Larry MacPhee: Biology

REvolutionary Thinking: Social Darwinism

It has been argued that assigning evolutionary-genetic explanations to our bad behavior is to excuse it with a "get out of jail free" card; a modern day version of "the devil made me do it." This is the assertion of Sharon Begley in a recent Newsweek article that assails Evolutionary Psychology. She correctly addresses some of the weaker theories and dutifully knocks them down, but then goes on to throw out the entire approach, claiming that Darwin just has nothing to say on the subject. But Evolutionary Psychology remains valid and valuable as a framework for making predictions which can be tested scientifically by experiment and observation. It's a positive step that these predictions are now being tested and, in some cases, challenged. That's how science works. When we don't find what we predict, we then go back and look at our assumptions, as is done by the researchers she references. We don't throw out the entire field as a misguided, dated, sexist approach to explaining human behavior. That says more about the agenda of the author. But in addition to, apparently, not understanding the scientific method, Begley also misses an important point about humans. While there can be no doubt that our genes sometimes drive us to do things that our conscience tells us not to, humans have a large brain and a long life. We are more capable of learning and are more influenced by our upbringing and experiences than perhaps any other animal. The phenotype, or appearance (including behavior), of an organism is a combination of genes, environment, and the interaction of the two. As such, humans are more capable of resisting their biological destiny than any species that lacks long term memory, self awareness, empathy, a conscience, and guilt. It may be that our noblest and most selfless acts occur just because of this non-genetic influence. And if anything separates us from the animals, this is it.

REvolutionary Thinking: The origin of life

People often wonder if there is life out there in the universe. While this is purely a speculative exercise, what can we infer? Let's start with the assumption that life arose on Earth by a natural process and that no miracle happened because, if one did, we are wasting our time talking science. If it happened here by natural means, then there's no reason it couldn't happen elsewhere. How likely that is depends on what the process is, and on the number of planets in the universe where conditions are amenable. Here's what we know. The Earth formed about 4.5 billion years ago, and life was detectable as early as 3.9 billion years ago, so life appeared relatively quickly after conditions allowed. The early Earth was very different from the present one. There were periods of heavy asteroid bombardment that kept the surface molten and made life impossible for the first few hundred million years, but eventually the crust cooled and became a "primordial soup" of chemicals. There was little oxygen, but water, methane, ammonia and hydrogen were abundant. There was an atmosphere, lots of lightning, more intense radiation, strong tidal forces from a closer moon, and probably freeze thaw cycles at least in some places. Almost certainly, there was heterogeneity. When scientists recreate those conditions in the lab, amino acids are produced over a short period of time. Amino acids are the building blocks of proteins, and that's what living things are made of, so we're on the right track. But how organic molecules assembled into more complex forms and gained the ability to self-replicate is still a hot topic in biology and there is not a single accepted theory that explains it all. However, once molecules gained the ability to self-replicate, then Darwinian selection acts to favor the ones that do it most effectively and major leaps forward would naturally occur. At what point these molecules become "living" depends on your definiton of life, but we are well on our way towards it. So yes there is probably life out there in the universe, and possibly even elsewhere in our solar system on the moons of the gas giants, under the ice around geothermal vents. But intelligent life? Life capable of communicating with us? Intelligence advanced enough to cross the void of interstellar space and visit us? Those odds on those bets are increasingly slim. Let's remember that for the next two billion years or so after life first appeared, there was nothing more complex than a single celled bacterium.

REvolutionary Thinking: Endosymbiosis

Some people get the creeps when they think about organisms that live on us or in us. But what's really incredible is that there are organisms in our cells that long ago became a part of us! Inside the cells of virtually all complex organisms are little structures called mitochondria, commonly referred to as the "powerhouse" of the cell. Plants have additional structures called chloroplasts, which are more like nature's version of the solar panel. Mitochondria and chloroplasts, two of the most important cellular organelles, have an intriguing origin. They resemble in many ways the more primitive single-celled bacteria. They are double membraned structures which contain their own unique DNA; distinct from the DNA of the nucleus. The outer membranes of the mitochondrion and chloroplast resemble those found in eukaryotic or complex cells, while the inner membranes resemble those found in prokaryotic or primitive bacterial cells. The DNA of the mitochondrion forms a ringed chromosome characteristic of bacterial DNA. It is now generally accepted that these organelles, vital to the survival of the cells that house them, originated from the incomplete consumption or invasion of single celled creatures millenia ago. These single celled organisms were adopted by the cell and became an integral part of the multicellular organism, reproducing themselves when the greater cell divides. The theory of Endosymbiosis, first ridiculed but now widely accepted, proposes that the complex eurkaryotic cells found in multicellular organisms arose from symbiotic associations of simpler prokaryotic organisms. Without the energy producing mitochondria and the photosynthetic chloroplasts none of the eukaryotes, the "higher" animals, plants, and fungi, would exist. We owe it all to the lowly bacteria that live within us and nourish us.

