Sperm in all animals originated 600 mil. years ago

MSNBC ^ | July 15, 2010 | Live Science Staff

[goodusername]

“Anyway, no one really knows how to define a species, and there is controversy about any proof that one species has ever become another species. The concept of Ring Species is sometimes mentioned as pretty good proof. But Ring Species seem to provide evidence of salamanders turning into … salamanders. And seagulls turning into … seagulls. Not everyone is impressed by this. “

—One could argue that Australopithecines turning into Homo sapiens is just apes turning into apes, and so isn’t really evolution at all.

“Now, what’s higher than a Species? Well, in ascending order you get Genus, Family, Order, Class. Now we’re at a pretty high level. An example of a Class would be “mammal” or “fish”. No one in their right mind imagines that a fish would – POOF! – turn into a mammal. That would be crazy, right?
What’s above Class? Well, at an even higher level you have a Plylum. An example would be Vertebrates or mollusks. A scallop turning into a mammal? I don’t think so. Hey, wanna know what’s really interesting about the Cambrian Explosion?? That’s when almost all the Phyla suddenly appeared. Basically, 600 million years ago, Phyla just started popping into existence. It’s not clear that there was much of anything as an intermediate step. One day you have mollusks, then the next day you have vertebrates. Wild, huh? I don’t think a nifty invention like sperm will help a mollusk suddenly evolve into a whole new Phyla – like a vertebrate — but who knows?
Now, remember, we have a hard time really explaining lions and a tigers and speciation and how they might have evolved within the Felis genus. No really good explanation for that – just a Theory. We call them species but we don’t really know what we mean when we say that. But, 600 Million Years Ago (so they say) much more magic things were happening – POOF!”

—I get the impression that you believe that the start of a new phyla requires a larger ‘jump’ than the start of a new species. Actually, it’s no different. In fact, it’s not really possible to know if one is witnessing the start of what will become a new phyla.
Phylum require what is sometimes known as a “retrospective coronation”. That is, a group of somethings can only become classified into a new phyla long after the time that the phyla is said to have started.

Essentially, by definition, a phyla is not something that can form very recently - or that could form tomorrow. It’s a label that would we put on a group of life forms only after many speciation events. An analogy to a phylum and how it forms might be like the start of a new language – or better yet a language family (such as the “Romance Languages” of Latin, French, Romanian, etc). The witnesses to the time of the beginning of Latin probably wouldn’t have seen it as the beginning of a new language, but instead as merely a variation of another language (probably Greek?). And even if someone did see it as the beginning of a new language (which is highly unlikely) they certainly wouldn’t have seen it as the beginning of a whole new family type of languages. And thus the beginning of a language family is also something that, essentially by definition, is something that could only have occurred long ago. It won’t happen today. And the time that we call the beginning of a language will always be a case of “retrospective coronation”. Anyone living at the time of the beginning of Latin would have looked at that start as just a population of people speaking barely any differently than other population - we can look back and call that time the beginning of a new language (and new language family) only because of our position far in the future and knowing what occurred later.

Likewise, no sane taxonomist living at the time of the ‘Cambrian Explosion’ would separate many of the lifeforms he sees into separate phyla as we do today. There wasn’t much differentiation between most of the ‘phlya’ at that point. Many of what we regard as separate phyla from that period are just slightly different wormy things that are close cousins of each other. Look at many of the lifeforms at that point and notice that, even when there’s excellent preservation, it’s often debated as to which phyla to put it in – this is because many of the phyla were so alike. For instance, what are thought to be early chordates at this time – Pikaia, Yunnanozoon, and Haikouella – in each case it’s debated as to whether they are chordates or some other phyla. And, as mentioned, in most cases the only reason for feeling the need of placing many of the lifeforms into separate ‘phyla’ is because of retrospective coronation.

Also, the Cambrian ‘Explosion’ wasn’t as impressive as once thought – the ‘explosion’ has been fizzling for the past century. It used to be thought of as the beginning of life, but it was found that that isn’t true. Then it was thought to be the beginning of multicellular life, but that isn’t true either. Then it was thought to be at least the start of animal life, but that isn’t true. Today, I often see it claimed, from many biologists, that the Cambrian Explosion was the start of “most animal phyla”. Looking at the actual data though, even that may turn out to be a gross exaggeration.

