Ancient Predator Revealed!
by JJS P.Eng.And no, I don't mean your mother-in-law! 
As reported by CTV.ca:
Scientists from Canada, Britain and Sweden have pieced together the fossils of a super underwater predator dubbed the Tyrannosaurus rex of the Cambrian era.
New research reveals fossils found in the Rocky Mountains nearly a century ago and thought to be parts of other creatures actually belong to a whole new carnivore that roamed the seas 500 million years ago — the hurdia victoria.
Ain't he cute?! I vote we re-name him Shrimpy! 
I thought I'd pass this along to stir the pot encourage lively debate. Enjoy!
March 19th, 2009 at 8:05 pm
Oh man I'd love to put some ID critics in the water with this baby.
Comment by Bradford — March 19, 2009 @ 8:05 pm
March 19th, 2009 at 8:57 pm
I vaguely remember some TV documentary about finding that creature. The paleontologists who found several fossils of this species found it odd that each one was always eating shrimp when it was fossilized.
Then it dawned on them – those weren't shrimp tails they were seeing, those were the critter's mouth!
Did Neo-Darwinism predict co-option of a body part from one species to form an extremely similar-looking body part on another species but with an entirely different placement and function?
I think even Lamarck would have been shocked at such an idea.
Comment by angryoldfatman — March 19, 2009 @ 8:57 pm
March 19th, 2009 at 11:32 pm
Looks like an Anomalocaris with an enlarged rostrum to me.
Comment by Allen_MacNeill — March 19, 2009 @ 11:32 pm
March 20th, 2009 at 9:40 am
Looking closer, if the "head" were actually a carapace over the thorax (i.e. behind the eyes), this thing would look a lot like a lobster without claws at the ends of its forelegs. Since none of the fossils of Anomalocaris include this carapace-like structure, it's not clear if they are closely related. However, almost all fossils of Anomalocaris are disarticulated (to the point that, for many years, various pieces were thought to be separate animals). Therefore, it is possible that all Anomalocaris originally had the same carapace but, because of its size and consequently different density, all except the one associated with the Hurdia fossil have been missing the carapace.
That's the problem with paleontology; unless you already know what you're looking at, it's really hard to figure out what you're looking at.
Comment by Allen_MacNeill — March 20, 2009 @ 9:40 am
March 20th, 2009 at 9:45 am
Also, these "babies" were about 60 cm long (for the Americans out there, that's less than a yard long). The picture at the top of this thread has nothing to show scale, so it looks quite imposing. However, since most of the other arthropods in the same assemblages were less than the length of a cheap cigar, this "baby" would still have qualified as a "macrophagous" ("big-stuff-eating") predator.
For more on Anomalocaris, go here:
http://www.trilobites.info/anohome.html
Comment by Allen_MacNeill — March 20, 2009 @ 9:45 am
March 20th, 2009 at 9:52 am
an interesting discussion for this group might be the evolution of metamerism, which seems to have been the crucial evolutionary innovation in both arthropods and vertebrates (not to mention most plants). Metamerism (i.e. segmentation, with multiple, almost identical body segments) is the main "theme" in the evolution of the bauplans of most large multicellular organisms.
So, is metamerism part of the "front-loading" hypothesis?
Comment by Allen_MacNeill — March 20, 2009 @ 9:52 am
March 20th, 2009 at 10:01 am
For example, here's what Wikipedia has to say about bauplans and metamerism:
It now appears that the homeobox control mechanism for the production of segmented bodies evolved among organisms that were not segmented. So, would the homeobox regulation of metamerism be considered as a "front-loaded" pre-adaptation?
As an evolutionary biologist, I would assert that the modification of the ancestral homeobox function (i.e. longitudinal differentiation) into the regulation of longitudinal metameric development would qualify as an example of evolutionary exaptation, which Stephen Jay Gould emphasized as one of the principle mechanisms of macroevolution. What say the FLID supporters here?
Comment by Allen_MacNeill — March 20, 2009 @ 10:01 am
March 20th, 2009 at 10:05 am
angryoldfatman asked:
If by "Neo-Darwinism" you mean current evolutionary theory, the answer is "yes"; that's exactly what exaptation is all about.
Comment by Allen_MacNeill — March 20, 2009 @ 10:05 am
March 20th, 2009 at 10:14 am
A discussion of exaptation could also lead to a discussion of spandrels in evolution, which gets at the heart of the "pan-adaptationist" viewpoint held by many evolutionary biologists and virtually all ID supporters.
