Okay, we’ll dive right into part two:
- Different parts of the tongue are specialized to recognize certain tastes. False! This one was a surprise to me because I remember seeing a whole chart about where on the tongue certain things are perceived when I was in high school. In reality humans can only detect five different kinds of tastes: salty, sour, sweet, bitter, and umami. Umami is Japanese for “delicious taste”, it means the savory, meaty taste that is characteristic of broth. Flavors are different than taste, flavors involve smell as well as taste. Don’t believe me? Plug your nose and an apple will taste the same as a raw potato. All five basic tastes can be perceived anywhere on the tongue where there are taste receptors. In fact the myth of the “map of the tongue” was published in a text in 1942 which was written by a guy who misinterpreted someone else’s research, and then other textbooks just copied it!
- Dogs are color-blind. False! In fact dogs see colors better than cats do. The idea that very few mammals can see colors came from a survey done in 1942, but in 1993 a much more extensive survey indicated that most mammals have at least some degree of color vision. Humans and rhesus monkeys have the best, called “trichromatic color vision.” The next step down, “robust dichromatic color vision” is what animals like dogs, pigs and most monkeys have. This is also the category that color-blind humans fall into. Then we go down to “feeble dichromatic vision,” including the domestic cat. “Minimal color vision” is possessed by mammals such as the raccoon. Interestingly, when a gene carrying a third photopigment was introduced into photoreceptors of an adult male squirrel monkeys, they soon displayed excellent trichromatic vision. This suggests it may be possible to one day correct color-blindness in humans!
- Each side of the brain controls the muscles on the opposite side of the body. True! This is most easily proven when a person has brain damage. Brain damage to the primary motor cortex produces partial paralysis on the side of the body opposite the brain lesion.
- There are no anatomical differences between men’s and women’s brains. False! Many parts of the brain are different between men and women. Some structures in the female brain are larger than their male counterparts, while some structures in the male brain are larger than in the female brain.
- In some animal species every individual is female. True! In 2001 a species of spider mite was discovered which consists entirely of females. Apparently all of the newborns are clones of their mothers, and any ‘incidental’ males undergo a sex change via a bacterium.
- Some people are “born gay.” Uncertain. There was a fellow in 1991 who did some research and claimed he discovered a difference in the preoptic area of the brain–a certain area was different in size in gay men and women than in those that are straight. However it was later shown that this may be the result of homosexuality rather than the cause. There has been other research since, but to date no scientific test has been able to discover a biological determinant in homosexuality versus heterosexuality.
- Most of our energy is expended just maintaining our body temperature. True! Body temperature for most mammals is between 97 – 100 degrees F. Our bodies integrate the demands for nutrients and water to result in a set range of body weight that is remarkably narrow. Regulating our internal resources is complicated by the fact that staying alive requires us to use up some of them. Our homeostatic mechanisms are continually challenged by these unavoidable losses, which require us to gain and conserve heat, water and food constantly. Animals lose about 33% of the energy in food during digestion, another 55% is consumed by basal metabolism (basically maintaining our regular body processes, such as temp regulation), so only about 12% is utilized for active behaviors.
- We can lose weight permanently by surgically removing fat from our bodies. False! Ouch, that one hurt didn’t it? In animals, if body fat is surgically removed they will eat until they regain–with remarkable precision–the amount of fat that would be normal for them. Needless to say these results are not encouraging to humans considering liposuction, usually the fat simply returns after the procedure. The only current surgical intervention that produces significant and long-lasting effects is gastric bypass surgery, however it is accompanied by significant complications and risks–illness and death remain real threats.
- The peaks in cases of depression and suicide occur around Christmas holidays. Super False! The National Center of Health Statistics, part of the CDC, found that suicides actually drop during the Winter months and over the holidays by as much as 40%, and peak during Spring and the Fall. The suicide rate is, in fact, the lowest in December!
Alright, that’s it for this installment. Part three of four is coming up next, where I’ll look at (among other things) just how active the brain is while we sleep, if sleepwalkers are actually acting out their dreams, if one side of our face is more expressive than the other, if prolonged stress can cause heart disease and if it’s true that scientists are not actually sure why antidepressants work!