Emersonian – Catchup

Our white Christmas turned into a white New Year's

And a white January in general

A flattened box made an impromptu sled.

I tested it out first for Emerson

We decided a trashcan lid was more his speed

There was even a lid big enough for both of us.

Throwing ice chunks was our winter sport

Once the world thawed out, Emerson could go to the park with Grandma Bopp and Grampa Wood

We managed a few visits to the zoo.

Emerson is an expert at the petting zoo.

Sort of.

The requisite rhino photo for Grandma Hritz

Just cause it's a zoo doesn't mean it's not a playground, too.

Jenny turns 20 this year, I think. We got her in 91/92, right?

Easter!

Candy hunting at the county park

Emerson even hugged the Easter bunny.

Dying eggs is serious business.

Depending on who you are.

It's fun until you run out of eggs.

Easter Egg hunting at home!

Those boots have gotten a lot of mileage

What's better than Easter Egg Hunting? Easter Egg Hunting with a sucker.

Maybe a little bit of a sugar buzz?

And so, Easter 2011 marks the beginning of Lego

More egg hunting, this time at Grandma's!

A visit to Grandma Bopp's and Grandpa Wood's means seeing Petey, too!

And riding the horse.

And all kinds of fun!

I’m quite behind, or Emersonian Christmas 2010

Sorry these are so late.  Who feels like snow now?

Christmas Lights

Christmas Morning

Exciting, right?

Getting the hang of it

Yay!

Christmas was white

Yay! (some more)

Wee had snow at Mom's house, too.

At Grandma Bopp's, fun equals balls

Merry (late) Christmas!

A Case for Evolution, Pt. 5 – Why not Intelligent Design?

I hope that I’ve presented a compelling argument for evolution so far, which would by default also present a compelling argument against young-earth creationism.  What I haven’t addressed yet is intelligent design, and for good reason.  Intelligent design is a tricky think to pin down; it means different things to different people, from a “dba” for creationism to what is essentially evolution with a prime mover (which is, I believe, the Catholic stance).  Since I’ve already addressed creationism, for the purpose of this essay I’ll treat intelligent design as “intelligent evolution” – that is, evolution with a deific catalyst and guiding hand.  I’ll treat the god involved as a stand-in for the Christian God, who has the properties of being all-knowing, all-powerful, and good. The arguments against a demiurge like Gaia, Ptah, or Marduk are more difficult to address, since you need to be able to definitively list the attributes of a god to present counter-evidence.

I’ve also avoided intelligent design so far because I don’t think it’s diametrically opposed to evolution, and evolution was meant to be the scope of the essay.  You can be convinced of evolution and still be a good Christian.  You can be convinced of evolution and still be a good many things; since the theory of evolution doesn’t speak to abiogenesis or the origin of the universe or ethics, or even body-soul duality.  But I think that that once a person has made a study of evolution and accepted the basic tenets, they can make arguments – convincing arguments – against a deistic demiurge.  Consider this chapter, if you will, an appendix to the rest of the essay.

I think it’s important first to give attention to what I believe are the primary arguments for intelligent design (and if I’m presenting them unfairly or missing any substantial arguments, as always please let me know!): The fine-tuning of the universe, and the Watchmaker hypothesis.

The fine-tuned universe (http://en.wikipedia.org/wiki/Fine-tuned_Universe) theory suggests that the fundamental physical constants (the speed of light, the size of the electric charge of the electron, the relative mass of electron to proton, etc.) are tuned to a very narrow band, where altering them even by a couple of percentage points would preclude the possibility of life as we know it.  Stars would not form, so heavier elements like oxygen and carbon (much less iron) would be incredibly scarce, and there would be no chance of finding protein, much less life.

There are a three significant responses:

First, that the universe isn’t as fine tuned as we’ve been led to believe, at least from a cosmological perspective (http://en.wikipedia.org/wiki/Fine-tuned_Universe#Disputes_on_the_extent_and_existence_of_fine-tuning) The “goldilocks” bands in these constants within which stars could form is quite a bit wider than has been claimed, and once you have stars performing fusion you get heavier elements, and the rest is abiogenesis and evolution.  Of course, this response is based on mathematical models and not practical experience (nobody is running around varying universal constants in laboratories and trying to spark stars into existence), but so is the original claim.

Second, if the universe is fine-tuned, it could be the expected result of cosmologically-scaled evolution.  Just as species tend to produce viable offspring (or they wouldn’t be species for long!) universes produces viable baby universes.  This argument relies on the concept that black holes are spouting baby universes in new dimensions, which is questionable at best.  Still, the  fine-tuning mentioned is actually tuned to create stars; carbon-based life is only an interesting by-product.  Stars beget black holes, and black holes beget universes with the same constants as the parent universe (excepting, perhaps, some cosmologically-scaled genetic mutation).  Thus, our universe exists with the constants it has because universes with those constants are most likely to reproduce.  Purely in terms of statistics, we’re most likely to find ourselves in a universe that can sustain stars, and thus life.

The third response says, “Of course we find ourselves in a universe that’s able to sustain life, if we didn’t, we wouldn’t be having this conversation, would we?”  This is generally referred to as the Anthropic Principle (http://en.wikipedia.org/wiki/Anthropic_principle).  This response recalls the statistical discussion in a previous chapter about the likelihood of your parents producing you – the chance you’d come out as you are is astronomically small, but you were going to be like somebody one way or the other, and the you that popped out won the lottery, so it’s too late to argue now.  Douglas Adams had an amusing take on how this concept of fine-tuning works (as quoted by Richard Dawkins):

… imagine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’ This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it’s still frantically hanging on to the notion that everything’s going to be all right, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.

The watchmaker analogy is an argument for the existence of a creator god that is at least as old as 1686, but is quoted most commonly in the words of William Paley:

In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer, that, for anything I knew to the contrary, it had lain there forever: nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer I had before given, that for anything I knew, the watch might have always been there. (…) There must have existed, at some time, and at some place or other, an artificer or artificers, who formed [the watch] for the purpose which we find it actually to answer; who comprehended its construction, and designed its use. (…) Every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater or more, and that in a degree which exceeds all computation.

But the watchmaker analogy is not really an argument; it’s a rhetorical device meant to establish the plausibility of the statement that you can tell, simply by looking at something, whether or not it was the product of intelligent design on the basis of its orderliness versus complexity.  Ignoring the obvious problem of the teleology of a watch versus that of a human, the problem with this argument arises when it is applied as equally to vestigial structures and other evolutionary quirks as to items of so-called “irreducible complexity” (“so-called because of the previous chapter’s discussion).  Consider, for example, the number of vestigial features in humans.  Just a starter:

Goose bumps (http://en.wikipedia.org/wiki/Goose_bumps#Anatomy_and_biology) are an involuntary reflex to cold or strong emotion.  In other mammals, goose bumps have the useful feature of making the creature appear larger, or of trapping an insulated layer of air against the skin.  In humans, there is no benefit. In fact, the feature is uncommon on our head and genitals, where we actually have hair.

