Clues To Ancestral Origin Of Placenta Emerge In Genetics Study

Bye Bye troll

Charlemage:

There is nothing in that paper that proves the religion of evolutionism. If human placentas evolve from egg shell linings in birds by random chance, then why don’t human placentas evolve every time you fry an egg? You add energy to the chicken egg, so why doesn’t the evolution happen every day at the breakfast table?!

Charlemage logic matches up with www.youtube.com/watch?v=FZFG5PKw504

PvM:

Bye Bye troll

Charlemage:

There is nothing in that paper that proves the religion of evolutionism. If human placentas evolve from egg shell linings in birds by random chance, then why don’t human placentas evolve every time you fry an egg? You add energy to the chicken egg, so why doesn’t the evolution happen every day at the breakfast table?!

If Charlemage ever bothered to learn elementary biology or even zoology, he would realize that human placenta would have more in common with a monotreme’s egg (such as that of an echidna), than a chicken’s egg, if only because humans are more closely related to echidnas, than they are to chickens. Plus, Charlemage would have already realized that the mammalian placenta is derived from the membranous structures of the typical amniote egg, in that, instead of anchoring the embryo to the lining the inside of the eggshell, and providing gas exchange with the outside without dehydrating, the egg’s membranes now provide an attachment to the internal surface of the uterus, and provide a means of gas- and nutrient exchange with the mother, as well as to protect the fetus/embryo from the mother’s immune system.

David Stanton:

Perhaps it would be better to embrace the science rather than whine about the supposed “moral implications”. Otherwise, when the science becomes so overwhelming and undeniable, people might just remember the moral behavior of those who tried to deny the science and forget that science still can’t make any moral decisions for you.

Personally, I prefer to think of the “moral implications” of Darwin’s dangerous idea to be along the lines of “expanding one’s understanding of life is a good thing in and of itself, but if it can be used to benefit others, it’s even better.”

Females that lay eggs are oviparous (monotremes, birds, and most reptiles, amphibians and fish). Some reptiles and fish retain the eggs in the body, hatch them inside, and give birth to hatched young (“ovoviviparous”). However, in some cases the young are retained inside the female and start to be nourished from the mother’s bloodstream. This involves the development of a placenta. That seems like a very complex affair, but we see independently developed placentas at various stages of development in placental mammals, wombat-koala marsupials, a bunch of snakes and lizards, and some fish.

Thompson et al. (1) refer to viviparity evolving in over 100 separate lineages within lizards and snakes. Most of their placenta are comparatively simple (see here, #2), but at least one is in some ways comparable to the mammalian placenta in its complexity (here, #3)

Just to cite a few examples in fish, although there are many more, in sharks, the bull shark, whitetip reef shark, lemon shark, blue shark, mako, porbeagle, salmon shark, the silvertip shark, the Hammerhead, and the whale shark have placentas.

Also, the topminnow offers a particularly interesting set of examples. Specifically, Reznick et al. (in Science, 2002, #4) studied placenta development in topminnows (Poeciliopsis).

The evolution of complex organs is a source of controversy because they require the contributions of many adaptations to function properly. We argue that placentas are complex, that they have evolved multiple times in Poeciliopsis, and that there are closely related sister taxa that have either no placentas or intermediate stages in the evolution of a placenta. Furthermore, placentas can evolve in 750,000 years or less, on the same time scale as suggested for by theoretical calculations for the evolution of complex eyes. Independent origins of such complexity, accompanied by sister taxa that either lack or have intermediate stages in the evolution of the trait, present an opportunity to study the evolution of novelty and complexity from a comparative, evolutionary perspective.

My links don’t seem to be working in preview, so here they are. 1 = www.bio.usyd.edu.au/staff/thommo/pdfs/2004/139ThompsonAdamsHerbertBiazikMurphy2004.pdf

2 = http://icb.oxfordjournals.org/cgi/c[…]act/32/2/303

3 = http://www.pubmedcentral.gov/articl[…]artid=391591

4 = http://www.bec.ucla.edu/papers/Rezn[…]_1-24-05.pdf

Stacy S.:

Now that we live in pretty good shelters that keep wild animals away from our young … can we go back to laying eggs please? :-)

I do understand your wish that is shared by many females.