Personally, I am not a "pan-adaptationist". Unlike my mentor, Will Provine, I think that many of the characteristics of living organisms are "frozen accidents". Stephen Jay Gould (along with Richard Lewontin) was also a critic of the pan-adaptationist viewpoint in EB and ID, which is not surprising since he was first and foremost a paleontologist, who (as I mentioned above) had to figure out what the various structures in a fossil were "for" (including, of course, the idea that they were "for" nothing at all).
Comment by Allen_MacNeill — March 20, 2009 @ 10:14 am
March 20th, 2009 at 11:06 am
Hey Allen
First I think we would all agree that we should all give a shout out to our own personal God for metamerism. It is the greatest thing since sliced bread.
I think this would be a great place to explore frontloading but a couple of questions must be answered before we can move forward.
1) Is the ancestral homeobox function the least costly mechanism for longitudinal differentiation from an evolutionary standpoint?
2) Are other mechanisms even possible?
How we answer those questions would go a long way to determining if frontloading played a role IMHO
Peace
Comment by fifth monarchy man — March 20, 2009 @ 11:06 am
March 20th, 2009 at 1:04 pm
Allen MacNeill,
Hi Allen. Could you give a short paragraph explanation of "pan-adaptationism"? Thanks!
Comment by chunkdz — March 20, 2009 @ 1:04 pm
March 20th, 2009 at 1:45 pm
"Pan-adaptationism" is the idea that virtually all of the characteristics of living organisms are adaptations. That is, one can reasonably ask what the various characteristics are "for"; what is their function or purpose in the life of the organism? Gould and Lewontin called this the "Panglossian Paradigm" in their famous 1979 paper "The spandrels of San Marco and the Panglossian Paradigm: A critique of the adaptationist programme" (you can read it here: http://ethomas.web.wesleyan.edu/wescourses/2004s/ees227/01/spandrels.html). In terms of evolutionary mechanisms (such as the origin and elaboration of metamerism), adaptations are the result of natural (or sexual) selection, and are what ID supporters point to as the things that an Intelligent Designer would design into an organism.
Gould and Lewontin argued that many of the characteristics of organisms are what they called "spandrels", not adaptations. That is, they are characteristics that are not directly associated with increased fitness. Rather, they are "accidents" that can (but don't necessary have to be) modified through selection into adaptations.
Gould went further in elaborating this idea in a paper that he co-authored with Elizabeth Vrba in 1982 (you can download it here: http://evolutionanddesign.googlepages.com/Gould__Vrba_1982_Exaptation.pdf) in which they referred to such characteristics as exaptations. In the context of this thread, the homeobox regulatory mechanism of non-metameric ancestral metazoans (such as flatworms) would qualify as an exaptation for the homeobox regulatory mechanism of their metameric descendants. In Gould's concept of the term, the original homeobox regulatory mechanism would have evolved first in non-metameric animals, and then become modified later in the dominant metameric forms (i.e. arthropods and vertebrates). If I were a FLID supporter, I would propose that the homeobox regulatory mechanism for body regions was a "front-loaded design element" that, once it was in place, could be modified extensively via standard evolutionary mechanisms to produce the various metameric metazoan bauplans.
But I'm not; indeed, I go all the way the other way. I have come to think of all of the characteristics of living organisms as exaptations. That is, none of them start out as functional adaptations at all. Rather, they begin as essentially random developmental accidents, which then become co-opted via selection to produce what we perceive as functional adaptations. I believe that this was Gould's view, which he tempered somewhat to mollify the intensely adaptationist viewpoint taken by the Neo-Darwinian "mainstream".
Comment by Allen_MacNeill — March 20, 2009 @ 1:45 pm
March 20th, 2009 at 1:58 pm
Oh man I'd love to put some ID critics in the water with this baby.
Allen Mac_Neill:
OK Allen, point made.
But a hungry one might cause an ID critic some discomfort. Since we at TT are not barbarians this might suffice to teach a lesson. But if the warning goes unheeded a pool full of the creatures might do the trick. 
Comment by Bradford — March 20, 2009 @ 1:58 pm
March 20th, 2009 at 1:59 pm
fifth monarchy man asked:
I don't think there is any way to determine this, without knowing if there are alternative ways to accomplish the same thing; that is, the production of multiple, nearly-identical body segments. As far as we know, all metameric organisms use the same underlying genetic regulatory mechanism to produce segmented (i.e. metameric) bodies. Furthermore, this regulatory mechanism almost certainly evolved among organisms that were not metameric, but then became modified later in those descendant lines that became metameric. Sean Carroll's book, Endless Forms Most Beautiful has a good, relatively simple description of how the homeobox regulatory mechanism is tied to metamerism.
