Evolution of the Placenta

Let me give you an example. One big novelty in mammalian evolution is the placenta. Many modern papers hypothesise that key changes required for placenta were incorporated through viral infections.
Now how does common ancestry explain anything about the development of the placenta? The true mystery is in how a viral genome turned out to be such a beneficial fit.
Hence my statement that the faster the change, the more trivial common ancestry becomes as an explanation.
Would you agree?

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Can we have someone who knows something about evolution explain this? I am not an expert but I do know enough to know that you are mashing up the science. Dr. Swamidass, please help us.

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Are you kidding me?

Sure… I would be glad if anyone pitched in.

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Not kidding at all. There is an expert in evolutionary biology right here. He is a practicing scientist who is working at the frontier in that science. Ask him for help understanding the science.

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I am not trolling, George. He has questions about science. The real expert here is Dr. Swamidass. Let him tutor him.

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This is really an interesting topic that I’ve already written about before, along with @vjtorley . I’ll dig that up and show you later.

Also @T.j_Runyon is a scientist in training, and certainly has insight to offer. I’ve often learned from him, especially because he is a paleontologist, and I am not.


Thanks for the kind words. @Ashwin_s I haven’t forgot about you. I will return to this. Crazy day.

@Ashwin_s take a look at this article, and ask your questions from there:


@jongarvey this is an interesting case of intrinsic teleology and neutral evolution at the same time.

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@vjtorley continues to amaze me with the amount of work he puts in

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Also found these interesting papers:



Hi @swamidass,
I had a look at the article. It’s definitely interesting. Off the bat, my first impression is that @vjtorley argument doesn’t hold.
The basic argument is that synctin being clade specific is evidence. for common descent. For example, human beings and apes share the gene in the same location. I will grant that point.
Then he goes on to say that a designer could have shown evidence against common descent by designing human beings with a different type of synctin (say that of a mouse). This is a logical fallacy because of two reasons-

  1. It assumes the primary motivation of design is to disprove humanities theories of evolution.I don’t see any reason to think that.
  2. Even if humans had a different synctin gene (say that of a mouse), it could be easily explained by the baton pass hypothesis.This is why rapid changes can make common descent a trivial observation.
    Common descent could be true irrespective of which synctin human beings had.

@vjtorley used an explanatory frame work in science as below-
" If hypothesis A predicts that X must occur, and no other known hypothesis makes that prediction, and X occurs, then hypothesis A is a better explanation of X than other hypotheses, and (ceteris paribus) more likely to be true."

My question is. What do you do if the hypothesis predicts everything from A to Z? In cases where evolution happens fast or the precise mechanisms are not known, I suspect common descent can explain any set of data. I read a paper once that made the staggering claim that the appendix evolved 29 times in mammals. This was not seen to be a problem for common descent. I doubt humans having a different synctin would be much of a problem.

Another observation is that co-option of a viral system in animals should not be so simple. In my experience as an engineer, systems that work in one machine will not fit in another unless a compatibility is designed.I don’t know much about genetics ,so I will shelve that as an intuition. If anyone knows more, I would love to understand.

I found stages of the placental development in mammals very interesting.

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Have you read the article yet @Patrick? When you do, I’m curious how you’d respond to @Ashwin_s. I helped @vjtorley with that paper two years ago.


I don’t see much point of explaining the relative superiority of a broad and flexible theoretical framework compared to you having zero theoretical frame as a predictive alternative.

Let us know when you have come up with something… ANYTHING. Then we can compare.

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The two papers are over 10 years old. Okay I read them. Seems pretty straightforward evolutionary discoveries. Has the results held up? What are the recent findings? Do they are credence or does it need updating?

I mean the article from @vjtorley. It’s two years old.

Too much flexibility can be a bad thing. A hypothesis that is compatible with every empirical observation (Like ID. This is also a concern I have with Theism in general) is a poor one. There has never been a theory that has agreed with every empirical observation. Never. Theories and frameworks have to take on auxiliary hypotheses. But when a theory starts to get a little too cozy with them it becomes a little troubling. Common ancestry is no where near that point. I think @Ashwin_s big misunderstanding is that he thinks common ancestry can be used to explain everything. And that’s just not true.

It was excellent. Slamdunk in my opinion. But why does Dr. Gauger deserves such attention? It is not like she is some leading light in evolutionary biology. She has her conclusions in mind before she does the analysis (IDer did it). She backs into her conclusion by saying "Hey look over here, our understanding is weak, therefore I can insert the IDer into the gaps in understanding (which aren’t real gaps at all). She does not DO real science, just reports on perceived gaps found the work of others. Real science hasn’t taken her or Discovery Institute seriously for 10 years if they ever did. As the courts said ID is creationism which is religion not science. Having a real scientist of your caliber who actually does science elevates her to higher level than she has earned and deserves. She belongs with Dr. Jeanson, Dr. Faulkner, Dr. Lisle, and Dr. Snelling as former scientists who no longer do science but use their previous scientific credentials to mock, distort, ridicule the real accomplishment of today’s real scientists. It lacks integrity and she should be treated as such at real scientific conferences and by real scientific journals.

11 posts were split to a new topic: Does QM and Relativity Contradict Evidence (or Each Other)?

In cases where change is step by step over long periods of time , common descent makes a fairly narrow range of predictions.
However, the faster the change, the bigger the leaps involves in each step… the set of possible outcomes become bigger. If you have a big enough toolkit, all things are possible… hence common descent will predict every alternative.
This is one of the disadvantages of not being coupled with a specific mechanism.
Edit: Add to the above, the conviction that there has to be some natural explanation for all phenomenon.