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This is an essay I wrote for a science course which describes a plausible natural selection scenario for how a parasitic lancet fluke evolves to be capable of a neurochemical 'mind control' of an ant host. I am not a professional scientist, so I claim no expertise on these subjects. The post to which I am responding was made by a fellow student, and was a response to an earlier post I made in a discussion of environment and responsibility. Here, I am countering a statement that my references to the lancet fluke (more info here: http://www.ted.com/talks/dan_dennett_on_dangerous_memes.html ) and the fish-tongue-eating-crustacean known as Cymothoa exigua (more info: http://www.youtube.com/watch?v=vAlEfrwr8aU ), which he refers to as "two horrifying examples", demonstrate that "nature [is] out of balance, or is a battle of Good-vs.-Evil? Perhaps even an unsettled balance of natural selection, due to our negligence of humans disrupting nature's preservation?." My rebuttal follows, edited for typos, and with off-topic text removed.

As to the 'two horrifying examples', I would argue that neither example is one of an out-of-balance nature nor a battle of good-vs-evil. Neither appears to be affected at all by human activity. The lancet fluke, for instance, is not alone in its ability to take over another creature in some useful way, there are literally countless examples like this one. Nature simply favors any ability which gives a member of the species an advantage over others of its species, and by extension, sees advantages in species which are generally better adapted than other species competing for the same resources -- which should not be confused with group selection, a concept which is controversial and outside the mainstream in biology, though there are absolutely well-respected biologists holding positions in favor of group selection, but I digress.

Let me create a hypothetical progression of lancet fluke behavior. This is purely a mind exercise with few details and backed only by my readings in biology and behavior, but I think it serves us well and presents a plausible pathway, even if incorrect and flawed in real details. Also note that when I use singular terms, such as 'fluke', I'm referring to a statistically signficant set of flukes acting in some way or possessing some characteristic, and am not suggesting that a single specific fluke was responsible for each stage.

The lancet fluke, like all parasites, requires a host, and we know that the first cycle in the fluke's existence takes place in the body of a snail ("Dicrocoelium dendriticum"). Originally, it is easy to imagine a life cycle that saw the fluke exist completely within the snail, and there are countless parasites for which this model is quite typical.

However, natural selection will favor any genetic change which gives an advantage over other members of the species, even if that edge is very small. Imagine, then that the snail spits up a slime ball which contains living lancet flukes. (Snails do in fact do this and theory holds that this is a likely vector taking the lancet fluke into the ant's body ("Dicrocoelium dendriticum")). The ant, which either physically contacts or otherwise ingests the slime ball, becomes a secondary host for any members of the fluke species which can survive and reproduce during this second stage. Initially, this was probably only a bare few, but enough flukes possessed the ability to live in the snail, survive in the slime ball, and then live in the ant's body that this ability was strongly favored by natural selection to the exclusion of the flukes which could not do so. ***

So, now we have a fluke which has evolved a survival trick which extends its life and offers it an advantage which allows it to reproduce and pass down genes which also tend to favor this trick. Again, this isn't anything inherently good or bad, and certainly didn't require human intervention, this is really the way natural selection works. It is cold, without emotion, and without forethought. It is simply a process which rewards (without intent) any advantage to survival possessed in the genes of a replicating entity. The fluke which survived the slime ball stage and took advantage of the ant-body stage was more likely to reproduce than one which died in the ant's body, and given that this survival had a large reliance on genetics, was also more likely to produce offspring which could likewise take advantage of the ant-body stage.

From there, you can imagine that ants are regularly eaten by ruminants such as cows and sheep. Ants crawl all over grass and other delicacies enjoyed by grazers, so it is inevitable that large numbers are swallowed by such beasts. Natural selection again gives pressure: if any fluke was capable of surviving in the gut of a cow, that fluke was again more likely to reproduce offspring capable of doing the same.

So at this point, we have a fluke which has gone from living solely in the belly of snail to a naturally-selected subset that was capable of surviving the snail coughing it up in a slime ball, being swallowed by an ant, and then being swallowed by a cow. We haven't yet gotten to the 'mind control' ability, but that comes next.