Again, there seems to be no way to find out. All we know is that all of the known metameric animals use essentially the same mechanism to regulate the development of their multiple body segments. Without alternative examples, even asking this question seems pointless.
In both cases, it is of course possible to speculate endlessly on how metamerism might be regulated. However, what we know (and the only thing we know) is how it is regulated.
Comment by Allen_MacNeill — March 20, 2009 @ 1:59 pm
March 20th, 2009 at 2:07 pm
Taking this back to the original premise for this thread, it's probably not an accident that the "mouth-arms" of both Anomalocaris and Hurdia victoria look like the segments abdomens ("tails") of shrimp. If they developed using the same regulatory mechanism as shrimp (they are all segmented arthropods, after all), the production of segmented appendages using a relatively slight modification of the homeobox program for segmented bodies would produce exactly that: "mouth-arms" that look a lot like shrimp.
That's why I suggested that the enlarged "head" of Hurdia victoria might actually be a carapace very similar to the thoracic carapace of modern lobsters and shrimp. Just look at the figure and move the enlarged "head" back over the body until it lies behind the eye stalks, et voila! an ancestral lobster, sans claws.
As I tell my students, nature rarely has to evolve something completely new; all it has to do is to tinker with an existing structure or function to get a new one. And, as any coder knows, it's easier to copy and modify old code than it is to write new code from scratch.
Comment by Allen_MacNeill — March 20, 2009 @ 2:07 pm
March 20th, 2009 at 2:11 pm
Standing in a pool full of Anomalocaris or Hurdia would be like standing in one of those tanks full of lobsters at the grocery store; squirm-inducing, but not really dangerous (I wonder if Anomalocaris would go down well with drawn butter?)
Comment by Allen_MacNeill — March 20, 2009 @ 2:11 pm
March 20th, 2009 at 2:16 pm
There is some good discussion in this thread, but what I want to know is how would "Shrimpy" taste? I would first boil shrimpy, and then grill him and baste him with a butter and garlic sauce. Can anyone suggest a good side dish to go with Shrimpy?
Comment by JJS P.Eng. — March 20, 2009 @ 2:16 pm
March 20th, 2009 at 2:17 pm
*mouth watering* mmmmm, grilled Shrimpy!
Comment by JJS P.Eng. — March 20, 2009 @ 2:17 pm
March 20th, 2009 at 2:24 pm
If you had a blimpy with your shrimpy, would that qualify as surf and turf?
Comment by Allen_MacNeill — March 20, 2009 @ 2:24 pm
March 20th, 2009 at 2:26 pm
Allen MacNeill, the 21st century Dr. Seuss!
Comment by JJS P.Eng. — March 20, 2009 @ 2:26 pm
March 20th, 2009 at 2:45 pm
Hey Allen,
I'm not talking about actual metamerism I’m talking longitudinal differentiation it seems to me that it is at least theoretically possible to accomplish longitudinal differentiation with out a homeobox regulatory mechanism.
if an alternate mechanism was “designed” by a genetic engineer or discovered in alien life it could then be compared to the mechanism we have. To determine the relative evolutionary cost.
I would think answering my questions is defiantly doable maybe not with present technology but surely in the future. It would allow a positive test for the various models in question.
because
If it turns out that no alterative model is even possible it lends credence to Dentons’ "Natures Destiny" model.
If it turns out that there are other possible mechanisms but that the homeobox regulatory mechanism was the least costly evolutionary speaking for primitive animals with out metamerism then MET gains additional plausibility
IF it turns out that the ancestral homeobox regulatory mechanism was extravagant it would make FLE more likely
Again it seems to be just a question of going to the lab and as TP likes to say “Doing science”.
Peace
Comment by fifth monarchy man — March 20, 2009 @ 2:45 pm
March 20th, 2009 at 3:01 pm
Allen MacNeill,
Thanks Allen for the informative reply.
I'm reminded of one of your examples of macroevolution from your blog. Namely the algae that developed multicellularity while under predation.
Do you believe that sudden multicellularity in response to predation is best explained as a random developmental accident? If so, why?
Comment by chunkdz — March 20, 2009 @ 3:01 pm
March 20th, 2009 at 3:35 pm
Imagine a mechanism that could sense via something like pheromones what cell type it’s neighbors were (as apposed to their position), and also that senses the relative numeric strength of all cell types in the given organism.
