Archive for July, 2008

Jul 16 2008

More Evidence that Autism is Genetic

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Much of the controversy surrounding autism in recent years is based upon the premise that there is an autism epidemic – that autism rates are climbing. However, the evidence strongly suggests that this is not the case and that autism diagnoses are increasing through a combination of broadened diagnosis and increased surveillance and awareness. However, proponents of various discredited theories, such as those anti-vaccinationists who claim there is a link between vaccines and autism (there isn’t) want to believe there is a true epidemic because that in turn implies an environment factor (like the vaccines they despise).

But the environmental hypothesis of autism, while impossible to completely eliminate, has not been fairing well. On the other hand, the theory that autism is largely (if not entirely) genetic has been very fruitful. Researchers are finding more and more genes that correlate strongly with autism. Also, studies have shown that the risk of autism rises with paternal age – suggesting that aging sperm may play a role. It is also true that as our ability to diagnoses autism more reliably, and based upon earlier and more subtle signs, we are finding that infants show early signs of autism – before they receive most of their vaccines or environment has much of a chance to play a role.

Essentially, multiple independent lines of evidence are converging on the conclusion that autism is dominantly genetic. Well, now there is yet another line of evidence supporting this conclusion

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17 responses so far

Jul 15 2008

Tasmanian Devil Evolution

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Growing up on Bugs Bunny this was my image of a tasmanian devil. Only later in life did I come to know the real animal, through books, documentaries, and now the internet. The tasmanian devil is the largest marsupial carnivore in the world (after the extinction of the tasmanian tiger).

For the past decade the tasmanian devil population has been decimated by an unusual disease – an contagious cancer. Devils commonly bite each other in the face as part of their social interaction, especially during mating. A facial cancer that can be spread through biting has reduced the devil population by about 90%. The cancer is fatal because it eventually prevents the devil from feeding. This has prompted breeding programs in captivity to rescue the species. It is believed that the cancer is able to spread in this fashion partly because the devil is so in-bred, therefore genetic diversity is low and devil’s immune systems do not reject what amounts to a tissue graft.

There are several distinct populations of tasmanian devils in Tasmania, all but one are affected by the cancer. There are two populations held in captivity as insurance. Biologists are also working on a vaccine for the cancer. The clock is ticking, however, because it is feared that the red fox, an invasive species, may take over the tasmanian devil’s habitat while the populations are low.

But, evolution may succeed first without the need for human intervention.

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5 responses so far

Jul 14 2008

MIT Announces Another Solar Breakthrough

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I have been following the solar power news for some time out of personal interest. It seems to me solar power is likely to play an important and growing role in meeting the world’s energy needs. It is environmentally friendly, very modular (you don’t need a huge energy plant to use solar, unlike, say, nuclear), and can be unobtrusive.

Also – we are being bathed in more solar energy than we currently need to run the world. According to Wikipedia:

  • The total solar energy absorbed by Earth’s atmosphere, oceans and land masses is approximately 3,850 zettajoules (ZJ=10^21 joules) per year.
  • Global wind energy at 80 m is estimated at 2.25 ZJ per year.
  • Photosynthesis captures approximately 3 ZJ per year in biomass.
  • Worldwide electricity consumption was approximately 0.0567 ZJ in 2005.
  • Worldwide primary energy consumption was 0.487 ZJ in 2005.

That means that the Earth receives 7905 times the energy from the sun as we currently use. This means that we would need to cover only 0.12% of the earth with 10% efficient solar panels to meet current needs – if we ran everything on solar.

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8 responses so far

Jul 11 2008

Jonathan Swift Predicted the Moons of Mars

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Well, not quite, but he came close.

I was recently asked about the claim that Swift wrote about the moons of Mars in Gulliver’s Travels, published in 1726, and that he knew that there were two moons and exactly described their size and orbital period. The implication is that Swift somehow knew about the moons of Mars, Phobos and Deimos, a century and a half before they were discovered. It turns out that his predictions, if you can call them that, were accurate enough to be an interesting coincidence, but not so close that we have to consider it anything but that.

Gulliver’s Travels

If you have never read this book, I highly recommend it. The animated and live-action movies are fun for kids, but they contain almost none of the biting social satire, and generally leave out the most interesting parts of the book.

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Jul 10 2008

A Psychic By Any Other Name

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Is still a fraud.

Laura Day is a psychic, although she calls herself an “intuitionist.” What’s an intuitionist? Well, it’s someone who can access information not available to the senses. On Day’s website she offers advanced intuition techniques that include telepathy and clairvoyance. In other words – she’s a psychic.

The only difference is in marketing. Day’s clientele are not the middle-class moms who want a quick tarot card reading. They are not the desperate parents who turn to the chain-smoking Sylvia Browne for a glimmer of information on their missing child. They are not the new-age types who go in for crystals and head scarves.

Day caters to corporations and celebrities. So she attires herself accordingly and calls herself an intuitionist instead of a psychic – to give a bit of cover to executives who might be a little embarrassed about making business decisions based upon magic. The scam works – she claims she gets 10k a month per client and holds down five clients at a time, raking in millions.