Jacobsen’s organ (or the vomeronasal organ; http://en.wikipedia.org/wiki/Jacobsen%27s_organ#In_human_beings) is the chemoreceptor in the nose of many mammals that allows them to detect pheremones.  There is still some debate over whether the organ exists in adult humans (though much less over whether it exists in fetuses, then atrophies), but there is agreement that there are no nerve pathways to the brain in humans – that is, even if it remains unatrophied in adults, it can’t be used.  The area of the gene that codes for it has become non-functioning in humans.

Darwin’s tubercule (http://en.wikipedia.org/wiki/Darwin’s_tubercle) is that little point on the back of your ear.  In humans it has no function; in other mammals it provides necessary structural support for a pointed ear.  Meanwhile, it’s worth noting that just as many mammals have muscles that allow them to move and rotate their ears, so do humans.  In the case of (most) humans, however, those muscles are atrophied, connect to nothing, and are non-functional.

The plantaris muscle (http://en.wikipedia.org/wiki/Plantaris_muscle) that runs under our foot is a very useful muscle for primates that grasp with all four limbs.  In humans the muscle is so atrophied it is frequently mistaken for a nerve by medical students, and so useless that it is generally the first thing to be harvested for tendon reconstruction elsewhere in the body.  The palmaris muscle is a similar structure in our hands.

The third eyelid (or nictitating membrane; http://en.wikipedia.org/wiki/Third_eyelid) is the transparent third eyelid common birds and reptiles that provides their eye protection from flailing prey and moisture during long staring sessions, but without cutting off vision.  It’s found in some mammals as well (camels, polar bears, and seals, for example); dogs and cats have them, but theirs are not well-muscled, so you usually only see them when the animal is waking up from sleep.  Humans also have a vestigial remnant of this third eyelid, but it’s functionless.

The male nipple.  I’ll just leave that there.

Our five toes – or, specifically, our fifth toe appears to be a vestigial feature.  It’s an extra thing to be broken or at least stubbed (as I reminded myself this morning), yet removing the pinkie toe doesn’t cause any loss of functionality or balance, and quite a few people put almost no weight on that toe when they walk.  It’s a liability. Most other walking creatures have only four toes on the ground (consider the near-ubiquitous dewclaw in quadruped mammals – another example of vestigiality), but primates who grasp with their foot find their fifth toe as useful as we do our pinkie finger.  And since our ancestors were primates, we get a fifth toe.

Likewise, the coccyx (or tailbone) is vestigial in humans, and a small number of people are borne with atavistic tails in its place.  While the coccyx still has nine muscles attached to it, including one necessary for defecation, these can be successfully reattached to the sacrum with no loss of functionality (something, presumably, an intelligent designer could have done easily).  What do we get for having a coccyx?  Only the very painful possibility of a fracture.

Going back to our watchmaker analogy, what would you say, upon opening a watch, if you found mounting points for a different type of mechanism, gears with unused ratios, or a gap where previous models had used a winding spring instead of a battery? Probably nothing, because we’re used to this kind of re-use – it’s cheaper, it’s easier and it allows the manufacturer to save on the costs of retooling parts and redesign.  But what kind of god does this?  An all-powerful god, for whom a new design is no more difficult or costly than re-use?  A god who sees the future and the end of all things, but fills our anatomy and genome with countless dead ends?  Is it fair to call this god “lazy”?  Was this god busy with something else, or disinterested?  Are this god’s eyes truly on every sparrow?  Aside from a brief mention of ERV’s in a previous chapter, we have not even addressed the cases where inclusion of these vestigial features poses us a real danger.

Think of our wisdom teeth, which helped our pre-agricultural ancestors chew cellulose – plant fibers in grass and leaves.  When you have a diet like that, the more teeth the better!  But our modern jaws aren’t as large as those of our ancestor species, so we run into the problem of impacted wisdom teeth. Estimates on the number of Americans with at least one impacted wisdom tooth run as high as 90%; extraction of wisdom teeth is now a routine procedure.  Pain is generally the worst problem a person with an impaction is likely to face these days (with our better dental hygiene), but in the past the combination of partial eruptions and caries could lead to advanced tooth rot (and potentially fatal complications), and that does not count the (smaller) possibility of developing a malignant tumor at the site of the impaction (about 1-2% of all impactions, per wikipedia: http://en.wikipedia.org/wiki/Wisdom_tooth).

Think of your appendix, which also seems to have been useful in the past for digesting cellulose.  (There are some claims that the appendix plays a role in our immune system, but this is not born out in decreased immune function among those who have had an appendectomy.)  Acute appendicitis has a high mortality rate, and it affects about 7% of Americans over the course of their lifetime.

Were these oversights on a creator god’s part, or was that god worrying more of our plant-eating ancestors than modern humans?  These might sound like sarcastic questions, but they are serious.  What would you think of a human designer proposing these same features?  So, If the watchmaker analogy holds, what do these kinds of designs say about the designer?

Consider the route of the vas deferens (http://upload.wikimedia.org/wikipedia/commons/0/08/Route_of_vas_deferens_from_testis_to_the_penis.png), which rises up from the testes to loop over the ureters, then descend past the bladder to the penis.  In our ancestor species, the testes were internal (that’s the case for most mammals and other animals in general); as they descended to their modern external location, the vas deferens was “hooked” on the ureter, like a leash is hooked on a tree when a dog and its owner choose to walk on different sides.  Would not a creator god have prevented this complication, and prevented subsequent cases of infertility and ureter obstruction (and subsequent infection?)

Consider, too, the route of the recurrent laryngeal nerve (http://en.wikipedia.org/wiki/File:Gray622.png), which allows us to speak (and allows other animals to vocalize).  It leaves the brain, travels all the way down the neck, loops under the aorta, then travels back up to the larynx, taking more than a foot to accomplish what the superior laryngeal nerve does in inches. (Note especially the image here: http://www.icr.org/article/recurrent-laryngeal-nerve-not-evidence/).  This is common in all mammals, so as you might imagine, in giraffes this creates a nerve pathway nearly fourteen feet longer than it needs to be!  The second link above, as well as http://creation.com/recurrent-laryngeal-nerve and http://www.evolutionnews.org/2010/10/the_recurrent_laryngeal_nerve_039201.html argue that this is not bad design, because this nerve also enervates the heart and trachea along the way (though they do not address why it wouldn’t be a better design for the vagus nerve to enervate those, since it’s going down there anyway, or for the laryngeal nerve to continue on that way after passing the larynx, rather than looping back to make the larynx the final destination), or because redundant pathways provide backups (though they do not address why a simple left-right redundancy would not suffice, or that a looped pathway provides multiple points of failure to a critical organ), or because human circuit design is frequently circuitous (though they do not seem to realize this exposes their god to claims of limited resources or lazy design).  From a strictly evolutionary viewpoint, the route makes sense.  Our distant ancestors, fish, have no larynx or even a neck, but they use the same nerve to enervate their gills.  As the laryngeal function developed in the trachea, it is understandable that nerves which serve the respiratory system would continue to serve new features there; the unfortunate consequence in mammals is the location of the voicebox at the top of the throat and a nerve that couldn’t come untangled from the aorta.  Would not a perfectly intelligent designer have foreseen this consequence and disentangled them to begin with?