Suppose it also compelled each cell to seek out it’s own kind.
A cell with such a mechanism could simply flip a genetic switch to change the cell types of it’s descendant cells into what was needed for the organism as a whole at a particular time and send them on their merry way.
I realize such a mechanism would be tremendously ineffective for a large complex animal but for the simple small organisms that first developed longitudinal differentiation it might be just the thing.
I would think a Big Brain genetic engineer could develop such a thing and test it’s viability and evolitionary cost. Maybe not today but soon.
peace
Comment by fifth monarchy man — March 20, 2009 @ 3:35 pm
March 20th, 2009 at 6:36 pm
chunkdz asked:
If the fossil record is reliable, the answer is "yes". Life was prokaryotic and unicellular for 3 billion years. Then, following the endosymbiotic origin of eukaryotes, it remained unicelluar for another half billion years. However, almost as soon as multicellularity arose, it "exploded", producing the fantastic diversity of multicellular animals, plants, and fungi that we see today and in the fossil record of the Phanerozoic. Why?
The reason is obvious and surprisingly simple: the bigger you are, the easier it is for you to eat someone else, but the bigger you are, the less likely you are to get eaten. This is known as the "macrophagy hypothesis". It took three billion years for multicellularity to evolve (a strong argument for its unlikelyhood), but once it did, it initiated an evolutionary "arms race" that resulted in the "Cambrian explosion" (which should really be called the "Phanerozoic explosion", as it only began in the Cambrian, but continues to the present). The evolution of multicellularity therefore qualifies as an "autocatalytic" process; once set in motion, it drives itself exponentially from then on.
Here's the overall pattern (rounded to the nearest half billion years):
(there's a nice diagram here: http://upload.wikimedia.org/wikipedia/commons/f/fe/Geologic_clock.jpg)
Origin of Earth: 4.5 billion years ago
Origin of life on Earth: 4 billion years ago
Origin of eukaryotes: 1 billion years ago
Origin of multicellularity: 500 million years ago
Multicellular eukaryotes: the remaining 500 million years
In other words, it took almost 90% of the entire history of life on Earth for multicellularity to evolve, and only the remaining 10% for almost everything we see around us to evolve. This is a strong argument for the idea that multicellularity is not likely, but if it happens, it produces an extraordinary amount of diversity of form and function.
Comment by Allen_MacNeill — March 20, 2009 @ 6:36 pm
March 20th, 2009 at 8:15 pm
ID supporters love to talk about the complexity of the cell and how unlikely then find it. Yet when you consider that 90% of the history of life has been focused on evolving better cells it suddenly seems expected.
As such it would be a strong argument against Front Loading too, no? If life was front loaded for multi-cellularity it should be a more likely outcome. Unless you want to argue that life was front-loaded purely for bacteria.
Comment by Todd Berkebile — March 20, 2009 @ 8:15 pm
March 20th, 2009 at 8:35 pm
Todd
Or you could say that bacteria was performing a vital preliminary function that made multi-cellularity possible.
Is it just me or do I smell yet another FLE pridiction
Have a good weekend everyone. I’ve been babysitting for the past week but it’s about time to get back to the real world for a while
peace
Comment by fifth monarchy man — March 20, 2009 @ 8:35 pm
March 20th, 2009 at 8:49 pm
You seem to be confusing a "prediction", which is made in advance of data, with a "rationalization", which is made after the facts are known to force the facts to fit your theory.
Comment by Todd Berkebile — March 20, 2009 @ 8:49 pm
March 20th, 2009 at 8:59 pm
Ok how about this
Prediction……. multi-cellularity is highly unlikely (perhaps impossible) on a planet without a large amount of free oxygen.
let the experments begin.
peace
Comment by fifth monarchy man — March 20, 2009 @ 8:59 pm
March 20th, 2009 at 10:21 pm
Allen,
I was actually talking about the algae mentioned in your blog, not the first multicellular creature.
Do you think the algae that you mentioned in your blog went multicellular as a result of a "random developmental accident"?
Comment by chunkdz — March 20, 2009 @ 10:21 pm
March 20th, 2009 at 11:17 pm
Thanks for the non-pedantic part of your answer, Allen, but exaptation (if the Wikipedia entry is correct) isn't applicable here since, as I said right off the bat, the body parts on the two creatures mentioned ("Shrimpy" and shrimp) come nowhere near each other – a sort of mandible for one versus an entire posterior for another.
