Archive for the ‘evolution’ category

The failure of Intelligent Design

February 18, 2011

“Were there no example in the world of contrivance except that of the eye, it would be alone sufficient to support the conclusion which we draw from it, as to the necessity of an intelligent Creator.  It could never be gotten rid of; because it could not be accounted for by any other, supposition, which did not contradict all the principles we possess of knowledge.[i]

–William Paley, Natural Theology, 1857

“To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.  Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple…can be shown to exist…then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.[ii]

– Charles Darwin, On the Origin of Species, 1859

“By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution.”[iii] 

–Michael Behe, 1996.

Charles Darwin refuted the teleological argument from design in 1859.  Apparently Behe didn’t get the memo.  Through his theory of evolution by means of Natural Selection, Darwin accomplished what earlier evolutionists could not.  Unlike previous theorists such as Lamarck and Erasmus Darwin, Darwin (and Alfred Russel Wallace working with him) provided a working mechanism for evolution. In short, Darwin’s theory of Natural Selection replaced Paley’s divine watchmaker with a blind watchmaker; the selective force of nature.  Following the strengthening of Darwinian theory by intellectuals on both sides of the Atlantic Ocean, especially after the development of the Modern Synthesis in evolutionary biology, evolutionary theory effectively replaced “Design” as a creative force.

Natural Selection, therefore, is able to explain organs and features of organisms formerly relegated to creation by an “intelligent Designer”, or a “divine watchmaker” of sorts.  Regardless of whether it is Paley’s eye or Behe’s bacterial flagellum, evolutionary theory effectively explains the development of these organs and features.  Therefore, the “Watchmaker hypothesis,” in both its historical and modern forms, does not present an effective challenge to the efficacy of evolutionary theory.  Thus, the argument from “Design”, or “irreducible complexity”, is not an adequate tool with which to challenge evolutionary theory.  Both fail to undermine the strength of evolutionary theory on closer inspection.  Although one might ask “what good is 2/10ths of an eye?”, any working “eye” is better than no eye at all.  Even if we are referring to just a few light-sensitive cells that are useful for an organism to detect light or predators, these cells will provide a definite survival advantage compared to organisms that lack these cells. In time, variation and selection can and do build more complex organs through differential survival rates.  In the case of “irreducibly complex” organs, the key flaw in Behe’s argument is the fact that he fails to account for the fact that so-called “irreducibly complex” organs can and do have other uses if a component or group of components are removed from them.  Natural selection works by jury-rigging and adaptation of available features, not by the design of new ones.  Therefore, the “watchmaker hypothesis” fails on all counts.

Another key aspect of modern arguments from design is the “fine-tuning” argument for the existence of the universe. This argument, stated simply, alleges that since the universe appears to be “finely tuned” for the existence of life as we know it (i.e. cosmological constants are exactly what they need to be for life to exist as we know it), that the universe therefore must be designed.  While this argument seems cogent at first glance, it is, in fact, fatally flawed.   In fact, the apparent “fine tuning” of the universe is exactly what one would expect if life evolved.  Natural selection produces organisms that are well-fit to their environment.  If life did, in fact, evolve, it did so in this universe, on this planet, governed by the constraints placed upon it by the existing cosmological constants.  You do not build a vehicle that sinks quickly but has really good wheels if you are only going to be using it in an ocean.  Rather, you construct a vehicle that is well-adapted for oceanic travel.  Natural selection works the same way.  It is governed by physics and chemistry as well as biology and ecology.  Natural selection, in short, is as much a slave to cosmological constraints as organisms are to their dietary requirements.  Thus, the cosmological argument is as much a failure as the “watchmaker hypothesis”.

Another key argument advanced by Intelligent Design proponents can be described in the following manner. The proteins/molecules/cells, etc. that make up life are extremely complex.  It is extremely improbable that they developed through solely naturalistic means. Therefore, these features must be designed.  However, this approach is philosophically and scientifically flawed.  Scientists have done a decent job exploring the origin of life. Even though scientists have not definitively explained the origin of life, they have developed some tantalizing glimpses at possible explanations for this event. This topic is relatively complex, and a bit intensive for a short post, so if you’re interested I’ll refer you to the work of Robert Hazen as a first guide to this topic. See, for example, his book “Genesis“. I will focus on the philosophical flaw with this argument in this post.