Given that this fluke has now a genetic advantage, however small, over other flukes and over other competing species, it may appear well off. But natural selection does not offer species many opportunities to rest. Likely, the snail, ant, and cow bodies have experienced pressure to be able to survive this invasion. Any fluke infestation which killed its host too soon probably didn't live long enough to reproduce (and likewise, neither did the host). This fatality-condition is shared by both fluke and host genes. Any combination which resulted in death for the pre-reproductive fluke or host whittled down the combination of fluke and host genes which were selected for, and only those flukes with genes which allowed the host to survive and reproduce while also allowing itself to suvive and reproduce enjoyed significant advantage over those which did not, in terms of leaving offspring.

Imagine, then, that the ant develops a set of defenses against the fluke. Perhaps natural selection favors ants which are less likely to position themselves somewhere they might be grazed upon. Perhaps behaviors which result in staying low to the ground or holding along the edge of fields (rather than in the middle of them) would find these ants less likely to be eaten. Naturally, this is bad news for the fluke which, by now, rather expects to get on with its third stage of life in the belly of the cow.

So here comes one of the amazing parts of natural selection: its ability to derive complex and apparently abstract behavior out of a few basic rules. Differential survival means that any advantage, no matter how small, is enough for the process of natural selection to reward these small advantages with the ability to leave more offspring. Imagine that a line of flukes possess a mutation which allows it to secrete a chemical trigger to the ant which prevents the (newly developed, in evolutionary time) behavior which has protected the ant from being eaten as often by cows. We don't need to posit that there was intent here, perhaps various mutations in the fluke had occurred which generated different chemical excretions. We only care hear about the one that actually affected the behavior of the ant in a way advantageous to the fluke.

Suddenly, the fluke has pressured the ant to change its behavior, and the ant is now more likely to return to its original behavior, or demonstrate a new behavior, which left it more likely to be eaten by a cow. This sort of chemical triggering is well-documented and I won't go into details here, except to mention that bacterial and viral infections use all manor of chemical triggers to affect a myriad of things. Again, there doesn't need to believe this is done with intent. For every thousand mutations which change the way chemicals are produced by a parasite, perhaps only one will ever have anything other than a neutral (or negative) effect on its host. This variety, between parasites which possess this one-in-a-thousand mutation and those which do not, is all natural selection needs to differentiate between them. If the chemical allowed its possessors to survive and reproduce more frequently, it is straightforward to see that this would be an advantage that future generations were more likely to possess. The fluke never needed to plan this devious trick, it was just along for the ride built by its own (marginally, but significantly) superior genes and subjected to pressure from natural selection.

The last step here is just an extension of the previous. Once a chemical trigger is in place which advantaged flukes being able to produce it, it is just a short distance to chemical triggers which directed the ant to repeatedly climb the blade of grass. The process is the same as above, so I won't repeat it here.

And so, we've looked at an entirely plausible explanation for how natural selection would deliver a lancet fluke capable of 'mind control' over an ant, living originally only in the belly of a snail, but evolving a complicated adaptation which saw it survive several stages of life in hosts from snail to ant to cow. I'll not go into the tongue-eating-crustacean situation since it too would have gone through a process mirroring this one.

Again, there is no need to posit intent or 'good vs bad', this is just the way natural selection works. Harsh, cold, or heartless, perhaps, but those really are human concepts which we anthropically apply to the world around us.

I'll not get into the 'reason for human existence' since that is a teleological subject probably best left alone here (and to avoid any heated emotions from all of us who have our beliefs or lack-there-of). I am, however, completely in agreement with you about reducing the toxins we dump, and I hope that rational and reasonable people, maybe even ourselves, can study and implement strategies which do just that.

References:

Wikipedia. (n.d.) Wikipedia - Dicrocoelium dendriticum. Retrieved on October 2, 2009 from http://en.wikipedia.org/wiki/Dicrocoelium_dendriticum

*** as a digression, natural selection doesn't necessarily produce an all or nothing differential survival, as Darwin himself explained in On the Origin of Species. The hypothetical situation described above might find that one species of lancet fluke, which evolved from the original species found only in snails, evolved adaptations which required life cycles in both snail and ant, while a second species evolved, also from the original species, which did not. This process works again at the point in which the fluke moved into a third stage in a ruminant body. Differential selection is a manner in which species are not only selected for, but the fuels the divergence of species from their common ancestry.