One could argue that the ways of a designer are mysterious and beyond our comprehension, but what does that tell us?  If we were made in the image of the designer even on a metaphorical level, should not the watchmaker analogy hold, and we would recognize both excellent and poor design? Wouldn’t we expect to see upright human posture supported by a spine and bones ready-made for such a position, rather than an unstable adaptation from a quadrupedal posture? (http://www.fireandknowledge.org/archives/2007/12/22/our-imperfect-backbone-miller/) Or does the watchmaker analogy fail, and we cannot differentiate intentional design from evolutionary “mistakes”?

Evolution’s design is an emergent quality of semi-random events, so it makes sense both that we’d see re-use of homologous features like the pentadactyl limb and complete redevelopment of the same feature (like eyes, which have evolved independently at least fifty different times (http://en.wikipedia.org/wiki/Evolution_of_the_eye, and sometimes better than others).  Why would a creator god choose to cobble a panda “thumb” (pronounced as “wrist-spike”) from of a sesamoid bone (http://en.wikipedia.org/wiki/Sesamoid_bone#Panda_anatomy) rather than just giving the panda the articulating opposable digit already available in other creatures that need to grasp?

Any of these arguments, taken individually, could be marginalized, but I hope I’ve presented a sufficient number of them to establish a pattern – a pattern whose reasonable conclusion requires increasingly complex logical gymnastics to avoid.  These may not constitute an argument against gods in general, but in general it’s impossible to conclusively prove the non-existence of a thing.  (That holds for both gods and celestial teapots (http://en.wikipedia.org/wiki/Russell%27s_teapot).)  What I hope I’ve done is show that if a creator god is assumed to have the certain characteristics of the Christian God, the evidence that suggests naturalistic evolution overwhelms the evidence that suggests intelligent design by such a god.

In closing, think for a little bit about the size of the universe – really think about it.  As many times as I do it, it’s still mind-boggling. http://www.youtube.com/watch?v=17jymDn0W6U.  About the biggest number I can deal with in my head is the number of people in a packed stadium – say about 40,000 people. That’s about the population of a moderately-sized city, or more than 250 times the number of people a person can reasonably be expected to interact with and know (http://en.wikipedia.org/wiki/Dunbar’s_number).  You need a block of these packed stadiums, five long and five deep, to hold a million people.  (Already my mind’s grasp on the scale is beginning to slip.)  You need 7,000 such blocks blocks (think 70 wide, 100 deep) to hold the number of people living in the world today.  That’s just people.  We may be pretty smart, and we may have a massive impact on our planet, but there are probably about 100,000 ants alive for every human alive.  And that’s not even counting whales and horses and three-spined sticklebacks and all of the other multi-cellular creatures.  There’s lots of those. So that’s a huge number, but just a drop in the bucket compared to the number of bacteria, which is probably around five million trillion trillion (or five with thirty zeroes after it).  That’s a huge number, but that’s just Earth, which is just one rock orbiting a pretty unremarkable star.  Back of the napkin math suggests that there are one hundred stars in the universe for every grain of sand on every beach on Earth.

How can we even begin to take seriously any theory that suggests we’re the center of things?

A Case for Evolution, Pt. 4 – If we evolved from monkeys, why are there still monkeys?

In this chapter of the essay, I’m going to try to address common arguments against evolution.  A few of these arguments I chose based on previous conversations but in order to make sure that I was fairly seeking out the best, most reasonable arguments against evolution, I posted threads on several forums and on facebook requesting those who don’t believe in evolution to link to or explain their best arguments. Unfortunately I had no takers.  (This probably says more for my poor choice in forums than a lack of available arguments.)  To fill the gaps, I’ve distilled the arguments from the top search results for “arguments against evolution” (avoiding pro-evolution sites that are addressing the arguments).  My attempt in distilling these arguments has been to use a selective filter only so far as to include actual arguments against evolution instead of appeals to scripture.  That said, if I’ve missed any arguments against evolution that seem persuasive to you, please let me know so I can attempt to address them here or admit that I cannot.  If you do propose an argument, though, please be familiar with it yourself – don’t just link me to an endless page of opposition.  Tell me what you think doesn’t make sense.

Scientists can’t agree on or prove how the universe formed.
This is essentially true (though it would be incredibly untrue to say that there isn’t a general consensus regarding the big bang and the expansion of the universe, and it would deceptive not to say that recent study has born out the general theory, though specifics are still being debated).  That said, the argument doesn’t say anything about evolution.  It is a general logical error to say that because the theory of creation contains an origin story for the universe, that evolution must also.  Consider, again, that the Catholic Church embraces both a creator god and evolution.  If, however, you’d like to argue the relative merits of creationism versus the big bang theory, we can address that in a different thread.  If you’d like to read more about the big bang, the following are good places to start: http://en.wikipedia.org/wiki/Big_bang, http://www.talkorigins.org/faqs/astronomy/bigbang.html

Scientists can’t agree on/prove how chemicals became life.
While we’re closer to evolution here because we’re now dealing with life, the theories surrounding abiogenesis also do not speak to evolution.  Again, while creationism addresses the origin of life, evolution does not.  The two theories do not map equally.  If you’d like to read more about abiogenesis, the following are good places to start: http://en.wikipedia.org/wiki/Abiogenesis, http://www.talkorigins.org/faqs/abioprob/

Evolution is statistically impossible.
A common anti-evolution argument is that cellular life is statistically improbable: the chance of all of the proteins necessary even a simple bacterium self-assembling in a single place is so minute as to require an Earth 100 billion years old before we’re even within the realms of possibility; not only that, but if it were statistically possible, why don’t we see life reappearing across earth?  As it’s stated, this objection is actually just a subset of the previous argument about abiogenesis, but the concept is worth dealing with anyway.

Firstly, something does not have to be statistically probable to be true.  If your parents’ gametes could have produced up to 100 million different possible combinations (as we discussed in the first chapter), the chance that you are the one that would result is infinitesimally small – your parents would have had to have had a child every year for 10 million years to even have a 10% chance of producing you.  If there are 10 quadrillion possible viable human genetic combinations (as previously discussed), and about 100 billion humans have lived, the chance of you being produced by any set of parents is roughly 1 in 100,000 – very poor odds indeed.  And yet here you are!

