What is the standard for evidence in biology?

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Specifically, what is the evidence for common descent?(Not quite) famously, Darwin mused about the similarities of taxonomic hierarchies in linguistics and biology and asserted that the hierarchies must ultimately point to common descent. (Chapter XIV, On the Origin of Species) That’s common descent as distinguished from microevolution.

The linguistic equivalent is the single origin of all languages (eminently unproven and deemed unprovable) as distinguished from a language family (with demonstrable relevant organic shared features).

Darwinists are welcome to present their evidence. From Rumraket, we have the observation that all organisms can reproduce, “Nesting hierarchies are evidence of common descent if you know that the entities sorted into hierarchies can reproduce themselves. And that particular fact is true of all living organisms.” Good start.

From Joe Felsenstein we have the doubt that the border between micro- and macroevolution can be determined, “OK, so for you the boundary between Macro/Micro is somewhere above the species level. How far above? Could all sparrows be the same “kind”? All birds?” Not very promising.

From Alan Fox, “Darwin predicted heritable traits. Later discoveries confirmed his prediction.” Questions: Which heritable traits specifically? Was there a principled improvement over Mendel? And how does this lend credence to common descent?

Thanks to all contributors.

706 thoughts on “What is the standard for evidence in biology?”

  1. DNA_Jock: My highly selective perspective comes from my background in molecular biology: Eukaryotes are a hopeless and confusing mess of jury-rigged kludges. Prokaryotes are smooth, relatively efficient machines.

    Interesting! I never studied molecular biology closely enough to realize that. My bio background is in comparative vertebrate anatomy and paleontology.

    John Harshman: It only seems to exist if you ignore most of the tree of life and highlight a few carefully chosen bits, chosen because you can force them into your pattern. And even there it works only because you employ vagueness and word play.

    Agreed.

    John Harshman: The things that make humans (including, of course, Charlie) special are local adaptations to local environment, not the grand scheme and end goal of all nature.

    Yes, this is absolutely crucial. And that’s true even though those local adaptations to local environment include culture, language, technology — and all the complex social institutions that those make possible.

  2. Kantian Naturalist:
    DNA_Jock,

    CharlieM’s picture is certainly anthropocentric, for sure.

    There are good reasons for why we might take a peculiar interest in human uniqueness. There is something there to be explained about why it’s human beings that have developed culture, technology, art, religion, philosophy, and science — while other primates have not.

    My objection to CharlieM’s account is that while there are good reasons to take an interest in human uniqueness, his way of doing so is epistemologically irresponsible. One can construct that narrative only by deliberately ignoring everything that doesn’t fit into it. CharlieM’s anthroopocentrism makes a Procrustean bed out of the history of life.

    The more responsible (but far more difficult) approach is to understand human uniqueness from a biological point of view, rather than understand the history of life from the anthropological point of view . But doing that requires understanding a good deal of biology!

    The whole point is to look at each and every organism’s relation to biology. We are the only organisms on the planet which rise above our biology. Biology gives us our senses, we augment them with giant telescopes, electron microscopes and the rest. We develop prosthetic limbs, artificial lungs, pacemakers, MRI scanners and on and on.

    Plastic surgeons do a roaring trade in “improving” on biology. Who could argue that breast enhancement is not an advancement in frontal protrusion:)

    Our biology is what makes us generally the same as all other animals, you only have to look at DNA. Our rise above biology is what makes us uniquely human. Of course if you want to judge humans from a biological point of view there are many areas where we are inferior to other animals, I’m would not argue with that.

  3. CharlieM: We are the only organisms on the planet which rise above our biology.

    By your criterion (which is another Charlie-centric one, by the way), can’t you also say the same about the Galapagos woodpecker finch, chimpanzees, and New Caledonian crows, all of which have been known to make and use tools?

    Anyway, so what if we rise above our biology? What does that have to do with your claims about evolution? And what, if anything, does all this have to do with the thread topic?

  4. DNA_Jock: Charlie reminds me of warty bliggens

    I’m flattered. To be compared with a creature from the same stock as my all-time hero, Toad of Toad Hall, fills me with great joy.

  5. John Harshman: By your criterion (which is another Charlie-centric one, by the way), can’t you also say the same about the Galapagos woodpecker finch, chimpanzees, and New Caledonian crows, all of which have been known to make and use tools?

    Anyway, so what if we rise above our biology? What does that have to do with your claims about evolution? And what, if anything, does all this have to do with the thread topic?

    I thought that this thread had just about run its course so I didn’t see much harm in going off topic. I suppose I should have started a new thread. I might still do that if I can find the time. I was enjoying the discussion, but I won’t take it any further here.

    P.S. I found the ref where I read about temperature control in mammals and birds: Continuity And Evolution Of Animals
    By N.S. Sharma    , page 162

  6. CharlieM: I found the ref where I read about temperature control in mammals and birds: Continuity And Evolution Of Animals
    By N.S. Sharma, page 162

    Not much to go on there. It’s a popular work with no references. Your source just repeats the assertion without supporting it.

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