As you might have noticed from the lack of non-book review posts here, I've been quite busy lately. Family was in town for a couple of weeks, plus I've had considerable work and school responsibilities lately, so I've had little time to keep up here.

A highlight tonight will be listening to Bart, better known by his Atheist Camel nom de plume Dromedary Hump, on The Infidel Guy Show this evening. Hump is a fantastic blogger I've mentioned before when I reviewed his unexpected gem of a book The Atheist Camel Chronicles. To listen to Hump on IG this evening at 8pm ET, go here.

Last night was another treat as I tuned into the first presentation from the Darwin Lecture Series. The presenter was the extraordinary history of science professor Everett Mendelsohn, who described The World Before Darwin with wit and excellent insights. I'd just read The Reluctant Mr. Darwin so I had some knowledge of the material, but Mendelsohn's presentation is engaging and enjoyable to absorb. An MP3 recording of the webcast is already available here, and a video copy will be up soon (check the Darwin150 site for more details).

A report on a new Bahamian law which was aimed at stopping marital rape (a law which has not yet been passed) has been making the rounds as outrage grows over the comments made by men cited in the report. Often using the Bible as proof that men cannot rape their own wives, some of the comments are straight out the Stone Age.

Elvis Russell told the Journal that he does not support the bill either because there is no such thing as rape within a marriage.

"Even if a woman says no to her husband it still can't be considered rape because she is his wife. He already paid his dues at the church and she already said 'I do,' so from then on, even if [a man] forces sex on his wife, it isn't rape," he said.

"I disagree with the bill because I disagree that a man can rape his wife. The Bible tells me that a man's body is his wife’s and her body is his. How could he rape her?" asked Ms. Sweeting.

"If a man wants to have sex with his wife he is supposed to [have sex with her] regardless of what the circumstances [are]. I don’t see why he should be charged with raping his own wife, she is never supposed to say no," said Ms. Clarke.

"If I were married and my husband wanted to have sex with me I wouldn't stop him, [because] I'm not supposed to, even if I was tired or feeling sick, I wouldn't tell him no."

There are some rational responses in the article, thankfully, but yet again, the Bible is used as a primary source for institutional evil, in this case belief that a husband cannot rape his wife. Does the Bible provide some people with inspiration for good? No doubt. But it also clearly provides some people with inspiration for evil.

If you look at the map above, you can see the countries which have outlawed marital rape (shaded in pinkish purple). What is striking is just how many places in the world still allow husbands to rape their wives. Many of these nations are undoubtedly religious and use scriptural doctrines to deny that marital rape can even occur. I don't know what China's excuse is, nor why many Eastern European nations have failed to enact laws protecting wives (what's up, Greece?). Regardless, the idea that wives are owned property may not be derived from scriptural sources, but this notion has absolutely been preserved in the literal interpretations of various scriptural passages, leaving millions of women the world over forced to endure marital rape. Welcome back to the Stone Age.

A judge on Wednesday struck down a 2006 state law that required the Kentucky Office of Homeland Security to stress "dependence on Almighty God as being vital to the security of the commonwealth." ...

Homeland Security officials have been required for three years to credit "Almighty God" in their official reports and post a plaque with similar language at the state’s Emergency Operations Center in Frankfort....

"This is the very reason the Establishment Clause was created: to protect the minority from the oppression of the majority," (Judge Thomas Wingate) wrote. "The commonwealth’s history does not exclude God from the statutes, but it had never permitted the General Assembly to demand that its citizens depend on Almighty God."

State Rep. Tom Riner, D-Louisville, a Southern Baptist minister, placed the "Almighty God" language into a homeland security bill without much notice.

Riner said Wednesday that he is unhappy with the judge’s ruling. The way he wrote the law, he said, it did not mandate that Kentuckians depend on God for their safety, it simply acknowledged that government without God cannot protect its citizens.