REvolutionary Thinking: Restoring a Fishery

An interesting thing has happened in some of our better managed fisheries. While the fish remain numerous and the population healthy, year after year the average fish length has been decreasing! Modern technology helps us to be very good at catching fish so it would be safe to assume that fish are simply being caught before they reach a large size. But something more subtle is happening. Regulators, with good intentions, have imposed minimum size limits that protect fish from capture until they have a chance to reproduce, thereby allowing the fishery to be sustainable. One way to do this is to require that the holes in the nets fishermen use are large enough that small fish can escape. The minimum size limit is set somewhere beyond the size of first reproduction. But there is an unintended consequence; it creates selective pressure that favors reproduction at a smaller size and earlier age. This has caused the stock to evolve in a way that, while it continues to thrive, makes it less desirable to us commercially. A recent study of the silverside showed that not only does this happen but it can be reversed. The key is to modify the regulation so that fish beyond a maximum size cannot be taken. This will keep the largest fish alive and reproducing most successfully, driving selection back in the opposite direction. But how to not catch the big fish may be a bigger practical challenge, since fish are generally dead when they come up in the nets and we can't just throw the big ones back.

REvolutionary Thinking: Living at Elevation

Scientists have been studying human adaptations to living at high elevation. Both the native Tibetans and the Peruvians are far better at it than someone who's ancestors are from lower elevations. But more interesting is the finding that the Tibetans are significantly better at it than the Peruvians. Why? They've been doing it for a much longer period of time, and have accumulated a bigger bag of evolutionary tricks. Remember that human population originated in Africa, spread out across Europe and Asia, and only "recently" (between 15 and 20 thousand years ago) migrated across the land bridge connecting Asia to Alaska, ultimately reaching South America. So compared to the people living in the Andes, the people of the Himalayas had a really big head start.

REvolutionary Thinking: A Cure for the Common Cold

The common cold has been tough to beat. Its trick is that it keeps mutating, changing its exterior appearance so that our immune system fails to recognize it from one time to the next. But it may be that the long sought cure for the common cold is not far off. Scientists have been busily sequencing the DNA of cold viruses and they have found that while the parts of the genome that code for its superficial appearance evolve rapidly and allow the virus to hide from our immune system, there is a core sequence that is remarkably conservative. Targeting medicines at this critical part of the virus will be more effective, since it cannot change these sequences and continue to replicate. So the virus can camouflage itself any way it wants but we'll be able to spot it by something more akin to a heat signature. If it can't hide, our immune system will take care of the rest.

REvolutionary Thinking: Survival of the Cutest and the Spiciest

Normally, when we think of survival of the fittest, we imagine that the strongest or the fastest or the toughest will be the most successful and leave behind the most progeny. But remember, one must both survive and reproduce and ensure the survival of one's children in order to successfully pass along one's genes. It's no use being tough if you never get to mate, and it's no use producing a lot of babies that all get eaten. There are an amazing variety of strategies for success. One particularly odd way of achieving high "fitness" is to hitch one's cart to another successful species. Think of the guinea pig. This small furry creature which originated in the Andes mountains of South America has become a favorite small pet because it is gentle, cute and makes sounds that are pleasing to people. On its own, the guinea pig would not be nearly as numerous as it is today, but as long as humans enjoy keeping them as pets, the humble guinea pig has a fabulously successful survival strategy; be cute. Chili peppers have a similar strategy. Many plants produce nasty substances to make them less palatable to predators. Originally, the capsaicin (the spicy stuff) in chili oils was designed to discourage grazing mammals from eating the fruits of the chili plant. But humans discovered that, in small doses, adding spices to food makes it more tasty. The chili plant is now grown all over the world just because people like to eat it. So humans carry a whole collection of species along with them. For a while, horses had it really good because they were so useful to humans, but their luck has turned. And it's not all positive. Rats, cockroaches and mosquitoes are also far better off because of humans. We have brought them with us to the the four corners of the earth.

