Uprooting Darwin's Tree of Life?

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The bicentennial of evolutionary theorist Charles Darwin's birth will be celebrated on February 12th. My personal celebration got started early with a visit to the excellent Darwin exhibit at the American Museum of Natural History in New York City three years ago. One spine-tingling moment for me was viewing the famous page from Darwin's 1837 notebooks in which he first outlined his idea of the evolutionary tree of life.

darwin tree of life

In Darwin's schematic, ancestral species are at the bottom with later species diverging from the trunk into a branching tree of descendants. A 150 years after the publication of Darwin's On the Origin of Species, some biologists are questioning whether the tree of life really exists. A fascinating article with a bit of an overhyped title –"Darwin Was Wrong"—in the New Scientist looks at how advances in molecular biology are turning the tree of life into a web of life. 

As researchers began comparing genes between species, especially among microbial species such as bacteria, amoebas, and archaea, they found that these creatures promiscuously engage in horizontal gene transfer (HGT). As the New Scientist reports:

The true extent of HGT in bacteria and archaea (collectively known as prokaryotes) has now been firmly established. Last year, [researchers] examined more than half a million genes from 181 prokaryotes and found that 80 per cent of them showed signs of horizontal transfer.

So the bottom of the tree of life is a messy web of life. But HGT doesn't end with single cell microbes. As more and more plant and animal genomes have been sequenced, researchers have discovered that multicellular creatures also experience horizontal gene transfer. It turns out the hybridization, cross-breeding between species, is a major force driving evolution. For instance, wheat is the result of the combination of the genomes of three different ancestral grass species. And our species may be the result of interbreeding between the ancestors of chimpanzees and earlier human species.

Viruses also carry genes between multicellular species. As the New Scientist notes:

Other cases of HGT in multicellular organisms are coming in thick and fast. HGT has been documented in insects, fish and plants, and a few years ago a piece of snake DNA was found in cows. The most likely agents of this genetic shuffling are viruses, which constantly cut and paste DNA from one genome into another, often across great taxonomic distances. In fact, by some reckonings, 40 to 50 per cent of the human genome consists of DNA imported horizontally by viruses, some of which has taken on vital biological functions.

Nevertheless, Darwin's central insight regarding natural selection and descent with modification as being the origin of species remains firmly grounded. The New Scientist article concludes:

…the tree concept could become biology's equivalent of Newtonian mechanics: revolutionary and hugely successful in its time, but ultimately too simplistic to deal with the messy real world.

One final note: The fact of promiscuous and natural horizontal gene transfer between species should undermine the claims of anti-biotech activists. For example, the activist consortium, Consumers International's scientifically ignorant "Say No to GMO" campaign states: 

Genetic modification (GM) is a major change in food production; Genes are transferred between unrelated species, for example from animals to plants. This technology makes it possible to break species boundaries set up over millions of years….

Well, yes. But we now know that what biotech scientists are doing is what nature as been doing for millions of years, just doing it more precisely and with the aim of benefiting our species. We don't have to wait around for nature to randomly mix up the genomes of three grass species to produce a useful crop variety. 

In any case, it is definitely worth your while to read the whole New Scientist article here.

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  1. He is in Hell now.

  2. It sounds like Darwin was “wrong” in a way analogous to how Newton was realized to be “wrong”, when Einstein came up with his relativity theory.

  3. This technology makes it possible to break species boundaries set up over millions of years….”

    Well, yes. But we now know that what biotech scientists are doing is what nature as been doing for millions of years, just doing it more precisely and with the aim of benefiting our species. We don’t have to wait around for nature to randomly mix up the genomes of three grass species to produce a useful crop variety.

    The anti-GMO argument is more of an “unintended consequences” argument, no?

  4. Cross-breeding isn’t a shock to the system. They’ve actually figured out that two species can cross-breed and produce fertile off spring so long as they haven’t been separated by more than about 10k years of evolution, give or take. Nor is it a surprise that Darwin didn’t get it exactly right, he was the first guy to figure it out, they usually just get the basic idea out there.

  5. I told you Darwin was wrong! Jesus rules!

  6. Can they create an effective species that can rid us of invasive species like fire ants yet not become a nuisance in their own right? I would welcome that.

  7. Nick, your second criteria is important. I dread to think of the US South overrun with aardvarks.

  8. Can they create an effective species that can rid us of invasive species like fire ants yet not become a nuisance in their own right? I would welcome that.

    Any advance which solves n problems creates n + m problems of its own, with m being proportional to how neat and shiny the new advance is.

  9. I dread to think of the US South overrun with aardvarks.

    really? i think it would be aawesome!