Dr. Myers had more to say about the recent research reports concerning the vestigial (or non-vestigial) nature of the appendix. In part one, Myers made it clear that the reporting on the research was misleading and unnecessarily derisive to Darwin and his work. In part 2, Dr. Myers tackles the meat of the research itself, and has some fascinating descriptions of the digestive system to share:

The interesting thing about the transition is that it makes a couple of other odd dead-ends. The cecum (pink) is a small pouch that goes nowhere, while the appendix (red) is a slender projection from the cecum. These are variable in size both within a species and between them — some humans are born without an appendix, and within the majority that have them, there's at least a two-fold variation in size. Between species, the variation is even greater: most mammals don't have an appendix at all, and some have huge ceca and appendixes. The enlarged cecum in most of these species is used as a fermentation chamber, in which hard-to-digest food resides while resident bacteria help break it down....

The cecum is an entirely new concept to me, being a non-professional science geek with little knowledge of the digestive pathways. I find it fascinating that this vital part of our gut has only rarely been featured in the sources I've read (many of which do make points about the appendix and intestines). More from Myers:

If the appendixes in marsupials and euarchontoglires are actually homologous, that should imply that their last common ancestor had a cecum/appendix…and the pattern is explained by widespread and frequent loss of the organ. The authors acknowledge this idea, but admit that there's also a problem with analyzing it: it depends on loss being far more likely than gain, and there aren't any probabilities that we can assign to such events. Fair enough. It does mean, though, that this analysis is insufficient to come up with an answer.

What I'd like to see is patterns of gene expression. That region in the plumbing where the small intestine becomes the large intestine is an interesting transitional zone which must be defined by some kind of patterning molecules; furthermore, I'd expect some kind of gene regulatory network has to be at work in that area to specify the different regions of small intestine, cecum, appendix, and large intestine. What are those genes? Which ones are expressed in the different regions? How do they interact and how are they regulated? You can see how my brain is turning over: I want to know about the developmental and molecular events going on here. That's where we'll be able to resolve the questions of appendix evolution.

I'm also unconvinced by the argument that retention of a feature for 80 million years is necessarily evidence of selection for a specific function. Another possibility is that it is entirely structural: there is a patterning pathway that sets up the transition from small to large intestine, and as a side effect it defines a few intermediate zones, the cecum and appendix. These are mostly harmless, and so are retained as entirely neutral characters that are not easily pared out without disrupting gut function. I say mostly harmless, because one lesson of the phylogeny is that a lot of lineages seem to have edited the structure out altogether. Again, it could just be loss of a neutral character, but it could also be an indication that usually, the appendix is a detriment.

A more solid answer would emerge if, for instance, the molecular networks behind the formation of the appendix in monotremes and humans were compared, and found to use the same toolkit of genes — then we'd have to regard it as highly probable that they are homologous, and the last common ancestor had an appendix. Or conversely, if the mechanisms used by the afrotheria, the xenarthra, and the other mammalian groups that lack an appendix to switch off appendix development were identical, that would suggest that the last common ancestor of the eutheria had that mechanism, lacked an appendix, and those euarchontoglires definitely did re-evolve the appendix.

Show me trees built from genes, then maybe I'll accept the interpretation with more confidence! I just think that one thing these data do show us is that the appendix is a remarkably labile organ, making the appearance or absence suggestive but not conclusive.

As for the argument that one function of the appendix that is significant in modern human populations is as a bacterial reservoir for recovery of gut flora after losses due to disease, that seems entirely reasonable. However, the fact that the appendix has an incidental function that can be useful to individuals in specific circumstances does not mean that the appendix isn't a vestigial organ, nor does it necessarily mean that its retention has been selected for. That some modern human populations have significant mortality from diarrheal symptoms (from cholera, for instance) seems to me to be a relatively trivial factor in a study that shows persistence of the appendix over many tens of millions of years, especially when no evidence of differential survival by individuals having or lacking an appendix is known.

As I posted a few days ago, a group of researchers has made some interesting claims regarding the appendix.

