Exactly. There is no reason to expect a nested hierarchy from design.
What we would expect from design (mind) is the violation of the nested hierarchy we see in Sals flower.
I would argue no, not every step. While the advance in technology has a definite progression, the steps forward are marked by teleology, where form follows function by design. New features are invented by need, or appropriated from existing technology and integrated as required.
So you can have trucks with four wheels, and others with six or more; such changes can come out of the blue, and can be functional or whimsical, depending on the objectives of the design team. Organisms do not do this. An animal that glides is not striving for full on flight. A lungfish is not trying to become terrestrial. A hippo like creature is not longing for the deep blue sea. Unlike technology, there is no teleology at work.
That is why trucks can have a various wheel counts, but all vertebrate flyers, whether birds or bats or pterodactyl, must sacrifice independent fore limbs for airfoils. If they were designed, why not simply add the wings? There is no real correspondence between the hierarchy of technology and the tree of life no, no matter how the grouping is done, because one actually is a progression of design and the other actually is a story of incremental adaptation.
but that is exactly what we find:
many genes are shared between some species but not in other species between them. there are many examples of non-hierarchical cases, as we should expect to see under the design
scenario.
image from “evolution by gene loss”.
That’s what we would expect to see from gene loss and common ancestry. What you can’t explain is the phylogenetic signal.
5 Likes
John Harshman on October 13, 2017 at 11:12 pm said:
Here is an explanation of Sal’s favorite figure. The trees each represent one of the areas in the Venn diagram, with the most parsimonious interpretation (or one of them if there are several) represented for each. I only had room for 8 of the 15 areas, but the others are similar. A red bar represents gene loss and a green bar represents gene gain. Every tree with only one bar fits the tree perfectly and supports the nested hierarchy. Every tree with two bars doesn’t fit the tree perfectly. Note, however, that the one-bar trees all have many more genes than the two-bar trees, as if the probability of two events on a tree is much less than the probability of one event. Of course that only makes sense if there’s a tree. Otherwise there is no explanation for the differences in number among areas of the diagram. See, phylogeny does explain stuff.
5 Likes
That is due to gene loss. When you compare the gene sequences they do share you get the expected phylogeny.
This directly contradicts your earlier claims that design would produce a nested hierarchy.
4 Likes
Roughly speaking, most of those genes seem to follow the tree pretty well. In general you can predict the gene presence or absense in some particular species by looking at it’s most close relative.
You are showing the opposite of what you are claiming. In all likelihood, the more genes we included to use for generating a phylogeny using presence/absence, the more likely it is we’d end up with the canonical phylogeny. Even in the tiny data set of 13 genes used in your figure, there’s obvious nesting hierarchical structure in the presence/absence of genes.
3 Likes
Chimerarachne is a spider-like being from the Cretaceous. It’s considered to be a survivor of an early arachnid group, possibly the Uraranedia. It’s possible ancestors lived millions of years earlier. To use your “12345” expectation, this would be 1234…5. Not out of place. Strike 1.
Scansoriopteryx is apparently known from only a single fossil specimen. According to Wikipedia, “The provenance of the Scansoriopteryx type specimen is uncertain, as it was obtained from private fossil dealers who did not record exact geologic data.” So we don’t actually know how old it is. If we don’t know where it’s place in the fossil record was, there’s no grounds for saying it’s out of place. Strike 2.
I doubt you will acknowledge either of these errors.
Your main example is, unlike the previous two, actually relevant. But it still has major problems.
It is, as you note, a trace fossil not a body fossil. It’s possible (but unlikely) that it’s not a tetrapod trackway at all, but instead - as some more recent papers than that cited on Wikipedia argue - a result of fish feeding activity.
It isn’t that far removed in time from the other fossils. It’s likely that elpistostegids and early tetrapods lived in neighbouring habitats for millions of years, and the body fossils we do have, which are extremely scarce, will not represent the first appearance of the (group of) species they belonged to, but some point along the evolution of that type of animal. This comes back to my ignored comment that evolution is a branching process, not a linear one, and that one (group of) species doesn’t necessarily go extinct before the next branches off.
But the main problem with describing this as an out-of-place fossil is that we simply don’t have enough fossils of evolving tetrapods to be certain what the pattern is. As Per Ahlberg, one of the authors of the paper cited by Wikipedia* writes in a later paper:
"All we have is a small number of positive statements that one or more tetrapods were present in a particular environment at a particular time. On a planetary scale, these pinpricks of light in the darkness of deep time are almost infinitesimally small. … Forced to extrapolate from our meagre store of data points, we are always in danger of joining the dots wrongly."