The philosophical argument inherent to this portion of the Intelligent Design argument can be re-phrased in the following manner.  A million (pick your favorite large number here, and replace “A million” with it if you’d like) lottery tickets are sold for a lottery. One ticket must win.  Each ticket represents a possible combination of proteins (the building blocks of DNA).  The “winning ticket” is the actual combination generated by nature.  According to the Intelligent Design approach, since a million tickets (possible protein sequences/amino acids) exist, the chances of drawing the winning ticket are extremely low, and therefore no ticket will win.  However, we know this to be false; one ticket ultimately DOES win.  Therefore, as improbable as the development of DNA sequences was, by nature, it was at least possible.  And, in fact, there are possible ways to increase the probability of the development of complex protein sequences (Hazen discusses the possibility of proteins growing within the microstructures of carbonate rocks, a hypothesis which explains the extremely high proportion of “left-handed” amino acids). Therefore, the Intelligent Design perspective once again proves flawed.

Before closing this essay, I will mention a few other key claims/approaches fronted by Intelligent Design proponents. The first is Dembski’s Explanatory Filter, which fails miserably as a tool to supposedly discern design in nature (see critique here). The second is the claim that natural selection cannot “increase information” in a genome.  Here’s a rebuttal for that claim as well.  Finally, perhaps the most ridiculous claim advanced by Intelligent Design advocates such as Stephen Meyer is the claim that the “Cambrian Explosion” somehow undermines evolution.  This is the old “there are GAPS!!!  Gaps in the fossil record!” argument trotted back out to play. Even a cursory glance at modern paleontology proves such a claim irreparably flawed.  A good explanation of why such an argument is flawed can be found in one of my all time favorite books on transitional forms, Donald Prothero’s “Evolution: What the fossils say and why it matters“.  For a good online critique of the “Cambrian Explosion” argument advanced by Design advocates, see Keith Miller’s article (part one here and part two).

Therefore, as demonstrated, upon closer inspection, the arguments against evolution advanced by Intelligent Design proponents consistently fail to withstand scrutiny.  I consciously avoided arguments from social ills in this post (“well evolution influenced Hitler, or communism, or what have you”) due to the extremely flawed nature of this type of argument.  What is more important is attacking so-called “science” of Intelligent Design.  As I’ve shown here, even a cursory critical glance at the pseudoscientific structure of Intelligent Design reveals massive and irreparable flaws. Therefore, Intelligent Design fails as a science.

Works Cited:
Behe, M.  Darwin’s Black Box: The Biochemical Challenge to evolution. Free Press, New York. 1996.

Darwin, CR. The Origin of Species.  Harvard University Press, Cambridge.  First Ed. facsimile, 2002 (1859)

Paley, W. Natural Theology: or, Evidences of the Existence and Attributes of the Deity, Collected From the Appearances of Nature. Gould and Lincoln, Boston, 1857

Happy Darwin Day 2011!

February 12, 2011

February 12th, 1809.

Two individuals are born an ocean apart, in vastly different economic settings.  One, an American, is born in a one-room cabin in Kentucky (just west of the old Colonial realm).  The other, a Englishman, is born in Shropshire, England, to a prominent doctor, himself the son of a major 19th Century intellectual, and the daughter of a prominent British pottery maker.  These individuals, of course, are Abraham Lincoln and Charles Darwin.

Although Darwin and Lincoln never directly corresponded, the two share more than a common birth-date.  Both were considered to be lazy during their formative years. More importantly, both were ardent abolitionists.  Lincoln grew into abolitionism from a more neutral position, ultimately issuing the Emancipation Proclamation on January 1st, 1863.  Lincoln, is remembered as much for the American Civil War as he is for ending slavery in America.  Charles Darwin became an abolitionist as a result of both first-hand experience and, possibly, family upbringing (the Wedgewoods were well-known British abolitionists).

Darwin and Lincoln, then, share a common historical legacy.  Both rejected slavery, Darwin for moral reasons, Lincoln perhaps for both moral and pragmatic reasons.  However, the two individuals are remembered differently by the general public.  Lincoln is often praised (at least in Northern America) for his decisive moves to both preserve the American nation through the Civil War and for ending American slavery.  Darwin, however, is condemned in many circles for his role in decentralizing the biological status of the human species through his theory of Descent with Modification by means of Natural Selection.

Does Darwin deserve to be condemned?  By publishing his theory, Darwin was not attempting to unilaterally destroy theism.  The Origin was published in a wider intellectual and historical context that already included multiple texts advocating “evolutionary” thought. Some famous predecessors to the Origin include Robert Chambers’ Vestiges of the Natural History of Creation (1844) and Lamarck’s evolutionary model (first documented in 1800).  Darwin’s grandfather, Erasmus Darwin, also published an evolutionary account of life in a book titled Zoonomia during the 1790s.  Natural Selection, then, was born into an intellectual scene which was already used to theories of evolution.  However, Darwin and Wallace’s Natural Selection had one feature that Lamarck, Chambers, and Erasmus Darwin’s work lacked: a working mechanism.  Therefore, Darwin (and to a lesser extent in the public realm Wallace) are remembered (wrongly) by many as the first evolutionists.  As a result, they are most often condemned for the idea of evolution.