Not only does the appendix have functionality (namely, it provides a reservoir for healthy bacteria to hide out during digestive or intestinal issues such as diarrhea), the researchers have determined that the appendix has evolved at least two seperate times and has only recently (for humans) developed problems such as severe inflammation.

A great deal of the article references Charles Darwin and his misconceptions about the appendix. PZ Myers, never one to miss an opportunity to set the record straight, has weighed in over the weekend on the way Darwin was used throughout various articles in highlighting the research:

Charles Darwin is dead. Your research can't be very cogent if your approach to drum up interest is to dig up a 120-year-old corpse and kick it around; is there anyone alive who disagrees with you who can put up a more informative and entertaining struggle? What this does is pick this one fellow as a symbol of the whole edifice of evolutionary theory, which has the advantage of making one's work seem very, very important (even if one is stacking the deck to do it), but has the disadvantage of giving every creationist on the planet something to masturbate over, and they're icky enough without your help.

It's also annoying. Charles Darwin was wrong about many things — I'll even give an example at the end of this article — and it's part of the nature of science that everyone's work will be revised and refined over time, and some of us will even be shown to be completely wrong. It's rather unseemly to collect a lot of data that Darwin did not have, run it through PAUP 4.0 on a fast computer, map the data onto a molecular consensus phylogeny, and cackle gleefully over discovering something Darwin did not know. Really, it doesn't make you a better scientist than Darwin.

To make it even worse, people who do this can't even make the corpse-fight a fair fight — they have to stuff the pathetic dead body with straw. In this case, they're padding Darwin's investment in the appendix a fair amount. They cite one work by Darwin, The Descent of Man, which mentions this issue. He wrote one whole paragraph on the topic, and here it is, in its entirety; it was presented briefly as part of a long list of human rudimentary structures, such as wisdom teeth, muscles of the ear, and the semilunar fold of the eye.

With respect to the alimentary canal, I have met with an account of only a single rudiment, namely the vermiform appendage of the caecum. The caecum is a branch or diverticulum of the intestine, ending in a cul-de-sac, and is extremely long in many of the lower vegetable-feeding mammals. In the marsupial koala it is actually more than thrice as long as the whole body. (46. Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441.) It is sometimes produced into a long gradually-tapering point, and is sometimes constricted in parts. It appears as if, in consequence of changed diet or habits, the caecum had become much shortened in various animals, the vermiform appendage being left as a rudiment of the shortened part. That this appendage is a rudiment, we may infer from its small size, and from the evidence which Prof. Canestrini (47. 'Annuario della Soc. d. Nat.' Modena, 1867, p. 94.) has collected of its variability in man. It is occasionally quite absent, or again is largely developed. The passage is sometimes completely closed for half or two-thirds of its length, with the terminal part consisting of a flattened solid expansion. In the orang this appendage is long and convoluted: in man it arises from the end of the short caecum, and is commonly from four to five inches in length, being only about the third of an inch in diameter. Not only is it useless, but it is sometimes the cause of death, of which fact I have lately heard two instances: this is due to small hard bodies, such as seeds, entering the passage, and causing inflammation. (48. M. C. Martins ("De l'Unite Organique," in 'Revue des Deux Mondes,' June 15, 1862, p. 16) and Haeckel ('Generelle Morphologie,' B. ii. s. 278), have both remarked on the singular fact of this rudiment sometimes causing death.)

Note why Darwin classed this appendage as vestigial: because it is greatly reduced compared to the homologous organs in non-human relatives, and because it currently exhibits a great range of variation, which is apparently non-functional. These are criteria which the paper in question does not refute at all. Darwin does say that the appendix is "useless", and the paper will show some evidence that that is wrong. It's also irrelevant.

The reason why it is irrelevant is that the presence of some function is not part of the definition of a vestigial or rudimentary organ — Darwin obligingly concedes that evolution will salvage some utility out of organs with little retention of their original function, but which are present as a consequence of contingency....