Please, allow some nitpicking. What do you mean by “wild animals”, as compared to … what?

Regards

Eric

Stanton, do you think that wolves are “wilder” than rabbits?

Stanton:

Eric Finn: Please, allow some nitpicking. What do you mean by “wild animals”, as compared to … what?

As in actual predatory animals, such as large eagles, wolves, jackals, lions, tigers, and bears that would seize and feed upon the young of other animals, including those of humans.

Regards

Eric

Stanton:

Eric Finn:

Stanton, do you think that wolves are “wilder” than rabbits?

Tell me, moron, which is more likely to attack and eat an unguarded five-year old child, a wolf, or a rabbit?

I do not know the reason you are attacking every post I make, apart from me being a moron.

Panda’s thumb has been a great asset for me, not only by providing information, but also providing me an opportunity to discuss items that puzzle me.

Stanton, if your aim is to stop me posting on this site, you are very close to achieving that goal.

Regards

Eric

As a parent of an egg, I wouldn’t be concerned about a bunny eating my offspring. True. Unless it were the Evil Easter Bunny.

Many of your comments sound like those a concern-troll creationist would make, especially your comment about how the Theory of Evolution is incomplete because it does not proscribe behavior like a religion, and that you ask painfully obvious questions, like questioning about wild animals and young children, despite the fact that there is a monstrously huge source of literature about the dangers of mixing wild animals with children, as well as the myriad examples (re: literally true horror stories) of how wild animals will bite, eat, scratch, claw, sting, and pass disease and parasites to young children.

Forgive me if I sound cruel, but, I don’t care to restrain myself around people who make light or appear to make light of mixing wild animals with children, especially when I keep hearing horror stories like when a woman set out to get a picture of her son being kissed by one of the bears in Yellowstone, only to have him be mauled to death when she lured a bear into kissing her son by smearing his cheek with jam.

If you aren’t a troll, I apologize: instincts die hard.

Eric Finn:

Stanton:

Eric Finn:

Stanton, do you think that wolves are “wilder” than rabbits?

Tell me, moron, which is more likely to attack and eat an unguarded five-year old child, a wolf, or a rabbit?

I do not know the reason you are attacking every post I make, apart from me being a moron.

Panda’s thumb has been a great asset for me, not only by providing information, but also providing me an opportunity to discuss items that puzzle me.

Stanton, if your aim is to stop me posting on this site, you are very close to achieving that goal.

Regards

Eric

From the article:

They found that the placenta develops in two distinct stages. In the first stage, which runs from the beginning of pregnancy through mid-gestation, the placental cells primarily activate genes that mammals have in common with birds and reptiles. This suggests that the placenta initially evolved through repurposing genes the early mammals inherited from their immediate ancestors when they arose more than 120 million years ago. In the second stage, cells of the mammalian placenta switch to a new wave of species-specific genes. Mice activate newly evolved mouse genes and humans activate human genes.

For those of you interested in thinking logically, let’s break this down. There are two types of ideas in this paragraph: facts, and “suggestions.” The facts are that all most of the genes activated during the first stage are common to mammals, birds, and reptiles; and during the second half, mice activate genes unique to mice, and humans activate genes unique to humans.

This is science, and absolutely fascinating.

The “suggestion” is that because similar genes common to several species are activated during the first stage, they are “ancient” genes.

This is not science. It’s speculation, premised on the assumption of common descent, and with absolutely no evidence, novel or otherwise, to support it.

By analogy, a hybrid vehicle and a model T both have tires made of rubber (something in common), and things not in common (the unique design of their engine). The inference to evolution is like saying, “Well, because we know that hybrids and model T’s are related, we can conclude that tires are ancient and inherited by both.”

That’s an absurd inference.

The real challenge here is to understand how those genes came to work together in coordination – is there a feasible stepwise pattern from “no placenta” to “protoplacenta” to “mammalian placenta?”

Not yet. Quite the contrary, it looks like there’s a sudden switch from universal genes (all of which are still inexplicably coordinated) to species-species genes (all of which are also still inexplicably coordinated). Like noticing that certain elements of different computer models are shared, and certain elements are radically, uniquely, different in a highly coordinated manner.

That inference is also not science. It’s an inference. It’s the design inference. But it’s just as reasonable, if not superior, to the alternative.

