Evidence for Evolution - Your Elevator Pitch

Wouldn’t modification in-situ make common descent irrelevant?

I dont know why people equate common descent with evolution. To me,the entire point of evolution is that it is “unguided”.
Would you view “Guided evolution” as evolution?

Yes. If we’re talking about vertebrates, it would generally be the presence or absence, shapes, and relative sizes of bones.

Yes. Tree finding algorithms operate by looking at and evaluating lots of trees, assigning some kind of number that represents the fit of data to tree for each, and picking the tree(s) that have the best fit. The easiest one to explain is parsimony, in which the criterion is the minimum number of changes needed to explain the data on the tree.

Only up to a point. Since the record starts at the simplest possible cells, there’s no way to go but up. But once complexity goes much above that point, up and down are equally reasonable. Most fossils are from that world.

Not sure what you mean by that. Modification in situ would be a form of common descent.

Of course. How else?

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It wouldn’t be natural. Hence my question about the importance of evolution being unguided.

I do. It’s because the term ‘evolution’ includes common descent by definition. There are just a few main claims of the theory, made famously explicit by Darwin, and common descent is one of them. In fact it is common for people to equate ‘evolution’ with common descent. If your point is that ‘evolution’ in scientific parlance means more than that, then you’re right, but then:

Well, when you say “to me,” I guess you can then say anything you want, but I think this is a pernicious falsehood. Certainly it is wrong to say that this is the “entire point”; that’s like saying that the “entire point” of embryology is that it is “unguided.” It’s true that lots of people think that evolution (and the rest of the cosmos) is “unguided” but that’s not the “entire point” of a vast explanatory framework like evolutionary theory.

I would. To argue otherwise would abuse the English language, for starters.

EDIT: I botched the last sentence, which now reads “I would” and explains why, with the words I had before.


Answered, I hope.

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I very much agree.

Evolution and common descent (though not necessarily universal common descent) are tightly linked. “Unguided” is not a central claim of evolution, because even natural selection is a type of guidance.

What scientists react strongly against is claims that there is scientific evidence of intelligent guidance when these claims cannot be substantiated.


34 posts were split to a new topic: Ashwin: is evolution guided or unguided?

First of all, thanks, this is super helpful.

Now a couple of questions.

Given that non of the tree’s are going to perfectly fit the data, how wide is the variation in tree’s that have a “reasonable” fit? Are there any that would not suggest common descent? I assume “reasonable” could be defined using normal statistical measures (e.g. something along the lines of within 2 standard deviations).

When we create the best fit, what percent of the data doesn’t fit the tree? To what do we attribute that data?

And finally, how close do the best fit from the fossil phylogenetic tree a genetic phylogeny tree’s align? And again, to what do we attribute the differences?

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Regarding the title of this thread: “elevator pitches” always make me a bit nervous.

Again and again, I have been involved in conversations with creationists where the argumentative tactic is: get me to concur with some highly simplified statement of what evolution is, or what the evidence for it is. Then attack that statement of what evolution is as incomplete, or that evidence as insufficient.

So, when asked for simple and short explanations, I will usually give them, but with the proviso that they ARE simple and short explanations which do not really cover the ground. So if someone wants a shortened statement of evolution like “natural selection acting on random mutation,” fine. But if someone wants to play the game of saying, “ah-hah! But that’s false, because there’s genetic drift,” it just gets a bit ridiculous.

This is actually the tactic of numerous creationist books: strip evolutionary theory down to natural selection plus random mutation, and then start bringing up things that aren’t strictly part of that to “debunk” evolution. The recent book by Shedinger did that right and left: every bloody thing in biology was deemed to not be part of “Darwinism,” hence evolution is false.

If I had to give an elevator pitch for evolution, I’d say “read a book.” But if I had to give an elevator-length explanation for what I personally find incredibly compelling, it would be the faunal succession as set out in the fossil record.


Sometimes trees do perfectly fit; not often, mind you, but I’ve seen it myself on one occasion. I’m not sure what you mean by the rest of that sentence.

It wouldn’t suggest common descent if the fit to the best tree were no better than expected from a randomly chosen tree, to pick an example. If you consider the set of all possible trees as a distribution, there should be a strong peak in the neigborhood of the best tree.

Varies immensely, so no way to answer that.