From E. O. Wilson’s “The Diversity of Life”: “The number of living animal phyla … is about thirty-three. Of these, approximately twenty comprise animals large and abundant enough to leave fossils of the kind preserved in beds of the Burgess Shale type. The number of Cambrian phyla identified with confidence remains at eleven.”

That was in 2001. Doing a bit of research to see what the latest numbers are, it looks like there are now 36 animal phyla (due to some reclassifying – notice that defining ‘phyla’ is problematic as well), and of these about 17 are thought to be identified from the Cambrian fossil record (so less than half). And of these 17, most existed prior to the Cambrian Explosion (Porifera, Mollusca, Annelida, Cnidaria, and Arthropoda, and probably Chordata, Nematode, Echinodermata, Brachiopods, and Placozoa). Most of the rest make their appearance well after the Cambrian (e.g. Rotifers, Onychophora, Nematomorpha, Echiura, Annelida).

So of the 36 or so phyla, perhaps 7-10 originated during the Cambrian Explosion (and that number could shrink as the fossil record of the pre-Cambrian continues to improve). More phyla appeared both before, and after the CE, than what appeared during the CE itself. So after the CE we have little wormy things, but no amphibians, no reptiles, no mammals, no insects (which make up 3/4 of all species), no birds, no dinos, no trees or flowering plants, etc etc. All of these have formed since then. That’s a bit more than a “tweaking” as you put it earlier.

[Stultis]

Phyla just started popping into existence. It’s not clear that there was much of anything as an intermediate step. One day you have mollusks, then the next day you have vertebrates. Wild, huh? I don’t think a nifty invention like sperm will help a mollusk suddenly evolve into a whole new Phyla – like a vertebrate -- but who knows?

Yeah. That would be "wild". But nothing like that happened.

In all too typical antievolutionist style, you have this completely bollixed.

"Vertebrates" are not a phyla. Vertebrates are part of the the phylum Chordata, animals with notochords.

The notochord is a simple rod shaped body, formed from cells of the mesoderm, which defines an axis in the early embryo, later replaced in complex animals by the spinal cord. The notochord only persists through life in simple Chordates, like this (the lancet amphioxus):

Vertebrates do not show up in the fossil record until tens of millions of years after the first appearance of chordates. Even then the earliest (probable) vertebrates were very simple compared to modern animals with skeletons. For instance Myllokunmingia, about 524 million years old:

The first animals with anything remotely like a "modern" skeleton, i.e. having a skull that included a jaw -- the Gnathostomata or "jawed vertebrates" -- took many more tens of millions of years to evolve, not appearing until well into the Ordovician.

You've employed a standard creationist trick, trying to imply that modern groups, at their first appearance, were as distinct and different as they are today.

In fact nothing like that is ever the case. All higher taxa, at their earliest appearance, a very similar to other related contemporaneous taxa.

The differences which technically define the higher are small, piddling items of detail, like the embryonic addition of a notochord. Such small things only have their momentous significance in retrospect, when we look back from the many additional differences (e.g. crania, jaws, spinal chords, vertebrae, limbs, etc, etc) in modern forms.

Of course this pattern (higher taxa first appear with only slight differences distinguishing them, and the full packages of traits which significantly set apart later forms accumulate piecemeal over time) is exactly what we must find if evolution is true, which is why creationists cannot permit themselves to acknowledge it.

[Stultis]

And the time that we call the beginning of a language will always be a case of “retrospective coronation”. Anyone living at the time of the beginning of Latin would have looked at that start as just a population of people speaking barely any differently than other population - we can look back and call that time the beginning of a new language (and new language family) only because of our position far in the future and knowing what occurred later.

Interesting. In my post just above I made exactly the same point (if not as well) even though I wrote mine before reading yours.

I even wrote a paragraph (but then edited it out) about how a taxonomist living at the time could never justify classifying Cambrian chordates as a distinct phyla.

[Stultis]

BTW, as (I believe) with all PLoS (Public Library of Science) research, you can read the full article online for free:

Widespread Presence of Human BOULE Homologs among Animals and Conservation of Their Ancient Reproductive Function

[Stultis]

So when a gene changes, that is proof of evolution. But when a gene does not change, even when it was expected to, that is also proof of evolution.

