Thursday, 18 April 2013

Gallstones - Another Little Gem From The Intelligent Designer

Opened gallbladder containing numerous gallstones
You have to hand it to the Intelligent Designer. Just look at the way it came up with the idea of gallstones. Whatever would we do without them?
A gallstone is a crystalline concretion formed within the gallbladder by accretion of bile components. These calculi are formed in the gallbladder but may distally pass into other parts of the biliary tract such as the cystic duct, common bile duct, pancreatic duct, or the ampulla of Vater. Rarely, in cases of severe inflammation, gallstones may erode through the gallbladder into adherent bowel potentially causing an obstruction termed gallstone ileus.

Presence of gallstones in the gallbladder may lead to acute cholecystitis, an inflammatory condition characterized by retention of bile in the gallbladder and often secondary infection by intestinal microorganisms, predominantly Escherichia coli and Bacteroides species. Presence of gallstones in other parts of the biliary tract can cause obstruction of the bile ducts, which can lead to serious conditions such as ascending cholangitis or pancreatitis. Either of these two conditions can be life-threatening and are therefore considered to be medical emergencies.

The archetypal sufferer from gallstones has the five 'f's:
  • Female.
  • Fertile.
  • Fair.
  • Fat.
  • Forty.
Fair referring to skin colour.

However, many exceptions are found and gallstones are not uncommon in men, postmenopausal and thin women and non-Europeans although less so than in Europeans. They are very rare in young people.

The problem starts because body fluids with a high concentration of anything and especially salts, lend themselves to the formation of stones by simple chemical processes. Unfortunately, many of these fluids are collected in temporary stores such as, in the case of gallstones, the gallbladder. Stones may also form in places like the kidneys where they can obstruct the outflow of urine, causing kidney damage or be passed down the ureter to the bladder causing excruciating pain and sometimes accumulating there to obstruct urination, or salivary glands causing the flow of saliva to be obstructed and the face and neck to swell up as saliva accumulates.

The function of the gallbladder is to store bile until food is present in the small intestine. It then contracts squirting bile down the bile duct into the small intestine where it plays a role in digestion of fats. Bile is actually a waste product produced by the liver from dead red blood cells, or rather from the haem part of haemoglobin from which most of the iron has been removed and recycled. When the bile duct is obstructed bile is retained by the liver and passes into the blood where it causes jaundice and shows up in the urine which resembles freshly brewed tea or black coffee. If not treated, this can cause renal failure.

The problem is compounded by the fact that, for no apparent good reason, the bile duct joins with the duct from the pancreas to form the hepato-pancreatic duct before it joins with the small intestine at the 'ampula of Vater', so any obstruction in the hepato-pancreatic duct also obstructs the pancreatic duct. As well as controlling blood sugar levels with insulin, the pancreas also produces enzymes for digesting proteins so any obstruction or damage to the pancreas can also cause it to begin to digest and eventually destroy itself. Infections in the bile duct can also spread to the pancreas causing acute inflammation of the pancreas or pancreatitis which is fatal in about 25% of sufferers (though not all these are caused by gallstones).

It would be a particularly nasty and vicious intelligent designer who came up with this example of bad design which, in the time before anaesthetic surgery and before modern medicine would have been a common cause of death, especially of females in midlife and still is in people without access to health care. There is no purpose to gallstones; there is no purpose to them predisposing to infection by normally benign intestinal bacteria; there is no benefit from the pancreatic duct uniting with the bile duct and so making it easy for the pancreas to become involved with gallstones and any infection they may allow. Unless, of course, the purpose was to cause illness and death.

The entire system is a kludge; an "it'll do" solution which has its origins somewhere in evolution and particularly in embryology, and so we are stuck with it.

To understand why evolution, which we would expect to eliminate these kludges and lead to perfection of 'design', has not eliminated gallstones or 're-designed' the hepato-pancreatic duct we need to look at the common predisposing factors above. The reason is the same reason we have not eliminated cancer and degenerative diseases like Alzheimer's, motor-neurone disease and Parkinsonism. There is little or no benefit to the genes from any mutations which would bring about these changes because they only present as problems after we have produced our offspring.

If there is no benefit to the genes there can be no evolution other than random genetic drift. The link to fair skin, which, in evolutionary terms provided some benefit particularly in a cloudy, relatively sunless north west Europe, suggests some linkage between changes in melanin (the dark pigment) production in the skin and gallstone formation, so they may simply be an unfortunate by-product of an otherwise beneficial mutation in the context of an environment with a lot of clouds. And that evolutionary change expresses before we produce offspring by reducing the incidence of rickets in growing children.

What benefit there might be to the genes in having mothers live long enough to be grandmothers, and so helping to raise the next generation carrying her genes is much less obvious than it would be if they affected her reproductive success directly, since her grandchildren are only one quarter her on average, but never-the-less we should expect to see some evolutionary change towards eliminating the formation of gallstones and/or reducing their potential seriousness over time even for that small advantage. But then we only evolved fair skin relatively recently so there will not have been time yet for this effect to be noticeable. Gallstones are probably part of the cost of evolving fair skin in a cloudy environment and we will still need to bear that cost for many years, possibly hundreds of thousands yet.

As an example of intelligent design and especially the design of an omni-benevolent designer, gallstones fail badly. Any designer who came up with this idea is neither intelligent nor benevolent. As an example of the mindless, undirected and amoral process of evolution, gallstones are readily understandable.

Sorry, Discovery Institute and your willing stooges who push fundamental Bible literalism disguised as science with 'Intelligent Design'. You have very many of these examples to explain. Ignoring them and relying on the ignorance of your credulous victims won't work with rational people.

submit to reddit


No comments :

Post a Comment




Related Posts Plugin for WordPress, Blogger...
Web Analytics