The problem with evolutionists is they take perfectly good science, and make ridiculous, unfounded proclamations of “yet more evidence than evolution.” The problem’s not in the science. The problem’s in your interpretation thereof.

By analogy, a hybrid vehicle and a model T both have tires made of rubber (something in common), and things not in common (the unique design of their engine). The inference to evolution is like saying, “Well, because we know that hybrids and model T’s are related, we can conclude that tires are ancient and inherited by both.”

It seems to me that there are two problems with your analogy. One is that rubber tyres are an ancient feature of cars (in so far as anything is). Secondly, we know that hybrid vehicles and Model T’s are not related in the same way that organisms are because cars do not have babies.

Also, as Henry says, there is massive amounts of data showing the relationships between mammals, birds and reptiles. It would be foolish not to make use of this information.

Henry J:

ungtss,

Your argument presupposes that every piece of evidence has to support the whole theory all over again. There’s at least a couple of problems with that approach.

1) An already established theory is supported by the totality of the relevant evidence, not any one piece thereof.

2) Once the general principles of a theory are established as being well supported by the evidence, it is quite reasonable to regard those principles as being well supported by the evidence.

Henry

Henry: Thank you for your very thoughtful response. My impression, and the impression of those who think like me, is that the belief that the “totality or relevant evidence” unequivocally supports common descent stems from the same faulty inference.

1) A (usually very interesting) scientific fact is identified;

2) An unfalsifiable, unobservable inference is drawn from the scientific fact, and called “scientific fact.”

3) Nobody argues over the fact. It’s obvious and uncontroversial. But everybody argues over the inference, because it is not obvious, and is enormously controversial.

Early on it came down to sheer physiological similarity: “Humans and apes are physiologically similar. Therefore they are related.” Faulty, obviously. Paradigm-dependent.

Later on it moved on to embryos: “Embryos of diverse species look similar. Therefore they are related.” Faulty, obviously. Also paradigm-dependent.

Lately it’s been all about ERVs: “A tiny minority of the 10s of thousands of ERV-like sequences in the genome appear in identical places in some (not all) humans and some (not all) chimps. Therefore we’re related.” Also faulty. Never mind that we haven’t determined if the ERVs are set in the whole population (which would be a prerequisite to infer common descent) nor that the observed ERVs are known to be capable of infecting both humans and simians independently, nor that the vast majority of the ERV sequences are NOT shared by the humans and simians that have thusfar been sequenced. In fact, the argument comes down to selection bias. Scan the 10,000-some-odd ERVs in both genomes, find 1 or 2 in the same place, and conclude common descent. Don’t bother to check to see if the ERVs are set in the respective populations. Don’t mention that even given independent infection, one or two are bound to end up in the same place given tens of thousands of ERVs.

The observed facts regarding ERVs are clearly consistent with both an evolutionary scenario and an ID scenario.

And now it’s the fact that diverse species use similar proteins early in placental development. Therefore we’re related. That’s faulty. If we were to genetically engineer life forms to colonize another planet, we would ABSOLUTELY use similar designs in diverse species. Computer programmers do that today, borrowing and tweaking subroutines, then plugging them into wildly different software packages. Why shouldn’t we expect similar mechanisms for placental development.

It all comes down to that same inference – which is philosophical in nature, not scientific. Nobody’s arguing about the facts in front of us. We’re all arguing about interpretations of facts that cannot, by their very nature, be directly observed.

Any two wheeled vehicles may be shown to be derived from a common ancestor; the material used for the wheel-to-road interface (“tyre”) is a contingent detail.

Automobile “lineages” have often borrowed innovations developed in other “lineages” of technology, such as computers, lights, seat belts, refined metals, plastics (and maybe even internal combustion engines as well; I don’t recall for what those were originally developed, but I strongly suspect it wasn’t cars). Technology doesn’t follow the strict nested hierarchy expected of species that evolve without swapping significant amounts of DNA between species. That limits the usefulness of the analogy. Plus, unless there’s an explanation as to why the bioengineer(s) didn’t reuse already developed technology outside of the taxon in which it was developed, the biology as technology argument actually works against the notion that the details of life on Earth were deliberately engineered.

