Beats me. Margulis took the secret to her grave, apparently.
As far as I know, Margulis was focused more on endosymbiosis as it related to the early evolution of eukaryotes and nucleated cells. These seem to be more one-off events than a pervasive mechanism through the whole of evolution.
This is not positive selection. The requirement is to correlate DNA changes to improvement in fitness or reproductive success.
In an environment with malaria the sickle cell trait does improve fitness. We even know the specific DNA changes involved.
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Her assertions were far broader than that. She wasnāt just talking about the origin of the eukaryotes. Weāre talking about most evolutionary events - not necessarily endosymbiosis.
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Broken feature A helps with adaption to specific environment B. This explains adaption to an environment but does nothing to explain complex sequences required for new features like eyes.
Iām not sure you understand how sickle cell trait works. It is an irriducibly complex trap for the malaria parasite. The protein acquired new functions.
Is this right?
[quote]So how can it be that free haem is at once dangerous and protective? Soaresās findings suggest that a mechanism similar to vaccination is at work.
The low levels of free haem circulating in the blood of mice carrying the sickle-cell gene stimulate the production of an enzyme that breaks it down, called haem oxygenase-1. This releases small quantities of carbon monoxide ā a gas that in large quantities is highly toxic.
In the low concentration found in the blood of the mice, however, carbon monoxide seems to play a role in preventing the accumulation of haem after infection with the malaria parasite. It is this limitation of levels of haem that appears to protect against the disease developing.[/quote]
Have you read her work? There is a proposal for how eukaryotes evolved. I donāt see how symbiosis can be classified as random mutations.
If you are interested, you could do it yourself and come to a conclusion.
It is! It is just a different type of mutation.
I am not so sure. I am linking to talk that Lynn Margulies gave regarding endosymbiosis. There is a video of how the eukaryotic cell is supposed to have evolved. The video is from 5 minutes to 28 minutes. Forget mutations, she didnāt even mention DNA in the presentation.
http://www.voicesfromoxford.org/video/Homage-to-Darwin-part-2/63
Is expanding the definition of mutation the answer to all these new mechanisms of change?
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That was the definition of mutation from the beginning. There has always been many different types of mutations. Also, we have directly observed the evolution of endosymbiosis in the lab. @Perry_Marshall even includes this in his book. Mutation just means a āchange,ā and there are many types of changes. Certainly, also, the evolution endosymbiosis also includes DNA mutations too.
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I donāt think thatās how most people use the term mutation.
If mutation means change, then random mutation would be random changeā¦
Perhaps it would be helpful to be more specific.
I thought we were talking about science, not most people. Why does is matter how most people use the term?
Ok fair enough.
By your definition, even change in DNA brought about by genetic engineering by human beings is a mutation. Whatās the use of such a general term?
Yes! That is exactly right! Mutations are introduced into DNA my scientists in a process called site directed mutagenesis. The term works great. It is very effective and clear, as long as you know its meaning.
So then, the word that restricts mutations to natural processes would be the word ārandomā.
Why do you think Shapiro is wrong in classifying mutations that are not random with respect to fitness as "non random. Your example of the immune system was Avery good example.
Edit: wrote function instead of fitness by mistake.
False. Random mutations can be directed by God.
Because all the mutations he notes are not entirely predictable. They have an ordered component, and a random component. The are most certainly not ānon-randomā as in meaning no randomness. They are both random and ordered.
If mutations are random with respect to fitness or function,(Dawkins described it as mutations are random in that they donāt try to āimproveā the organism, University of Berkeley terms it as mutation not trying to supply what is needed). How does that work with God guiding them?
Are you claiming that Godās guidance in certain specific instances is possible while maintain an āappearanceā of randomness?
Are you equating randomness with predictability? Can elaborate on your train of thought?
Ashwin - it looks as though the debate is over. Dust becoming Adam was a mutation completely compatible with standard evolutionary theory, after which neutral drift and natural selection did the rest. It works for princes turning into frogs, too.
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