No, we aren’t. But this isn’t a problem for my position, because I don’t believe the idea of “fitness” drove the creation of humans at any point. However, evolution is supposed to be pushing ever further in the direction of fitness. That’s supposed to be the driving force behind the process. Yet, in every environmental niche in which humans live, you’ll also find abundant single-celled organisms. Much more abundant than humans, making them more reproductively fit than we are. Thus it becomes very implausible to think that “fitness” would have ever driven our development in the first place.
In terms of our distribution, where is the source of all this beneficial development? According to the models I’m getting from the evolutionists, it apparently is supposed to be the tiny sliver of beneficial mutations that exist to the right of the threshold of selection. Truly, “the harvest is plentiful, but the laborers are few”!
It helps that selection deletes the negative mutations and preserves the positive ones. So, in the end, it isn’t only plausible, but also directly observable. Pretty cool stuff.
Once again you forget that these beneficial mutations get fixed and accumulate over time in a population. That allows the population to explore a move to “higher ground” on the local fitness peak until the benefit of going higher is outweighed by the costs. Major evolutionary events like the rise of multicellularity allowed population to explore many more niches and discover many more local fitness optima. It also sometimes had the negative effect if a species became too specialized in one tiny niche the species would not be able to adapt quickly enough and would go extinct if the niche suddenly vanished.
Only with an extremely oversimplified version of events. You’re essentially saying that selection is 100% effective. Anything that is big enough to be selected is always selected. This ignores one very big problem: noise. There are many, many things affecting reproduction that have nothing at all to do with genetics. And this fact alone is a major limiting factor on the scope of what selection is really able to accomplish. (It’s certainly not the only countervailing factor).
If beneficials and deleterious mutations were of equal strength and frequency, then we might get away with saying that noise doesn’t matter, since it affects both sides equally. But as we know, that’s not the real world. Since beneficials are very rare, the overriding of noise is much more problematic. Our rare beneficials are significantly likely to be lost.
Our DFE shows a threshold of selection. It should also show a horizontal threshold of noise intersecting the Y axis. I believe realistically speaking, virtually none of the selectable beneficial mutations would go above that threshold.
No one said or implied that anywhere in this thread. Why do you have to continually misrepresent the statements of others just to attack the silly strawman of your own making?
This is why it’s so difficult to have any sort of meaningful dialog with you. Your rhetorical tactics may serve you well in apologetic circles but they suck in science discussions.
I think the correct way of looking at fitness is as a dichotomy of two different but related concepts: absolute fitness and reproductive fitness. I explained that in the SFT debate that was posted a while ago.
But here what these guys are saying makes no sense even from a purely evolutionary point of view. I don’t see how they can say that an organism can somehow become maximally fit for a given niche, such that further improvements are impossible. There’s always new ways to get better, unless you’re God.
Yes, environmentally contingent fitness. When the terrestrial ancestors of whales evolved to adapt to a fully aquatic life, did they get more reproductively fit than their cousins who remained on land? In water, yes. On land, no.
In a similar way, the transition from prokaryotes eukaryotes, and on to mammals is simply not required to yield a continuous increase in reproductive fitness in all environments, all it requires is that there have been the environmental conditions and selective pressures necessary to facilitate this transition. That the environment has favored certain changes.
The push towards fitness must always be understood in the context of some niche, not some absolute scale where everything gets better and better. This is why the fitness of the bacteria in the LTEE is measured as fitness relative to the ancestor in the flask environment, not fitness relative to the ancestor in all possible environments.
You’ll note that different bacteria are adapted to different environments, they can’t do everything. The bacteria that live in your gut can’t survive for long outside it. Bacteria that thrive in superheated fluids deep in the Earth’s crust won’t grown in your refrigerator. And so on. There is no superbacterium that is both hyperthermophilic and hyperpsychrophilic, can metabolise everything, and tolerate all the extremes at both ends of the scales of temperature, pressure, pH, humidity, and so on, at which life has been found. They move into a particular niche and then adapt to it, often times at the cost of adaptations tailored to the ancestral environment. You’ll note you can’t live off CO2 and H2 gases.
There have been a great many such local environmental transitions between prokaryotes and humans such as mammals. Initially an organism that colonizes a new environment will find it might have lower reproductive fitness in the novel environment, compared to the one it was already adapted to. But because there is abundant unused resources in the novel environment, it pays off to move into it in the first place. So now it has to adapt and compete in this novel environment. This is what happened when bacteria in the LTEE first were moved to the specific flask environment used as the experiment began, and again later when the ability to transport citrate under aerobic conditions evolved.
Your picture of what evolutionary history is supposed to have been like is completely wrong and out of sync with what evolutionary biologists actually think happened.
So you’re saying the reason the LTEE experiment has failed to produce anything other than bacteria by means of evolution is simply because their flask environment isn’t the right one? They need to find some other environment that will result in bacteria becoming non-bacteria?
Disregarding concepts you left out like time and scale, yeah pretty much. It’s a bit more complicated than that, but yes the conditions aren’t right to facilitate the evolution of something other than bacteria. It was never the purpose of the experiment to explore what conditions produce non-bacteria from bacteria.
I hope it doesn’t come as a surprise to you that you won’t get terrestrial animals evolving into whales if you don’t have any large bodies of water that provide those opportunities. Why didn’t polar bears evolve in the jungle? The conditions weren’t right, obviously.
It also needs to be said that “bacteria” is an extremely diverse and old clade of life, and different species of bacteria can be so different from each other as any two species of animals can be by any objective measure. Compare a jellyfish to a frog. They’re both eukaryotes. What you’re saying is basically that you are surprised to find that after a mere 20 years of adaptation, an eukaryote is still an eukaryote.
This is why the idea of macroevolution is inherently unfalsifiable. The time factor can always be invoked to explain away any failure to reproduce the alleged effect in action.
None of that follows at all. The fact that time IS a factor relevant to macroevolution doesn’t mean it can always just be invoked. And you have to admit that time must be a factor. After all if some macroevolutionary transition is inferred to have required ten thousand consecutive mutations(say), then running an experiment that only allows time for two hundred can’t be said to constitute a meaningful test of the postulate.
Isn’t one of the assumptions behind Sanford’s Genetic Entropy the idea that organisms’ genomes were originally perfect? That would mean there wasn’t a way to improve.