“The single most important take-home message from this survey of the evidence is that the fossil record of the fish–tetrapod transition is actually very poor and consists mostly of gaps”
The history of tetrapod evolution we have is based on very limited information, and extremely tentative. It’s still being revised with the discovery of fossils and re-evaluation of exiting fossils and ideas. To say that the Polish tracks are out-of-place is overstating the case simply because we don’t yet know enough about the place to be certain where they should go. While this isn’t strike 3, it’s not a run either.
In short, you’ve provided by your own criteria one fossil that isn’t out-of-place, one fossil that we can’t evaluate, and one fossil where the terrain is still being mapped. That’s nowhere near enough to justify your claim of many out-of-place fossils. Claim rejected.
*and a recognised expert on early tetrapods with whom I’ve had of previous encounters.
They’re only described as bat-like because they’re membraneous rather than feathered. The wing skeletal anatomy actually resembles birds more than bats - fossils suggest the wing was supported by the forearm and fused digits, rather than being between splayed digits. Ambopteryx does not have a mixture of features from two diverse clades. The only reason to think it might is to focus on the superficial description “bat-like” and ignore the details. Cf “duck-billed”. This is also what your ‘phylogenies’ do.
5 Likes
P.S. I learnt a hell of a lot while researching this post. I doubt you did or will learn anything.
4 Likes
When I read your post I felt sad about all the time you spent doing that research, knowing it will simply be ignored, but at least you learned something yourself. And of course I did.
5 Likes
Whats required is to show gene loss and gain from random genetic change plus selection is viable. From what I can see from one of the papers SCD sent me exploring this hypothesis I don’t think it is. This is based on a mix and match of WNT gene types that are mission critical for embryo development and very well preserved.
Look at figure 1.
What is not required is to convince you that these things happen. The evidence has already been given, and your stubbornness in no way refutes that evidence.
If they are mission critical then how are they able to survive without them?
5 Likes
It’s an observed fact. For example, we have seen significant deletions in the LTEE.
Nevertheless, many species don’t have all of them. So clearly they don’t need them to live and function.
Also, they’re diverged duplicates. They have been gained by duplication, and are lost by deletion. Both of these mechanisms are observed facts, they happen routinely.
2 Likes
Because stem tetrapods evidently branched out over tens of thousands of years. Humans did not. We have a good enough understanding of mammal, and more specifically primate, evolution that it would be shocking to discover Cretaceous humans. If we discovered Cambrian tetrapods, then we’d be shocked. Eifelian tetrapods? Not so much.
2 Likes
They don’t explain the pattern and the WNT family blows the nested hierarchy concept away especially in non vertebrates.
No, as I explained to SCD above, it’s the other way around.
2 Likes
Could you answer a question, Bill: Exactly what do you expect to accomplish by repeatedly denying and ignoring the explanations you have received for the alleged “problems” you think exist?
I ask the same question of @scd.
3 Likes
More on the fish-tetrapod transition:
We have seen that elpistostegids were present in the lower reaches of major rivers, and in deltas and estuaries, from the late Givetian until the mid-Frasnian. Although we need to be careful about statements of absence in the tetrapod fossil record, because they are so easily confused with mere absence of evidence, it is probably fair to say that tetrapods were not present – or at least not abundant – in these environments at that time. If they had been reasonably common they would almost certainly have been found alongside the elpistostegids. Judging by the footprint evidence, the tetrapods were living in the upper parts of river drainages and around shallow water bodies on the coastal plains. These environments were not conducive to the preservation of body fossils.
The most puzzling aspect of the elpistostegids is their complete absence from the fossil record during the Eifelian and early part of the Givetian. The Baltic mega-delta was already in existence at the beginning of the Middle Devonian (Tovmasjana 2013), and the fossil assemblages of its Eifelian and early Givetian strata have been studied extensively (e.g., Obruchev & Mark-Kurik 1965; Lyarskaya 1981), without any trace of elpistostegids being found. Presumably they were somewhere else, either environmentally or biogeographically, but at present we have no evidence as to where.
https://www.cambridge.org/core/journals/earth-and-environmental-science-transactions-of-royal-society-of-edinburgh/article/follow-the-footprints-and-mind-the-gaps-a-new-look-at-the-origin-of-tetrapods/03CDF19859875BB5F43B6AB81C5E476A/core-reader
In other words, based on the present evidence I would predict that in the coming years, as palaeontologists investigate rocks representing deltaic (and similar) environments from the Eifelian and early Givetian outside of the Baltic mega-delta, we will find more early elpistostegid body fossils. Time will tell. Given how much new material is coming out of China, and that I know Chinese researchers are exploring the sediments representing the area around Devonian South China sea, I’m pretty confident.
1 Like
Have you looked at the WNT chart in the paper I cited originally from SCD? There is no rhyme or reason to the pattern of WNT genes in invertebrates. It does not follow the tree at all. Are you familiar with the WNT gene family?