In order to ascertain if the fossil record supports the neo-Darwinian theory of speciation as a result of mutation and natural selection I am looking for the strongest possible case in the affirmative.
I would like the most important examples of transitional fossils, a brief explanation about why they are significant to the field, and if possible a link to a relevant article. If you don’t have a link just the name of the fossil will do; I am searching myself as well. Thanks in advance!
The reason this is relevant to Sacred Scripture is that I wish to know if it is necessary for me to attempt to interpret the accounts in Genesis 1-11 to account for billions of years or not.
Pakicetids are the mammal family that has been identified as an ancestor to modern whales. The earliest species in this family areestimated to have lived between 49 and 54 million years ago. The main identifying feature of Pakicetids are their unique ear structure, which is only shared by other cetaceans, the family of dolphins and whales. Another piece of important evidence is that their fossils have only ever been found in ancient waterbeds, particularly around molluscs and plant beds. Their unique features, coupled with the existence of useless hip-like bones in modern cetaceans, has led to their acceptance as a transitional fossil.
The middle Devonian plant species Runcaria is considered to be one of the ancestors of seed-bearing plants, predating them by about 20 million years. It possesses important physical features of seed-bearing plants, but does not possess others, like seed coatings or mechanisms to pollinate seeds. Instead, it appears to have a large spiral-based structure outside its exterior coating that was able to capture pollen on the wind.
Finally, Australopithecus Afarensis is considered to be one of the biggest defining species in the evolution of humans. They lived about 3.9-2.9 million years ago in East Africa. They share features of both non-human great apes and humans. Their primary ape-like features are their arm and shoulder bones, which are more akin to those of gorilla and orangutan bones. Their primary human features are their teeth, more pointed and suited for crushing instead of grinding, and their legs and hips, which allowed the species to stand and walk upright, although less efficiently than true human species later. The main intermediary features are, of course, their hips, not as good at climbing as apes, not as good at walking as humans, and their skulls, which share more robust features of apes and more slim, circular features of humans. Their brains were also larger than those of other primates. Overall, their remarkable mix of ape and human features, combined with intermediary ones, marks them as an exemplary transitional species.
In this article: https://evolution-outreach.biomedcentral.com/articles/10.1007/s12052-009-0126-3
it is discussing how species are considered to be related to one another by inference even though there is not any evidence in the fossil record that a common ancestor actually exists. The author says that this is because the “family tree” has so many branches it is exceedingly unlikely that an actual ancestor is found in the fossil record. So, for the line from the pakicetus to the modern whale (pakicetus, ambulocetus, kutchicetus, radhocetus, dorudon, odontocetes, mysticetes), none of the species in the list are actual ancestors of the following species, but they are considered cousins.
How is this not a sequence of assumptions resulting in a conclusion? The shared feature in this case is the shape of the skull, which I’ll admit is interesting, but it doesn’t establish ancestry and it doesn’t show that any of these creatures are the whales we have today. The paleontologists admit that they haven’t found the common ancestor between any of the 7 species listed as relatives. But they assume that the ancestor exists.
What if there is no common ancestor between them, instead there might be 3 or 4 distinct ancestors that each evolved to have more specialized versions of characteristics they already had? This would remove the difficulty of a mammal losing its legs and gaining a blowhole and it seems consistent with evolutionary theory.
Well the easiest answer is simply that science is based on what evidence we have. We know the Pakicetus family is the only mammal family to possess features common in all cetaceans today at that point time, and after it disappeared or became less common in the record, more species similar to it emerged. Is it possible that more than one specific ancestor exists? Yes. Does that theory match the evidence? No. Going off what we have, common descent is the best, simplest theory that matches all evidence presented so far. If, like in the case of Archaeopteryx, more than one species is found in fossils that has those traits, scientists will revise their theories to meet the new evidence. Otherwise, we go with what we know. That’s just how science works.
This is true. However, these commonalities point towards the common ancestor, as was stated in the article you sent. Scientists make the assumption, based on all available evidence, that whales are related to Pakicetus species because of their common features. Whether they were the true ancestor of whales or not is not, and likely cannot be, known. It’s the progression of common features that makes evolutionary theory work. Some feature exists in one species in the fossil record, and then other ones appear with it later. We assume, then, that somewhere along the line, a species had that trait that diverged into those other species that we see. Maybe it was one of the species we saw in the record, maybe not. The point of evolution is that it explains why progression of common traits is pretty linear and doesn’t move backwards, and that traits don’t really appear out of nowhere.
So scientists are making an assumption. Perhaps this is the assumption that best explains the similarity, perhaps it isn’t.
It’s not true, however, that the progression of traits doesn’t move backwards. The fossil record has plentiful examples of creatures, like some forms of moss, and crayfish, that don’t show significant progress over vast amounts of time. Furthermore, genetic drift can cause populations that are isolated from a wider gene pool to develop disorders, such as the Afrikaner population of South Africa, which has an unusually high frequency of the gene responsible for Huntington’s disease. (https://evolution.berkeley.edu/evolibrary/misconceptions_faq.php#a3)
The issue I am trying to reconcile is how we can say that a common feature like the shape of the ear/skull is sufficient to establish a relationship between two species, particularly separated by millions of years according to the research. Are all vertebrates, then, distant cousins of some proto-vertabrate? And all life, as far as I know, shares the same fundamental DNA pattern. Does that mean that all life originated with a single ancestor? I think that the facts are not in evidence here.