Homoplasy. Consider DNA sequences: there are only four possible states at any position, so when a mutation happens, it can easily hit the same spot in the same way twice or more over a tree.

Again, it varies. But generally we find that the trees are much more similar than can be attributed to chance.

Most often I would attribute it to the paucity of data in the fossil set, relying as it does only on preservable features, a small subset of what we can get from extant species, and sometimes to mis-coding of fossil characters. And there’s also that old homoplasy; morphological convergence can affect many characters simultaneously in a systematic way.


I think we run with different type of YECs. The ones I have these conversations’ with are genuinely interested, but need enough evidence to convince them that it’s worth their time to investigate further.

Despite regular responses that I see, I haven’t yet found a clear, concise logical argument for evolution based on it’s evidence in terms a layman can easily understand. If anyone can point me to one that would be fantastic.

In regards to books, you only read those once you are convinced by the “elevator pitch”. What you suggest as a first read, that outlines the theory and arguments for evolution?

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And that was and is the strategy of the face-palm-worthy “A Scientific Dissent from Darwinism.” https://dissentfromdarwin.org/

“We are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged.”

As has been noted countless times on this and other forums, if not for the propaganda spin behind this infamous anti-evolution petition, we could all affirm (1) the skepticism which is inherent to all scientific inquiry, and that (2) “careful examination” should always be encouraged. (If one lacks a healthy skepticism and a passion for careful examination, one should not pursue a career in science.)

Of course, all of the above is “old news” to our Peaceful Science regulars but perhaps this summary will be of value to some visitors to this forum.

The has-been linguist in me leads me to wonder if some English-as-a-second-language readers (and even fluent English-speakers outside of North America) might be perplexed by the idiom elevator pitch. Long ago I used to do executive training and sales-training as a side-line, and in the 1990’s this expression became a catchy new label for a very old scenario: How does one encourage a business relationship, solicit a networking opportunity, or stimulate interest in a product/idea in a very limited time—such as a brief trip on an elevator? Supposedly this kind of situation arose when a salesperson would sit in a busy executive’s waiting room (waiting for him/her to leave the office) and could only make an introduction and sales pitch during an elevator ride with his/her target. Some of my client companies hired me to help their people develop and optimally deliver their rehearsed “elevator pitches.”


Indeed. And what’s more, I am not merely “skeptical” of the ability of random mutation and natural selection to explain all of the complexity of life: I’m downright sure that they do NOT explain all the complexity of life. But random mutation and natural selection, though key parts of modern evolutionary theory, are not ALL of evolutionary theory.


I’m certainly happy to help so far as I can. I think, though, that what you will find is that all explanations which are concise, tight and compact are incomplete, while all explanations that strive for completeness are non-concise. And all explanations, at any level, depend for their credibility upon data which are external to the explanation, and which are never concise.

If I had to crunch it all down to a paragraph it would run something like this:

“The history of life on the planet, as demonstrated by the fossil record, shows a long series of organisms. These originate as single-celled forms, followed by the earliest multicellular forms. Later multicellular forms have more complexity of construction and cell types. This goes on for some time and there is a very definite succession in which the creatures of one period look rather like the creatures of the preceding period with modifications – together, in most cases, with the continued existence of things which continue to look analogous to the earlier forms. This sequence gives us, for example, worms when there are no chordates, primitive chordates before early jawless-fish vertebrates, jawless fish before jawed fish, jawed fish before jawed, lobe-finned fish, lobe-finned fish before tetrapods, tetrapods before amniotes, amniotes before synapsids, pelycosaurs before therapsids, therapsids before mammals, early mammals before rodents, early rodents before sciurids, then, at the pinnacle, the Eastern Gray Squirrel. Some of these periods of change in this sequence are beautifully detailed – see Jenny Clack’s book Gaining Ground on the origin of tetrapods, for example, or Kemp’s Origin and Evolution of Mammals, for another. Some process must account for this gradual, layered, long-term change from the fauna of long ago to the fauna of today, and the fact that the fauna occur in this order and that the changes have this character of elaboration and addition to existing forms strongly suggests that the old forms are the ancestors of the new. Attempts to create a phylogeny on the basis of morphology generated a detailed picture of animal ancestry, before there was any substantial knowledge of genetics. Now, genetic analysis has massively confirmed that phylogeny, and genetics bears quite directly upon descent.”