What's even more amazing is that the two creatures arose in an extremely short time period in evolutionary terms. Mammals, given the same amount of time, changed very little. Our own bipedal ancestors supposedly arose 2 mya, and the differences between us and them are superficial in comparison to these two creatures.
Comment by angryoldfatman — March 20, 2009 @ 11:17 pm
March 21st, 2009 at 2:03 am
What "exploded" is a program that executed as many lines of "code" as was inputted, self-programming its evolution and self-terminating until the last line was hit.
Determined it was!
(Yoda)
Comment by computerist — March 21, 2009 @ 2:03 am
March 21st, 2009 at 2:47 am
Natural selection, as a "mechanism" did absolutely nothing except to indirectly "make sure" those lines of code got executed, newlines and all. NS, obviously, does not do anything else except act as a control mechanism, auto-regulating and subsequently auto-adjusting. Form and function is the result of not natural selection or a battle of "goo" (bigger goo vs. smaller goo), but a pre-programmed initial front-loaded state which initialized ("exploded") and created all the diversity we see today.
Comment by computerist — March 21, 2009 @ 2:47 am
March 21st, 2009 at 9:10 am
After all, humans are 'just' elaborated Deuterostomes. A tube with appendages to stuff food into one end. Microevolution.
It's called adaptive radiation. When a new niche opens up, evolution will proceed rapidly until reaching a new equilibrium. We can make the prediction that the fastest historical rate should not exceed the fastest observable rate. Also, if known mechanisms cannot explain the fastest known rates, then this would imply an unknown mechanism.
It has been observed that evolution can proceed many times faster than required to explain the historical pattern. That doesn't mean there are no hidden mechanisms, but they are not a necessity based on rate of change alone.
Comment by Zachriel — March 21, 2009 @ 9:10 am
March 21st, 2009 at 5:41 pm
Thanks for your reply, Zachriel.
You wrote:
The only problem here is actual observation would take millions of years. Of course we can and have only observed a miniscule fraction of that. That's a mathematical can of worms in regards to margin of error.
The only thing we can reasonably do is compare historical record to historical record and hope the conditions remained consistent enough for both records – apples to apples.
That does open up another avenue to ponder, though. How much does gravity inhibit the range of phenotypes? Would species diverge and diversify much quicker on a low-gravity planet? Or an all-water planet?
Comment by angryoldfatman — March 21, 2009 @ 5:41 pm
March 21st, 2009 at 9:53 pm
There are a number of direct observations of evolution and its rate. Fossil evidence indicates change on the order of a few darwins, but studies of guppies and finches show that evolution can proceed at thousands of darwins, magnitudes faster.
Gingerich, Rates of evolution: effects of time and temporal scaling, Science 1983
Reznick et al., Evaluation of the Rate of Evolution in Natural Populations of Guppies, Science 1997.
Those are always interesting questions. Answering them presupposes a theory of evolution.
Comment by Zachriel — March 21, 2009 @ 9:53 pm
March 21st, 2009 at 11:19 pm
Zachriel wrote:
Fascinating. I never knew there was such a unit as a darwin. I had to look it up.
It seems a little arbitrary to me, but then again my math skills have declined greatly since AP calculus in high school and statistics in technical college.
So? What's your point?
Perhaps Haldane's little formula could give us our answer. Are there more darwins involved in going from shrimp to Shrimpy than there are in going from Lucy to us? If so, how many?
Edit:
From Wikipedia:
Aw shoot. Oh well, so much for the usefulness of darwins in this situation.
Comment by angryoldfatman — March 21, 2009 @ 11:19 pm
March 21st, 2009 at 11:40 pm
Actually, during the entire Hadean Eon and part of the Archean Eon the "Earth" was essentially an "all water" planet. That is, there were apparently no continents the way we know them now. The continents are composed primarily of granite, which didn't exist on the early Earth. There is strong geological evidence that the only "dry land" prior to the early Archean was scattered basaltic islands (sitting over mantle plume "hot spots") similar to the Hawaiian islands. These weathered away relatively quickly and never coalesced into continents as we know them today.
Eventually the granite that forms the "basement" of our current continents formed in the crust, probably by fractional crystallization of lighter oxides of silicon and aluminum (accelerated by rapid mixing of crustal materials via subduction, remelting, and metamorphosis). The heavier elements (iron, nickel, etc.) all sank into the mantle, while the more buoyant granite eventually coalesced into continents. There is some evidence to suggest that the increase in atmospheric oxygen from cyanobacterial photosynthesis may have contributed to the formation of the granite "basement" for the continents.
