Questions From My Wife X: Cravings, fish, and mosquito bites. What? Should there always be a common theme?

Hey all! Here's a longer post to get caught up. I may take a break from writing, but it doesn't mean the wife stops asking questions.

Why do women as a group seem to enjoy chocolate more than men do?

Chocolate is composed of as many as 800 different chemical components, ranging from the good (anti-oxidant catechins) to the not-as-good (the fatty acids in cocoa butter). Thus, it seems likely that one of these compunds may have some influence on the hormones that differentiate men from women. A researcher at the University of Wisconsin-Madison has shown that female rats have heightened cravings for chocolate over their male counterparts. Further studies have shown that eating chocolate activates the hypothalamus (area of the brain that regulates hunger) while inactivating the amygdala (involved in emotion and memory). This finding may reveal why eating chocolate is soothing when upset or depressed.

Another hypothesis is that cravings come and go with increases and decreases in hormones. Progesterone is thought to promote higher body fat levels. As progesterone concentration increases towards the beginnings of menstruation, this may also be why women crave chocolate. However, much of this may be cultural. One study has found that the difference in chocolate craving between women and men in Spain (90 to 78%) is much closer than in American women and men (91 to 59%).

Why do people crave particular foods when they are lacking in nutrients those foods are rich in? How does your body know that food items (on non-food items like dirt for those with pica) have those nutrients?

Pica is a weird disease. It comes from the Latin word for magpie (pica) as these birds are found to collect and eat practically anything. A Missouri psychiatric museum contains a collection of nails, spoons, and pins removed from a female asylum patient's stomach. While large consumption of objects can indicate a type of autism or mental retardation, the most recognized cravings are seen in pregnant women.

Studies from the late 1960s and early 70s revealed that 35-40% of pregnant women consistently craved clay, starch, and soil. Very little research has been done on this disease, but there seems to be a correlation with ingesting of "non-food" with some kind of nutritional deficiency. However, it seems easier to prove that this is the case than to prove why this is the case. Animals made to be deficient in certain essential minerals are more apt to selectively ingest items that contain high quantities of the missing supplement. In people, iron deficiency and anemia seem the most likely to cause pica. Low iron levels have been shown to cause pagophagia, increased ingestion of ice. When the anemia is treated, the craving for ice goes away.

Besides the nutritional explanation, there are psychological and cultural hypotheses as well. For instance, papers by Vermeer and Frate in the late 1970s claim that the practice of clay-eating "ingrained in southern black society" stems from its use in Africa to promote fertility and lactation.

So, as it seems common in these blog posts to say, no one knows the answer to your question and apparently no one is really trying to find it. How the body can "know" that it has certain deficiencies is still a mystery.

Do fish really not feel pain? I never quite bought that -- seems like almost any animal would be evolutionarily able to feel pain for self-preservation.

Ok, I've been typing too much, so this'll be a quick one. Recent studies seem to indicate that, yes, fish feel pain, but this doesn't make them less tasty. They respond negatively to injections of bee venom and vinegar over controls, and may actually be more sensitive than humans. And is this really surprising? Fish are vertebrates and have a relatively complex nervous system in the grand scheme of the phyla charts.

Why do some people get stung by mosquitos a lot while others don't? I definitely fall into the first category, and would love to know how to sic the bugs on other folks for a change.

Female mosquitoes are the biters, and primarily find their victims through a type of smell. It seems possible that different people would have less appealing smells to the buggers and not attract them. Some of the major chemicals that mosquitoes detect are carbon dioxide and lactic acid, key components of respiration. People who sweat less generally get bitten less. Repellents like DEET work by blocking the mosquito's ability to pick up these olfactory signals. So, besides holding your breath whenever outside, just remember to wear plenty of repellent and avoid other floral-based chemical attractants like perfume and sweet-smelling lotions.

Questions From My Wife VIII: Quick Hits #2

Here we go, a bunch of quick answers to get back in the swing of things... As always, these are real questions from my real wife. Do you think I would take the time to come up with random things like this?

Why were so many split level houses built? Were they cheaper than building a regular old two-story house? Did people just really enjoy having random stairs in the middle of their house?

The classic split-level house, in which one side of the home is one-story and situated at a height between the other 2-story side, came into favor in the 1960s. The reason for their construction doesn't seem to be a matter of cost, but rather a way to compress a lot of house into a relatively compact area. Also, it can be a way to use uneven land in a useful manner. During the baby boom 50s, suburb expansion pushed into areas not previously considered appropriate for a neighborhood. It's yet to be determined whether the awkward design or its use as the model for the Brady Bunch house ultimately drove this style out of favor.

