Stop Being Afraid of AIDS

on Thursday, March 31, 2011

I've compiled some statistics about AIDS in Iowa, on a quest to determine the actual risk presented by AIDS. There are good reasons to use protection and practice safe sex, but it appears that AIDS risk is so small in the United States that it poses little threat to American health.

Random hookups involve spiders and scorpions

First, some of my misconceptions:

1. If you have unprotected sex with an AIDs victim, you'll get AIDS about 100% of the time. Turns out that the transfer rate is about 0.0005%, or 1 in 2,000.

2. If you share a drug needle with an infected person, you'll get AIDS. Actual transmission rate is about 1 in 150.

3. A lot of people have AIDS. Actually there are about 275 women in Iowa with AIDS, or approximately 1 in 5,500.

4. If you get a blood transfusion from infected blood you'll get AIDS. Actual chance is 90%, so I had this one basically right.

So it turns out AIDS isn't so easy to get. From these transfer rates and some additional data we can come to some interesting conclusions:

1. If you were to have completely random, unprotected sex with Iowan women, you could go through eleven million of them before you're expected to contract AIDS. Could be more, could be less, but that's our ballpark. To put this another way, you could have sex with every woman in Iowa and still have only a 13.5% chance of contracting HIV.

And another way -- men are capable of reproduction for about 22,000 days during their lifetime (age 15 till they die). An man could have sex with a random woman every day from puberty to death and have a 0.2% chance to contract HIV before he dies. The avg guy is going to sleep with over 1,000 times less women and enjoy an almost non-existent risk.

2. For women, transmission rates are higher, about double. So you can cut the numbers in half for women.

3. Receptive anal sex is very risky. Chances to get HIV after being fucked in the ass by a man with AIDS is 1 in 200, which is still less than sharing needles, I guess, but a pretty good way to get AIDS. Simply find an infected partner and let him rail you in the ass a couple hundred times and you're pozzed. Double the fun if you share needles at the same time.

4. Let's put this in perspective. Say a man has 100 random one night stands during his lifetime and never uses protection. His chances are 1 in 110,000. His chance to be murdered in Iowa is 1 in 833, car accident 1 in 85, and by falling 1 in 143. This relatively promiscuous man shouldn't really even have AIDs death risk on his radar.

Extra special gold star to anyone who can accurately answer this question:

"If a white male in Iowa takes an AIDS test and it show a positive result, what is the probability that he actually has AIDS? Current tests give false positives 0.0004 to 0.0007% of the time. 80% of AIDS victims in Iowa are male and there are about 1365 people in Iowa with AIDS/HIV right now. Of those AIDS victims, about 996 are black, 399 are hispanic, and 66 are white."

Infection rates for chlamydia, gonorrhea and syphilis are all low as well. Estimated risk of infection is 1 in 2,500 (0.04%). All are curable and non-fatal.

Pregnancy risk is about 2-10%.

Infection rates for Iowa:
Chlamydia: male 1/1,900; female 1/460
Gonorrhea: male 1/3,900; female 1/2,600
Syphilis: male 1/33,000; female, 1/500,000

Men with any STD in Iowa: 1 in 1,235 -- 0.08%
Women with any STD in Iowa: 1 in 391 -- 0.26%

Transmission rates are 20% for men and 50% for females for gonorrhea. If we assume 20% and 50% for all three, total risk to contract any STD from random sex is:

Men 1 in 2,470 (0.04%)
Women 1 in 1,955 (0.05%)

Every 5 miles you drive is as likely to kill you as unprotected sex with a stranger, and each commercial plane flight is over 3 times more likely to kill you. I think it's unfortunate that sex has become something so strongly associated with disease and fear.

"My entire adolescence and adult life – as well as the lives of many of my peers – has been overshadowed by the belief in a deadly, sexually transmittable pathogen and the attendant fear of intimacy and lack of trust that belief engenders." --Rebecca V. Culshaw, AIDS researcher.

Spontaneous Remission

on Tuesday, March 29, 2011

The following question was asked of the Harvard Medical School students and staff:

“If a test to detect a disease whose prevalence is one in a thousand has a false positive rate of 5% (95% accurate), what is the chance that a person with a positive result actually has the disease?”

Put another way:
1/1,000 people have cancer. A 95% accurate test for cancer is given to a random person. What is the chance he has cancer if the test says he cancer?

Only 18% of them were able to answer correctly.