Although evolutionary theory DOES have major implications for theology, evolutionary theory does not, in fact, disprove religion.  If one takes an extreme reductionist approach to theology and philosophy, evolutionary theory can be used in an attempt to reduce philosophy and theology to a mere consequence of physical and chemical forces.  However, as religious belief is a non-disprovable hypothesis (God could be out there, regardless of whether evidence exists for or against God’s existence), it is impossible to disprove God through mere science.  In fact, some theological positions incorporate both a relatively traditional conception of God and evolutionary theory.  For example, the Roman Catholic Church does not have an issue with evolution; they accept evolution as valid science, yet they also retain a role for creative acts by God.  Kenneth Miller’s Finding Darwin’s God provides a good example of one Roman Catholic biologist attempting to achieve a harmonious relationship between God and evolution, and is a worthwhile read.

Another key criticism of Darwin and evolution is that it creates social ills.  Evolutionary theory has been blamed for racism, the Holocaust, abortion, crossdressing, and numerous other things by its opponents.  However, such an approach is philosophically and scientifically unsophisticated.   Nuclear weaponry utilizes physics, so does that mean that Newton, one of the fathers of modern physics, is responsible for nuclear proliferation? Of course not! If I tried to make that statement, any sane person would (rightly) declare me to be a fool.  Scientific theories are not moral or immoral.  By nature, they do not have a moral stance (they are amoral).  They can be used for moral or immoral means, but a scientific theory, on its own, does not have a moral position.  Therefore, to blame evolution for society’s ills is at best an attempt to put a bandage on an underlying cause.  Darwinian theory is not, in itself, responsible for its application within society (for good causes or bad).  Yes, evolutionary theory was developed by human agents operating in specific places and times.  Therefore, there is an inherent human aspect to evolutionary theory. However, this human aspect is present in ALL scientific theories.  It is not the scientific theory that is the issue. It is how people choose to use it for extrascientific purposes.

Therefore, its time for society to stop condemning Darwin.  If you’ve got a problem with something in society, stop trying to blame people who are at best indirectly related to the root of the problem and actually attempt to fix the issue.  Let’s remember Darwin for what he actually DID contribute to society, rather than condemn him for the problems his theory allegedly caused.  The Darwinian Revolution is one of the key scientific revolutions in modern times.  And it is arguably the final step in the Newtonian Revolution.  First, Newton demonstrated that the universe operates according to fixed laws.  Then the heliocentrists come along and demonstrate that the Earth is not at the center of the universe.  Finally, Darwin comes along and places humanity right where it belongs, squarely within nature, as a part of nature rather than separate from it.  Although some might consider this step to be both theologically and scientifically radical, it is, to me, as elegant  to think of humanity as being intricately intertwined and tied to the rest of life on Earth as it is to think 0f humanity as somehow “above” and “separate from” nature.

The latter approach is flawed at its best, and dangerous at its worst. To forget that we are inherently and directly tied to the rest of the biosphere is to forget that our actions as a species have a direct, and often extreme, impact on that biosphere.  We are extremely capable of signing our own death warrants through our collective actions, and to accept that we are tied to the rest of the biosphere is to claim responsibility for our actions as well as for the wellbeing of life on Earth.  We are capable of destruction, yes, but we are also capable of preserving the small pockets of non-human life on this planet that we have not altered or destroyed.  This is one of the key lessons of the Darwinian Revolution, namely that the fate of the biosphere is inherently and directly responsible for our own fate as a species.

Darwinism, frankly, is not the root of all evil.  So let’s get over it, and fix the real problems facing this planet.  For me at least, crossdressing and atheism pale in comparison to starvation, homelessness, climate change, and the destruction of the biosphere.  First we need to fix the big problems facing humanity, and then we can argue about semantics.    Happy Darwin Day 2011, and don’t forget to remember Lincoln for a moment as well!

