What is fitness?

No, it isn’t. You asked about environments changing. They just have to be different to understand this very basic example.

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Where did the first egg layer come from? Not from an egg, for he wouldn’t have been the first egg layer, right?

Valérie, it is important to see that Sanford’s primary thesis is not that everything is going extinct, but that given only strict neo-Darwinism theory (RV+NS), all life forms are doomed to extinction (see in appendix 5 of his book his response to the objection that persistence of various forms of life disproves GE)

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This is accurate if you mean to say that Sanford himself believes that God will intervene in history before He allows all life to go extinct from mutations. Everything is on the trajectory of extinction, with the possible exception of bacteria.

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Yeah and it shows what you asked for, an example of a trait natural selection acts on, and how it’s fitness-effect depends on the environment in which the organism lives.

Sorry but I’m starting to think you’re just taking the piss.

No, there is no GE-like concept accepted by mainstream science.

I hate to have to guess, but you might have let yourself become confused by the fact that the human population is currently in a unique situation where we have developed extremely effective means of helping us survive, using medical science(surgery and drugs for example), agriculture and industrialization(people rarely starve to death in industrialized societies), and other technological aids of innumerable sorts such as transportation, hearing aids, wearing glasses etc. etc. Every single one of these helps people survive and reproduce in different ways. We have completely changed our own environment so it is very forgiving. As a consequence, there is very little natural selection acting on the human population, and hence deleterious mutations of even strong effect are allowed to accumulate.
This doesn’t, of course, constitute any kind of evidence that GE is real. It just means human ingenuity and cooperation have resulted in a very unusual form of environment with very little natural selection. For basically every other organism on Earth, the situation is radically different as they’re not helped by vast support networks of medical science, technology, and industry.

Alternatively you might be thinking of mutational meltdown, which is thought to occur in very small populations, or with repeated population bottlenecks, which can lead to the fixation of strongly deletersious mutations. It is thought that this can lead to eventual extinction if such repeated bottlenecks or continued very small population size persists, as the power of genetic drift can overwhelm selection against deleterious mutations in small populations.

What are “up” powers of evolution? If you are thinking of something that works against Sanford’s Genetic Entropy, the answer is that GE isn’t real because there’s no evidence that the vast majority of mutations have invisibly small deleterious effects(and importantly, there’s no evidence that the DFE of mutations is constant regardless of fitness or environment), so there doesn’t need to be anything that compensates for it.

Sanford’s thesis has not met it’s burden of proof. It’s not our job to prove it false, rather it’s Sanford’s job to show it is true. He and all his apologist friends have failed at that job.

One does not need to invoke “up” processes to compensate for imaginary “down” processes. The down process is imaginary. There’s no evidence for it.

Yes you missed the part where there’s no evidence for Sanford’s Genetic Entropy.

There is no data that shows GE is true in the first place, so that’s not necessary. I don’t need to disprove that you have an invisible fire-breathing dragon in your garage.

Now it just so happens that, logically speaking, the observation of life’s extreme age is evidence against genetic entropy. If you have a new theory that says life can’t have existed for millions of years, and I have observations that show life has existed for billions of years, then that should if you are a rational person (are you?) cause you to seriously doubt your own theory.

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Well, all eggs begin as single cells that emerge by cell division. They’re really “just” differentiated cells in the germline for multicellular organisms that reproduce sexually.

What exactly counts as an egg? The origin of “eggs” can be traced back, ultimately, to the division of the soma and germline by differentiation in the first sexually reproducing multicellular organisms with a germline. As far as I am aware sex predates multicellularity, so the origin of something we could call an egg must lie somewhere around the origin of multicellularity, where some cells differentiated to become exclusively somatic, and others to become germline cells.

https://www.nature.com/articles/420745a

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I’ll bet he wasn’t even a he. Of course there was no “first egg layer”. Evolution is generally a gradual process, and it’s unclear what stage in that process you would recognize as an egg. An egg is a large, immobile gamete contrasted with small, often mobile gametes. Goes way back.

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The sickle cell trait (HbS allele) offers some protection against malaria. Wouldn’t you know it, we find more people with the sickle cell trait in areas with malaria. This is due to positive selection for protection against malaria.

However, people who have two copies of the HbS allele can also suffer from sickle cell anemia, so there is stronger selection against the allele in areas without malaria. The global distribution of the allele has everything to do with natural selection, both positive and negative selection.

The stabilization process is negative selection against harmful mutations.

A continuous fossil record spanning billions of years demonstrates that life is not going extinct because of genetic entropy.

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There would have been a point where the difference between egg and non-egg would have been extremely blurry.

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Where is the hard data demonstrating this? I’m not talking about models, but actual data.

Gil, where did the first user of the spoken French language come from? He/she couldn’t speak French with anyone else or that person wouldn’t be the first French speaker, right?

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And horses who have been here for at least 700,000 years. Don’t let those inconvenient facts get in the way of your tall tales though. :slightly_smiling_face:

Yes, that was my understanding, just poorly worded.

Oh…you’re making Sanford’s argument for natural reservoirs! That’s a good one!

No, I’m not. I am making the argument that negative selection removes harmful mutations which stabilizes the fitness of a population.

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You are! That’s a great example of how H1N1 could become stable in birds which tolerate that particular strain but when it spills over to humans it begins to accumulate deleterious mutations.

Deleterious mutations would not accumulate because negative selection would remove them.

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Exactly. They would be removed in birds in almost all cases.

In humans, they would be removed at first and then accumulate.

They wouldn’t accumulate in humans because they would be removed by negative selection.

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No, Sanford’s idea is that natural selection can’t get rid of the deleterious mutations, remember? It’s because they’re almost all exclusively invisible to selection.

Pathogens aren’t people. If you read the book, he makes some references to simple organisms and how selection acts on them differently. I’m just getting into that part. If you read the book, you’d know that.