About two percent.
Assume that the test is performed on everyone regardless of symptoms of the disease. Out of every thousand people who receive the test, one has the disease and 999 do not. One out of every thousand tests are true positives. The remaining 999 should be negative results, but the 5% false positive rate means that 50 (49.95) of these people will receive false positives. Out of our 1000 tests, 51 return positive results, but only one of these actually has the disease, so the chance that a positive test identified someone who actually has the disease is 1/51 or about 2%.”

This result has interesting implications. Most of us are intuitively unable to assess probability correctly, and require training to understand it at all; and most highly intelligent people with relevant training in medicine still fail to understand probability. Importantly, some people diagnosed with diseases or conditions are likely to be treated unnecessarily, sometimes with risky treatments.

In deciding to treat, a doctor should first weight the risks of treatment against the probability that the patient actually has the disease. If the doctor is unable to accurately assess the accuracy of the tests, how can he make a reasonable decision about which treatment is best?

Divine Intervention Spontaneous Remission is an ancient Healing modality dating back 1,000 years to the Mayan civilization

This gives us a reasonable explanation for spontaneous remission-- the patients recovering may not have had the disease in the first place!

80% of Harvard Medical School doesn't understand what test results mean! Jesus! What the fuck!?

Flipping Coins

on Monday, March 28, 2011

Imagine we're flipping coins and I want to gamble. One of us will pick "heads-tails-heads" and the other gets "heads-tails-tails." Whichever three flip pattern hits first wins the bet. Which one do you want?

a. Doesn't matter
b. HTH
c. HTT

Almost everyone, including top mathematicians, will say it doesn't matter; flipping coins is 50/50, either pattern can hit first.

The answer is C

Heads-tails-heads will average 10 flips to hit, and heads-tails-tails will average 8 flips to hit.

This is important. It shows us how incompetent we are when it comes to logically thinking about probability.

Unfortunately, probability assessment is important in modern life, where we live among billions and have instant communication globally. Rare things happen, and we all hear about them, but don't have any idea why it seems like planes are falling out of the sky every day but it's still safe to fly.

It becomes even more important in courtrooms.

In a famous case in the UK, a well regarded pediatrician told a jury that the chances of having SIDS twice in one family was 1 in 73 million. He arrived at this figure by finding that the chance of SIDS occurring was 1 in 8,500 -- so he simply multiplied 8,500 by 8,500 and arrived at 1 in 73 million.

His calculations are completely wrong, yet went unchallenged by the defense. His calculation is only part of the story. We have no idea was the real probability is, because we don't know that SIDS is randomly distributed, how reliable the diagnosis is, or if there genetic factors, etc.

Thinking that the chance is 1 in 73 million is exactly the same as believing that a 99% accurate cancer test coming up positive means the patient has a 1 in 100 chance to be cancer free. As per my last two notes, we know this is not the case. We need to know how many people actually have cancer, and compare it to our personal test results.

Similar misunderstandings lead the way for the popularity of lotteries and casino gambling. We're all just idiots when it comes to big numbers and happenstance.

My First Album Is Out

on Sunday, March 27, 2011

1 -
The first random Wikipedia article you get is the name of your band.

2 -
The last four or five words of the very last quote of the page is the title of your first album.

3 -
Third picture, no matter what it is, will be your album cover.

4 - Use Photoshop or similar to put it all together.

I think this must be how bands are actually named and album art concocted.

Genetically Modified Food

on Saturday, March 26, 2011

"When a 1999 cyclone in India left millions of people in danger of starvation, some activists denounced relief societies for distributing a nutritious grain meal because it contained genetically modified varieties of corn and soybeans (varieties that had been eaten without apparent harm in the United States).

These activists are also opposed to “golden rice,” a genetically modified variety that could prevent blindness in millions of children in the developing world and alleviate vitamin A deficiency in a quarter of a billion more.

Other activists have vandalized research facilities at which the safety of genetically modified foods is tested and new varieties are developed. For these people, even the possibility that such foods could be safe is unacceptable.

A 2001 report by the European Union reviewed eighty-one research projects conducted over fifteen years and failed to find any new risks to human health or to the environment posed by genetically modified crops. This is no surprise to a biologist. Genetically modified foods are no more dangerous than “natural” foods because they are not fundamentally different from natural foods.

Virtually every animal and vegetable sold in a health-food store has been “genetically modified” for millennia by selective breeding and hybridization. The wild ancestor of carrots was a thin, bitter white root; the ancestor of corn had an inch-long, easily shattered cob with a few small, rock-hard kernels.