Megaloceros and orthogenesis

September 24, 2010

Megaloceros on display at AMNH

Megaloceros, commonly (and wrongly) known as the “Irish Elk” offers a good example of an organism utilized as proof of orthogenesis during the latter half of the 19th century and the early 20th century.  During this period, paleontologists utilized the term “orthogenesis” to explain trends in the fossil record.  Under the model of orthogenesis, once a species begins to develop, it continues to develop along that line and exhibits an inability to stop this process of development.  In the case of Megaloceros, the argument was structured such that through the process of orthogenesis, Megaloceros’ antlers grew to extreme sizes.  Ultimately, this unchecked antler growth caused the extinction of Megaloceros.  This example offers a good model to demonstrate why orthogenesis does not work.  A trait isn’t going to survive if it causes a problem for the survival of the organism in question.  Ultimately, even if selective pressures do support the development of larger antlers in Megaloceros, the antlers won’t get large enough to cause extinction.  If an individual Megaloceros has antlers so large that they end up getting caught in trees (part of the orthogenesis argument), then it’s not going to have much success with reproduction. Sure, a few individuals with extremely large antlers might get to reproduce, but as a rule, most of these will, in fact, be weaned from the gene pool.  This is why orthogenesis does not work.

If you’re interested in this topic, check out Stephen Jay Gould’s article “The misnamed, mistreated, and misunderstood Irish Elk.” The article is available in his 1977 book Ever Since Darwin.

evolution in action: ceratopsians and the paleontological evidence for evolution

September 24, 2010

Nearly everybody familiar with evolutionary theory and anti-evolution movements is familiar with the old refrain claiming that “the fossil record does not support evolution.”  However, such claims are extremely misguided, and stem from a major misunderstanding of what the fossil record does, in fact, show.  While one could pick any one of hundreds of fossil lineages to examine, we’ll look at one that most people are familiar with, the ceratopsian dinosaurs. To get a partial idea of the diversity of this group, I’ll post some pictures before continuing.

chasmosaur skull on display at AMNH

triceratops on display at AMNH

Protoceratops display at AMNH

While I’ve only shown a few specimens here, the ceratopsian lineage itself is far more diverse.  However, for the sake of ease and sanity, we’ll only look at a few key ceratopsians for our comparison.  For some basic paleontological background, ceratopsians are a Cretaceous group, thus existing towards the end of the reign of the dinosaurs.  The group as a whole was relatively successful, with a distribution throughout Western North America, Asia, and possibly Australia and South America as well.  They were herbivores, and tended to live in large groups.  In phylogenetic terms, the ceratopsians shifted from a relatively lightly built, at least partly bipedal, basal form such as Psittacosaurus, through slightly more robust forms such as Protoceratops, and ultimately towards larger forms such as Triceratops. Now I don’t want to speak in terms of “progress” or “orthogenesis” here; I’m not trying to imply that there was something inevitable about how these forms developed. Rather, it’s just the way it happened. Selective pressures pushed towards that direction, and natural selection responded by building larger, more robust forms.  Let’s take a quick look at the basic sequence:

psittacosaurus on display at AMNH, public domain pic from wikipedia

another psittacosaurus picture, this time on display in Copenhagen. Also from wikipedia.

Protoceratops on display at Carnegie Museum of Natural History, from Wikipedia

Triceratops at AMNH, from Wikipedia

With these specimens, you can get a pretty good idea of how body plans shifted during the phylogenetic history of the Ceratopsians.  However, don’t get the wrong idea here; it isn’t necessarily so that Psittacosaurus evolved into Protoceratops evolved into Triceratops. This isn’t how the fossil record works.  Rather, an organism like Psittacosaurus evolved into an organism like Protoceratops, and so on.  These specific examples show us a basic picture of the transition that occurred. They aren’t the full story.  We’re looking at over a hundred million years between us and them.  We don’t have the full picture.  Look at today’s biodiversity, and compare it to what’s available in the fossil record.  The fossil record itself is like trying to understand a person’s life by looking at a photo album, most of the pictures missing, with a picture of an individual, we’ll call him Bob, as a toddler, then as a highschooler going to the prom, then maybe as a middle-aged man with another younger man (perhaps his son?), then a funeral announcement.  We can get a basic idea of how his life unfolded, but there are many, many things that we can’t answer about his life.  This is the way the fossil record works. In order to understand how evolution operates over time, one has to look at the basic patterns visible in the fossil record. Sure, you can’t get a complete, full, exact picture of every species-to-species transition, but you can get a pretty good idea of what actually did happen in an evolutionary sense.

