Introductions and A Bit About Ghost Lineages

[Chad_the_Layman (Chad Stewart)]

The Ghostly Origins of the Big Cats

Hello Peaceful Science. I have posted in a topic so far, but this is my first Topic creation. Seems like you kind and friendly folk like instroductions, so let me start there.

I’m Chad, I live in Fort Worth, TX, work as a civil engineer and have a 4- and 6-year old (along with a sweet and lovely wife). I love both theology and science but am expert in neither. Well, science is part of professional life, so I could claim expertise in hydrology and hydraulics, but relating to you guys, was thinking in terms of PHD level expertise. I have a B.A. in Mathematics and a B.S. in Civil Engineering. For most of my life the sciences that exerted the greatest pull on my attention were physics and geology (nothing beyond undergrad and hobby level) with my interest in biology rising in recent years with what genetics has introduced to the discussion about evolution.

There’s the intro! Thanks for the warm welcome so far. It’s an honor to interact with y’all.

Now to some science…“science” on my level at least…

I linked to a youtube video by PBS Eons. First of all, if seeding the conversation with something this non-technical is subpar for this venue, please coach me up.

The video describes how difficult it has been to establish an ancient lineage for the big cats. It introduces the concept of ghost lineage. I introduced this as a topic for a couple of reasons.

First, I find it fascinating that we can watch a lineage get sorted out in real time. The ancestors of modern big cats have been difficult to find for lots of reasons, one of which is that we (humans) have (possibly) been looking in the wrong place. Africa seems to be the obvious place to look, but African digs haven’t turned up ancestral big cats. But a site in The Himalayas offered up a piece to the puzzle which appears to be an ancient big cat ancestor. Very cool.

Second, may I offer a comment about the evolution/design conversation (I have some theological and philosophical thoughts about that debate that I may share at some point, but that’s not this)?

Am I correct in thinking that the presence of a ghost lineage may be a gap into which a Design proponent might rush in order to offer a “design” argument?

My thought is just this (here’s where I risk bringing my un-expert thoughts to the experts)…

Science requires patience. The Big Cat family has been without proven ancestry. It might have appeared to some that this was proof that the big cats aren’t a tree branch, but a recently created tree. Instead, it appears, that the big cats are most likely a branch, and we just had to wait a while for the dirt to offer up a good clue.

There you go. That’s my simple introduction and layman level take on a fun science topic. Do with me and my thoughts what you will. You don’t even have to be gentle.

[Mercer (John Mercer)]

@Chad_the_Layman

Am I correct in thinking that the presence of a ghost lineage may be a gap into which a Design proponent might rush in order to offer a “design” argument?

Hi Chad,

Welcome!

@Chad_the_Layman

First, I find it fascinating that we can watch a lineage get sorted out in real time.

It is. We can also observe that IDcreationists, who should be jumping in, offer nothing of value during the sorting process, demonstrating that they do pseudoscience. @jeffb, this is an example of what I mean by creationists quitting actual science.

That was a great video–one can watch it at 2x with subtitles, and my only objection was the use of the verb “prove” at the very end.

@Chad_the_Layman

Am I correct in thinking that the presence of a ghost lineage may be a gap into which a Design proponent might rush in order to offer a “design” argument?

I agree with you there, but such gaps are likely to close with more evidence. Still, if one really believed in the hypothesis, there should be no hesitation.

Theologically, though, stuffing the Intelligent Designer (God) into such tiny gaps diminishes Him–in my opinion.

[Chad_the_Layman (Chad Stewart)]

@Mercer

Hi Chad,

Welcome!

Thanks! I feel welcome.

@Mercer

this is an example of what I mean by creationists…

Full disclosure, I believe the God of the Hebrew and Christian Bible created the world. But I think he most likely loaded the first seed (bang) with everything it needed to grow into what we observe today.

The ID folks take a bit of a whipping here, so not trying to start a pile on thread, but I do disagree with what I’ve read of the ID approach.

@Mercer

That was a great video–one can watch it at 2x with subtitles, and my only objection was the use of the verb “prove” at the very end.

Is it the word “prove” in this sentence: “jaguars are, for now, the descendants of ghosts: ancestors whose existence we can infer, but not yet prove?”
If so, what’s a more accurate way to express the idea that she tried to present?