Once the granitic continents formed (floating on the molten mantle), they blocked the outflow of heat from the core, eventually splitting and drifting apart and thereby setting in motion the drifting of the continents described in the theory of plate tectonics. This, in turn, set in motion a cycle of continental coalescence/splitting that we are currently somewhere in the middle of. The geological evidence to date indicates that there have been at least three supercontinent cycles since the end of the Hadean Eon.
To get back to angryoldfatman's questions, it seems not entirely accidental that the only form of life during the period when "Earth" (perhaps we should call it "Water") lacked continents was microscopic bacteria. The global oceanic ecosystem of that time would have been founded upon the photosynthesis carried out by neutrally buoyant cyanobacteria. This neutral buoyancy was due to their small size. As in the case of all algae, cells below a minimum size (about a mm or so) are effectively neutrally buoyant, which would have been extraordinarily important, as they would otherwise sink into the sub-photic zone and die.
The development of continents meant the development of shallow epicontinental “seas”, on which stromatolites (pillow-shaped microbial mats composed of layers of specialized bacteria) could anchor and evolve. This, in turn, set the stage for the origin of eukaryotes (from the very tightly packed denizens of the stromatolite mats), which eventually set the stage for multicellularity. It is clear from both the fossil record and the ecology of oceans and epicontinental shallow water today that continental shelves were and are necessary for multicellularity.
So, the continents couldn’t form until the crust had been churned and mixed with atmospheric oxygen produced by the bacteria that formed the whole of the biosphere for the first 3 billion years of life on Water. Once the continents had formed, they made life on Earth possible, and (in about a half billion years) multicellular life began and diversified extremely rapidly, covering all of the continents and their shallow water margins. The deep open ocean, therefore, is what the entire planet Water used to be like (sans multicellular organisms, of course).
As for a low gravity planet, the planet Water was essentially a low gravity planet, in the sense that aquatic microbes, like small neutrally buoyant fish, live in an environment in which gravity hardly matters at all. Gravity is only a very significant shaping force on land. Life in the water (and especially for pelagic organisms) is effectively life in a low gravity environment.
Now, a much more interesting question is, what about life without air? Recent discoveries of "deep life" in cracks in the Earth's crust indicate that some bacteria and many Archaea can live in cracks in hot rocks in which there is effectively no gaseous atmosphere at all, and in which liquid water is only intermittently available. Bacteria have also been shown to be able to survive virtually hard vacuum, which raises the interesting possibility that the earliest living cells originated in cracks in rocks in space, and arrived on Earth via infalling bolides. That would mean that, rather than having only a half million years for the origin of life on Earth, there would have been about nine billion years available for it in interstellar space, and it would have arrived on Earth (i.e. the planet Water) already up and running.
Comment by Allen_MacNeill — March 21, 2009 @ 11:40 pm
March 21st, 2009 at 11:50 pm
Reading gack through, it occurs to me that I didn't really answer angryoldfatman's questions:
Not directly, anyway. However, from my previous post, I can make some suggestions:
If the large-scale evolution of life on Water and Earth are a good indication, then gravity seems to be related to an increase in phenotypic diversification. Most of the phenotypic characteristics of animals and plants on Earth are related to the force of gravity, while most of the characteristics of the planktonic life in Water are generally indifferent to the pull of gravity.
Same thing for all-water planets. As I mentioned in my previous post, the massive diversification of multicellular life on Earth coincided with the formation of the continents and the invasion of the land. If the Earth had remained the planet Water, it is unlikely that this would have happened, as no selective pressure would have favored multicellularity, and lots of selective pressure would have favored remaining unicellular and small.
Ergo, if we are interested in finding multicellular life on other planets, we should skip those that are entirely covered with water (and those that are entirely dry land as well).
Comment by Allen_MacNeill — March 21, 2009 @ 11:50 pm
March 23rd, 2009 at 11:43 am
Allen MacNeill,
You didn't answer mine either. Oh well. But you did say this:
A claim that is clearly refuted by your own blog. Did you forget that we witnessed the birth of multicellularity in Chlorella pyrenoidosa in a watery environment? Does it also seem odd to you that in a single laboratory goof-up we were able to to witness in just 5 days the macroevolutionary event which you claim took billions of years to accomplish in the wild?
Comment by chunkdz — March 23, 2009 @ 11:43 am