Another thing to note about evolution, something which is often overlooked, is the fact that evolution can, in fact, transform entire bodies as a whole. The transmutation in body plan visible in our ceratopsian lineage is a complete one, with changes in cranial anatomy (just look back at some of the ceratopsian skulls shown to see it), body size, stance, and (as we’ll look at in a minute), sacral (a fancy word for the region of the backbone that runs through the pelvis) anatomy.  What you’re looking at is not natural selection working on just one trait at a time, but rather many traits, all interacting with each other, all being tweaked slightly through the differential reproductive success of different individuals, not as distinct parts, but as a whole.  People far too often think of natural selection as acting on just one trait at a time.  Sure, it can happen like that in rare cases, but a more full understanding of evolution implies that it is the body as a whole which is acted upon by natural selection.  Yes, individual traits play key roles in reproductive success. But it is the entire body, not merely one trait, which is the agent of reproduction.  Sure, you might have a reproductive edge because you have bigger horns than your opponent.  But you ultimately get to mate because you’re a complete organism, not just one sexy part.  Now that I’ve gotten your attention by talking about reproduction, let’s look at some hips:

psittacosaurus sacrum at AMNH

If you’re having trouble finding the sacrum in this picture, look to the right of the “gastroliths” arrow, right between the little guy’s (not sure if it’s male or female, but I digress…) hind legs. It’s the bone structure shaped more or less like this: )I(

Now onto the next specimen, Protoceratops:

Protoceratops sacrum, AMNH

Look in the same place on this one, right between the hind legs. I apologize about the crappy images with the last two pictures. I took both of them a few years ago, without this purpose in mind.  But I have them, so might as well use them as examples.  Now let’s check out a Triceratops sacrum:

Triceratops sacrum, AMNH

With these three sacrums, you can see how evolution has shaped one specific body part over time. However, after looking previously at the full bodies of these dinosaurs, its much easier to view this for what it is, natural selection tinkering away at one body part as it shapes the whole body.  Regardless, this series of sacrums at least helps to illustrate the relationship between these organisms.  But keep in mind, once again, that it is the entire body that evolves, not just one part.  What paleontologists look for in the fossil record is not “transitional forms”, but “transitional features”, such as our sacrum example, when trying to define evolutionary lineages (phylogenies).  This happens precisely because superficial traits (size, weight, etc) are relatively fluid.  In order to fully understand an evolutionary lineage, it is necessary to look at specific traits which are carried throughout a sequence.  While our sacrum example is not a perfect one, we can at least roughly view how one might find such a trait.  Yes, you can see it change through the lineage, but it is also possible to build a relatively complete picture of how the sacrum has changed throughout its evolution.  Therefore, it could be used to help understand phylogenetic relationships between ceratopsians. Thus, while natural selection does operate on entire bodies, specific traits are also extremely important in defining exact evolutionary sequences.  Both angles are necessary in order to fully define an evolutionary sequence.

Anyway, let me shut up before I make this post any longer/more painful to read.  So what exactly does our quick look at ceratopsians do?  Besides being a (relatively dull) way to kill a few minutes, it also provides an often overlooked example of an evolutionary lineage.  So read up on your ceratopsian evolution (I’ve tried to stay away from the boring, terminological stuff for the sake of a quick introductory glance; Donald Prothero’s Evolution: What the Fossils Say and Why it Matters has a really good discussion of ceratopsian evolution, and would make an extremely good starting point for looking at evolution in the fossil record in general), and be ready next time someone tries to explain away the basic examples of paleontological evidence for evolution like Tiktaalik, Ambulocetus, or Archaeopteryx.  Provide an example of a full lineage such as the ceratopsians, rather than one “transitional form” in a vacuum.  It’ll provide a much stronger proof if you’re ever trying to explain evolution to someone with an open mind that doesn’t know much about the subject.

On Progress: Philosophical Ramblings on the Nature of Evolution

April 10, 2010

Let us consider, for a moment, the pinnacle of evolution.  This group of organisms builds its own cities, engages in organized labor, builds stratified, complex societies, and even practices agriculture in a sense.  I am referring to ants.  You might argue that my momentary classification of ants as the pinnacle of evolution demonstrates a level of inane stupidity on my part, but please allow me a moment to explain myself.

What would you replace ants with in my model? Most likely, you are thinking “well humans, of course”.  But why?  What justifies the classification of humanity as the ultimate pinnacle of evolution? One might argue that we are currently the “dominant” species on Earth, but “dominant” is a tricky term.  Yes, we shape the environment itself in an extremely tactile and observable manner, but even the humble stromatolite has altered Earth’s atmosphere on a global scale (by releasing oxygen early on in life’s history on Earth).  Yes, we use tools and make war with each other, but chimps do the same thing.  Is it perhaps because we are still alive today? This seems like an even worse reason to assume human superiority than the previous ones.  Given the diversity of life on Earth today, the assumption that humans are somehow the pinnacle of an evolutionary process, while perhaps a nice idea from our perspective, is not a scientifically tenable hypothesis.