  10. Any advance which solves n problems creates n + m problems of its own, with m being proportional to how neat and shiny the new advance is.

    Steve Jobs is going to have a lot to answer for in that case.

  11. Steve Jobs is going to have a lot to answer for in that case.

    I think Jobs has an out in that, except in the single case of the iPod, nothing that Apple has ever created could reasonably be characterized as an “advance”.

  12. Nick,

    Don’t listen to BakedPenguin. Aardvarks would be Teh AWESome! Plus the venom of fire ants apparently cleaves DNA. Bad stuff. I HATE fire ants!

    “From hells heart, I stab at thee!”

    *drops aardvark on fire ant colony*

  13. DARWIN NOT ORIGINAL
    Darwin did not originate the idea of the “tree of life”,Lamarck produced one before him. Darwin did not originate natural selection,both he and Wallace admitted that they were beaten to the idea by Patrick Matthew and Charles Wells.None of the ideas (as opposed to examples)in “On the Origin of Species” is original to Darwin,all were published by others prior to 1857. Darwin is the only “genius” who never had an original idea(at least regarding evolution)! (search Google for “wainwrightscience” for details)
    Dr Milton Wainwright,Dept. Molecular Biology and Biotechnology,University of Sheffield,UK.

  14. We know what MC Hawkings has to say about this.

    http://www.youtube.com/watch?v=TGNRYNdVT7g

  15. Does HGT occur when a bat fucks a pig?

  16. Darwin’s insight has to appreciated in its original intellectual context.

    Before Darwin, the history of species would have been shown as a mass of individual straight lines. Darwin’s tree of life should that species begat species. It was one of history’s critical insights.

  17. Darwin is the only “genius” who never had an original idea…

    If I have seen so far, it is because I stood on the shoulders of giants.

    Or something.

  18. How do aardvarks taste?

  19. Does HGT occur when a bat fucks a pig?

    Can we use HGT to create a monkey with four asses?

  20. How do aardvarks taste?

    With their tongues, moran!

  21. The anti-GMO argument is more of an “unintended consequences” argument, no?

    Yes, no.

    It’s an “I like it when Africans die” argument.

  22. “bat fucks a pig” — your self loathing and hatred of your wife is staggering. Are you the bat or the pig?

  23. It’s not my fault you can’t get a Kids In The Hall reference, train boy.

  24. I just toured the property. Put me down for a half dozen aardvarks. And throw in a couple of aardwolves. I could use some good guard animals.

  25. Darwin is the only “genius” who never had an original idea(at least regarding evolution)!

    Oh, horsefeathers. Others had flash-in-pan insights that they scribbled down and never developed, Wallace included. Darwin spent years meticulously gathering evidence and thinking of responses to objections before they were raised by others.

    There’s a lot more to science than eureka moments. Especially, those that are never developed, researched and tested. If those who claim precedence to Darwin are great scientist my blog post make me a great novelist.

  26. Do aardvarks even eat fire ants? I understand they eat termites and some other insects but fire ants?

  27. Wait! hold that order.

  28. Maybe they can take an existing animal that is already a nuisance to some degree but not as objectionable, like stray dogs for example, and just splice in a gene that makes them like fire ants for food and also not get horribly allergic to the bites. A stray dog with aardvark genes (appetite, long sticky tongues, immunity) rather than non-native aardvarks introduced.

    Or maybe they can splice aardvark genes into evangelicals. They’re all over the South and it would be a nice FU for objecting to the science in the first place.

  29. Naga – according to Wikipedia, they do:

    “…the termites’ biting, or the ants’ stinging attacks are rendered futile by the tough skin…”

  30. How do aardvarks taste?

    A bit like Polar bear

  31. The bicentennial of evolutionary theorist Charles Darwin’s birth will be celebrated on February 12th.

    Spencer County, Indiana is all abuzz about a Feb 12, bicentennial this year as well.
    As is LaRue county, Kentucky.

    One of my favorite coincidences.

  32. BakedPenguin,

    I’m inclined to believe you but the shrillness of this . . . article . . . leads me to doubt.

  33. Naga, you should totally change your screen name to Aardvark Pumpkin.

  34. SugarFree,

    Negative. Pham Nuwen is my other cognomen. I just rarely use it.

  35. Way to wuss out, Aardvark Pumpkin.

  36. SugarFree,

    I’ll change it if you change yours to Slim Fast. (wink) Quid pro quo.

  37. Get to it.

  38. Wait! Did you just trick me into acknowledging that name? Crap!

    “He used her super-intellect on me! She’s like Hanibal Lecter.”