REvolutionary Thinking: When Cheaters Prosper

Why are we so unsuccessful at eradicating diseases that we can immunize against? The behavior of groups is an interesting application of game theory. There are certain situations where, if everyone makes a small sacrifice, everyone wins big. But getting everyone to play along is hard. The temptation of course, is to forego the sacrifice but collect the rewards. This can work for a while but if too many people do it or if you get caught the game is up. Take "herd immunity" as an example. If we could vaccinate everyone against measles, we could eliminate the disease from the face of the earth. There is a small risk of harm from a measles vaccination and there is a great risk of harm if one contracts the measles. Therefore, if most people get vaccinated, there is no penalty for failing to get vaccinated and there may even be a small benefit. However, if too many people start cheating, then at some point the risk of catching the measles rises above the risk associated with vaccination. This little lesson should remind us of an important point. Individuals don't do things for the common good; they do them for their own good. Natural selection works on the individual, not the group. Those who best take care of themselves and their close relatives pass along the most genes. Selflessness may be noble, but it's not a winning strategy. When you hear the phrase "for the good of the species," think again. While the species may benefit, the action would not occur if it didn't also benefit the individual.

REvolutionary Thinking: Racism

Why are humans so nasty to people who are different, and why are we so good at spotting people who aren't like us? A lot of it has to do with our evolutionary history as a species. Humans spread out of Africa in small bands of closely related individuals. They hunted and gathered and gradually settled into an agricultural way of life. At this point in our history, it was highly adaptive to be afraid of strangers because they were potential competitors. Strangers might kill you, enslave you, rape you or take your possessions if they had the ability to do so, and encounters with others were likely met with great caution. The more different these others were from you, either in looks, beliefs, language, or customs, the less likely they shared your genes. Meanwhile, your tribe was comprised of your close relatives and descendants. As you spread your genes, you spread your looks, your beliefs, your customs, your language, so meeting people like yourself was less of a threat. This also explains why intermarriage with nearby clans made sense. The more you mixed your genes with your neighbors, the more you and they would be assured of peaceful relations and the preservation of your genetic legacy. Eventually these loose organizations of like peoples formed our modern nation states as a way to protect themselves, and conflicts continue to arise where different groups clash. While we have less to fear from those who are different from us in the modern world, it still explains the instinctive negative reactions people have toward immigrants and those who don't speak our language or share our faith or our cultural practices.

REvolutionary Thinking: Living in Space

Astronauts who spend even short periods of time living in space come home with reduced bone density and diminished musculature. The Americans and the Russians have wasted decades and millions of dollars studying the negative effects of low gravity on astronauts and developing remedies to treat them. Why is this a completely wrong-headed approach? Would you push an astronaut out an airlock without a spacesuit and expect her to live? Of course not. Because humans don't adapt to extreme environments. Humans adapt the environment to meet their needs. We are fabulously successful as a species because we use technology to change the rules. Neil Armstrong is not evolutionarily distinct from a caveman, but his technology is far superior. A walking human is among the least efficient locomotors, but a human on a bicycle is among the most efficient. We don't try to breathe the dissolved O2 from water or extract it from the thin air of Mount Everest. We bring bottled air with us. In airplanes we pressurize the cabin to 1 atmosphere. We have not developed a greater tolerance for cold by evolving fur; instead we wear clothing and live in heated shelters. So if we don't try to live without air or heat or standard atmospheric pressure, why then, in space, should we try to live without gravity for more than brief periods of time? Sure we might enjoy brief forays in zero g the way we enjoy a dip in the pool. But we won't live there. Instead, we will need to create artificial gravity by spinning our ships to produce centripetal force. It will be expensive and technically difficult, but that's what it's going to take.