Of course, I am not implying that there is nothing special about the human species when Earth’s long history is considered.  Yes, we have technological and intellectual capacities far greater than that of other species here on Earth.  Our species has achieved great things, and this should not be overlooked.  However, on the same note, our connections to the world around us must also not be overlooked.  The human species is clearly a biological phenomenon at some deep and fundamental level; we are part of nature, one with the natural world.  If one reads evolution as a progressive ladder trending inherently towards human excellence, it is far to easy to overlook our connection to the greater world around us.  How does this ideology of progress work?

The ideology of progress is actually quite simple to grasp.  If one reads evolution as a progressive process in the sense we are focusing on, then one accepts that evolution inherently operates as follows:

first, nice simple life

then, more complex life

then, even more complex life

finally, upright, bipedal, conscious organisms with social capabilities.

Of course, the fossil record mirrors this trend to an extent. We start with invertebrates, then fish, amphibians, reptiles, mammals, primates, and ultimately humans as a late arrival on the scene.  However, the ideology of progress attempts to place a directional framework around life’s evolution on Earth.  A Progressivist would argue that life somehow inherently evolves in a directional sense, ultimately tending towards consciousness.  This mindset is reflected in many popular (as opposed to academic) texts dealing with paleontology, as well as in the depiction of evolution as a tree.  First, fish appear, and then disappear as amphibians appear. Then it’s reptiles replacing amphibians. And so on.  Such a mindset is culturally constructed rather than demonstrated by scientific data. In the model of evolution as a tree, humanity is ultimately placed at the top and center of the tree, with other lineages, such as reptilia, as side branches.  The message in such a presentation is clear: humans are the most important species on Earth.  Ernest Haeckel’s own evolutionary tree is perhaps the most beautiful illustration of such an idea. The illustration is public domain, so I’ll upload it in a minute, but here’s the wikipedia page where I borrow the image itself from. Anyway, here’s the image:

Haeckel's tree of life

However, Haeckel’s tree of life is extremely problematic. Species do not stop evolving once a more “advanced” group appears on the scene.   When amphibians first evolved during the Devonian, fish did not disappear, never to be heard from again. Nor did they stop diversifying.  Indeed, evolution still shapes new piscine permutations, even today.  If we were self-aware fishes rather than mammalian in nature, perhaps we would shape our evolutionary ladder in such a way that our fishy heritage would be the defining trunk of the tree of life, with humans off on some side branch of their own. Of course, we are not really fish, we are humans. Therefore, we understandably view our own species as the most important product of evolution (as demonstrated by Haeckel’s tree).  Such an anthropocentric model of evolution, while understandable, is not scientific in nature.

In fact,  Darwin rejected the ideology of progress inherent in Haeckel’s tree.  Darwin preferred the analogy of a coral, rather than a tree.  On p. 25 of the B Notebook (available here), Darwin states that “The tree of life should perhaps be called the coral of life, base of branches dead; so that passages cannot be seen.” Darwin was contemplating  tree-like models, but his tree, or coral, was inherently nonprogressive (image from here):

Darwin's tree, or "coral" of life

Note that in contrast to Haeckel’s tree, Darwin’s own illustration (although superficially tree-like) has no obvious pinnacle. Branches “A”, “B”, “C”, and “D”, each branch off in their own separate direction, with no single branch occupying an obviously central position on top of a well-defined trunk.  Thus, no progress inherent in Darwin’s own illustration of how natural selection works.

But what does this all mean? Is there a reason for my posting of these beautiful yet archaic images?  Trees, branches, corals, and progress…who cares?  This line of inquiry is useful for multiple reasons.  First, Darwin’s coral and Haeckel’s tree offer a wonderfully clear illustration of how one’s own biases can influence one’s science.  While Darwin’s coral suggests natural selection as a wholly non-progressive enterprise, inherent in Haeckel’s tree is his own, and indeed our own, anthropocentrism.  Haeckel’s tree places humans exactly where most of us view ourselves, at the top of the ladder and central to all life on Earth.  In Haeckel’s tree, non-human lifeforms are portrayed as inherently “lower” than humans. In Darwin’s coral, we are relegated to one branch of the larger model, diverging from other lifeforms in a similar manner to that of Haeckel’s tree, but merely away from other lifeforms rather than inherently upward.

So what?  Darwin drew corals to illustrate evolution but Haeckel drew trees. This split, in itself, signifies a far greater split within human society.  Most mainstream Western religious belief systems uphold a view of humanity similar to that presented in Haeckel’s tree.  Humans are presented as beings “Created in God’s image”, at the pinnacle of all life on Earth.  Darwin’s coral, being non-progressive in nature, seems to contradict these belief systems.