Secondly (and now that I’m done being flippant with statistics), the argument doesn’t take a number of important details into consideration.  Firstly, the case study for the argument – a minimal but modern bacteria called Mycobacterium genetalium which has about 400 different proteins – only needs about 256 of those proteins to survive.  Even that very simple bacterium, though, is on an order of complexity several magnitudes beyond what abiogenetists propose as the first protocells (consider, for example, the difference between viruses and bacteria).  The argument ignores the fact that these 400 proteins are created from peptide building blocks that do self-assemble easily and quickly in laboratory tests do to the chemical properties of the molecules involved, and that only the simplest need have assembled to produce protolife – the more complex proteins build off the others as the protolife becomes more complex.  In other words, the process is not random, any more than coins appearing in the correct slots in a coin sorter is random – conditions can favor certain results (likewise, in my flippant example above, the chance of you being produced by your parents is far greater than the “completely random 1 in 100 million”).

The question about why we don’t see abiogenesis happening frequently today is more subtle.  In response: firstly, conditions were different.  There was little to no molecular oxygen available on the early Earth; oxygen is highly reactive and breaks down unbound complex molecules (in fact, oxygen would have been a potent poison to early life).  Because there wasn’t life on the early earth, there weren’t bacteria just waiting to pounce on complex molecules as they would today – protolife would almost certainly be a favorite foodstuff of cellular creatures that encountered it.  Secondly, it’s not particularly surprising that even under idealized laboratory conditions abiogenesis has not reoccurred – not compared with the billions of years and entire planet worth of chemicals available the first time it happened.  That said, there have been some very promising test results, not just in producing amino acids spontaneously in early earth conditions (the famous Miller-Urey experiment: http://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment), but in spontaneous production of RNA: (http://www.wired.com/wiredscience/2009/05/ribonucleotides/, http://en.wikipedia.org/wiki/RNA_world_hypothesis#Support_and_difficulties).

We might argue, too, that even with the building blocks of RNA spontaneously appearing, the chance of useful data appearing in their assembly is as slim as the likelihood that the proverbial room full of monkeys will type out Shakespeare.  However, note (just for example) that of all the possible random combinations of 220 nucleotides, “a staggering 2.5 x 10112 sequences are efficent ligases”.  In other words, the chances are much more similar to a room full of monkeys tapping out recognizable words here and there, and that hardly seems like such an impossibility

I’ve drawn most of the response to this argument from this source: http://www.talkorigins.org/faqs/abioprob/abioprob.html.  I highly recommend reading through the link for more detail.

The law of entropy precludes evolution
This argument is fairly easy to address.  Most of those who employ this argument cite the 2nd law of thermodynamics, which in its oldest, most fundamental form states:
“No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature.”

Of course, what is usually meant is the downstream corollary,
“The entropy of a closed system (such as the universe) tends toward a maximum”.

Problematically for this argument, the Earth is not a closed system.  It is constantly being fed by energy, primarily from the sun, but also from the stars and the constant barrage of meteors and comets and dust.  Feeding energy into a system can produce a variety of results, but one only needs to bake a cake to know that simply “getting hotter” is not the only result.  Chemical changes occur in the presence of heat.  Note, too, that the creation of heavier elements (an increase of energy level and order) depends on the disordered fusion of hydrogen, and that this is going on constantly inside our sun.  Note further the chemists’ corollary to the 2nd law:
“Energetically, the second law of thermodynamics favors the formation of the majority of all known complex and ordered chemical compounds directly from their simpler elements. Thus, contrary to popular opinion, the second law does not dictate the decrease of ordered structure by its predictions. It only demands a “spreading out” of energy when such ordered compounds are formed spontaneously.”

Some may argue that complex chemicals like chlorophyll require life or a “patterning mechanism” to appear, but just like RNA this is untrue – chlorophyll and many other complex chemicals do develop spontaneously in the lab.  Organic processes are just much more efficient, exactly as we would expect.

Further recommended reading (and sources) are here: http://2ndlaw.oxy.edu/evolution.html, http://www.talkorigins.org/faqs/thermo/probability.html, and http://en.wikipedia.org/wiki/2nd_law_of_thermodynamics

Creatures do not gain new genetic information – they do not become more complex, they simply adapt or speciate within their “kind”
In essence, this is an argument that micro-evolution is granted, but macro-evolution is not.  We may see black-caps diverge into two species of bird, or we may see proto-horse become horse, but we don’t see grasshoppers become elephants.  Ignoring for the moment that there is significant evolution between the proto-horse and the horse (and even more so between proto-whale and whale!), and ignoring the fossil record in general, while we have observed “micro-evolution” and speciation (technically, speciation is macro-evolution) we would never expect direct observation of the kind of changes mentioned.  If we saw a frog become a fish over even the course of 200 years, that would be evidence against evolution; it would falsify the predictions evolution makes.  The only way we would expect to see that kind of transitioning between orders and classes is over millions of generatoins (i.e. – in the fossil record) and if the examples provided in previous chapters do not suffice, here is a feast of evidence: http://www.talkorigins.org/faqs/faq-transitional.html

Like begets like, and the vast majority of mutations are not favorable (two-headed calves, mermaid babies, Down syndrome, etc.)
There are several issues complicated together here.  Firstly, the kinds of mutations mentioned above are not the type we’d expect to produce favorable results: firstly, they’re generally major chromosomal problems (like an extra or missing chromosome), not just the addition or modification of a genome.  Secondly, those kinds of significant morphological changes (two heads or conjoined limbs) are too severe to re-enter the breeding pool – both people and animals both who suffer from significantly different appearances or constructions are much less likely to find mating partners.  Much smaller changes (like the ability to process milk, a change in eye or hair or skin color, increased hardiness to cold or heat) are the kinds of mutations we do see happening at the genomic level, and these are likely to persist in the gene pool.

Secondly, the mechanism that allows for speciation requires that breeding pools are separated.  Even if two-headed calves continued to breed normally with other cows, we wouldn’t expect them to speciate unless a particular herd in which two-headed calves appeared was separated from the rest over a very long period and two-headedness offered some advantage.  Among humans there is no separate breeding pool that has existed for any notable period of time (more than 10,000 years or so), so the biggest changes we’re likely to see are minor morphologies like facial structure, eye and hair and skin color, shapes of fingernails, etc.

Thirdly, most mutations are neutral – they aren’t even noticed.  Of the small portion that are noticeable and harmful, they are likely to be removed from the breeding population very quickly (as discussed above).  However, those that are favorable are much more likely to persist.  Therefore even if there are a hundred unfavorable mutations to every favorable mutation, the favorable mutations have a much more significant result over even a handful of generations, since they have the potential to propagate geometrically.