REvolutionary Thinking: Turning up the heat on cancer

Radiation and chemotherapy are the most common of the orthodox cancer treatments. They shrink tumors by scrambling the DNA of dividing cells, and cancer cells are among the most rapidly dividing. Unfortunately, the treatment can be as bad as the disease; radiation and chemo are also tough on rapidly dividing normal cells such as those found in the bone marrow, so they wipe out your immune system. Even if you survive the cancer, you are left with a severely compromised immune system and are vulnerable to all sorts of normally not too dangerous infections. But dating back to the 19th century, it has been observed that sometimes people who develop a high fever see their cancers remiss. Could it be that a coincidental infection jump starts the immune system into hunting for abnormal cells, which knocks out the cancer too? This is a very promising find. If we could artificially induce fever by introducing a benign foreign agent that triggers the full blown immune response, our own bodies might be capable of identifying and destroying abnormal cancerous cells. Maybe we could even plant these triggers in the cancerous tumors to help the immune system zone in on the problem.

REvolutionary Thinking: Problems with Teens

It has never been harder to be a parent or a teen. For purely biological reasons, parent-child conflict during the teen years is increasing. In pioneer days, people got married and started their own families around the same time that they matured physically. But modern teens are victims of two forces that pull them in opposite directions. Improving nutrition has been causing teens to physically mature at earlier and earlier ages. It gives a whole new meaning to the term "developed nations." It is now common for girls to become reproductively mature before the age of 10. Earlier physical maturity means not just earlier interest in sexual activity but earlier challenges to parental authority. But emotional maturity, good judgment, and a complete education, so necessary in our complex modern world, are developing later because they are products of time and money rather than nutrition. Teens are chafing against parental rules and demanding independence at earlier ages than ever before, but they remain financially dependent upon their parents for longer than ever before. Teens live in a world relatively free of natural dangers, and with few real responsibilities, yet they crave independence, adventure and excitement. They complain of boredom but lack common sense and good judgment. They live in a consumer culture and have no money. As a result, they often create their own trouble for stimulation. And they start earlier every year. The solution to this problem is even more radical, but I'll save that for later.

REvolutionary Thinking: Lactose Intolerance

Lactose is the sugar found in milk and other dairy products. Humans, being mammals, have evolved to drink milk from their moms. It's natural. It's good for you. It gives you an immune system boost. But many of us wean by the age of 2 and almost all of us do by age 5. During most of our evolutionary history, that was the last time we saw milk, so the genes that code for the production of lactase, the enzyme that breaks down milk sugars, are designed to shut down permanently once milk is no longer a major part of our diet. Without lactase, consuming dairy products leads to unpleasant abdominal cramping because we can't digest the milk sugars. In asian and african cultures, where commercially available dairy products are not common, this continues to be the case. But in cultures where humans have a long tradition of raising animals for milking, there is a prevalent mutation on chromosome 2 which prevents the shutoff of the genes that code for lactase. Humans who have evolved in pastoral settings are much more likely to have this mutation, which confers the very useful ability to digest dairy products.

REvolutionary Thinking: Political Systems

Which socio-political system works most like Darwinian evolution? Not democracy. Not communism or totalitarianism. It's the free market! A purely capitalist system allows the most nimble, the most clever, the most powerful, and the most ruthless to prosper. In a purely capitalist nation, there would be no entitlement programs like medicare and social security. The rich would have excellent healthcare and a comfortable retirement, and the poor would have none. There would be no corporate bailouts. If a company was struggling, it would be allowed to die or be absorbed by a stronger one. That's natural selection. Except for nepotism, it would be every man, woman and child for him/herself, and the only alliances would be ones of convenience. There would be lots of treachery but no ethical dilemmas. Laws would be made by the powerful to benefit themselves. The police would serve and protect those who paid them. Applying evolutionary principles to the way we choose to behave (Social Darwinism) is a scary concept. But if we're trying to understand why capitalism works so well, it's simple. It's survival of the fittest. Capitalism does not require that all men are created equal, nor that they have equal rights. Inequality isn't a problem in a capitalist system; it's the incentive. Want more than your neighbor has? Then beat him and collect your reward! And what country embodies this contradiction of ruthlessly selfish capitalism on the one hand with selfless Christianity and egalitarian democracy on the other? America. It's no wonder we're conflicted!