However, is such a contradiction between evolution and religious belief really necessary?  While religiously inspired anti-evolution movements see such a contradiction as inherent and deadly to either evolution or religion (choosing, of course, evolution as the ideology to reject), is such a contradiction really there?  Not necessarily.  While some evolutionary biologists, such as Richard Dawkins, are ardent atheists, others, such as Kenneth Miller, are devoutly religious.  As I argue in Gould’s Hopeless Monster, evolutionary theory can, in fact, co-exist with religious belief.  However, the two magisteria DO overlap in some cases, forcing some level of compromise in the zones where this overlap occurs in order to maintain coexistence.

Of course, if one wants to truly accept all implications of modern science, then religious beliefs will often end up shifting to accommodate science in these contested zones.   But this is not to imply that science disproves God.  Indeed, God is a supernatural hypothesis outside the magisteria of science; one cannot scientific prove or disprove the existence of the supernatural.  What science can and must do is to follow the available evidence where it leads in search of natural explanations for natural phenomenon.  So is Darwin’s coral or Haeckel’s tree the correct model for the diversity of life? The fact that the history of life on  Earth has followed a relatively contingent path of development over the past few billion years lends credibility to Darwin’s coral rather than Haeckel’s tree.

But what does this mean for religious belief? Surprisingly, not as much as one might initially think.  While such a model suggests that we are deeply tied to the web of life surrounding us, it does not necessarily exclude the existence of God.  As much as one might argue that a rejection of the ladder of progress somehow “lowers” the significance of human existence, why is such a statement necessary? One could just as easily argue that such a position rather elevates the position of non-human lifeforms, perhaps focusing on the unity of all lifeforms as part of God’s creation, if one wanted to debate the issue in theological terms.  Of course, such a discourse, while influenced by science, is not in itself scientific in any sense, since science cannot, by nature, answer theological questions dealing with the supernatural.

Now, moving away from the question of religion, let’s finally focus on the implications for science as a whole.  The ladder of progress is heavily embedded within the scientific community, even though, as we have seen, it is a non-scientific concept.  In fact, Michael Ruse (1996) has published an entire book, Monad to Man: the Concept of Progress in Evolutionary Biology, focusing on the subject.  If you’re at all interested in the question of progress after reading this post, I strongly suggest checking it out.  Regardless of whether we embrace Darwin’s coral or Haeckel’s tree, our choice has major implications for how we view life as a whole.  If we are to embrace Haeckel’s tree, then consciousness is likely to be the end result of an evolutionary programme, suggesting that self-aware life is likely to be ubiquitous, or at least fairly common throughout the universe.  If we are to rather embrace Darwin’s coral, then consciousness is likely to be far rarer in the universe.  So perhaps ironically, while Darwin’s coral seems to de-emphasize the importance of human life here on Earth, it may prove to be foundational to the importance of human existence in the cosmos as a whole.  If evolution does not necessarily trend towards consciousness, and if it is therefore plausible to argue that we are one of only a few (if not the only) “conscious”, self-aware species in the universe as a whole, then that is an intriguing thought.  If we are indeed organisms of an exceedingly rare nature within the cosmos as a whole, then perhaps such a plausibility is worth contemplating.

One Long Argument, one hungry blogger

November 19, 2009

In anticipation of the 150th anniversary of the publication of Darwin’s Origin of Species (November 24th; mark your calendars!), I figured I would address evolutionary theory.  The concept of evolution is one of the simplest in science, yet is often misunderstood.  While searching for a good illustration of how evolution works, I realized that I was hungry.  Heading out to the lobby, I checked the vending machines for something to eat:

 

Noticing the presence of M&Ms in the machine, I had an idea. M&Ms come in different colors; i.e. they have a built-in source of variation.  I opted for the ones with peanuts (E7), put in my dollar, and got a package.  Upon returning to the room, I opened the package of M&Ms, and laid them out to display the degree of variation within said population of M&Ms:

After examining the population, I realized that there was a level of variation such that we have a healthy population, with some traits being rarer than others.  Blue, Green, and Orange were designated as “common”, Brown as “uncommon”, and Red and Yellow as “rare”.  So we have a population with variation.  How does said population evolve?

Certain traits (in this case colors) are advantageous, while others are disadvantageous.  If a predator likes to eat red things, the red M&Ms are in trouble.  There is only one representative of that variety in our population, and this blogger does like red M&Ms.  Therefore, we have a disadvantageous trait, and said variety is removed from the gene pool, i.e. it goes extinct.