Creatures occurred fully developed in the Cambrian explosion without links to single-celled ancestors.  There is no satisfying link between ape and man.  Etc.
These issues have already been addressed in specific, but this is an opportunity to turn the argument around in general.  How many examples of evolution have to be provided?  Lack of evidence is grounds for lack of belief, but not alone grounds for belief in an alternate theory.  If you accept the evidence for evolution between reptile and bird, between proto-horse and horse, between wasp and bee, but don’t find the evidence for evolution between single-celled organisms and crustaceans convincing, or don’t find the phylogenetics between apes and humans convincing, tell me which is more likely – that evolution occurs in some cases but not in others, or that the particular detail in the overall theory is not adequately evidenced?  I would argue that the evidence in the mentioned cases is extremely compelling, but the point is that the theory of evolution is evidenced with thousands of examples, so does debate surrounding one or two of them (if it cannot be generalized to all of them, that is) shift the preponderance of the evidence?

In order for reptiles to have developed into mammals, we must see things like scales turning into fur, breasts developing from nothing, and external, hard-shelled eggs turning into placental sacs in the womb.
While we might presume that those kinds of things happened, we don’t need to see their development in the fossil record for their development to exist.  As mentioned above, the fossil record will necessarily be incomplete – frustratingly incomplete – and soft tissues that would show these kinds of changes are the least likely to survive in any appreciable way.  That said, while we may not see these particular changes in the fossil record, we may see evidence for their development in the chemical and genealogical history.  For example: Due to their chemical similarity, there is speculation that hair developed not from reptiles’ scales, but from their claws (http://www.msnbc.msn.com/id/27663717/).  There is some evidence that breasts didn’t develop from nothing, but from modified sweat glands (http://en.wikipedia.org/wiki/Mammary_gland#Evolution, http://scienceblogs.com/pharyngula/2006/05/breast_beginnings.php, http://en.wikipedia.org/wiki/Evolution_of_mammals#Milk_production_.28lactation.29).  The evolution of live birth is better understood that the other two developments, but it has also occurred numerous times, even recently (http://news.nationalgeographic.com/news/2010/09/100901-science-animals-evolution-australia-lizard-skink-live-birth-eggs/).

Some complexity is irreducible.  An eye is useless without its component parts.  A bombardier beetle would self-immolate without all features in place.
Irreducible complexity is a fact – there are systems that will lose their function if any one part is removed, but it is not true that examples of these preclude evolution.  Consider possible ways the system could have evolved: deletion of parts, addition of multiple parts, change of function, addition of a second function to a part, or gradual modification of all parts. Additionally, some systems once considered irreducibly complex might not be.  Bacterial flagella were thought to be irreducibly complex, but we are now aware of bacteria with simpler versions of flagella (they are missing “required” component parts) or which use some of the structures in an entirely different, and apparently more primative way – for secretion.

To address the two cases specifically, Darwin’s quote that the evolution of the eye seems “absurd in the highest degree” is generally indicated as proof that it could not have evolved.  What those who quote him fail to mention, though, is that he spent the next three pages explaining exactly the steps that could have produced the evolution of the eye:

• photosensitive cell
• aggregates of pigment cells without a nerve
• an optic nerve surrounded by pigment cells and covered by translucent skin
• pigment cells forming a small depression
• pigment cells forming a deeper depression
• the skin over the depression taking a lens shape
• muscles allowing the lens to adjust

We know all of these steps are possible because they all exist in animals living today.  We can even break these steps down further into smaller, intermediate steps and still find examples.

In the case of the bombardier beetle, it’s easiest to quote this link (http://www.talkorigins.org/indexcc/CB/CB310.html) whole-cloth:

This is an argument from incredulity. It is based in part on an inaccurate description of how the beetle’s bombardier mechanism works, but even then the argument rests solely on the lack of even looking for evidence. In fact, an evolutionary pathway that accounts for the bombardier beetle is not hard to come up with (Isaak 1997). One plausible sequence (much abbreviated) is thus:

1. Insects produce quinones for tanning their cuticle. Quinones make them distasteful, so the insects evolve to produce more of them and to produce other defensive chemicals, including hydroquinones.
2. The insects evolve depressions for storing quinones and muscles for ejecting them onto their surface when threatened with being eaten. The depression becomes a reservoir with secretory glands supplying hydroquinones into it. This configuration exists in many beetles, including close relatives of bombardier beetles (Forsyth 1970).
3. Hydrogen peroxide becomes mixed with the hydroquinones. Catalases and peroxidases appear along the output passage of the reservoir, ensuring that more quinones appear in the exuded product.
4. More catalases and peroxidases are produced, generating oxygen and producing a foamy discharge, as in the bombardier beetle Metrius contractus (Eisner et al. 2000).
5. As the output passage becomes a hardened reaction chamber, still more catalases and peroxidases are produced, gradually becoming today’s bombardier beetles.

All of the steps are small or can be easily broken down into smaller ones, and all are probably selectively advantageous. Several of the intermediate stages are known to be viable by the fact that they exist in other living species.

If we evolved from monkeys, why are there still monkeys?
This argument is, on the face of it, silly enough to dismiss.  Monkeys exist for the same reasons that your cousins exist – the fact that you were born does not preclude the existence of your parents or any of your relatives.  Monkeys did not “turn into” humans any more than your parents turned into you.

However, there is a more subtle reading: wouldn’t evolution predict that the environmental forces that favored humans over their ancestors would have eliminated those ancestors?  In fact, they did.  No one proposes that humans came directly from chimpanzees, bonobos, rhesus monkeys, or any living species of primate – we are their distant cousins, more distant to some than others.  We have a common ancestral species somewhere along the way, and that species is in fact extinct.  When you read this question as “If we evolved from proto-humans, why are there still proto-humans”, we see that the obvious answer is that there aren’t.  The species from which we evolved (discussed in a previous chapter) is extinct, and in at least the case of Neanderthal (a cousin,not an ancestor), we likely got rid of them either through too much war or too much loving – killing them off or interbreeding and absorbing them into our species.  (Recall that closely related species, like wolf and coyote or lion and tiger can regularly produce viable hybrids.)

Evolution is not happening now.  We don’t see transitional forms or new species appearing.
Evolution clearly is happening now, and we do see new species appearing – examples were given in previous chapters.  To deny this you must redefine what “species” means.  All we see are transitional forms – every species is either transitional or heading to a dead end.  The reason we don’t notice this is because we don’t know what to expect of species in a few million years – if we did, we’d certainly note that our contemporary species were “transitional”, just like we do when comparing species that lived several million years ago to those that are modern.