REvolutionary Thinking: Modern Ailments? Part I

Why is it that, in this age of incredible medical advances, people seem to develop illnesses that were unheard of in the past? Cancer, arthritis, heart disease and Alzheimer's seem to be running rampant. REvolutinary thinking may explain some of it. One argument is that, because we are all living longer, problems that appear later in life like heart attack and stroke, arthritis, cancer, and Alzheimer's, rarely manifested in the past because something else always got us first. More than a few people who would have died of infection or injury or in childbirth, or of plague, malaria, scarlet fever, or dysentery, are now living long enough to develop cardiovascular disease, arthritis and Alzheimer's. As the old saying goes, "If it ain't one thing, it's another!"

REvolutionary Thinking: Modern Ailments? Part II

Ok, so living longer might explain why certain health problems appear to be on the rise. But what about the diseases that affect children? Something else is going on there. One fascinating theory is that our environment has become too clean, and the result is a rise in autoimmune disorders. Our immune system is designed to attack foreign bodies that invade us. But in a world where our water contains no microbes, and our food is free of parasites, and our infections are eradicated with antibiotics, the immune system seems sometimes to find itself all dressed up with noplace to go. Without anything to attack, it turns on the body, or overreacts to things that really aren't much of a risk, like pollen or peanuts or your organs. A recent study showed that people living with multiple animals in the house have fewer pet allergies. In Mexico, people drink the water all the time, but Americans who drink it get gastrointestinal problems. Another study showed that respiratory problems and allergies are far worse among inner city residents. Less than 100 years ago, almost everyone lived on a farm in a dirty, biotic mess of manure and dander. Is it the urban smog, or do we all need to spend our formative years exposing ourselves to dirt, germs, and other unsanitary stuff in order to train our immune systems on what to attack?

REvolutionary Thinking: Hidden Causes of Disease

People used to think that stomach ulcers were caused by stress and diet. If you got ulcers, you had to change your lifestyle; no more stress and no more spicy foods. That's the way it was for years, and it was a life sentence. Even with those lifestyle changes, people could control ulcers but not eliminate them. Then it was discovered, to the disbelief of the medical establishment, that people who got ulcers had a particular bacterium in their gut, called Helicobacter pylori. If you had it, your risk of ulcers was far higher than if you didn't. With a short course of antibiotics, H. pylori can be eliminated and presto, no more ulcers. How many more lurking invisible microbes, either with us now or exposed to us in the past, could be the root cause of our ailments? What if you could get a vaccination against cancer? There is solid evidence that the presense of certain viruses can cause particular types of cancer. The most recent case, for which there is now a vaccination, is cervical cancer. If a girl is vaccinated against HPV (Human pappiloma virus) before she becomes sexually active and is exposed, she can ward off this cancer later in life. This vaccination is 100% effective against the strains of HPV that cause 70% of cervical cancers. Update: This work was just awarded a Nobel prize in 2008!

REvolutionary Thinking: Male Promiscuity

In the animal world, there are many different mating systems, but polygamy (one male mates with many females) is far more common than monogamy (one male, one female) or polyandry (one female, many males). Males of almost every species will attempt to mate just about whenever the opportunity arises. Females are, with rare exception, far more choosy. Why are males so promiscuous? The amount of energy it takes to produce a sperm cell is far less than that required to make an egg. If both sexes have a roughly equivalent amount of energy dedicated to reproduction, then it is the way that energy is apportioned that differs. Think of it this way. A male has 100 pennies (sperm) to gamble on 100 matings and a female has a dollar coin that she has to bet all at once on a single mate. This is further accentuated in birds and mammals, where fertilization is internal (and where the female is the incubator). And to protect her greater initial investment, the female is more committed to costly parental care. Does it start to seem a bit more obvious why women are the "rate limiting step" in reproduction? In a word, it's "anisogamy."

