Student Questions: Mosquito Repellent and Einstein's Gestation
Skeptoid answers more questions sent in by students all around the world.
Today we have some really cool questions sent in by students. First we're going to look at electronic mosquito repellents, then at the validity of the Petition Project signed by over 30,000 scientists who say anthropogenic climate change — meaning caused by humans — isn't happening. Next, what are the real facts about whether or not you can get sick from someone sitting near you in class? Finally we're going to look at a couple of really interesting biological questions. One is the explosive issue of athletes of different races: Is it true that some races are good at some sports? — because it sure seems like it. And last, the urban legend that Einstein spent an extra month in his mother's womb, which is what made him so smart. Let's get started with an important question on health that affects people all over the world:
Ultrasonic Mosquito Repellent
Yes, they've been tested, and no, they don't work. Field trials of electronic mosquito repellents conducted in ten different parts of the world where mosquito-borne malaria is a problem found no evidence that they repel mosquitos at all, and this includes those that are said to simulate the sound of a dragonfly's wingbeat. If you want to repel mosquitos, you've got to turn to chemical repellents. Since malaria is such a major cause of death in some parts of the world, a lot of money has been thrown at trying to solve this. According to the Centers for Disease Control, you can't do much better than DEET. Generally, synthetic repellents work better than natural repellents, although some plant-based compounds do work just as well. The old folk remedy of taking Vitamin B has been conclusively shown to have no effect whatsoever as a mosquito repellent. Citronella oil does work almost as well as DEET, but its shortcoming is that it must be reapplied every 30-60 minutes.
The best repellent of all, of course, is a properly closed mosquito net.
Scientists Reject Climate Science?
You're referring to The Petition Project, which has collected over 30,000 signatures of people worldwide who, supposedly, reject anthropogenic climate change. (In a moment I'll explain why I say "supposedly" reject it.) Understand two things about this petition. First, 30,000 is only about 0.3% of degree holders in the relevant fields, so we can be pretty certain that the vast overwhelming majority of scientists have rejected this petition. Second, the actual petition is fundamentally flawed in that it requires the signer to agree to three unrelated points, any one of which is debatable:
The Kyoto Protocol is a political question that has nothing to do with climate science itself, placing restrictions on wealthy nations while allowing the largest producers of greenhouse gases, China and India, to continue to do so without such restrictions. Plenty of people disagree with this strategy, regardless of their feelings about the science. The second point, that humans are not causing an increase in global warming, does contradict all the science that we have, which shows that humans burning fossil fuels is the overwhelming driver. The third point, that a rise in carbon dioxide is beneficial, is quite true in some cases. It's great for plants, for one thing. But the science shows that it will have other negative consequences that far outweigh the few benefits.
So how is the average person to respond when presented with such a schizophrenic petition? Some climate scientists may feel conflicted about any one or two of these three points. There's no doubt in my mind that the petition was consciously designed to be ambiguous, and to give as many people as possible some reason to agree with one of its points. The best example is showcased on the Petition Project's home page, which shows the petition signed by the late Manhattan Project nuclear physicist Dr. Edward Teller. Teller was profoundly concerned about global warming, and proposed sprinkling aluminum dust into the atmosphere as a much cheaper way to address the problem than the disastrous Kyoto Protocol. He was pretty much the opposite of a global warming denier. His being showcased on their home page proves, to me, that their Petition Project lacks integrity.
Can You Really Get Sick In a Classroom?
That's a great question, and an important one. Yes, you can potentially catch a cold from being near someone who has an active cold. The most likely way you'll catch it is through contact. We often don't realize how many things we touch: The doorknob to the classroom, the button on a drinking fountain, books and papers that might be passed around the room, the backs of chairs, etc. But guarding against this is the easiest thing to do. Wash your hands frequently. If you wash your hands throughout the day when you're near someone with an active cold, using soap and water or an alcohol-based cleanser, you have a very good chance of not catching it. Also be sure not to touch your face. The virus usually enters your body through your eyes, nose or mouth from your hand.
But there's one thing you can't control quite so easily: If that person is coughing or sneezing into the air, they put the virus into the classroom's air; and if that happens, then people nearby are indeed at much higher risk. Students with a cold who are actively sneezing or coughing should stay home. If they do come to school, they should cough or sneeze into a handkerchief or tissue. If they're just blasting away, then you may indeed have a problem, and not even a facemask will protect you from particles that fine.
Do Certain Races Have Certain Traits?
Yes and no: Certain populations throughout the world do indeed tend toward certain sizes and shapes, but this doesn't have as much to do with their race so much as with other factors. A great place to study this is Africa, where we see immense diversity of body proportions among different populations, ranging all the way from the Bambuti Pygmies of the Congo whose men average only 137cm (4'6"), all the way to the Watusi Tutsi whose men average 193cm (6'4") with many over seven feet. Populations of the same race also differ geographically: Caucasian men in the Netherlands average 185cm (6'1") but only 174cm (5'9") in Romania; Asian men in Taiwan average 172cm (5'8") but 163cm (5'4") in Cambodia. Worldwide, women average slightly shorter than men. Since athletic ability is dependent on size more than any other physical characteristic, it's never going to be accurate to correlate race with athleticism.
There are two main factors that determine a given population's physical characteristics. The first is their haplotype, a group broadly defined by a certain mtDNA mutation that identifies them as a group. There are several dozen main haplogroups in the world's human population, each subdivided into more specific groups. They can be mapped, showing the oldest haplogroups originating in Africa, and then newer haplogroups appearing over thousands of years as populations migrated through Europe, Asia, and the Americas. mtDNA is passed on by the mother only, so each of us can be traced back to a genetic land of origin based on our haplotype. We share many common physical characteristics with other members of our haplogroup, wherever they live; including other traits that affect athleticism like relative lung capacity, tendencytoward obesity, and so on.
The second factor is often more dramatic, and that's selection pressure from marriage. Although the Watusi are probably the world's tallest population, they are not genetically different from the rest of the Tutsi who average only 170cm, a full 23cm (9 inches) shorter. The Watusis' height is solely the result of selective marriage. The true story of human genetic diversity is much richer and far more interesting than simple racial stereotypes, which are (a) wrong and (b) obscure the actual science. It's a fascinating area of study.
Einstein's Lengthy Gestation
You're really asking two questions here: First, was Einstein born a month late; and second, are babies born late more likely to be smarter?
The first question is not easy to answer. Einstein was born in his parents' home in 1879, when prenatal care was both rare and unscientific. It's unlikely that anyone made records of the date of conception or his mother's menstrual cycles, however gestation time was generally understood as 40 weeks. None of the Einstein biographies I looked at said anything about any prenatal records having been preserved, so it appears this claim about Einstein is an invented urban legend and is not based on any actual history. There have been fictionalized accounts in which Einstein gestated longer, but those are dramatic inventions and also not based on historical record.
The second question is easier. The relationship between gestation and intelligence has been extensively studied, and we've learned that there is none. The healthiest babies are born on schedule, as both premature birth and prolonged gestation can result in troubled births.
And so, despite what your friend may have heard, the claim that Einstein spent an extra month in the womb, and was smarter because of it, is fiction.
Got a student question you'd like Skeptoid to answer? Students of all ages from anywhere are welcome. Come to Skeptoid.com and click on Student Questions for the easy instructions. I hope to hear from you soon.
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