Now, here’s the problem. Creationism is an industry dealing in deceit, and it has generated objections to all of that. Not substantial objections, of course; ludicrous and laughable objections. But even the YEC who doesn’t think about this stuff very much has heard some of them. If he hasn’t, and he relays that to a friend, he will start to hear them. At that point, DETAIL is all that will do. He’s got to make a serious and sincere study of it, and he’s got to understand evolutionary theory BEFORE trying to view it through the fun-house mirror of creationism, because that fun-house mirror will give him a caricature of evolutionary theory which he will have a hard time separating from reality, if he does not understand reality first.

I don’t buy that at all. I read all manner of books, including those whose contents I am curious about for all sorts of reasons. I read Mein Kampf recently. I certainly wasn’t convinced by an elevator pitch for that, and I didn’t need to be, because I wanted to UNDERSTAND something about Nazism, not just confirm existing beliefs (which, to be clear, are ANTI-Nazi!). Not long prior to that, I read Das Kapital, and likewise, I didn’t need to be convinced to become a communist first. Das Kapital sits on my shelf next to Herbert Spencer’s Social Statics (just as Marx and Spencer, who live on as a department store, sit in Highgate cemetery a stone’s throw away from one another). I have the Bible, the Koran, at least a dozen creationist books, books on economics from a dizzying variety of points of view, and contentious and interesting literature on any number of other subjects from cheese-making to archaeology. So, no; you don’t need to be convinced by the elevator pitch before you can inform yourself.

Indeed, who on earth gets convinced by elevator pitches? Not me! Holy cow, what a lousy way to do business! Every religion has its own elevator pitch – you’d have to believe them all, if they could summarize themselves in a short description? Every pseudoscience has an elevator pitch, too. Nobody should EVER be convinced by an elevator pitch to do anything except perhaps to say “golly, that sounds interesting. I’ll have to find out whether there’s really anything to it.”

Now, as to book suggestions, let me suggest something a bit out of the ordinary. People will often tell you to read Coyne, or Dawkins, or some such thing – books that are written as a kind of advocacy for evolutionary theory. I would recommend something else. Read something that acquaints you with the variety and scope of living things, like Colin Tudge’s The Variety of Life (now a bit out of date, but I don’t know a good substitute). March through the phyla and learn something about everything from Platyhelminthes to platypuses. And then get a good book on some aspect of the faunal succession: those books I mentioned by Clack and Kemp are nice, if a bit technical. Far better to see how evolutionary theory applies to particular topics than to just get a broad, simplified overview. These things do not “argue” for evolution at all, but the argument they do not make is ten times as compelling, to me, as the arguments people do explicitly make for evolution.



The video you link to is longer than 60 minutes.
Is there a specific time stamp where you summarize your elevator pitch?

On further consideration, it occurs to me that not 50 feet away from my desk as I was typing that is an elevator which I purchased. I must admit that I did purchase that elevator after, among other things, a sales pitch which, by the nature of the thing, must of course be considered to be an “elevator pitch.”


Completely agree. An elevator pitch is just something you use to pass the smell test. A good pitch should intrigue, not convince.

I heartily agree. My Zoology and Comparative Vertebrate Anatomy classes held some of the most compelling evidence for evolution. The vast majority of those classes were spent marching through the different orders of animals. It still makes me chuckle to think of humans as a tube within a tube, but its something that sticks with you after learning about the coelom.


I truly cannot understand how the biotic succession of the fossil record, in which biotas near each other in time resemble each other more than they resemble those distant in time, isn’t both clear and easily understood. Could you elaborate?


Hey, it all starts with a few layers of cells. Development is amazing. Some people say they’d rather have “a bottle in front of me than a frontal lobotomy,” but I’ve always said I’d rather be “a mate with a Sealyham than an acoelomate.”


I think maybe I wasn’t clear. I think the evidence itself, as you and others have described in this discussion is compelling.

What I find missing is a good and logical description of the evidence that someone with no background in the sciences can pick up and understand. This is the “elevator pitch” I’m looking for. Again, my primary audience is the people around me who would say, “I’m comfortable with my YEC view, give me a good reason to think about investigating the alternative”.

I’m going to try to write one if my own words based on the various posts in this discussion, and I’ll happy with any critiques once I do. However life is busy, so it might take a day or two for me to get around to it.

But again, if anyone is aware of one already written down, I’d love to be pointed to it.