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55 responses so far

Jul 09 2008

Quackery Down Under

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According to news reports a 36 year old Australian woman allegedly died after being treated with ozone therapy for her pancreatic cancer. The practitioner who gave her this bogus treatment is now facing a hearing.

The story is a tragic one and reflects, in my opinion, the erosion of medical ethics that results from tolerating blatantly unscientific therapies, para-professionals, and alternate philosophies of healing. It is impossible to maintain a standard of care without an object basis for evaluating treatments, i.e. science. Also, as Paul Krugman said in another context but one that applies here also, “When the public believes in magic, it’s springtime for the con-artists.”

In this case the woman, out of desperation, sought the ministrations of a practitioners using ozone therapy. This is pure quackery – the claim that ozone (a molecule of three oxygen atoms) has special healing powers because it delivers a boost of oxygen to the tissues.

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7 responses so far

Jul 08 2008

Smiling Babies, fMRI, Brain Modules, and Neural Networks

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I have two daughters, about to turn nine and six. They are, in my completely subjective and biased assessment, the most adorable things in the universe. They evoke in me a powerful and complex set of emotions – an experience that every parent understands and no non-parent can truly appreciate.

Despite concerns about the testability of evolutionary psychological explanations, it seems obvious that such a reaction in a parent would be favored by natural selection, as would be any features in a child that provoked such a response from their parents. This in turn suggests that much of the response of a parent to their child is hard-wired in the brain and genetically determined. This doesn’t rule out cultural and learned influences, it merely suggest that a strong parenting tendency will be coded in the genes.

A recent bit of research supporting this notion was published in the latest issue of Pediatrics: What’s in a smile? Maternal brain responses to infant facial cues. The study uses fMRI, which images blood flow to the brain from which the relative activity of various brain regions can be inferred, to measure the reaction of mothers to various pictures – their child happy, neutral, and sad and another child happy, neutral, and sad. The results:

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Jul 07 2008

UAO – Unidentified Astronomical Object

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Never underestimate the fallibility of human perception, memory, and cognition. Experienced skeptics understand this, but we still can’t help being stunned at times by the misperceptions and bizarre beliefs of some fellow members of our species. It takes the occasional reminder. Yes – Sheri Shepard did not know that the world is not flat, that guy on the French version of Who Wants to be a Millionaire did not know that the Moon orbits around the Earth (and he listened to the 56% of the audience who thought the Sun was the correct answer), and yes millions of people actually believe that magic water (otherwise known as homeopathy) can treat illness.

It is also true that the moon is commonly mistaken for an unidentified flying object (UFO).

People are generally surprised to hear this for two reasons: they underestimate the human capacity to be fooled by misperception and they underestimate how unusual the moon may appear in certain viewing conditions. I also acknowledge that for some people they are simply unfamiliar with the appearance of the moon, not being in the habit of looking up at the nighttime sky, or apparently of paying significant attention to the details of the world around them.

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16 responses so far

Jul 04 2008

The Not-So-Intelligent-Design of the Human Eye – Part II

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Yesterday I discussed the difference between the bottom-up design of evolution vs the supposed top-down design of a god/intelligent designer. I then used the human eye as an example of bottom-up design, made manifest by quirky and sub-optimal aspects that do not make sense from a top-down perspective. Today I will give further examples of the sub-optimal design of the human eye which predisposes to certain opthalmological diseases and disorders.

Angle Closure Glaucoma

Glaucoma results from increased pressure inside the eye. Between the iris and the cornea is a space called the anterior chamber which is filled with the aqueous humor – a clear liquid that is constantly made and drained from this chamber. If the drainage is blocked or slowed then the fluid will back up, increasing the pressure inside the eye. This pressure can damage the optic nerve resulting in blindness. In acute angle closure glaucoma blindness can occur within hours and it is therefore an emergency.

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Jul 03 2008

The Not-So-Intelligent-Design of the Human Eye

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Intelligent design (ID) is the notion (I am deliberately not referring to it as a theory, because as yet no one has put forth a formulation of ID that qualifies as a testable scientific theory) that life on earth was designed from the top-down by an intelligent agent. The historical and cultural background of ID is clearly documented (as was demonstrated in the Dover trial) – it is the latest incarnation of fundamentalist Christian creationism – and so the “intelligent designer” is simply a stand-in for the Christian God.

Regardless of what you call the top-down designer, any reasonable interpretation of ID/creationism predicts that life should show signs of top-down design. ID/creationism fails to be a scientific theory because its proponents refuse to make such reasonable predictions. In essence they argue that the designer (God) could have created life to look like anything – even absent any evidence of top-down design.

Evolution is the scientific theory that the various species of life on earth arose through branching descent, change and speciation over time. This is a decidedly bottom-up process of design with populations adapting to their immediate needs using the raw material that happens to be available to them. This raw material includes their existing biology in all its facets, including the variation within the population. Evolution is therefore unguided, unplanned, messy, quirky, and historically contingent.

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18 responses so far

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