Answering Misconceptions About Evolution

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I came across this passage in another blog, Alcaide's Cafe, written by Russell Husted. As a general rule, Russell's page is considerably more sophisticated and better written than most of its kind, but this passage came as a surprise to me. In this post, he discusses the fact that finding water and methane on Mars is not necessarily evidence of life on Mars, and on that point he is of course correct. Those things might provide evidence that microbial life was once present, or is now present, on Mars, but that is still an entirely open question. But he doesn't stop there. He seems to think that if we do find life on Mars, this will be a problem for evolution because that life, presumably, stayed at the microbial level and did not "advance" to more complex, multicellular life. He writes:

But here is the devilish thought that came to me, as I was thinking about all this. What if we really do find indisputable evidence that life once flourished there? The next question, surely, must be whether it ever "evolved"! Suppose we find that single cell life, perhaps even several types of single-cell organisms, flourished all over Mars, but we also find evidence that it did not evolve or "advance" into anything like what we have here on earth. Suppose it remained forever simple, never dividing into, and including, both plant and animal varieties, or multi-cellular forms, or anything we'd call "complex", or "higher forms"? Suppose that the methane, we've detected, actually is being produced by the natives who are still, after a billion or two years of occupation, no more than bacteria-like or algae-like? If life stayed that simple on Mars, does that not pose a bit of a threat to the theory of evolution? If the evolution paradigm is correct, should not life that "arose" on Mars, and persisted for a billion or two years, perhaps still surviving in hospitable enclaves today, have "evolved" in a pattern at least a bit like the history of life on earth?

I think the folks hoping to find life on Mars better be hoping, as well, to find "higher life" if they find any life at all. If they don't, it seems to me the argument that you and I exist all because of the creativity of "evolution" is substantially weakened, and the Genesis (Biblical) explanation looks a lot stronger.

This is false for two primary reasons.

First, he is assuming that the "evolution paradigm" (that's a teeth-clench phrase) requires that life must proceed along the same paths of life on earth. This is an unwarranted assumption. There is no requirement that life must have evolved beyong single-celled creatures. That life did follow the path from unicellular to multicellular forms on earth is the function of contingent events and there is no reason to assume that those same events would have taken place on Mars as well, or that contingent events that could have stopped that development did not happen on Mars.

Second, the existence of unicellular life for one or two billion years without the formation of multicellular life wouldn't be a problem on Mars because it obviously was not a problem on Earth. The first single-celled life on earth appeared at least 3.7 billion years ago, but the first multicellular life did not appear until some 2 billion years later. Since unicellular life, and only unicellular life, existed on earth for that long, it would hardly be difficult to believe the same thing happened on Mars, if that indeed turns out to be the case.

8 Comments

Somebody should point him to yesterday’s post of: Living words: Dearth and taxa - “primitive”.

I think he’s been watching too much Star Trek, and assumes that because its labeled “Science” Fiction, it means that scientists actually believe or support some of what it portrays on-screen (like all intelligent lifeforms are humanoids with 2 arms, 2 legs, reproductive organs between them, 1 face with 2 eyes, 2 ears, a nose, a mouth, some distinctive scar tissue that separates them from us, plus the ability to half-breed with humans from a thousand light-years away).

it of course misses the point – scientists rarely “believe” anything about science, except that the scientific method with its extensive research, control cases, experiments, and peer reviews, is the best way to study the universe.

as for what we “hope for”, well we speculate. that’s part of the process. we imagine a possibility that seems to fit the facts at hand, and then either look for more facts to support/contradict it in what’s available, or create an experiment case to create more facts to apply/filter the theory through, then eventually throw the whole damn thing out and start again.

personally, I think the most likely case of discovering life-related molecules on mars would come from looking at specific impact sites (non-volcanic craters) particularly by determining which were asteroid/meteor vs which were comets, and then seeing if the comet impact zones have them.

it would also help for there to be a published definition of “life” for the amature to consider. Does life require carbon, for example? (which emphasizing the methane issue implies, in spite of how simple the methane molecule is and how easy it is for nature to create). does it require replication (ie, RNA/DNA)? does it require reaction to stimulae? does it require consumption and conversion of resources in a controlled environment (e.g., o2 to co2 for the energy)? at what point is something “alive”?

as Sagan pointed out, many definitions of “life” could apply to other things like the stars themselves, so the definition being used in these local searches in our solar system should probably be made more clear.