What is the evolutionary purpose of allergies? Why do some people have them and other people don't?

Allergies are caused by a hyperstimulation of the immune system by some foreign entity. While it makes sense that the point of evolution would be to continually gain positive characteristics and remove negative ones, this isn't always the case. For instance, some negative mutations, like sickle-cell anemia, are kept in populations because they have other positive benefits. One possibility is that allergies are a side-effect of having a powerful immune system. While annoying, allergies are not generally lethal and would not be eliminated by evolutionary means. As for the second question, that's still a mystery. Scientists assume that genetics may have a role, but allergies are not consistently handed down to offspring. There are a few ideas for why allergies are becoming more common, such as the increased use of chemicals and antibiotics. Recent studies have suggested that as we remove more parasites and other small microbes from our systems, we may be losing subtle immunosuppressants that have previously repulsed allergic reactions. But, to tell you the truth, I'd prefer to get a little stuffed up in the spring than have a hookworm.

At what point in history did people start celebrating birthdays?

Many historians believe that the act of birthday celebration was spread by Roman soldiers practicing Mithraism, a pagan cult dealing in astrology. Not much is really known about how certain pagan holidays morphed into individualistic celebrations. However, in this time from the 1st-4th century, birthday parties became far more common throughout Asia and Europe.

Why does water taste extra cold if you have a peppermint in your mouth? Also, why does peppermint help settle your stomach?

The peppermint plant (above) is a sterile cross of spearmint and watermint, and is believed to have medicinal purposes because of its high menthol content. Menthol activates receptors in your mouth to form a cool sensation; the same cold-sensitive receptors that activate when you eat or drink anything that's cool. This is similar to the heat-sensitive receptors that become active in response to hot stimuli or chili peppers. So, when you drink water with peppermint, the coolness from the water is greatly exaggerated as the menthol is activating the cold receptors. This cooling feeling, along with its properties as a mild analgesic, pushes menthol in the forefront of different natural remedies, including upset stomachs.

Questions From My Wife VII: Not My Wife, Though She Also Asks Me About Poop

Taking another grant writing break to answer a reader's question. Stacy T. writes:

What does whale poop look like?

As far as I can tell, whale poop is a mystical substance. It's mostly water-soluble and appears as a giant cloud in the water. (See the image posted -- the ring shows whale flatulence bubbling to the ocean surface and that cloud is the poop.) Scientists can tell what the whale has been eating based on the poop cloud color -- this one probably had a good meal of bright red krill. Actually, scientists can look at the excrement to learn about the animal's health as well. Since whales poop mostly water (thus the cloud) any solid or waxy chunks indicate that the whale could be sick and not absorbing much of its foods' nutrients. One of the problems in whale research is the inability to observe whale poop. This would allow scientists to track migration habits and population levels over years of study. Interestingly a dog has been trained for the explicit purpose of detecting whale excrement for research.

Ambergris, a sperm whale bile duct excretion, is released from the whale's intestines. While technically not poop, scientists think that whales produce this in order to sweep large foreign items from their digestive system. Ambergris (literally "grey amber") has been used for centuries as a medicine and in perfume. And while gross, it is not actually a controlled substance, as it seen as a natural animal byproduct and has not been regulated since 2001.

Questions From My Wife V: Color Evolution

What is the point of hair and eyes coming in different colors? I get the evolutionary reason for different skin shades, but not the hair and eyes.

Actually, the genetics of skin color is very complex and is not yet fully understood. So far 4 genes regulating skin color have been identified, and there may be more yet to be found. There are a few theories for the diversity of skin color, such as the balance between avoiding exposure to ultraviolet radiation and production of Vitamin D. Darker skin has the advantage of blocking UV rays and reduced instances of skin cancer due to increased presence of melanin, but lighter skin lets in more light, which is crucial for the formation of vitamin D. Thus areas with less direct light, such as around the poles, have lighter pigmented skin.

However, many scientists view this idea as too simplistic, as it has obvious flaws. People living in the same latitudes -- the Australian aborigines and the Amazonian tribes; the Inuits and the Swedes -- have widely varying skin coloration. Plus most cancers are rarely factors in evolution -- most cellular damage is done far past prime reproductive age. Even Darwin didn't think natural selection had anything to with geographic variations of beauty traits. Current theories are returning to the viewpoint of Darwin and suggesting the evolution of skin color has more to do with sexual choice and picking partners by physical traits that happen to be socially important, but not much else.