It’s the one that explains best what we see today.
They didn’t need to. Evolutionary pressure doesn’t give some individuals greater fitness than others.
Drift within a species is different than trait change outside of it. My point was more on the level of “Why didn’t fish lose their vertebrae?”
First, millions of years is a relatively short timescale from a geologic perspective. The Dinosaurs lasted almost 160 million years. Second, it’s not merely one common feature, but a slate of them, that points to common ancestry, unless it’s a particularly major one. For example, the warm-bloodedness of mammals and our unique jaw structures, along with features like fur, point to common ancestry.
That’s the theory, yes. Pre-vertebral species are pretty small in number, pointing to a likelihood of one or a small group of common ancestors to fish.
This, I’m not so sure about. Chemicals combine in completely deterministic ways, so if abiogenesis is true (which I don’t believe it is), it’s completely likely for multiple, disparate populations to have existed early in Earth’s history.
My point in both the last thread and this one is that evidence points us to fact. Evolutionary theory may not be perfect, and likely isn’t. However, it gives us a simple, comprehensive way to view and predict the creation of certain features of life. If another theory is to overtake it, that theory must demonstrate better fitness to evidence and comprehensiveness. So far, nothing has.
You don’t need fossils. We have DNA. Genetic material is (typically) transmitted through descent. All living things share DNA. Rates of mutation and speciation can be estimated to a level that can assure you that yes, you must account for billions of years of evolution. The DNA observation is a fact. It is not a theory.
Based solely on DNA I am not sure the there is much convincing evidence for evolution. The mutations that we observe in populations today are overwhelmingly negative (i.e. Huntingtons, hox genes) or produce no effect on the phenotype of the creature. There is sickle cell anemia as an example of a mutation with a positive effect, but even in this case it causes disease. Furthermore, there is a convincing case against the mechanism of mutation for progress, which was posted in the previous thread: genetic entropy. Over a time period as long as geology seems to indicate it would be more likely that DNA would become meaningless rather than becoming more potent.
The situation for the whales was different because they don’t have any of the “missing links” but according to many of the sources I’ve read so far the study of evolution doesn’t focus on such links in the first place, but rather infers their existence for the reasons neatly summarized by CaptainPrudeman and continues in other pursuits.
Couple responses to make. First of all, evolution is slow. Really slow. It often takes millions of years for real change to be seen in a species. Second, humans experience basically no selective pressures at all in the modern world. None of us really have genes just bad enough that we die before having kids. Most of us, no matter our genetic makeup, will survive and thrive. Any mutations that could lead to something interesting usually just go away because they’re so often mixed from others. In addition to this, we’re a highly invasive species built to survive in harsh, hot environments that came into more lenient ones. Things aren’t changed anymore because, again, no pressure that leads to some individuals surviving and others not. Without some pressure to change, change doesn’t occur. That’s why modern humans are a bad counterexample to evolution.
On the contrary, the Cambrian explosion and other periods in the fossil record seem to show that evolution at times can be very fast. I think most evolutionary biologists would agree that it is typically slow, however, because we don’t observe the rapid progress of the Cambrian explosion in our time. This is another big problem with the classical view of evolution, which is that it at once requires incredibly long periods of time and simultaneously seems to happen all at once from a cosmic perspective (i do recognize that the Cambrian explosion was a period of some millions of years).
There is also recent evidence of species that can evolve in as few as two generations https://cosmosmagazine.com/biology/new-species-evolve-in-just-two-generations/. Not sure about the source, but interesting article.
Periods like the Cambrian represent the exception, not the rule. A wide range of ecological niches opened up and pretty much any significant change in biology made something new. Very few evolutions were dead ends, whereas after, a lot were. It’s like businesses in a new sector: A lot pop up when it becomes mainstream, but it’s harder to establish yourself after that’s been the case for a long time.
I think I have more reading to do on this topic. However, at this time I can say that the case for macro-evolution is not nearly as solid as the case for an old earth, scientifically. There are still assumptions with the old earth theory that are probably not proper for a CAF thread, but on the whole there is less guesswork taking place.
However, there are theological problems with applying Darwinism to the origins of Man (Is Man the center of God’s creation or not? Is it true that we have a single pair of first ancestors or not? If not then how can original sin be true? Did God actively direct evolution or not? If he didn’t then how can it be true that he “made Man from the dust?”), and I don’t find the explanations offered by the theory convincing as a predictor for speciation or as a driving force for events like the Cambrian explosion in the fossil record.
Science is only as good as its uses–pardon my engineering bias–and while Darwin’s theory is extremely important for cases such as antibiotic resistance in tuberculosis or the previously stated example of sickle cell anemia, macro-evolutionary principles have given us very few useful nuggets of information (none come to mind but I’m sure there’s at least one counter-example).
Anyway, I’m gonna take a rest from the forum for today. Thanks for corresponding with me!