[Mercer (John Mercer)]

@Chad_the_Layman

The ID folks take a bit of a whipping here, so not trying to start a pile on thread, but I do disagree with what I’ve read of the ID approach.

The worst is the claim that ‘both sides are interpreting the same evidence differently,’ when the ID side ignores most of the evidence and even blatantly misrepresents some of the most important evidence in evolutionary biology.

@Chad_the_Layman

Is it the word “prove” in this sentence: “jaguars are, for now, the descendants of ghosts: ancestors whose existence we can infer, but not yet prove?”

Correct. An important aspect of science is that nothing is ever considered to be formally proven. All conclusions are provisional.

Despite that, I won’t deny that you’ll occasionally hear scientists talking about proof.

@Chad_the_Layman

If so, what’s a more accurate way to express the idea that she tried to present?

Something like, “but there’s still more evidence needed before this relationship is as solid as the others in this tree.”

[swamidass (S. Joshua Swamidass)]

Nice to meet you!

[John_Harshman]

@Mercer

Something like, “but there’s still more evidence needed before this relationship is as solid as the others in this tree.”

Not even that. Fossil evidence is just not needed to show that big cats are related to other cats, to civets and mongooses, to hyenas, to dogs, weasels, and bears, and so on. The tree doesn’t depend on fossils but (mostly, these days) on DNA sequences. Fossils can help us figure out how to date the tree and they can tell us about lineages that left no descendants and those earlier than the divergences of living species. But they aren’t needed to confirm the tree.

[Mercer (John Mercer)]

Huh? Where did I even mention fossils?

[John_Harshman]

That’s the subject of the text you’re correcting, isn’t it?

[Chad_the_Layman (Chad Stewart)]

@Mercer and @John_Harshman, John and John, would it be accurate to say that the genetics show us what to expect of the tree that produced the modern big cats, and recent fossil discoveries have confirmed what genetics show, added detail to the tree, and added data to the overall study of the ancestral history of big cats.

Or is there a more accurate way to say that?

It seems like (from this layman) that it might be important to say things in a way that doesn’t discount the contributions made outside of genetics and to be able to talk about how each branch (of science) contributes data to the development of the story.

[Mercer (John Mercer)]

It shouldn’t be in the corrected version, which is why I used the far more general term “evidence.”

[John_Harshman]

In that case you’re going to have to change the entire video, since fossils are the context.

@Chad_the_Layman

recent fossil discoveries have confirmed what genetics show, added detail to the tree, and added data to the overall study of the ancestral history of big cats.

I wouldn’t say they’ve confirmed it, as that implies that further confirmation was needed. They’re compatible with the genetic data, which is nice. I wouldn’t say they add detail to the tree either; they add a different sort of information: age and more information about earlier morphology.

[Chad_the_Layman (Chad Stewart)]

@John_Harshman

I wouldn’t say they’ve confirmed it, as that implies that further confirmation was needed. They’re compatible with the genetic data, which is nice. I wouldn’t say they add detail to the tree either; they add a different sort of information: age and more information about earlier morphology.

This is great. You’re shining a light on my lack of understanding.

When you say “they”, I assume fossils, “add…age and more information about earlier morphology”, I don’t understand how that doesn’t add detail to the tree. What’s the relationship between the tree that genetics reveals and the information gained from the fossil record? In my amature mind genetics and the fossil record work together together to make the tree visiblle to human minds.

Wait, maybe towards the end of that paragraph I started speaking more accuratly…stay with me…

Have you ever seen the childs toy that allows kids to “paint” by dipping a brush in water and brushing water onto a page, which causes a picture that was already there, though invisible, to emerge?

So the tree already exists, of course, because the past has already happened. Then genetics and fossils (and other things) work together to make the tree visible.

Where am I going wrong? Am I on the right track? Or if that’s too messy. What’s the relationship between genetics, the fossil record and the tree?

[John_Harshman]

@Chad_the_Layman

What’s the relationship between genetics, the fossil record and the tree?

What’s commonly done is to plug fossils into the most parsimonious spots on the molecular tree. This can influence interpretation of the evolution of morphological characters. After that, you can use it to try to assign dates to internal nodes. I suppose you could call that additional detail, though I wouldn’t. To me, the tree is just that, a tree: a pattern of branches diverging from other branches.