REvolutionary Thinking: Antibiotics

Back in the 1950s, it seemed there was nothing a shot of penicillin wouldn't cure. So why are our antibiotics less effective than they used to be? When we catch a cold, the doctor will typically start by prescribing a cough medicine and a decongestent to treat the symptoms, leaving the cold to run its course. If the symptoms last more than a week, then a secondary bacterial infection like Streptococcus may be involved, and the doctor will then prescribe antibiotics. Antibiotics are useless against viruses like the common cold but people demand them, invoking the "just in case it's bacterial" argument. So where's the harm? If they've got a virus, it will clear on its own and if it's a bacterium, they nip it in the bud, right? Well, partly. But what's good for the individual is bad for the group. The more we expose an antibiotic to the bacterial population at large, the sooner a resistant strain will arise by mutation and spread by natural selection. So it's important to use our antibiotic ace-in-the hole only when we really need it. And when we resort to antibiotics, we need to use overwhelming force. When people start to feel better, they sometimes prematurely stop taking the antibiotic. This kills the weakest of the bacterial strains in their body but leaves the more resistant strains alive to reproduce and spread. The best example of this is Tuberculosis, which we nearly eradicated. Resistant strains have evolved in the homeless population where follow up treatment is difficult, and these killer strains are now spreading through hospital wards like wildfire. So avoid antibiotics until you need them, and, when you get them be sure to finish the prescription! If you don't kill it, you make it stronger! Taking a class of antibiotics out of circulation for a while can also help by relaxing selection. If there is any cost to being resistant, the resistant strains will die out in favor of the wild type and the antibiotic will then have renewed effectiveness. And the desperation strategy is to create a cocktail of many different classes of antibiotics when we encounter the tough ones, in the hope that throwing everything against them will work. Let's hope so, because if it doesn't we're all in trouble.

REvolutionary Thinking: Diet and Exercise

Throughout most of our evolutionary history as humans, food has been scarce and it took a lot of tough physical work like farming, fishing or hunting to fill the larder. Let's look at fat. Fat is not intrinsically bad. We need fat for nervous system development and cell membranes, and we store excess energy in fat for times when food is scarce. When our ancestors came across fat, our caveman bodies told us to eat all we could get, because it might be a long time until the next big feast. But in our modern world, which has appeared in the evolutionary blink of an eye, we are still listening to our old programming. What has changed is that it's hard to refuse those once scarce fats and simple sugars that are present in every meal, and the portion sizes seem to keep getting bigger. Since food is never scarce, we never burn those stored fats. The world has never seen such nutritional abundace as we have in the west. And we have never been less active. Between our car culture, our desk jobs, and all the modern conveniences, most of us get winded going up a flight of stairs or walking the groceries from the car to the house. We are paying for our "prosperity" with a whole new collection of afflictions like obesity, heart disease, poor circulation, back pain, and diabetes. And for many of those who do exercise, it's costing a small fortune at the local fitness club! So act like a caveman for better health; exercise heavily, avoid excess, eat foods in season, eat foods produced locally, and embrace the slow food movement. There was a recent study that showed rats kept near starvation and exercised heavily lived somewhat longer than their well fed and poorly exercised brethren. But as the joke goes, "Would we actually live longer or would it just seem longer?"

REvolutionary Thinking: Longevity Part I

There are more people alive today than in all of human history combined but, even after factoring for that stunning statistic, there are proportionally more people living past 100 years than ever before. Why? In the longevity discussion, people used to wonder what would happen to quality of life if people lived longer. Would we just be decrepit for longer, or would we be able to push back the onset of the symptoms of aging, a term gerontologists refer to as "senescence"? The answer seems to be that, with some exceptions, 50 really is the new 40, 60 is the new 50 and so on! It also appears that once people pass 90, their odds of dying soon actually decline for a while. Think of it this way. If you have a serious defect, then it will catch up with you eventually. But if you don't, or if it is repaired medically, then you may only die when your parts finally wear out. That seems to be what's happening with the very old. Why we wear out at all is the discussion for Part II.

REvolutionary Thinking: Longevity Part II

Why do we age? It is often useful to look at exceptions to develop a better understanding of the rule. Humans reproduce over a fairly long period of time, care for their young for an equally long time, and senesce gradually. But what about salmon, or squid or mayflies? They save it all up, and reproduce over a very short period of time, and then immediately die. Why is that? The evolutionary theory of aging proposes that your body has to hold you together long enough to pass your genes along successfully. Once that job is finished you, the container of your genes, become irrelevant. So the genes that help to keep us alive long enough to reproduce are favored, but the genes that keep us alive beyond that point are not. And the genetic defects that harm us before we reproduce are selected against, while those that harm us later in life are not. For the big bang reproducers, death is more abrupt than for organisms that reproduce over a span of time, and for those that care for their young even past the age of last reproduction. So could we devise a strategy that would allow us to live longer? It's already been done, and that's the topic of Part III.