Various quotes by famous scientists.
To treat them fairly, each quote has to be handled individually.  Some are taken out of context (like Darwin’s remark about the eye), and some represent a poor understanding on the part of the scientist (like Hoyle’s remark about the probability of evolution).  In all cases, though, an individual’s opinion is just that.  It’s not evidence.  When that individual publishes a paper with evidence backing up their opinion, it become evidence for or against the theory.  Even if Darwin  had recanted on his deathbed (he didn’t – http://www.talkorigins.org/indexcc/CG/CG001.html), it would not affect in any way the body of evidence gathered in the hundred and fifty years since.

While my interest in your arguments still stands, if you have a real interest in more substantial critique of most creationist/anti-evolutionary objections, this site is encyclopediac: http://www.talkorigins.org/indexcc/list.html

 

A Case for Evolution, Pt. 3 – The Fossil Record

The fossil record, as mentioned above, is one of the most compelling bodies of evidence for evolution – that there are fossils of extinct species at all is interesting, that we can see where modern most genera first appear in the fossil records in the last few million years is amazing.  We’ve recovered billions of fossils, from single cells to complete mammoths, from impressions left by ferns to the impressions of feathers surrounding an intact dinosaur skeleton.

And yet, the fossil record remains frustratingly sparse.  We may have billions of fossils from hundreds of thousands of species, but there are likely as many as 25 million species of insects alive today.  When you include other invertebrate and vertebrate animals, the number can only grow; when you include plants and single-celled organisms, the number skyrockets.  Does this undermine the fossil record?

In a word, no.  We expect the fossil record to be sparse relative to both the number of creatures and number of species that have ever existed.  Fossilization is an extremely rare event – not only must the creature remain undisturbed after its death (already this is a severely limiting factor, if we expect ancient carnivores and carrion eaters to be as effective as their modern cousins), but they must also be almost immediately removed from the oxygen and bacteria that cause decomposition. (For example, they might be covered in a sandy landslide, or sink to the bottom of a peat bog).  Once the creature has been removed from the immediate threat of decomposition, they still must encounter the unlikely conditions which allow the the skeleton (or other features) to mineralize; then, they must still remain undisturbed through thousands or millions of years of geological activity.  Finally, and perhaps most unlikely, we have to be lucky enough to stumble across them.  Aside from really exceptional fossil beds (http://en.wikipedia.org/wiki/Lagerst%C3%A4tte), fossils are generally rare, very difficult to access (thanks, solid rock!), and extremely expensive to extract and clean, without any of the lucrative payoff you get from other digging activities like diamond mining.  We should perhaps be amazed that we have anything approaching a fossil record at all.

If we had only a single complete fossilized skeleton of an extinct creature, it wouldn’t do much to prove evolution.  (A serious argument could be made for its effect on a creationist theory, however, and what an extinct species would have to say about the foreknowledge and power of a creator god, but disproving creationism is not the same as proving evolution.)  Similarly, even thousands or millions of fossils of extinct species wouldn’t lend themselves to support for evolution if they did not first lend themselves to patterns – to patterns showing that a) the fossils actually represented stable species and not one-off mutations, and b) the species, genera, and families they represent show progression over time, as we’d expect in the “family tree” predicted by phylogenetics.

As to the first point, while there are certainly controversially taxonomied fossils (especially in the hominid line) clearly there are ample examples beyond controversy.  We have more than thirty examples of Tyrannosaurus Rex (some skeletons complete or nearly so), more than 1200 specimens of just one species of smilodon, and Meganeura specimens (giant dragonflies) have been found in the UK, France, and the US, just to name a few examples.  The second point, though – that we can see examples of “progression” (not in the sense of intentionally building toward a specific form, but in terms of a transition across forms from one morphology to something substantially different) – requires a bit more evidence.

I could hardly begin to discuss anything like a broad overview of the family tree of all life and where the multitude of fossils fit in – that’s a topic that deserves at least a book (like http://www.amazon.com/Written-Stone-Evolution-Fossil-ebook/dp/B004HD4UEI/ref=sr_1_3?ie=UTF8&qid=1299381783&sr=8-3 or http://www.amazon.com/Evolution-What-Fossils-Say-Matters/dp/0231139624/ref=sr_1_1?ie=UTF8&qid=1299381783&sr=8-1).  I will touch briefly on five different fossil series showing intermediate or transitional forms, each of which are interesting for their own reasons: the horse, the whale, camelids, the bird, and humans.

Evolution of the Horse

Our modern horse, genus Equus, is a particularly interesting creature – even if for no other reason than its single-toed limbs. While the horse seems to have the same-shaped limb as most other mammals, it’s missing the eponymous feature of  the “pentadactyl” limb – the five toes.  We might suspect, though, that somewhere in its history, there is a horse ancestor – a proto-horse – with five toes.  Interestingly, we have fossils of just such a species, along with many others that show a gradual transition from five toes to our modern single toe – as well as a gradual transition to grazing teeth and the skull structure of the modern horse. (You may wish to read through http://en.wikipedia.org/wiki/Evolution_of_the_horse for a more thorough discussion than I can manage here.)

We start about 52 million years ago (hereafter “mya”) with a creature called Hyracotherium (http://en.wikipedia.org/wiki/Hyracotherium), which looked something like a cross between a rabbit and a deer, about the size of a dog.  (Note that Hyracotherium is definitely NOT a rabbit, as some have claimed: http://members.cox.net/ardipithecus/evol/lies/lie015.html.  The original confusion that caused the species to be named “hyrax-like” occurred because the the initial naming occurred when only a few teeth – not even an entire skull – had been found)  Hyracotherium had the five toes we’d expect in a mammal – four padded fingers and a fifth “thumb” off the ground, like a dog’s dewpad.  Fast forward a few million years through the fossil record by means of Orohippus (50mya http://en.wikipedia.org/wiki/Orohippus), Epihippus (47mya http://en.wikipedia.org/wiki/Epihippus), Mesohippus (40mya http://en.wikipedia.org/wiki/Mesohippus), and Miohippus (36mya http://en.wikipedia.org/wiki/Miohippus), and we can watch several changes occurring gradually: the creatures grow larger, their teeth begin to adapt to grinding and chewing (i.e. they become grazing teeth), and our proto-horses begin to walk on only three toes – meanwhile, the first and fifth toes have become vestigial nubs.

Note three important points – first, each of the examples listed above are not single species but entire genera.  There was no orderly escalator from Hyracotherium to modern Equus, but a series of branches constantly sub-branching.  Our Equus is simply the highest point in a brambles of Equids.  Secondly, each genus did not “replace” the one before it.  Orohippus may have appeared only a couple of million years after Hyracotherium, but species of Hyracotherium thrived for up to 20 million years – in other words some species of Hyracotherium existed even after Miohippus had appeared.  Lastly, the sample fossils that are used to define the genera are not proposed to be the specific ancestors of our modern horse – they are almost infinitely more likely to have been offshoot branches near the ancestors of the modern horse on the phylogenetic family tree.  They show a general trend in progression, but they may also possess features that don’t continue through to future genera, like a changing number of vertebrae.

