Aaron Carroll - Myths About Sex & Pregnancy

DR. AARON E. CARROLL AND
DR. RACHEL C. VREEMAN

ST. MARTINS GRIFFIN NEW YORK

Have you ever noticed a man with particularly big feet and wondered if other parts of him were just as large? While some claim that a mans penis size can be predicted by the size of his feet, others say that its the size of his hands or even his nose that really gives away the secret of whats in his pants. This idea of comparing body parts to estimate hidden assets may have originated with discriminating shoppers, but it may also have its roots in real science. The Hox gene in mammals plays a role in the development of the toes and fingers, as well as the penis or clitoris. Given how rarely one hears gene expression mentioned along with the talk of penises and feet, it seems much more likely that this myth springs from our desire, as humans, to identify patternseven when the pattern is not really there. We like to have explanations for things we see, and we like to group like things with like things (in this case, appendages on men).

Despite the similar genetic controls for these protuberances, men with big feet do not necessarily have bigger penises. While at first, the prospects for estimating penile length with a quick glance at a mans feet seemed promising, science now shows us that this is not the case. A study of sixty men in Canada suggested that there was a weakbut statistically significantrelationship between penile length and both body height and foot length (rememberstatistically significant doesnt necessarily mean significant in real life). However, a larger study of 104 men, done by two urologists, Drs. Shah and Christopher, which measured penises when pulled to their longest lengths, found that shoe size and penis size were not correlated with one another. An even larger study called the Definitive Penis Size Survey, which looked at 3,100 men, also found no relationship between shoe size and erect penis size. This was even when men reported their size, as opposed to direct measurement. And when men are asked to report the length of their own members... well, lets just say that science also shows us that exaggeration routinely comes into play. Furthermore, the Definitive Penis Size Survey was never peer-reviewed or published in a scientific journal. We trust the results from Drs. Shah and Christopher the most, but this survey backs them up. Studies also show no link between finger length and penis size. You can look at a guys feet or hands all you want, but they wont tell you anything else about how he measures up.

You know that you can achieve your dreams if you just put your mind to it. After all, youre only using 10 percent of your brain, right? Imagine what you could do with that other 90 percent!

Its time for a reality check. People have believed that we only use 10 percent of our brains for over one hundred years. Unfortunately, all that means is that people have been wrong for over one hundred years. As early as 1907, self-improvement gurus and motivational speakers were convincing their audiences that they could reach greater heights of achievement if only they could tap in to some of their unused, latent brain power. Some people even claim that Albert Einstein first said that most people only use 10 percent of their brains, or that he was a genius because he used more of his brain than the rest of us. Neither of these claims is true! There is no official record of Einstein saying such a thing.

The myth of the unused brain has been debunked in great detail by an expert in neuroscience, Dr. Barry Beyerstein. Many studies of patients with brain damage suggest that harm to almost any area of the brain has specific and lasting effects on a human beings capabilities. If this myth was true, it would not be a big deal to hurt various parts of your brain. Most of the time, however, thats not true at all. You will be affected by damaging almost any part of your brain.

Different types of brain imaging, including CT scans, MRI scans, and even more detailed techniques, show that no area of the brain is completely silent or inactive. Much more than 10 percent of the brain is busy at work virtually all the time. Furthermore, the many brain functions are localized to very specific areas of the brain. Each region has its own special job. When brain surgeons go in and probe the brain, area by area, they cant just find the nonfunctioning 90 percent, because they see functions for almost every area. Moreover, when scientists observe the responses of individual brain cells or neurons (called micro-level localization) they do not find any gaps or inactive areas. Even studies of cell metabolism, which look at how the parts of the brain metabolize or process chemicals, reveal no dormant areas.

So, as depressing as this may be, you are probably stuck with what youve got. You are, in fact, using 100 percent of your brain. Of course, you can still question the old adage you cant teach an old dog new tricks, since you can always keep learning new things. In fact, many studies show that keeping your brain stimulated might help to decrease dementia and brain impairment as you age.

Have you ever walked across a cemetery and thought about the growing, curling fingernails of the corpses beneath? This disturbing idea is probably the kind of thing you heard around a campfire as a kid. It has such a morbid appeal that artists have used this image in books and movies for a long time. Johnny Carson even joked, For three days after death, hair and fingernails continue to grow, but phone calls taper off. Despite the popularity of this idea, its just not true. To quote the expert opinion of forensic anthropologist William R. Maples, It is a powerful, disturbing image, but it is pure moonshine. No such thing occurs.

This myth does have some basis in reality. After you die, your body dries out or becomes dehydrated. As the skin dries out, it shrinks (this is a different kind of shrinkage than what happens to a man in cold water). The shrinking or retracting of the skin around the hair and nails makes them look longer or more prominent compared to the shrunken skin. Its just an optical illusion, though; the nails and hair havent actually grown at all. In order to keep growing, hair and nails require a complex mixture of hormones that are just not available to the body after death. Studies of the cellular regulation of hair growth confirm that a person would need to be alive for their hair to keep growing. Theres no need to book a haircut and manicure for your corpseno matter how long its been since the last one.