REvolutionary Thinking: Homosexuality

If homosexuality is heritible then how can it persist, since homosexuals should pass along fewer, if any, genes to the next generation? A new evolutionary theory of male homosexuality has been recently proposed that might just explain it biologically. What if there was a gene or genes that caused its owners to be more attracted to men that those who didn't carry it? Such a gene would be passed down to both male and female children. Men with this gene would be more attracted to men than the average man, but females with this gene would be more attracted to men than the average female. If that was the case, then although gay men would not pass along these genes, the female relatives of gay men would have more than the average number of children, and that would preserve this gene in the population. It's all hypothetical, of course, but it seems that someone checked the reproductive output of the female relatives of gay men, and this may indeed be the case. http://www.slate.com/id/2194232/

REvolutionary Thinking: Future Topics

• Childbirth, c-sections, and "advanced maternal age"
• The domestication of dogs: An alternative theory.
• The origin of life
• Mitochondria and chloroplasts: why do they have their own DNA?
• Orthodontia: Why are our mouths so crowded?
• Population size and rates of evolution.
• Why babies look like their fathers, and why people say they do.
• Why good looking young women attach themselves to older men.
• Why people in small towns are friendly.
• Longevity Part III: A recipe for living longer.
• A radical proposal for managing teens.
• The meaning of life?
• Is there life and/or intelligence out in the universe?
• Face recognition in babies, monkeys, and machines.
• Skin color and human origins
• Spotting a terrorist isn't so easy as racial profiling
• When inbreeding isn't a bad thing

Why Darwin is still controversial

As a scientist and biology teacher, I have often wondered why so many people are so bothered by evolution. The evidence is overwhelming and there is near unanimity among scientists. There is hardly another theory that is so elegant and so intuitive. But it's overly simplistic to imagine that so many people are tied to a literal translation of scripture. After all, most people don't go around taking an eye for an eye and a tooth for a tooth. If they did, we'd meet a lot more toothless and eyeless people. I used to think that it was a failure to grow up intellectually. Galileo was excommunicated for trying to displace the Earth from the center of the universe, so it must be hard for some to accept that man is just another inconsequential creature that came up from the primordial ooze. If we're not special, then maybe there's no purpose? Or is it just a lack of imagination? But how can we not see reflections of ourselves in the great apes? In their hands, their expressions, their physiology. Or is it that, because they look like men but act like animals, they embarrass us and make a mockery of our higher aspirations? But there are some very smart people from both ends of the political spectrum who take issue with the idea that our genes make us who we are. They just don't want it to be true. Because if genes, rather than our upbringing, control our actions then free will is in jeopardy. To the liberals, this is unsettling because it argues for capital punishment rather than incarceration and reform. To the conservatives, it is disturbing because it would be pointless to suppress homosexual tendencies. People have a visceral fear of atheism because they think religion keeps people in line. If we were all atheists and evolutionists, wouldn't there be anarchy? Darwin says look out for yourself and that undermines the very fabric of civilization. Why should I fight for my country? Why shouldn't I take the last portion of food, or steal from your shop, or park in the handicapped spot, or hit on your wife? So long as I don't get caught. Dangerous thoughts.

Type I and Type II

In statistics, there are two kinds of errors. You can detect a relationship that doesn't exist. This is sometimes referred to as a false positive or Type I error. Or you can fail to detect a relationship that does exist. This is referred to as a false negative or Type II error. Take for example, a pregnancy test. If you are not pregnant and the test says you are, that's Type I. If you are pregnant and the test says you're not, that's Type II. This is the trade-off between power and robustness. A test is powerful if it is very good at detecting relationships. Powerful tests sometimes give a false positive but rarely produce a false negative. Robust tests sometimes produce a false negative but rarely give a false positive. So if you want to be certain you are right, pick a robust test. If you want to be certain that you don't miss anything, pick a powerful test. What approach would you take if you were searching for cancer cures? How about looking for WMDs in Iraq? Or being pregnant? Or seeking the death penalty?

Precision and Accuracy

Although these two words may come up together in a thesaurus, they have quite different meanings. Precision is about repeatability whereas accuracy is about closeness to truth. If you are shooting at a target, and all of your shots are left and above center, you are precise but not accurate. A broken wristwatch is accurate twice a day.