Plants are Darwinian creatures with no particular desire to be eaten, so they did not go out of their way to be tasty, healthy, or easy for us to grow and harvest. On the contrary: they did go out of their way to deter us from eating them, by evolving irritants, toxins, and bitter-tasting compounds. So there is nothing especially safe about natural foods. The “natural” method of selective breeding for pest resistance simply increases the concentration of the plant's own poisons; one variety of natural potato had to be withdrawn from the market because it proved to be toxic to people.

Similarly, natural flavors — defined by one food scientist as “a flavor that's been derived with an out-of date technology” — are often chemically indistinguishable from their artificial counterparts, and when they are distinguishable, sometimes the natural flavor is the more dangerous one. When “natural” almond flavor, benzaldehyde, is derived from peach pits, it is accompanied by traces of cyanide; when it is synthesized as an “artificial flavor,” it is not.

A blanket fear of all artificial and genetically modified foods is patently irrational on health grounds, and it could make food more expensive and hence less available to the poor. Where do these specious fears come from?

Partly they arise from the carcinogen-du-jour school of journalism that uncritically reports any study howing elevated cancer rates in rats fed megadoses of chemicals. But partly they come from an intuition about living things that was first identified by the anthropologist James George Frazer in 1890 and has recently been studied in the lab by Paul Rozin, Susan Gelman, Frank Keil, Scott Atran, and other cognitive scientists.

People's intuitive biology begins with the concept of an invisible essence residing in living things, which gives them their form and powers. These essentialist beliefs emerge early in childhood, and in traditional cultures they dominate reasoning about plants and animals.

Often the intuitions serve people well. They allow preschoolers to deduce that a raccoon that looks like a skunk will have raccoon babies, that a seed taken from an apple and planted with flowers in a pot will produce an apple tree, and that an animal's behavior depends on its innards, not on its appearance.

They allow traditional peoples to deduce that different-looking creatures (such as a caterpillar and a butterfly) can belong to the same kind, and they impel them to extract juices and powders from living things and try them as medicines, poisons, and food supplements. They can prevent people from sickening themselves by eating things that have been in contact with infectious substances such as feces, sick people, and rotting meat.

But intuitive essentialism can also lead people into error. Children falsely believe that a child of English-speaking parents will speak English even if brought up in a French-speaking family, and that boys will have short hair and girls will wear dresses even if they are brought up with no other member of their sex from which they can learn those habits.

Traditional peoples believe in sympathetic magic, otherwise known as voodoo. They think similar-looking objects have similar powers, so that a ground-up rhinoceros horn is a cure for erectile dysfunction. And they think that animal parts can transmit their powers to anything they mingle with, so that eating or wearing a part of a fierce animal will make one fierce.

Educated Westerners should not feel too smug. Rozin has shown that we have voodoolike intuitions ourselves. Most Americans won't touch a sterilized cockroach, or even a plastic one, and won't drink juice that the roach has touched for even a fraction of a second. And even Ivy League students believe that you are what you eat. They judge that a tribe that hunts turtles for their meat and wild boar for their bristles will be good swimmers, and that a tribe that hunts turtles for their shells and wild boar for their meat will be tough fighters.

In his history of biology, Ernst Mayr showed that many biologists originally rejected the theory of natural selection because of their belief that a species was a pure type defined by an essence. They could not wrap their minds around the concept that species are populations of variable individuals and that one can blend into another over evolutionary time.

In this context, the fear of genetically modified foods no longer seems so strange: it is simply the standard human intuition that every living thing has an essence. Natural foods are thought to have the pure essence of the plant or animal and to carry with them the rejuvenating powers of the pastoral environment in which they grew. Genetically modified foods, or foods containing artificial additives, are thought of as being deliberately laced with a contaminant tainted by its origins in an acrid laboratory or factory. Arguments that invoke genetics, biochemistry, evolution, and risk analysis are likely to fall on deaf ears when pitted against this deep-rooted way of thinking.

Essentialist intuitions are not the only reason that perceptions of danger can be off the mark. Risk analysts have discovered to their bemusement that people's fears are often way out of line with objective hazards. Many people avoid flying, though car travel is eleven times more dangerous. They fear getting eaten by a shark, though they are four hundred times more likely to drown in their bathtub. They clamor for expensive measures to get chloroform and trichloroethylene out of drinking water, though they are hundreds of times more likely to get cancer from a daily peanut butter sandwich (since peanuts can carry a highly carcinogenic mold).

Some of these risks may be misestimated because they tap into our innate fears of heights, confinement, predation, and poisoning. But even when people are presented with objective information about danger, they may not appreciate it because of the way the mind assesses probabilities.