Questions behind variations of eye and hair color are very similar to this. Sure, it could have happened for a reason. Legitimate scientific evidence exists that suggests the color of the iris shapes the ability to see in certain light conditions. But while it is more comforting to assume natural selection is involved, it seems more likely that it is not.

Sexual selection is a complicated theory, and not only attributed by Darwin to be the basis of racial differences, but also the general hairlessness of humans and possibly the creation of humor, music, and art. One theory by John Maynard Smith suggests that the human brain was created to its cumbersome levels by sexual selection -- very much like the plumage of a male peacock.

Outnumbered?

Two new techs from China were hired today, bringing the ratio of Chinese to American workers in this lab to 4:3.

Definitely more disturbing, the ratio of women to men is now 6:1.

Questions From My Wife IV: Quickies

A bunch of quick hits:

1) Why does it make you sleepy to be warm?

This basically has to do with the human body's response to overexertion. Increased body temperatures have a tendency to "cook" tissues, so the autonomic nervous system activates a fatigue or tired response. This makes you slow down to hopefully decrease your body temperature to normal levels.

2) When did Sesame Street establish that Snuffleupagus was real and not a figment of Big Bird's imagination?

Aloysius Snuffleupagus was finally revealed to the adults on November 18, 1985. Apparently, according to Wikipedia, "Snuffy's performer, Martin P. Robinson, revealed that Snuffy was finally introduced to the main human cast mainly due to a string of high profile and sometimes graphic stories of pedophila and sexual abuse of children on shows such as 60 Minutes and 20/20. The writers felt that by having the adults refuse to believe Big Bird despite the fact that he was telling the truth, they were scaring children into thinking that their parents would not believe them if they had been sexually abused and that they'd just be better off remaining silent."

3) Why do I get a sinus headache when it's rainy/muggy out?

Apparently if you don't have a sinus infection, you can't really have a sinus headache. What you're experiencing is probably a migraine. Very little is known about this condition (sorry) but sufferers are often hypersensitive to a variety of internal and extrenal stimuli (certain foods, hormonal conditions, stress, and even weather conditions). High humidity and low barometric pressure have been shown to induce the headaches in a large number of migraine sufferers.

Until next time, sports fans.

Questions From My Wife I: Hair Loss?

[A brief intro: My wife likes to ask me questions about anything and everything that pops into her head. I don't mind; she's pretty good about me staring at her with a confused look and no answer in sight. I'lluse this forum as an outlet on attempting to come up with a decent answer for her. And if anyone else has any questions they'd enjoy watching me fumble around on for a few paragraphs, feel free to drop a comment. --G]

You always complain about how much I shed. Why does the hair on some people's heads fall out more often than other people's, but they are not going bald?

Before answering this one, let me give the readers a quick overview of my living condition. I cohabitate with one black cat, one shaggy mutt, and one long-haired wife. It seems as if there is a constant struggle to keep stray hairs off of the bathroom sink and out of the kitchen. I'm constantly finding long dark hairs on my clothing and have recently begun finding them at work attached to my lab coat.

So the question is, where does she keep coming up with new hairs without going bald, and how can we somehow package this and sell it to 40-something execs in sports cars?

On average, the human head contains between 120,000 to 150,000 hairs growing from follicles -- pockets of cells designed to grow individual hairs. This process, like many in the body, takes place in the form of a cycle. First, the hair grows and divides within the follicle, in a process very similar to mitosis. Next, a cellular signal is given and the hair stops being made, and the root is pushed closer to the tissue surface. This is where the hair will fall out. However, the bulb still remains connected to its original location via a series of small nerves and will return to grow another hair in the course of a few months. This cycle can take anywhere from months to years depending on the location, care, and other environmental factors. For instance, eyebrows only take 3-4 months to complete a cycle, whereas it can take scalp hair 3-4 years.

The matter close at hand is it seems like the more hair you have, the more you will lose. Obviously, the longer it is, the more noticeable it is. People lose, on average, around 100 strands of hair a day. Why you don't go bald from it is another issue.

Baldness, or alopecia, isn't well understood. One factor may involve slowing of the hair's growth stage, leading to normal hair loss without rigorous replenishment. This is a reason why chemotherapy leads to hair loss. Cancer drugs keep cells from dividing, and this includes the production of new hair. In addition, the male androgen hormones (testosterone) seem to deplenish hair growth, while female hormones such as estrogen are protectants. Thus, when women have low estrogen levels postpartum or postmenopause, extreme hair loss can occur, similar to male-pattern baldness.

