“There is so much variation possible within biology that defining what is a “species” is a difficult process. Since many things do not have concrete definitions, scientists must take care to define terms as they use them—which means that one scientist’s definition of “species” is not necessarily universal.”
Yes, that’s correct, but I see that problem as a necessary consequence of Darwin. In Origin of the Species, one of his main contentions was not simply that species could vary, but that the very idea of species as truly distinct groups that were “quantized”, so to speak, was false. His theory depends on a notion of species that is highly gradated and flexible.
Conveniently, such a notion, once accepted by scientists, allows a lot of leeway to finding evidence for Darwin’s ideas. If his contention is wrong, then mistaken classifications arising from it can contribute to false evidence, claiming events as “speciation”, which would not qualify under a more accurate definition. Even if the contention is correct, the ethereal standards would make it hard for scientists not to introduce bias into their classifications, and hence into their evidence for speciation.
“That said, the definition I use is that a species consists of a group of organisms that do not naturally breed outside of their group.”
I’d say that’s a broad definition, because of the word “naturally”. Naturally could mean they don’t breed because of circumstances, such as geographic separation. Or it could mean that they don’t breed simply due to preference. Neither of those things gives us much useful biological information, so why should we base an important biological categorization on it? This is how we arrive at birds which are basically identical being placed in different species just because they live on different islands.
“I should mention that species which came into existence within the span of human history (within the last 10,000 years or so) include such familiar species as cows and corn.”
Again, citing these as speciation events, in defense of the theory, depends on a flexible definition of species derived from the theory. We invented agriculture, and bred existing wild bovines until we wound up with the varieties of modern cow, and likewise for maize. There’s no mystery as to how these varieties differentiated from their ancestors, it was simple breeding, not evolution.
“For all I know, humans and chimps are completely capable of producing viable mixed offspring that may even be fertile. We choose not to.”
Well, there was the legend of the Soviet scientist who may have tried it, but there’s probably no real data. Considering the vast morphological differences and the 2 extra chromosomes, I don’t think it’s a likely scenario.
“Many thousands of years ago, homo sapiens in what is now Europe interbred with homo neanderthalensis, yet the two kinds of humans are generally considered separate species.”
Yes, but under a different definition of species, this fact itself is enough to state that Sapiens and Neanderthals were not separate species. It’s a great example of how a flexible definition of species allows an evolutionist to support their arguments in a circular fashion.
If you call whatever you want a species, then you can classify two breeds as separate species, and if you find evidence those two breeds actually interbred, instead of invalidating your classification, it is cited as evidence that the flexible definition of species, which started the chain of logic, is correct!
“Chihuahuas and Great Danes do not interbreed, yet are generally considered the same species.”
Chihuahuas and Great Danes are only considered the same species because scientists are unable to deny the fact, since we have direct historical knowledge of their breeding, and so we know the origin of their morphological divergence. If, on the other hand, scientists only had fossils of Chihuahuas and Great Danes to work with, I have no doubt that they would be classified as separate species.
“It is not the fault of scientists that nature does not draw clear boundaries for us to use when trying to decide what separates different species, or that our language groups organisms in a manner that doesn’t reflect nature.”
Well, as to the first part, it may be difficult for us to determine clear boundaries sometimes, but I don’t think that means they do not exist. We can determine some boundaries with certainty, and others we cannot. Darwin took that as evidence that the boundaries should be questioned, while I take that as evidence that our methods are simply less than optimal.
“I did not specifically mention biology and genetics, because all hard sciences are, in fact, different aspects of physics. Evolution very much proceeds according to the laws of physics.”
Above of the quantum level, physics is fairly deterministic. We observe a phenomenon, and if our theory is correct, we can use the theory to predict the phenomenon accurately. Now, evolution depends on random factors to contribute changes to a genome. Absent these factors, the genome is recombinated and selected, but it’s not producing a new species. So, the basically deterministic processes of reproduction and selection contribute to shifting existing genetic information within a species, but the random processes must contribute the necessary new information.
That’s why evolution requires timescales on the billions of years, because, without them, the proposal that the regular deterministic processes, normally dominant in our scale, would be essentially dominated by the irregular random processes, is not sensible. It’s like suggesting that the random molecular motion of the water molecules in the ocean could overwhelm the gravitational influence of the moon, from time to time, if everything aligned correctly. It could happen, but if you base a theory on the necessity of it happening, with regularity and to a degree that has a statistically significant result, you need a timescale that starts heading towards infinity.
That aspect of the theory isn’t deterministic, and it just creates a nebulous notion of causality that can be stretched to accommodate any bias. To make matters worse, we apply that notion in retrospect, to events we can’t really witness, and let our speculations run amok. There’s no need to propose a testable hypothesis as to how the nondeterministic forces caused a specific change that the deterministic forces could not, it’s just taken as a given. They become the “deus ex machina” to answer any question on demand. That is not in line with good physics, as far as I’m concerned.
“I’m not sure why you mentioned abiogenesis; I’m fairly certain it was definitively disproved back in the 1600s.”