Continuing back to our Equus progression, Parahippus (http://en.wikipedia.org/wiki/Parahippus) is perhaps the first true equine – at least among the fossil record we have.  Parahippus still had three toes on each limb, but only the center one was substantially load-bearing. By this time, the ancestral horse had also reached the size of a large pony.  Merychippus (http://en.wikipedia.org/wiki/Merychippus) followed, and from it we see three branches of equines develop, Hipparion (http://en.wikipedia.org/wiki/Hipparion), Pliohippus (http://en.wikipedia.org/wiki/Pliohippus), and Protohippus (http://en.wikipedia.org/wiki/Protohippus), the latter of which continued through Dinohippus (http://en.wikipedia.org/wiki/Dinohippus) and Plesippus (http://en.wikipedia.org/wiki/Plesippus) to our modern genus Equus about 4.5mya.  By the time of Plesippus, the protohorse had had abandoned the two vestigial nubs of the second and fourth fingers and stood on a single toe; and our proto-horse had reached the size of an Arabian horse.  Of course, even after we reach the genus Equus, the fossil record shows a wide variety of species before we get to the zebras, donkeys, and horses we see today.

If you haven’t already, I highly recommend following the link to the wikipedia page on horse evolution (http://en.wikipedia.org/wiki/Evolution_of_the_horse), at least to see the pictures illustrating the gradual changes in toes and teeth from Hyracotherium through Equus.

The horse lineage is important evidence for evolution because while the difference between Hyracotherium and Equus is dramatic, an uncommonly populated fossil record shows gradual changes across many genera and millions of years accumulating to that dramatic difference.  This evidence is particularly consistent with the theory of evolution, but does not fit well into a creationist theory that does not include evolution.  And, while the horse lineage is probably the best documented, it’s certainly not the lineage in the fossil record.

Evolution of the Whale

The whale (and cetaceans in general) are a peculiar bunch – mammals who live entirely within the water, though they have to breathe air to live.  If we didn’t already know they existed, we’d think they were unlikely even as science fiction, yet until the intervention of human over-hunting, cetaceans thrived.  It’s clear that whales had terrestrial ancestors from the appearance of internalized, vestigialized features (like the “fingers” in their fins, the frequent floating bones of their now-missing hind legs, and the internal ear that now picks up sound from their jawbone), and while their lineage is not as well-documented as Equus, it is possible to trace back through proto-cetaceans to likely precursors of the whale (judged by unique features like ear construction and the shape of their teeth).

You can follow the link to Wikipedia (http://en.wikipedia.org/wiki/Evolution_of_cetaceans) for more depth, but in short, the lineage runs back through the first fully marine cetaceans (like Basilosaurus (http://en.wikipedia.org/wiki/Basilosaurus) and Dorudon (http://en.wikipedia.org/wiki/Dorudon), who still had hind legs, though their pelvic bones had completely separated from the spinal column), through the protocetids (like Protocetus (http://en.wikipedia.org/wiki/Protocetus) and Rodhocetus (http://en.wikipedia.org/wiki/Rodhocetus), whose sacrum had already defused into separate vertebrae, and whose nostrils had already begun to move from the front of their snout toward the top of their head, and what would eventually become blowholes), and through the mammalian-amphibious Ambulocetus (http://en.wikipedia.org/wiki/Ambulocetus) and remingtoncetidae (http://en.wikipedia.org/wiki/Remingtonocetidae) (who were like alligator/otter hybrids, equally at home on water or on land with their load-bearing legs), and all the way back to pakicetids (http://en.wikipedia.org/wiki/Pakicetid) and Indohyus (http://en.wikipedia.org/wiki/Indohyus), both proto-whale possibilities whose ears and teeth show the first indications of the unusual structures in whales.

Again, the intent is not to show that these fossils were directly in the line of descent between a  dog-like creature and our today’s Cetaceans, but rather that the creatures they represent show the transitional forms we’d expect between an Indohyus and a modern whale – that transitional forms exist and thrived during the times we’d expect.  Whether a specific creature is or is not directly in the ancestral line is a detail for paleontologists to argue about, but doesn’t bear directly on the fact that transitional forms do exist.

The tone at the beginning of this link (http://www.talkorigins.org/features/whales/) is a bit shrill, but the details are terrific.

Evolution of Camelids

Camelids make another interesting case study, not so much because they shows the transition from one form to another, but because their history explains the origins of three different “families”: the llamas and alpacas of South America, the dromedaries of Africa and the bactrians of Asia.  You can find a bit more detail here (http://en.wikipedia.org/wiki/Camelid#Evolution), but the key is in this image: (http://en.wikipedia.org/wiki/File:Camelid_migration_%26_evolution_DymaxionMap_01.png).  North America is where camelids first appeared in the fossil record, and in that same fossil record we can see (http://en.wikipedia.org/wiki/Camelid#Extinct_genera_of_camelids) that until very recently (geologically speaking at least, probably until the last ice age and the proliferation of man in North America) that camelids were still varied and common here. The three “families” mentioned above were the migrants from the central location.

Evolution of the Bird

The evolution of the bird (http://en.wikipedia.org/wiki/Origin_of_birds) – and specifically their descendance from dinosaur reptiles – is probably the second most contentious case study in evolution, specifically because of Archaeopteryx (http://en.wikipedia.org/wiki/Archaeopteryx, http://www.talkorigins.org/faqs/archaeopteryx/info.html), the first-discovered “early bird”.  Though plenty of other early birds are now known (http://en.wikipedia.org/wiki/Jeholornis, http://en.wikipedia.org/wiki/Rahonavis, http://en.wikipedia.org/wiki/Unenlagia, http://en.wikipedia.org/wiki/Buitreraptor, http://en.wikipedia.org/wiki/Hesperornithiformes, http://en.wikipedia.org/wiki/Ichthyornithes, etc.) and Archaeopteryx isn’t even considered a direct ancestor of modern birds, it is still an excellent example of a “transitional” form between a raptor-like dinosaur and something like today’s raven – it has feathers and the opposable big toe of birds, but the unfused thoracic vertebrae and rear-skull entry of dinosaurs.

There remains some considerable contention as to what branch of dinosaurs produced birds, or even if another upstream branch of reptiles called archosaurs were their ancestors, but there is no remaining doubt amongh those who study evolution that birds came from reptiles (or, as some would say, that they are still reptiles).