So basically, losing hair is normal. I should just get over it. Interestingly, in my research I found a few theories on why baldness happens in evolutionary terms. Apparently, in gorillas, a large forehead is considered a sign of maturity. The apes with the largest foreheads were seen as the most attractive. Others claim that's it's just a normal process of going from hairy ape to naked man.

So don't despair, balding men. Blame your ancient ancestors.

Gender in Cancer Science. Two quick points for discussion on a boring Friday afternoon.

It's been known for a while now that increased exercise decreases women's breast cancer risk. However, in the January 2007 edition of Cancer Epidemiology Biomarkers & Prevention (I'm sure everyone here has a subscription), a group of German researchers discovered that only household activity had a significant effect on breast cancer risk. Occupational and recreational exercise made absolutely no difference. The study looked at over 200,000 women of varying ages, demographics, and nationality, so it's hard to really argue with many of their methods. And, like many Epidemiology studies, don't really give an explanation as to why this could happen.

This whole thing seems fishy to me, as I don't see why mopping floors would have an different effect on the body, then say, walking up stairs. Maybe it's the cleaning product? And I'm not sure it has much to do with the male-dominated science industry -- the main author on the study is a woman.

On another note of issue is the recent news that Merck will stop lobbying for mandatory support of its new HPV vaccine, Gardasil. Human papillomavirus has many subtypes, but the sexually transmitted kind has been linked to cervical cancer. Merck seems to be afraid of the fundamentalist backlash -- getting this vaccine would, of course, only encourage young women to engage in promiscuous sex, as there would no longer be any reason not to. Never mind the fact that this may prevent nearly 7,000 women a year from getting cervical cancer (note: this is my own rough number, figuring % vaccine success and # of new cases/year).

Is there any reason I'm missing as to why you wouldn't you give your daughter an HPV vaccine? Why don't elected governmental representatives have the courage to stand up for what's right? If this was a vaccine for a male-dominated disease, would the government treat it differently? Though it's really unfair that increased sexually activity seems to diminish the prostate cancer risk. Girls get it rough sometimes.

Still no baking soda volcanoes. (Science fair part II)

So day #2 didn't take long. The winners from last week, along with winners from another school presented their topics with a 10-12 minute Powerpoint presentation. I was in the Physical science category, and got to see some diverse projects from the effects of fly ash in concrete to effects of antioxidants on cholesterol. I was pretty impressed for the most part. How many times in high school did any of you have to present results to a panel of 2-3 scientists? I would have had some pretty bad jitters, I think.

So we were in and out in about an hour with a few breaks to jam free chicken salad sandwiches and Baked Lays down my pie hole. These private school kids know how to host an event.

The whole thing got me thinking about how much I enjoy teaching. I loved giving the kids pointers on how to approach certain problems. And that it's okay not to know the answer to a question. You just have to have a decent idea of how to find the answer. I'm not sure I would be the best in a classroom situation for that very reason. Too many open book tests. But I may try to start tutoring at some point, possibly when I feel comfortable enough in my current job that I could sacrifice a few hours.

I was disappointed that no one created a civilization in a tooth. (Science fair part I)

Last Thursday, I was invited to a local private school, in order to help judge their annual science fair. I was never really into these growing up, but I jumped at the chance to meet other postdocs in the community. Plus, I figured I could help encourage some young local science minds. I enjoyed science as a child, but never had much help coming up with good ideas. I think I only did two – as they were mandatory in the 4^th and 5^th grade – and neither was well thought out. One of them involved growing sweet potatoes in water under various colors of light bulbs. Mostly they just rotted. In the other, I constructed a maze in a shoe box and watched if a small viney plant could work its way through to the light opening at the end. Kinda cool, but no real experiment here – it either would or wouldn’t. Or in my case, it just died midway through.

Nevertheless, I had hope that the scientists of the future would have better luck. The entries were divided up into 5^th grade, Junior (6^th-8^th grades), and Senior (9^th-11^th) and further divided up by category. I took Behavioral and Social Science as it seemed that this was a reluctant category to judge. And soon I found out why. Doing a science project is mandatory. And if you don’t/can’t/shouldn’t do science, then you make your classmates fill out surveys and throw something together for the Behavioral and Social Science category. What effects do different types of music have on test taking? Not many. Does ESP work? Probably not. Hey, do you want to see all of this stuff I found on the internet about the Stroop test? Not particularly.