No. What supports evolution (not proves, since no scientific theory is ever proved) is that the patterns are consistent, in conformity to evolutionary patterns of relationship, across the great diversity of species.

So, for instance, as the article says, most sex genes evolve fairly rapidly, and so vary quite a bit among taxa. However, if you find a particular gene that doesn't vary that much between, say, deuterostomes and protostomes (these are the two main divisions of bilaterally symmetrical animals, with protostomes including arthropods, nematodes, molluscs, et al, and deuterostomes including Chordates, like us, sea urchins, et al) then -- if evolution is true -- it must also vary little, and in fact even less, when compared across diverse species within each of these groups, and likewise within each progressively smaller subgroup.

Any exception to such patterns must be correlated with specific and identifiable divergences in form or function.

In fact there are many, many, many thousands of very specific genetic traits and patterns -- variations among homologous genes, appearances of new genes, divergences of gene families, chromosomal mutations, transposable elements and relict viruses, etc, etc -- that must independently, but simultaneously, conform with evolutionary patterns of relationship. Collectively there have to be millions of opportunities for elements of this data to flatly contradict evolution, but so far that never happens.

[Stultis]

Then how did man and animals reproduce b4 the 600M year milestone?

Well, sex had existed for many hundreds of millions of years previous to this.

Even before multicellular organisms existed, single celled eukcaryotes (protists, more complex than bacteria, but still single cells) had been having sex, as they still do today. Basically it's just an alternation of generations. Haploid (half the genetic compliment) protists fuse to create the diploid (full genetic compliment) generation, which then creates the haploid cells, and so on.

The origin of sperm simply meant that the gametes, the sex cells, were now dimorphic, having different male and female forms. Before that they were the same. Initially this was probably a very minor innovation, and only grew to have great significance retrospectively as many other associated changes and innovations were added on.

[Stultis]

What was the sequence of progression from no-sperm critters to virile critters?

See my preceeding to CTOCS.

Then you’ve got the whole mechanism to deliver the sperm, the tubing, blood supply, stimulant mechanism, and the ejaculatory musculature.

Then, in the same generational sequence and locale, you’ve got to explain how the female system showed up on the scene with all of its hormones, tubing, sperm-receiving hardware, nerves, ovaries, eggs, genes, blood supply, and the knowledge to use the package in concert with the male.

See also my preceding. None of these changes need to have been concomitant. These would have been very simple animals, maybe even pre-animals. The only thing that happened, at first, was that they went from releasing undifferentiated gametes to releasing dimorphic gametes. This initial innovation allowed many other innovation to follow.

But, really, even this was just a new way of doing what had been done before, even by singled celled eukaryotes. At least I think it's the case (although I'm no expert) that some protists create haploid cells which are sexually "typed" in some fashion that they can only fuse with opposite types. In practice the same as eggs and sperm, although it's a different mechanism.

[Stultis]

In genetics class, we discussed the fact that every species alternates between haploid and diploid generations.

I keep finding that, here at the end of the thread, I'm making the same points other posters have made upthread. Maybe I should read the whole thread before making replies!

[exDemMom]

But, really, even this was just a new way of doing what had been done before, even by singled celled eukaryotes. At least I think it's the case (although I'm no expert) that some protists create haploid cells which are sexually "typed" in some fashion that they can only fuse with opposite types. In practice the same as eggs and sperm, although it's a different mechanism.

The other day, I was using E. coli for an experiment, and I was explaining to my research colleague (a gynecologist) that the cells we were using are male. Male bacteria make "sex pili" which they use to puncture the female bacteria and insert DNA. If the inserted DNA contains all the genes for the sex pili, the donor becomes female and the recipient becomes male. Yeast are not classified as male or female, but as "alpha" and "A" mating types. They mate by fusing into diploid cells, although S. cerevisiae (bread/beer and also lab yeast) seem to have a preference for the haploid state.

To make a long story short, sexual reproduction seems to have been around pre-multicellular organisms.

[James C. Bennett]

That’s fascinating!

[James C. Bennett]

Your replies were an excellent addition to the thread.

Thanks for making the case so succinctly!

[whattajoke]

Well, this thread was perhaps the most refreshing one on FR (on this topic) I’ve read in about 7 years.

thanks.