in the descent of Homo sapiens from hominid ancestors. To my knowledge, though, he never realized what Haldane and genomics have helped us to see here, that sex can greatly reduce the toll required for a certain measure of evolution."

Comment: This cement-headed Darwinist is insanely confused. He doesn't recognize Haldane's timing dilemma. He thinks a random beneficial mutation can simply appear and every design will be just fine in the time allotted. What he does recognize is death, and I might add extinctions, as a high important part of the process of evolution from simple to complex. dhw doesn't seem to understand all those necessary extinctions led to humans