I think you are thinking of spontaneous generation, which was just a certain flavor of abiogenesis. Currently, abiogenesis usually refers to the idea that life originally arose from non-living matter of some sort. It’s a general assumption of a broader kind of evolutionary thinking, that includes areas like the current cosmological model, stellar evolution, planetary formation, etc. It’s not a part of the stricter definition of just the biological theory, but since the biological theory is generally accepted, and since science is naturalistic, it is almost a natural consequence to assume abiogenesis.
“When the theory forms the basis of a whole group of scientific disciplines (in this case, the life sciences), then objecting to it is, in fact, engaging in anti-science.”
Nonsense. It doesn’t matter how much science has been built up around a theory, it’s never “anti-science” to raise challenges to it. That is simply defending orthodoxy for orthodoxy’s sake.
“I do not consider blanket rejections of theory as being in any way comparable to the normal testing and refinement of theory that scientists constantly engage in.”
First of all, few people blanketly reject evolution. I don’t argue that natural selection is incorrect, and that is a fundamental part of the theory. If I were to support another model, it would have to incorporate natural selection, so it would necessarily be a refinement of the existing theory. Refinement doesn’t exclude the abandonment of even a major part of a theory.
“I seriously doubt that Einstein blanketly rejected quantum mechanics; most likely, he was not convinced by the evidence and thought there might be other explanations for the observations that led to the description of quantum mechanics.”
He didn’t blanketly reject QM, and I don’t blanketly reject evolution either, so where is the “anti-science”? I think it’s a flawed theory which leads to flawed results, and I have plenty of arguments to support that. I may prove to be wrong in my arguments, as Einstein proved to be after Neil Bohr and company bested him, but I’m not “anti-science” for making them.
First of all, as a working scientist, I have never read and will probably never read On the Origin of Species. I spend all day long reading about the latest advancements in my current field; I simply do not have the time or energy to read a historical document. When I speak of evolution, I speak of the current theory or of the biological process, not of Darwin's particular formulation of the theory, which has undergone considerable refinement.
The problem of trying to define species is that nature did not produce distinct groups of organisms that could be neatly categorized into different species. That isn't a problem of definition, it's the essence of biology.
Conveniently, such a notion, once accepted by scientists, allows a lot of leeway to finding evidence for Darwin’s ideas. If his contention is wrong, then mistaken classifications arising from it can contribute to false evidence, claiming events as “speciation”, which would not qualify under a more accurate definition. Even if the contention is correct, the ethereal standards would make it hard for scientists not to introduce bias into their classifications, and hence into their evidence for speciation.
Speciation is not an event, but a continuously on-going process. Think of how a baby becomes an adult: it is not the result of an event, but of slow change occurring over several years. There are no distinct lines between infant and toddler, toddler and child, child and adolescent, etc. Clearly, humans and finger monkeys are separate species, but if one could go far enough back in time, observing specimens every few generations, one would see the two species eventually converge until they appear to be the same.
I should also add that no one is trying to "find evidence for Darwin's ideas." Darwin used the experience of decades of personal observation, as well as the body of scientific literature from his time, to develop his theory. The theory in its modern form provides a guide for further research. The evolutionary process is a central feature of biology that cannot be ignored when trying to do research.
I’d say that’s a broad definition, because of the word “naturally”. Naturally could mean they don’t breed because of circumstances, such as geographic separation. Or it could mean that they don’t breed simply due to preference. Neither of those things gives us much useful biological information, so why should we base an important biological categorization on it? This is how we arrive at birds which are basically identical being placed in different species just because they live on different islands.
I purposefully used the word "naturally", because humans can intervene and force all kinds of breeding or hybridization that does not occur spontaneously. If you take into account cross-breeding forced by humans, then the already blurry idea of species becomes even more muddy. Factors such as geographic location or breeding preferences are quite important. When a population is split, the longer the two parts of the original population are separated, the more different they become. At some point, they become different enough to warrant being called different species.
Again, citing these as speciation events, in defense of the theory, depends on a flexible definition of species derived from the theory. We invented agriculture, and bred existing wild bovines until we wound up with the varieties of modern cow, and likewise for maize. There’s no mystery as to how these varieties differentiated from their ancestors, it was simple breeding, not evolution.
Were it not for the evolutionary forces shaping biology, no amount of breeding would have produced cows or corn. In scientific terms, natural selection describes the process by which populations change, becoming gradually more suited to their environment, and artificial selection where humans breed only those individuals with traits that benefit the humans. These are both evolutionary processes.
Well, there was the legend of the Soviet scientist who may have tried it, but there’s probably no real data. Considering the vast morphological differences and the 2 extra chromosomes, I don’t think it’s a likely scenario.
I've heard rumors of Soviet human/chimp breeding experiments, but I have no evidence that such unethical experiments ever happened. The fact that two ape chromosomes fused at some point to become one human chromosome isn't such a big deal, really. The genes are all there in either case, and our genomes are nearly identical. I can think of no biological reason that a human/chimp hybrid could not exist; what keeps us from making that hybrid is our sense of morality.
Anyway, I will have to finish this later. I must head off to work, where no doubt, I'll be spending several hours reading about the consequences of evolutionary pressures. In the area of public health, evolution is a rather big consideration.