Chances Are Our Hearing Didn't Evolve "To Do" Anything

[jabbr]

@Jud ok how about this: suppose the so-called "junk DNA" is actually part of the machinery which generates diversity i.e. the proverbial Monkey sitting at the typewriter ... so is it really junk? because without it you are lacking a mechanism which actively generates polymorphisms... doesn't sound like junk to me ... sounds like those hopping retrotransposons are actually doing things your blogger nee "scientist" can't imagine ... and there's more ... and it's all in articles that I posted links to, and I understand it's a lot to try to understand because this stuff is highly technical but you asked

 

 

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[Jud]

@jabbr I do want to discuss further re your post above about generating diversity. But meanwhile while reading about a different subject (evolution of the citric acid cycle) I came across this essay, which I thought was really well done: http://www.nick-lane.net/LAM%20BioEssays.pdf

 

Are folks familiar with this, and what do you think of it? (Some interesting stuff about relationship to the "RNA World" in here.)

[bluesman]

What is advantageous to an individual's survival becomes advantageous to the species - is this not the very premise at the heart of evolutionary genetics?

I've enjoyed reading this thread but stayed on the sidelines until now. Your commonly held belief is not held as gospel by some pretty serious scientists. Some intense and very interesting work by Blair Hedges and his group at Temple University (paper, suppl 1, suppl 2) makes a very strong argument for his belief that "clock-like change at different levels suggests that speciation and diversification are processes dominated by random events and that adaptive change is largely a separate process". His extensive study of genomic data on more than 50,000 species in about 2200 published studies strongly suggests that adaptation is decoupled from speciation and is not a driver.

 

This is certainly at odds with the traditional picture of evolution. But when you think about it, there's little truly strong evidence that evolution meant survival of the fittest through speciation - association is not causation. With the new knowledge gained from genomic and statistical efforts that were impossible only a few years ago, Hedges' work makes perfect sense. As you might expect, traditional scientists argue against Hedges, e.g. Michael Benton: “[E]volution...happens in fits and starts. A change in the environment, such as a rise in temperatures after an ice age, might spark a burst of speciation as organisms adapt to their new surroundings. Alternatively, a single remarkable adaptation such as flight in the ancestors of birds or hair in mammals might trigger a massive expansion of animals with those characteristics." But Hedges argues that while such bursts do occur, the vast majority of speciation is commonplace and evenly spaced - and the data do seem to support his conclusion.

 

Jabbr, it's not "a monkey sitting at a typewriter" - it's an infinite number of monkeys sitting at an infinite number of typewriters. The fact that one of them types the Gettysburg address is a purely random event with astronomical odds against recurrence. Hedges makes a strong case for the role of randomness in speciation, apart from the steady timetable he derives from his tree of life. A scheduled event is hardly random, but I suppose the timeline of speciation could well be independent of its biologic drivers.