A statement like “The chance of dying of botulism poisoning in a given year is .000001” is virtually incomprehensible. For one thing, magnitudes with lots of zeroes at the beginning or end are beyond the ken of our number sense. The psychologist Paul Slovic and his colleagues found that people are unmoved by a lecture on the hazards of not wearing a seat belt which mentions that a fatal collision occurs once in every 3.5 million person-trips. But they say they will buckle up when the odds are recalculated to show that their lifetime chance of dying in a collision is one percent."

Quoted from The Blank Slate, by Steven Pinker

When Does Life Begin?

on Friday, March 25, 2011

"The closest event we can find to a thunderclap marking the entry of a soul into the world is the moment of conception. At that instant a new human genome is determined, and we have an entity destined to develop into a unique individual.
Human embryo, at the 16-cell stage, on the tip of a pin.

The Catholic Church and certain other Christian denominations designate conception as the moment of ensoulment and the beginning of life (which, of course, makes abortion a form of murder). But just as a microscope reveals that a straight edge is really ragged, research on human reproduction shows that the “moment of conception” is not a moment at all.
A baby 6 days old implanting in womb

Sometimes several sperm penetrate the outer membrane of the egg, and it takes time for the egg to eject the extra chromosomes. What and where is the soul during this interval? Even when a single sperm enters, its genes remain separate from those of the egg for a day or more, and it takes yet another day or so for the newly merged genome to control the cell. So the “moment” of conception is in fact a span of twenty-four to forty-eight hours.
2500x magnification of sperm and egg

Nor is the conceptus destined to become a baby. Between two-thirds and three-quarters of them never implant in the uterus and are spontaneously aborted, some because they are genetically defective, others for no discernible reason. Still, one might say that at whatever point during this interlude the new genome is formed, the specification of a unique new person has come into existence. The soul, by this reasoning, may be identified with the genome. But during the next few days, as the embryo's cells begin to divide, they can split into several embryos, which develop into identical twins, triplets, and so on.

Do identical twins share a soul? Did the Dionne quintuplets make do with one fifth of a soul each? If not, where did the four extra souls come from? Indeed, every cell in the growing embryo is capable, with the right manipulations, of becoming a new embryo that can grow into a child. Does a multicell embryo consist of one soul per cell, and if so, where do the other souls go when the cells lose that ability? And not only can one embryo become two people, but two embryos can become one person.

Occasionally two fertilized eggs, which ordinarily would go on to become fraternal twins, merge into a single embryo that develops into a person who is a genetic chimera: some of her cells have one genome, others have another genome. Does her body house two souls? For that matter, if human cloning ever became possible (and there appears to be no technical obstacle), every cell in a person's body would have the special ability that is supposedly unique to a conceptus, namely developing into a human being.

True, the genes in a cheek cell can become a person only with unnatural intervention, but that is just as true for an egg that is fertilized in vitro. Yet no one would deny that children conceived by IVF have souls.

The idea that ensoulment takes place at conception is not only hard to reconcile with biology but does not have the moral superiority credited to it. It implies that we should prosecute users of intrauterine contraceptive devices and the “morning-after pill” for murder, because they prevent the conceptus from implanting.

It implies that we should divert medical research from curing cancer and heart disease to preventing the spontaneous miscarriages of vast numbers of microscopic conceptuses. It impels us to find surrogate mothers for the large number of embryos left over from IVF that are currently sitting in fertility clinic freezers.

It would outlaw research on conception and early embryonic development that promises to reduce infertility, birth defects, and pediatric cancer, and research on stem cells that could lead to treatments for Alzheimer's disease, Parkinson's disease, diabetes, and spinal-cord injuries.

And it flouts the key moral intuition that other people are worthy of moral consideration because of their feelings — their ability to love, think, plan, enjoy, and suffer — all of which depend on a functioning nervous system. The belief that bodies are invested with souls is not just a product of religious doctrine but embedded in people's psychology and likely to emerge whenever they have not digested the findings of biology.

The discovery that what we call “the person” emerges piecemeal from a gradually developing brain forces us to reframe problems in bioethics. It would have been convenient if biologists had discovered a point at which the brain is fully assembled and is plugged in and turned on for the first time, but that is not how brains work.

The nervous system emerges in the embryo as a simple tube and differentiates into a brain and spinal cord. The brain begins to function in the fetus, but it continues to wire itself well into childhood and even adolescence. The demand by both religious and secular ethicists that we identify the “criteria for personhood” assumes that a dividing line in brain development can be found. But any claim that such a line has been sighted leads to moral absurdities.