I note that in an earlier posting called “Again: Intelligent Evolution or Lucky Design?” Husted propagates one of the core creationist canards, that

In fact, a good argument could be made that all we’ve ever seen is “devolution”, or a gradual running down of the system. We have never seen a species get made. We’ve seen genetic drift and adaptation, but no complete case of species creation!

and

The truth is, the only good evidence we really have is of the disappearance of pre-existing species! Lacking concrete and complete evidence of creative evolution, we might just as easily conclude they were all “created” by a Divine Creator, or Intelligent Designer.

I’m not inclined to comment over there, but someone who does may want to refer him to the various resources that provide accounts of observed species formation.

RBH

Re:speciation or at related to it, are large breed dogs and toy breed dogs still the same species in any meaningful way? A collection of great danes and chihuahuas of both sexes won’t produce mixed breed puppies (I wouldn’t think).

What’s most hilarious about that post is that the author blithely jumps to saying the Genesis account must look a lot stronger, when the Genesis account makes no mention whatsoever of Mars!

I wonder if anyone has studied constraints on multicellularity – how much biological productivity is needed to support a multicelled organism, with its differentiation and support structures and so forth.

By biological productivity I mean biomass production, energy acquisition, and stuff like that.

Mars organisms’ metabolism would likely be much like early Earth organisms’ metabolism as inferred from the metabolism of the more basal members of Bacteria and Archaea – anaerobic lithotrophy (inorganic chemotrophy) / chemosynthesis.

Here is a nice page on biochemical redox reactions (found with Google, searching for methanogenesis kcal mol).

Compare:

methanogens’ energy source (anaerobic): 4H2 + CO2 -> CH4 + 2H2ODG0 = - 8.3 kcal/mol

methane oxidation (aerobic): CH4 + 2O2 -> CO2 + 2H2ODG0 = -193.5 kcal/mol

23 times more energy per methane molecule!

So a Mars organism may not have much by way of resources to spare for becoming multicellular.

Photosynthesis gets around that difficulty, but an organism has to be illuminated for that to happen, and that means living at the surface. Which would be very difficult to do on present-day Mars, though there is evidence of the former presence of liquid water on that planet’s surface.

(DG0 is the change of amount of chemical energy; negative is release of that energy)

I have a class this semester called Introductory Biology for Nontechnical Majors. Recently we learned about something called "Hardy-Weinberg Equilibrium," in which a population does not evolve under certain conditions. Those conditions were listed as:

  • The size of the population is very large or effectively infinite
  • Individuals mate with one another at random
  • There is no mutation
  • There is no input of new copies of any allele from any extraneous source (such as from a nearby population or from mutation)
  • All alleles are replaced equally from generation to generation (natural selection is not occuring)
  • I’m hardly an expert, but it seems to me that Mars may well provide a perfect environment for Hardy-Weinberg equilibrium among microbial life. Furthermore, if microbes were discovered on Mars, and were determined to never have evolved due to Hardy-Weinberg equilibrium, wouldn’t that be more evidence in support of evolutionary theory?

    The Hardy-Weinberg theorem only applies to the genomes of sexual reproducers with a well-defined diploid phase – it’s the statistics of diploid-phase alleles.

    Many of the more “primitive” organisms, however, violate some or all of these conditions. Many protists and fungi have only a transient diploid phase, and they reproduce asexually much of the time. Prokaryotes reproduce exclusively asexually, though they do exchange genes among themselves occasionally.

    Since anaerobic chemosynthesizers like methanogens are all prokaryotes, and their source of energy may be too weak to support fancy structure, so Martian organisms may all be prokaryote-like – asexually-reproducing, with no well-defined nucleus or other such organelles, etc.

    So I predict that Hardy-Weinberg won’t help us understand Martian-microbe genetics very much.

    But other tools of evolutionary biology certainly will.

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    This page contains a single entry by Ed Brayton published on April 9, 2004 12:58 PM.

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