For the first year, students stood by their posters while the judges went around giving them scores on various categories. And for the most part, they weren’t that bad. My main problem is that, at least for the large surveys they conducted, the students didn’t extrapolate much good information from them. One guy in the Senior level collected a massive amount of surveys (~100) on other students’ sleep schedules. He thusly concluded that his fellow students woke up earlier on weekdays rather than weekends. Shocking. But he not only gathered information on waking time, but also what time students typically went to bed, and whether or not they felt rested during the day. It wouldn’t have been much more work to do a quick check to see what percentage of people who claim to be tired in class also go to bed after 2 AM. You know, something moderately interesting. After asking him about this, he just stared at me, confused.

But not all of them were bad. One student looked if different colored paper had any effect on the ability to take math tests. Another found that people are more likely to memorize an object with a smell if they are not related. For example, more people remembered the smell of chocolate associated with an iron than with a mug. My only guess is that the test subjects had to try harder. Basically, if you had a good idea and some kind of conclusion, you did pretty well.

To get a break from the sameness of the survey club, I also judged the Junior Environmental Science category. Beyond a girl that grew carrots in sand under different amounts of light (I had a soft spot in my heart for that one) and a guy that found info on biofuels on the internet and glued them to a board, not much was there. The winner, however, collected hundreds of cans on the side of the road and discovered that an overwhelming majority were from beer. In soda, a huge percentage was Mountain Dew and there was surprisingly little littered Diet drinks. This was an interesting idea that was missing just a few things to get a “Best of Show” prize.

So what I did get out of this day? Well, sore feet and a so-so lunch for one. But it was very refreshing to see kids that really got excited about their projects. Sometimes I get bogged down with my own, and I couldn’t help but get refueled by their enthusiasm. So what's next? Regionals. Powerpoint. This Thursday.

Expect Part II -- The Reckoning soon.

At least they still have hydrant urination to fall back on.

Can humans track smells as well as dogs? You wouldn't think so, but a recent study has shown that we might have similar abilities in this regard. As least in tracking a chocolate scent. Basically, the researchers at UC Berkeley found that 2/3 of undergraduates (interestingly enough, slightly more men than women -- but this may not be statistically relevant) were able to follow a ~10 meter chocolate scent trail in a field. The back-and-forth motion followed, as shown in the picture, is comparable to a hunting dog's path in tracking prey.

Amusing to me, the picture of the guy on his honches was the cover to the most recent Nature Neuroscience journal.

And, because I haven't been able to figure out how exactly to post videos to the blog, here's a link to the the methodology.

Just because you need another reason to exercise.

A recent study by a group at the UAB Department of Nutrition Science claims that body composition may have an impact on the growth and spread of cancer. Traditional views have pointed towards calorie intake as the main problem in obesity, but it seems that what the body does with these calories is the main concern.

In the first experiment, mice genetically prone to pancreatic cancer were kept at two temperatures -- the cooler the ambient temperature, more energy (as calories) is required to maintain normal body functioning -- and fed the same amount of food. The mice kept closest to normal body temperature predictably became more obese than the other set, but also became significantly more inundated with cancer. The mice that had to expend more energy in the cooler environment retained generally normal pancreas tissue.

To further clarify this result, the researchers kept the mice at different temperatures, but allowed them full access to as much food as they could take in. This would keep both sets of mice at a relatively similar body composition to show whether actual food intake or the controlled temperature had any effect on the spread of cancer. In this scenario, the mice held at the lower temperature consistently ate more, had similar body mass, and thus had similar instances of cancer as the other group.

The actual link between obesity and cancer is still unclear. Leptin seems a likely candidate, as this hormone is not only involved with fat retention, but also in the induction of oxidative stress (cell damage caused by the creation of oxygen free radicals also linked to aging, neurodegenerative disease, and cancer). As a hormone, increased leptin is supposed to tell the brain when hunger is satisfied and to stop eating. But people suffering from obesity are resistant to its effects (much as they are similarly resistant to effects of insulin, thus the increase in occurence of type II diabetes). More and more leptin is produced without satiating effect, wreaking havok on other systems. The transgenic obese (ob/ob) mouse shown in the picture above has a mutation in which its brain is similarly resistant to leptin. The cancerous mice in the study were shown to have a huge increase in internal leptin levels.

So what does all of this mean? Well, basically, leaner bodies tend to handle calories better. Of course, this doesn't increase drug companies' revenues or really help anyone's day-to-day lives. Even though the research shows that caloric intake doesn't in itself cause cancer, excessive eating does lead to increased body fat, obesity, and then disease. Though maybe lowering the thermostat a few degrees over these winter months couldn't hurt.