If a portion of the gut, a digestive organ, is diminished in size such that it no longer contributes to the primary function of the organ, but does retain a secondary function, such as assisting in immunity, or as the authors of the recent paper will argue, in acting as a reservoir of bacteria for recolonizing the gut, then it is still a vestigial organ. It has lost much of its ancestral function.

I do not understand why this is so hard for so many people to comprehend. Biology is plastic and opportunistic. Accidents of history will always still be incorporated into the whole of the organism; we make do, or we die. Just because something is does not mean that the entirety of its nature is the product of selection.

This is an older video of Robert Wright, author of Non-Zero and (since the interview) The Evolution of God, interviewing philosopher Daniel Dennett. Very interesting hour-long discussion of philosophy, mind, and consciousness.

Researchers from Duke, Arizona, and Arizona State have concluded that Charles Darwin was wrong.

No, not about natural selection or speciation.

He was wrong to believe that the human appendix was a vestigial organ with no modern function. Not only does the appendix have functionality (namely, it provides a reservoir for healthy bacteria to hide out during digestive or intestinal issues such as diarrhea), the researchers have determined that the appendix has evolved at least two seperate times and has only recently (for humans) developed problems such as severe inflammation.

The latest study demonstrates two major problems with that idea. First, several living species, including certain lemurs, several rodents and a type of flying squirrel, still have an appendix attached to a large cecum which is used in digestion. Second, Parker says the appendix is actually quite widespread in nature. "For example, when species are divided into groups called 'families', we find that more than 70 percent of all primate and rodent groups contain species with an appendix." Darwin had thought that appendices appeared in only a small handful of animals.

"Darwin simply didn't have access to the information we have," explains Parker. "If Darwin had been aware of the species that have an appendix attached to a large cecum, and if he had known about the widespread nature of the appendix, he probably would not have thought of the appendix as a vestige of evolution."

He also was not aware that appendicitis, or inflammation of the appendix, is not due to a faulty appendix, but rather due to cultural changes associated with industrialized society and improved sanitation. "Those changes left our immune systems with too little work and too much time their hands – a recipe for trouble," says Parker.

That notion wasn't proposed until the early 1900's, and "we didn't really have a good understanding of that principle until the mid 1980's," Parker said. "Even more importantly, Darwin had no way of knowing that the function of the appendix could be rendered obsolete by cultural changes that included widespread use of sewer systems and clean drinking water."

This has been going around for a while now as a rebuttal to those who say the government should have no role in health insurance or medical care, author unknown.

This morning I was awoken by my alarm clock powered by electricity generated by the public power monopoly regulated by the U.S. Department of Energy.

I then took a shower in the clean water provided by a municipal water utility.

After that, I turned on the TV to one of the FCC-regulated channels to see what the National Weather Service of the National Oceanographic and Atmospheric Administration determined the weather was going to be like, using satellites designed, built, and launched by the National Aeronautics and Space Administration.

I watched this while eating my breakfast of U.S. Department of Agriculture-inspected food and taking the drugs which have been determined as safe by the U.S. Food and Drug Administration.

At the appropriate time, as regulated by the U.S. Congress and kept accurate by the National Institute of Standards and Technology and the U.S. Naval Observatory, I get into my National Highway Traffic Safety Administration-approved automobile and set out to work on the roads built by the local, state, and federal Departments of Transportation, possibly
stopping to purchase additional fuel of a quality level determined by the Environmental Protection Agency, using legal tender issued by the Federal Reserve Bank.

On the way out the door I deposit any mail I have to be sent out via the U.S. Postal Service and drop the kids off at the public school.

After spending another day not being maimed or killed at work thanks to the workplace regulations imposed by the Department of Labor and the Occupational Safety and Health Administration, enjoying another two meals which again do not kill me because of the USDA, I drive my NHTSA car back home on the DOT roads, to my house which has not burned down in my absence
because of the state and local building codes and Fire Marshal's inspection, and which has not been plundered of all its valuables, thanks to the local police department.

And then I log on to the internet -- which was developed by the Defense Advanced Research Projects Administration -- and post on Freerepublic.com and Fox News forums about how SOCIALISM in medicine is BAD because the government can't do anything right.