On Friday, September 17, 2021 at 4:12:34 PM UTC-4, Glenn wrote:
> On Friday, September 17, 2021 at 12:03:06 PM UTC-7, Peter Nyikos wrote:
> > On Thursday, September 16, 2021 at 8:05:32 PM UTC-4, erik simpson wrote:
> > > Even further back:

> > Than what? The last part of the title could be misleading, because the
> > original unicellular-to- multicellular transition was "even further back"
> > than the unicellular-to- multicellular transition that the authors talk about.

> Such thoughts immediately came to my mind, after reading the OP. So I should assume that others have as well, and some more extensively,
> and with more knowledge of the current claims of science than I. But I wasn't surprised to find the up front claim "How animals evolved from a single-celled ancestor..."

Which is true in a sense, but with the screwy definitions that cladistic classification
has produced, the default assumption is "last single-celled ancestor of all living animals".
The movers and shakers of present day systematics are no more respectful of
fossils than the average creationist.

And so, that elusive entity might have been the last common ancestor of animals and
fungi, or even further back, with all living animals evolving from a multicellular
entity that may have already been well on the way to solving the
"cell adhesion, cell–cell communication and gene regulation"
problems that the abstract talks about.

Note, however, that many different groups of fungi have also solved these problems.
So the big question is whether that elusive "last single-celled ancestor of all living animals"
was a lot further back than the first (multicellular, by this scenario) fungus, or
whether fungi solved all these problems independently of animals. My vote goes
for this second alternative.

> In a brief exchange with Ron a month or so ago, he claimed that first life would not have been encapsulated (for lack of a better or more technical term) by a membrane, but free "swimming" so to speak.

Ron O is an immovable dogmatist on many things, so it wouldn't surprise me if he
was as unequivocal as you make him sound. But it's stupid to say that the first
efficient replicator had no outer membrane, because then every chunk of RNA,
or whatever, that preceded it was at the mercy of a bewildering variety of other
organic compounds that it would have been shielded from by a properly
permeable [not too little and not too much] membrane.

> And he could be right.

I'm not ruling it out. His scenario also has advantages. This is one debate that
OOL theorists have had for over half a century, perhaps over a century in various forms.

> Of course, if I claimed that first life would have been multicellular in the same sense of lacking individual membranes in "cells", I'd be labelled a kook.

Yeah, you aren't Ron O, who is much more popular than you [just ask Hemidactylus], and
who could probably get away with it.

Since you are Glenn, your theory would be lampooned as a throwback to 19th century
hypotheses about something (I forget the name, but it would have been one big mass of
"protoplasm") covering the bottoms of the oceans.

You'd have to distance yourself from that sneer by hypothesizing big chunks,
no bigger than the biggest living thing today
[some titanic fungus millions of years old, in Oregon IIRC]
with various centers of active genomic reproduction to whatever degree of fidelity
was possible.

>I think it is a fact that we don't have a clue as to what first life was or what happened early in the "tree" of life, which as I understand is turning into something of a bramble bush.

"mycelium" is the term I use. Strands merging and splitting in an intricate web,
until lateral transfer has "cooled" to where a number of trunks emerge from the
ground, each a portion of the tree of life. And perhaps all but one of the trunks
died out to produce the Tree of Life that is "visible" today.

Or perhaps two: eubacteria and archae. The dominant theory now is that
eukaryotes came about when (1) an archaebacterium went into symbiosis with
one or more kinds of (2) eubacteria. (1) went on to become the nucleus as
more and more of the (2) surrendered their genetic material to it.

In fact, the "supradominant" theory is that we "know" what kind of eubacterium (2) was.
I forget the name, but I could easily look it up, and so can you, because Minnich
was mercilessly raked over the coals a month or so ago in talk.origins for daring to question
the precise identification that this "supradominant" (2) at Dover, 2005.

As far as the Overdogs of talk.origins are concerned, it is all settled science, just like
"Birds are dinosaurs. The debate is over."

> And I suspect that we will never, until and if OOL research actually produces something besides rhetoric.

Agreed.

Peter Nyikos
Professor, Dept. of Mathematics -- standard disclaimer--
Univ. of South Carolina at Columbia
http://people.math.sc.edu/nyikos

PS I've left in the rest below, because it segues reasonably well with what I wrote above.
> >
> > In fact, unless we restrict our attention to eukaryotes, it was MUCH further back,
> > although multicellular prokaryotes are most unlikely to be in our past.
> > > https://royalsocietypublishing.org/doi/pdf/10.1098/rsob.200359
> > >
> > > "How animals evolved from a single-celled ancestor, transitioning from a
> > > unicellular lifestyle to a coordinated multicellular entity, remains a fascinating question.
> > > Key events in this transition involved the emergence of
> > > processes related to cell adhesion, cell–cell communication and gene
> > > regulation. To understand how these capacities evolved, we need to reconstruct
> > > the features of both the last common multicellular ancestor of
> > > animals and the last unicellular ancestor of animals. In this review, we summarize
> > > recent advances in the characterization of these ancestors, inferred by
> > > comparative genomic analyses between the earliest branching animals and
> > > those radiating later, and between animals and their closest unicellular relatives.
> >
> > Something not made explicit here but provided in the article: the closest
> > unicellular relatives of animals are assumed to be closer than the closest
> > multicellular relatives.
> >
> > This being sci.bio.paleontology, it needs to be pointed out that it is
> > extant close relatives that are considered here. If we turn our attention
> > to fossils, there are some "wild cards" that could upset this assumption,
> > including one we talked about earlier this year:
> >
> > "A possible billion-year-old holozoan with differentiated multicellularity,"
> > by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe,
> > Martin Saunders, Charles H. Wellman,
> > Current Biology 31, 1--8 June 21, 2021
> >
> > https://www.cell.com/action/showPdf?pii=S0960-9822%2821%2900424-3
> >
> > Erik, you and John and I commented on it in several posts, and Glenn [I hear you going "hiss" :) ]
> > and Trolidous ["yay!" I say, and you can too] each doing one post. I did the OP:
> >
> > https://groups.google.com/g/sci.bio.paleontology/c/2KXAzM6x-q4/m/Nc8Q2U5jAQAJ
> > Billion year old fossils of an exciting new sort
> > May 28, 2021, 10:07:55 PM
> >
> > [Yeah, almost a month before the putative date of the article. I haven't tried to figure that one out.]
> >
> > For those who missed that earlier thread: "holozoans" are all eukaryotes closer to
> > animals than to fungi, cladistically speaking. Most holozoans are unicellular, but
> > * Proterospongia* is a colonial choanoflagellate, and may even be an extant exception
> > to the authors' assumption: a multicellular [just barely] holozoan that is closer to
> > animals than any unicellular one.
> >
> > However, the colonies are less differentiated than those of the gigayear-old
> > extinct species, and it might well be the closest-to-animal non-animal holozoan known.
> >
> >
> > Of course, unless we find some way to include them in the genomic analysis
> > [gigayear old DNA may be nonexistent anywhere]
> > these "possible holozoans" are not likely to of any use to the main research in the article:
> > >We also provide an updated hypothesis regarding the transition to
> > > animal multicellularity, which was likely gradual and involved the use of
> > > gene regulatory mechanisms in the emergence of early developmental and
> > > morphogenetic plans. Finally, we discuss some new avenues of research
> > > that will complement these studies in the coming years."
> > Looks to be well worth reading. Good catch, Erik.
> >
> >
> > Peter Nyikos
> > Professor, Dept. of Mathematics -- standard disclaimer--
> > University of South Carolina
> > http://people.math.sc.edu/nyikos