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Haldane’s Dilemma is still really a dilemma

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Despite decades of public relations. From Chase Nelson at Inference Review:

Haldane, one of the founders (along with Ronald Fisher and Sewall Wright) of mathematical population genetics, was the first to quantify such a limit on the speed of adaptive evolution. He concluded that the cost of selection “defines one of the factors, perhaps the main one, determining the speed of evolution.” Cost was the main reason Motoo Kimura proposed the neutral theory of molecular evolution. Many others cite its importance.

Nelson’s point is that “In general, the number of individuals combining several specific characteristics decreases exponentially with each additional requirement.”

For one thing, the requirements must all work together in the same live body. For example, a beagle has an amazing sense of smell but is otherwise a stupid dog, relative to others, and would not last long in nature. It would get torn apart by a wolf, who — maybe with a lesser sense of smell — at least understands the importance of shutting up and moving surreptitiously, working with the pack, while hunting. But that, along with pack discipline in general, is an additional requirement for selection.

The implications for mammalian evolution were considered so severe that the issue became known as Haldane’s dilemma.

Despite Haldane’s work, a massive body of literature has accumulated asserting the primary role of natural selection in evolutionary change, often implying rates of adaptive evolution that exceed plausible limits. I maintain that cost, though often neglected in contemporary studies, remains as important as Haldane’s mathematical theory of selection. By setting a limit on the number of selective evolutionary changes, Haldane provided a simple way to test the plausibility of many evolutionary scenarios. More.

A growing number of biologists seeks a serious examination of this issue, as an alternative to Darwin pieties, and good luck to them.

See also: Has there really just not been enough time to observe Darwinian evolution at work?

Beagles hunting:

Remove earplugs. Meanwhile, wolves hunting (as always, with no human assistance):

The reductionist bottom-up reverse engineering research approach takes the scientists on a long and winding road that leads to ‘surprising’ and ‘unexpected’ discoveries, while the Big Data keeps piling up on the clouds. Biology research is by far the most fascinating field of serious science these days. Because it’s a WYSIWYG deal. Unfortunately some otherwise interesting papers may contain irrelevant text with archaic pseudoscientific hogwash which makes the whole paper look like low grade bovine excreta. The evo-devo folks struggle to find a serious case that may satisfy the conditions described @1090 in the thread “A third way of evolution?” to no avail. Complex complexity. The more we know, the more we have to learn Dionisio
I have to say (reluctantly) that I haven’t seen any rigorous quantitative argument yet as to why this could be the case. Mung
It is easy to see why Haldane’s conclusions posed a dilemma for biologists interested in mammalian evolution. Human and chimpanzee species diverged from a common ancestor approximately 4.5 to 13 million years ago.34 Humans currently have an average generation time of 30 years, chimpanzees 20 years.35 At most, 500,000 generations have elapsed. Given Haldane’s limit, this makes for 3333.3 adaptive differences.36 Can roughly 3000 changes explain all of the complex adaptive differences between humans and chimpanzees? This is Haldane’s dilemma. It is a dilemma that has been exacerbated by genome sequencing. Humans and chimpanzees both have genome sizes of roughly 30 billion nucleotides. Yet these species differ by some 30 million fixed nucleotide differences.37 If these differences were fixed individually by positive selection, then the substitution rate would have been 1.5 substitutions per year in each line of descent, or 30 per generation—a biological impossibility. [Chase Nelson]
Eric Anderson: Do you seriously think 340 beneficial mutations in DNA could turn an ape-like creature into a human … ? ... VJTorley: I have to say (reluctantly) that I haven’t seen any rigorous quantitative argument yet as to why this could not be the case. [source]
We should ignore the cost of selection because it is inconvenient and would just confuse the public and cause them to question us. Mung

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