… their central position on deep evolution, which is that the most recent universal common ancestor (MRUCA) is complex not a simple bacteria and “is the root of eukaryote and akaryote lineages” containing “more than a thousand Superfamilies.” Kurland and Harish think MRUCA represents complex survivors from a now extinct biosphere.
On horizontal gene transfer as routine:
Charles Kurland: We have to remember there’s only a little background of horizontal gene transfer in bacterial populations. The simple reason is that bacteria eat DNA. So sequences are going in all the time. Most of them get chopped up.
But I agree completely with what Jeff Errington said. We think that the most recent universal common ancestor [MRUCA] was the product of a lot of HGT and Carl Woese described the reasons for this.
The thing is once you see the phylogeny of the sort that we have, that Ernst Mayr predicted, where the akaryotes are separated in their descent from the eukaryotes, the obvious possibilities for akaryotes to make eukaryotes are just not there. But that’s the essence of the symbiosis hypothesis — the bacteria gets together with an archaea and it makes a eukaryote, the bacteria becomes the mitochondria and the archaea becomes the nucleus cytoplasmic host. That’s the theory. It’s very, very clearly specified that way.
It’s interesting because it was Lynn’s [Margulis] attempt to explain why DNA was found in the cytoplasm of eukaryotes, and it turned out to be DNA located in mitochondria. It turned out to be DNA located in chloroplasts. Her idea was that: Ah, the mitochondria, the chloroplast, certain kinds of flagella, were actually originally bacteria. Her idea was that if you look at mitochondria, the DNA that was there was the whole genome of that bacteria.
It turns out that it’s nothing like that. And we should have been much more suspicious of the hypothesis as soon as it was discovered that a minor fraction of information for mitochondria is coded in the mitochondria. We should have been very suspicious of that.
These models may, of course, reappear, refurbished with new evidence.
Later in the interview, Kurland notes that he is not an ardent fan of dogma in science:
It’s definitely a problem. It gets embedded in the education system. There’s no one who takes a biology course that does not believe archaea plus bacteria make eukaryotes. It’s a rule now. It’s beyond criticism now. Well, let’s see if we can change that.
His view is highly advisable:
Suzan Mazur: You’ve gotten some serious support there from the Royal Swedish Science Academy, from the Nobel Committee.
Charles Kurland: Yes. But I think if it were up to most molecular evolutionists, we would be starved to death. More.
Ah yes. Survival of the fittest really is true in some places. 😉
See also: Origin of life: We are all descended from a “complex” ancestor? In the biosphere we know, there was probably never any such thing as a “simple” cell, which is the likely reason the innumerable “it all comes down to” theories of the origin of life don’t work. But now, how can we research pre-Snowball Earth?
Origin of life: Do L-form bacteria hint at origin of primordial cells? So then the ability to switch back and forth is a form of stasis from earliest times?
Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more
Life continues to ignore what evolution experts say
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