Humans

The evolution of humans is – at least between evolutionary theorists and creation theorists – the most contentious case study. However, because we’re a topic of great interest to ourselves, we’ve received a great deal of study from ourselves; more that can be usefully summarized here in a way that’s more convincing than the examples above.  The fossil list (http://en.wikipedia.org/wiki/List_of_human_evolution_fossils) and the writeup of human evolution on Wikipedia (http://en.wikipedia.org/wiki/Human_evolution) are extensive, and worth at least a cursory glance if not careful study.  The matter is complicated by the concept of human exceptionalism (http://en.wikipedia.org/wiki/Human_exceptionalism) – the idea that humans aren’t just part of the fauna – but once the human fossil records and history are compared to those of other species, it becomes more difficult to deny that humans have a history significantly different from other animals, and that exceptionalism is a matter of philosophy and psychology, and not genetics or biology.

Arguments against the Fossil Records as Evidence for Evolution

Several specific arguments were raised in comments on these posts, and I’ll address them directly here.  (I note that there are in fact -countless- arguments against the fossil record in general and fossils in specific – many of them completely groundless, and many of them very relevant and worthy of engagement.  Answering every argument is far outside the scope of this essay, but if there are any particular arguments you feel are persuasive and applicable, please direct me toward them.)

Argument One: (Source: http://www.strengthsandweaknesses.org/Weaknesses/Fossil.Record.Gaps.htm) – The gaps in the fossil record are a significant weakness.

I can’t argue against the the fact that there are substantial gaps between the species we see in the fossil record when we fit them into the tree predicted by phylogenetics.  The hypothetical “bough” in the link above shows a 3% fill rate, but I’d be surprised to see it even as high as 1%.  But gaps in the fossil record are not evidence against evolution, nor do they undermine the theory in any way.  Due to how uncommon fossilization is, we will always have gaps in the fossil record – even if we were able to excavate the entire Earth.

Still, if we have even one transitional form between two species – if we can draw even a very dotted line between two genera – we have evidence for evolution.  But we have countless dotted lines, and some of them (like the horse), are less dotted and more solid.

The question is, how much accumulated evidence do you require before it becomes overwhelming?  Once set, you cannot move your goalposts without sacrificing your dignity.  A singled dotted line might be interesting but an outlier – a work of fancy rather than reason – but two or three are a pattern, and two or three hundred are substantial by any measure.  The more fossils appear, the more gaps we will have between them since transitions are never as abrupt as a single generation.  And the more fossils we find to fill the gaps, the more we may realign our theory about the descent about a particular line; but continued refining of the details of the theory does not affect the validity of the theory as a whole.  We may not have even a dotted line for some genera, but if evolution is indicated for some, would a lack of intermediate fossils suggest two different forces in play – evolution for some, and divine creation for others?

Argument Two: (Source: http://www.truthinscience.org.uk/site/content/view/48/65/) –  A) There is significant debate between evolutionists as to the mechanism by which it occurs (particularly between smooth transition and punctuated equilibrium), thus creationism. B) The Cambrian Explosion (http://en.wikipedia.org/wiki/Cambrian_explosion) is a major stumbling block for evolutionary theory.

The first argument does not take much to refute – there is evidence for both smooth transition and punctuated equilibrium (and, in fact, evidence that each occur in in difference scenarios; smooth transition as creatures refine competition to maximize a particular niche and punctuated equilibrium as creatures encounter new niches that have not been filled, as in the case of adaptive radiation), just as there is evidence on both sides of a number of current academic debates among those who study evolution.  None of those debates undermine our understanding of evolution as a general theory, both sides of the debate are only refining aspects of evolution and require the basic tenets of evolution to make sense.

To say that ongoing academic debate about aspects of the theory becomes an argument against the theory in general is along the lines of encountering a debate between artists arguing if a particular shade is blue-green or aquamarine, and therefore proposing that colors do not exist and the shade is gray.  The argument mentioned in particular is not “Evolution can only exist if in the form of punctuated equilibrium” or “Evolution can only exist if in the form of smooth transition” but “We have evidence for a greater frequency of smooth transition” and “We have evidence for a greater frequency of punctuated equilibrium” and then a debate following as to whose evidence could in fact be reinterpreted in the light of the other’s understanding.

As mentioned in the first chapter of this essay, scientific theories are always open to be challenged, both in part and in whole, when new evidence presents itself.  The evidence in both cases supports evolution; the difference is that different models of evolution are better supported by one kind of evidence than another.

The Cambrian Explosion in the second part of the argument (http://en.wikipedia.org/wiki/Cambrian_explosion) is a challenge, and much more worthy of discussion.  The particular quote much-bandied by creationist websites that comes from Dawkins’ The Blind Watchmaker is:

“…the Cambrian strata of rocks, vintage about 600 million years, are the oldest ones in which we find most of the major invertebrate groups. And we find many of them already in an advanced state of evolution, the very first time they appear. It is as thought they were just planted there, without any evolutionary history. Needless to say, this appearance of sudden planting has delighted creationists.”

Note that the actual full quote is:

“Before we come to the sort of sudden bursts that they had in mind, there are some conceivable meanings of ‘sudden bursts’ that they most definitely did not have in.mind. These must be cleared out of the way because they have been the subject of serious misunderstandings. Eldredge and Gould certainly would agree that some very important gaps really are due to imperfections in the fossil record. Very big gaps, too. For example the Cambrian strata of rocks, vintage about 600 million years, are the oldest ones in which we find most of the major invertebrate groups. And we find many of them already in an advanced state of evolution, the very first time they appear. It is as though they were just planted there, without any evolutionary history. Needless to say, this appearance of sudden planting has delighted creationists. Evolutionists of all stripes believe, however, that this really does represent a very large gap in the fossil record, a gap that is simply due to the fact that, for some reason, very few fossils have lasted from periods before about 600 million years ago. One good reason might be that many of these animals had only soft parts to their bodies: no shells or bones to fossilize. If you are a creationist you may think that this is special pleading. My point here is that, when we are talking about gaps of this magnitude, there is no difference whatever in the interpretations of  ‘punctuationists’ and ‘gradualists’. Both schools of thought despise so-called scientific creationists equally, and both agree that the major gaps are real, that they are true imperfections in the fossil record. Both schools of thought agree that the only alternative explanation of the sudden appearance of so many complex animal types in the Cambrian era is divine creation, and both would reject this alternative.”

Again, the tone is a bit more shrill than constructive, but its point is clear.  The problem is one of a fossil gap, not one of an unexplainable feature of the fossil record.  As we see with human fossil lineage, once attention has been drawn to a subject, studies and funding follow – now pre-Cambrian multi-cellular creature fossils have begun to accumulate.  See the latter sections in the wikipedia link: http://en.wikipedia.org/wiki/Cambrian_explosion#How_real_was_the_explosion.3F.  Still, the Cambrian Explosion was a particularly aggressive adaptive radiation, which leads to the question of what caused or allowed for it – continue on through the Wikipedia link for possible explanations of the new “niche” the radiation exploited.