If we set the boundary for personhood at birth, we should be prepared to allow an abortion minutes before birth, despite the lack of any significant difference between a late-term fetus and a neonate. It seems more reasonable to draw the line at viability. But viability is a continuum that depends on the state of current biomedical technology and on the risks of impairment that parents are willing to tolerate in their child. And it invites the obvious rejoinder: if it is all right to abort a twenty-four-week fetus, then why not the barely distinguishable fetus of twenty-four weeks plus one day?

And if that is permissible, why not a fetus of twenty-four weeks plus two days, or three days, and so on until birth? On the other hand, if it is impermissible to abort a fetus the day before its birth, then what about two days before, and three days, and so on, all the way back to conception?

We face the same problem in reverse when considering euthanasia and living wills at the end of life. Most people do not depart this world in a puff of smoke but suffer a gradual and uneven breakdown of the various parts of the brain and body. Many kinds and degrees of existence lie between the living and the dead, and that will become even more true as medical technology improves.

We face the problem again in grappling with demands for animal rights. Activists who grant the right to life to any sentient being must conclude that a hamburger eater is a party to murder and that a rodent exterminator is a perpetrator of mass murder. They must outlaw medical research that would sacrifice a few mice but save a million children from painful deaths (since no one would agree to drafting a few human beings for such experiments, and on this view mice have the rights we ordinarily grant to people). On the other hand, an opponent of animal rights who maintains that personhood comes from being a member of Homo sapiens is just a species bigot, no more
thoughtful than the race bigots who value the lives of whites more than blacks.

After all, other mammals fight to stay alive, appear to experience pleasure, and undergo pain, fear, and stress when their well-being is compromised. The great apes also share our higher pleasures of curiosity and love of kin, and our deeper aches of boredom, loneliness, and grief. Why should those interests be respected for our species but not for others?

Some moral philosophers try to thread a boundary across this treacherous landscape by equating personhood with cognitive traits that humans happen to possess. These include an ability to reflect upon oneself as a continuous locus of consciousness, to form and savor plans for the future, to dread death, and to express a choice not to die.

At first glance the boundary is appealing because it puts humans on one side and animals and conceptuses on the other. But it also implies that nothing is wrong with killing unwanted newborns, the senile, and the mentally handicapped, who lack the qualifying traits. Almost no one is willing to accept a criterion with those implications.

There is no solution to these dilemmas, because they arise out of a fundamental incommensurability: between our intuitive psychology, with its all-or-none concept of a person or soul, and the brute facts of biology, which tell us that the human brain evolved gradually, develops gradually, and can die gradually. And that means that moral conundrums such as abortion, euthanasia, and animal rights will never be resolved in a decisive and intuitively satisfying way.

This does not mean that no policy is defensible and that the whole matter should be left to personal taste, political power, or religious dogma. As the bioethicist Ronald Green has pointed out, it just means we have to reconceptualize the problem: from finding a boundary in nature to choosing a boundary that best trades off the conflicting goods and evils for each policy dilemma.

We should make decisions in each case that can be practically implemented, that maximize happiness, and that minimize current and future suffering. Many of our current policies
are already compromises of this sort: research on animals is permitted but regulated; a late-term fetus is not awarded full legal status as a person but may not be aborted unless it is necessary to protect the mother's life or health.

Green notes that the shift from finding boundaries to choosing boundaries is a conceptual revolution of Copernican proportions. But the old conceptualization, which amounts to trying to pinpoint when the ghost enters the machine, is scientifically untenable and has no business guiding policy in the twenty-first century. The traditional argument against pragmatic, case-by-case decisions is that they lead to slippery slopes. If we allow abortion, we will soon allow infanticide; if we permit research on stem cells, we will bring on a Brave New World of government-engineered humans. But here, I think, the nature of human cognition can get us out of the dilemma rather than pushing us into one. A slippery slope assumes that conceptual categories must have crisp boundaries that allow in-or-out decisions, or else anything goes. But that is not how human concepts work.

As we have seen, many everyday concepts have fuzzy boundaries, and the mind distinguishes between a fuzzy boundary and no boundary at all.  'Adult' and 'child' are fuzzy categories, which is why we could raise the drinking age to twenty-one or lower the voting age to eighteen. But that did not put us on a slippery slope in which we eventually raised the drinking age to fifty or lowered the voting age to five. Those policies really would violate our concepts of 'child' and 'adult,' fuzzy though their boundaries may be. In the same way, we can bring our concepts of life and
mind into register with biological reality without necessarily slipping down a slope."

-Steven Pinker, The Blank Slate