While the red variety goes extinct, the blue, green, yellow, and orange varieties go on living happily, and breeding (unfortunately I cannot make M&Ms reproduce…bear with me).  Eventually, some event occurs that alters some portion of our population (be it a behavioral change, mutation, etc).  In this case, we’ll use a reference to 2001 A Space Odyssey.  A monolith pops into the scene.  The blue and orange M&Ms are attracted to it.  The other M&Ms run away:

 

 

If you are not familiar with the scene this is referencing, it is available here.  So the Blue and Orange varieties gain some sort of differential survival advantage (call it “intelligence”) from contact with the monolith.  We’ll say that the monolith is radioactive and caused rapid mutations within the Blue and Orange genomes; we’re not looking at long periods of time here, so I’m taking a leap here and increasing the speed of our demo.  The Blue and Orange varieties chase off the other varieties of M&Ms due to their inherent differences (we’ll say through a mountain pass), and then return to their own region.  A landslide (or in this case a giant screw falling in the middle of the picture) blocks off the pass, separating the blue and orange varieties from the other varieties:

After separation, you have two separate varieties, which compete amongst themselves, and evolve along separate paths.  This is called allopatric speciation:

Eventually, an earthquake or something of the sort removes the geographic barrier, and the populations mix once again:

If the two populations have been separated long enough, and evolved along different enough lines, then they will be able to coexist without competition.  If this is the case, populations will stabilize between the two without much competition:

 

OK, but what has this little thought experiment demonstrated about evolution?  Evolution through natural selection, at its most basic level, requires variation within a population.  When dealing with living organisms, this variation is provided by genetic mutation.  Genetic mutation is pretty much random in nature.  However, certain mutations are favorable for survival, other mutations are unfavorable, and some are neutral.  Darwin’s model of natural selection is based on a competition for resources; certain individuals will just be better able to compete for resources.  These individuals are the ones that will tend to leave the most offspring.  Natural selection works by weeding out unfavorable mutations and increasing the population of organisms with favorable mutations.  Mutation is random.  Natural selection is not.  Natural selection will inherently favor those organisms that have traits which give them an edge for survival.  In our M&M analogy, if predators like to eat red M&Ms, then red M&Ms will likely be rarer (or go extinct quicker) than other varieties.  If some gazelles run faster than others, and the slow ones are the ones that generally get eaten by lions, then natural selection will gradually increase the average speed of the gazelle population as a whole.
Within our M&M analogy, we saw a rapid “Poof”-style evolutionary shift in which some M&Ms drastically changed form after coming into contact with a monolith.  I do not mean to imply some sort of magical evolutionary process in which a bird suddenly hatches from a lizard egg; that’s saltationism, and saltationism is wrong.  However, given the right conditions and environmental pressures, evolution can happen relatively quickly.  When you separate one large population into two smaller ones (our screw-landslide), you decrease the size of the gene pool, and thus enlarge the potential impact of a given mutation.  As such, relatively small populations can often change relatively quickly.  In some cases, once the separated populations come back into contact with each other, they have evolved along separate enough paths that they do not directly compete with each other, allowing for the coexistence of both groups.  In other cases, both groups do still directly compete with each other.  In these cases,  natural selection once again weeds out certain individuals, and allows others to prosper.

As demonstrated, evolution through natural selection is an extremely simple process. Some organisms are better adapted than others, and these well-adapted organisms will tend to reproduce more often, eventually taking over the population. However, as demonstrated through our brief, rough look at allopatric speciation, natural selection is not the only force involved in controlling the evolution of life on Earth.  Environmental factors also can play a major role.  Barriers between populations are also important.  Meteor impacts and other mass extinction events can drastically shift the course of evolution on Earth.  But can evolution explain the diversity of life on Earth?

Given the long period of time for which the Earth has existed (approximately 4.6 billion years), we certainly have had enough time to evolve the diversity of life on Earth.  While some have raised questions (generally pseudoscientific in nature) about the ability of evolution to explain the origin of the eye, or transitions between major groups of animal, for example, these objections are weak.  While we have a working mechanism for evolution, and a huge amount of evidence in support of the idea that life on Earth is the result of a long, drawn-out process of evolution, there is no mechanism given for these arguments against evolution.  No defined laws which would forbid the evolution of the eye.  No tactile reason to believe that one could not evolve a bird from a dinosaurian ancestor, or an amphibian from a fish.  The evidence is clear, and the process is as elegant as it is simple.  Evolution happens.

 

neat source; James Hall obituary

October 30, 2009

If you’ve been following my blog for a while, you may remember my “In the Footsteps of Giants” post.  In it, I mention New York State Geologist James Hall.  Interestingly enough, his New York Times obituary is accessible online (click here, PDF format).  Hall was an interesting figure, and his obituary sheds more light on his life.  Hall worked closely with the likes of Charles Lyell and Louis Agassiz, and published some noteworthy works of his own (especially focusing on the geology of New York).  The obituary is short, and well worth spending a minute or two to read.