  39. Clearly we need to back our oars here. We are dangerously close to going FULL RETARD.

  40. LLAW?

  41. We are dangerously close to going FULL RETARD.

    We are already there.

  42. Laugh Like A Wookie

  43. Ah. My geekiness did not follow on that one. That photo . . . is clearly doctored. Unless we have slipped into META-RETARDED. Then we are fucked.

  44. It’s OK. I just made it up. But you watch… it’s gonna be a thing.

  45. I hope not. First the Ringu coding, now this? You vision for the world frightens me.

  46. Can’t I just do the worm instead?

  47. I release you from your bonds of fealty.

  48. Thank you m’Lord. I was actually having an identity crisis for a few minutes and typing my real name for a bit.

  49. By the way… Laugh Like Jabba The Hut.

  50. Sure, if you were set up like Jabba, it’d be easy to laugh.

  51. Kind of a misleading article.

    The entire premise of HGT is that genes transfer between species — but of course, this depends entirely on your definition of species.

    If Chimp ancestors and Human ancestors mated successfully, many would say that this indicates they were not separate species at all.

    In fact, far from overturning Darwin’s thinking, chimp ancestor/human ancestor matings are exactly what Darwin predicted would have happened early on in the “splitting” procesess. How could it be any other way?

    Darwin, of all people, recognized that speciation was a long, gradual process, that would have produced numerous “hybrids” when viewed from a far off future vantagepoint.

    Now the virus transmission, on the other hand, is something he didn’t predict.

  52. search Google for “wainwrightscience” for details

    A google search for “wainwrightscience” reveals that you chronically spam blogs, if that’s what you mean.

  53. I caught the Jabba reference. Thats why I linked to the worm video.

  54. SugarFree,

    Sticks and stones.

  55. One final note: The fact of promiscuous and natural horizontal gene transfer between species should undermine the claims of anti-biotech activists. For example, the activist consortium, Consumers International’s scientifically ignorant “Say No to GMO” campaign states:

    Genetic modification (GM) is a major change in food production; Genes are transferred between unrelated species, for example from animals to plants. This technology makes it possible to break species boundaries set up over millions of years….

    Well, yes. But we now know that what biotech scientists are doing is what nature as been doing for millions of years, just doing it more precisely and with the aim of benefiting our species. We don’t have to wait around for nature to randomly mix up the genomes of three grass species to produce a useful crop variety.

    Hmm this sounds familiar…..

    Oh yeah I remember making the same argument over 3 years ago….and getting chastised here in the comments for it.

    Therou where are you now? Or Biologist? guys?

  56. The anti-GMO argument is more of an “unintended consequences” argument, no?

    Yes, fringe environmental lefties can also be found to be dead wrong by accident.

  57. Cross-breeding isn’t a shock to the system. They’ve actually figured out that two species can cross-breed and produce fertile off spring so long as they haven’t been separated by more than about 10k years of evolution, give or take

    No, this is about DNA crossing not only the species barrier but across Kingdoms.

  58. … Here is the crux of the dilemma — either I repudiate God’s command concerning the genocide of the Canaanites, or I conclude that there exist circumstances when ethnic cleansing is acceptable.

    There’s another alternative. I might begin to question the biblical text itself. Maybe God did not order the massacre of civilians. Maybe Joshua projected his desires upon God to provide religious justification for taking another person’s house and land.

    This, of course raises complex questions. Are there parts of Scriptures that are not from God but projected onto God? A disturbing question indeed; Jesus seems to have thought so, telling his disciples, “You have heard it said …, but I say unto you?.”

    Hence I return to my original premise: To attempt to look into God’s face usually means an encounter where the wrestling might leave you wounded.

    Forgive me while I limp away and store up my energy, so that on another day I can again attempt to look into God’s eyes to ascertain God’s character.

    — Miguel De La Torr, associate professor of social ethics, Iliff School of Theology (Denver)

  59. What on earth does that last post have to do with anything?

  60. Darin was right:
    Who said that the tree starts from the trunk? That is what He assumed, the tree starts from the roots down under ; The tree of life started in a way that we cannot see just like the roots of a tree are buried underground. No answer still on how it all started, we are is still in the darkness.
    In any case there are many types of trees and vegetation, life also arose in the same manner. no clear understanding on how it all started and where it is heading.

  61. Uprooting Darwin’s Tree of Life? – Hit & Run : Reason Magazine – 4:29pm
    Jan 28, 2009 … “bat fucks a pig” — your self loathing and hatred of your wife is staggering. Are you the bat or the pig? reply to this …

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