Faulty, obviously. Paradigm-dependent.

But that goes right back to what I said earlier, which I’ll paraphrase here: if a principle has already been established as being supported by evidence, it makes no sense to have to reinvent that principle for a new piece of evidence.

What supports a theory is the patterns that occur repeatedly and consistently throughout the relevant evidence, of which nested hierarchy is perhaps the most important. There’s also divergence of types over time, lack of types that don’t fit in the heirarchy, geographic clustering of close relatives (at least with types that aren’t globally mobile). On a side note, as I understand it, the geographic clustering was what initially caused Darwin to reach his conclusion.

Without details on what “Intelligent Design” actually says (those do seem to be in short supply), with the simplest interpretation of “life was deliberately engineered” I would expected there to be massive exceptions to all of those patterns (e.g., frequent sharing of technology outside the taxon in which it originally appeared, geographic redistribution of derived species, species that don’t fit the hierarchy, DNA differences that don’t fit the hierarchy, maybe even species showing up long before several of their presumed predecessors.)

Henry

You characterize exceptions to nested hierarchies as a prediction of ID. Yet vehicles, which are obviously intelligently designed, have nested hierarchies. You have “Vehicle,” “Utility vehicle,” “Pickup,” “Extended cab,” “4WD,” colors, options, etc. It is easy to draw a nested hierarchy of automobiles.

It is indeed. However, if you prepare nested trees based on, say, the spark plugs, the speedometer or the seat covers, you will get different trees. In biology, you would get the same tree.

Initially taxonomic trees of organisms were thought of in just the same way as you could think of them with vehicles. For example, plants were distinguished on whether or not they had seeds, whether the seeds were borne in flowers, whether the seedlings had one cotyledon or two and so on. However, it became apparent that organisms placed in one group had many different features in common and to a large extent it did not matter what features were used, an essentially similar pattern emerged. This, basically, was the stimulus for considering common descent.

These days, data can be collected on all kinds of things, for example the exact distribution of the amino acids in proteins with specific functions. The data are thrown into a computer program that has no idea of what outcome is expected yet the resulting trees conform remarkably closely to trees derived from other data. The results are not as good for plants as animals because genetic material can be transferred from one species to another by diseases. However, for animals I have seen data in which the probability of getting as good a match or better by pure chance was 1 in 10360. It is far more than ‘sheer physical similarity’. When biologists talk about a ‘nested hierarchy’ what they mean is a nested hierarchy that is the same regardless of the traits used (obviously things that are variable or easily change such as animal weight are not considered or are given very little emphasis).

Ungtss,

You seem to be under the mistaken impression that biologists are all idiots and are only out to fool you. That is incorrect and illogical. Why would any scientist care what you think?

Homology is determined based on objective criteria. With genes there are statistical tests that can be employed to determine homology. With anatomy, homologous structures must be the same structure coded for by the same genes and produced by the same developmental pathways. Homoplasy in the data is reduced by careful examination of the characters involved BEFORE the clasdistic analysis is performed. We know the mechanisms of mutation and we know the relative and absolute rates of change for molecular characters. We avoid homoplasy by choosing characters that evolve at a rate appropriate to reduce the probability of convergence and reversal. The reasoning is not circular. The nested hierarchy is the result not the assumption.

As for endogenous retroiviruses (ERVs) or SINE insertions, we also know the mechanisms of transposition. There are literally millions of insertion recognition sequences in eukaryotic genomes. The probability of shared insertions by chance alone is extremely low. There is also no known mechanism for reversal, making this the perfect character for phylogenetics. Insertions persist through speciation events, thus shared insertions are strong evidence of common descent (the alternative being that God copied the mistakes). Now here is the important point, insertions are not only shared between species, but they are shared in a particular pattern, they are found in a nested hierarchy! In fact, it is the same hierarchy that is reconstructed by gene sequences, morphological analysis and the fossil record. Check out the Talk Origins archieve on plagarized errors in the Molecular Genetics section.

The nested hierarchy is exactly what is predicted by descent with modification. It is inconsistent with the hypothesis of a designer. If you insist that it is consistent, then you must explain why the designer created exactly the pattern that would be expected from common descent and no other. Is God trying to fool you as well? If so, you better play along, you know how she gets when she’s angry.