40 Debunked Myths: Clearing Up Common Misconceptions – Part 2

Alcohol does not necessarily kill brain cells. Alcohol can, however, lead indirectly to the death of brain cells in two ways: (1) In chronic, heavy alcohol users whose brains have adapted to the effects of alcohol, abrupt cessation following heavy use can cause excitotoxicity leading to cellular death in multiple areas of the brain. (2) In alcoholics who get most of their daily calories from alcohol, a deficiency of thiamine can produce Korsakoff's syndrome, which is associated with serious brain damage.

27. Human blood in veins is not actually blue. Hemoglobin give blood its red color. Deoxygenated blood has a deep red color, and oxygenated blood has a light cherry-red color. The misconception probably arises for two reasons: 1) Veins below the skin appear blue or green. This is due to a variety of reasons only weakly dependent on the color of the blood, including subsurface scattering of light through the skin, and human color perception. 2) Many diagrams use colors to show the difference between veins (usually shown in blue) and arteries (usually shown in red).

28. Water-induced wrinkles are not caused by the skin absorbing water and swelling. They are caused by the autonomic nervous system, which triggers localized vasoconstriction in response to wet skin, yielding a wrinkled appearance. A 2014 study showed no improvement in handling wet objects with wrinkled fingertips.

29. The notion that goldfish have a memory span of just a few seconds is false. It is much longer, counted in months.

30. Bats are not blind. While about 70% of bat species, mainly in the microbat family, use echolocation to navigate, all bat species have eyes and are capable of sight. In addition, almost all bats in the megabat or fruit bat family cannot echolocate and have excellent night vision.

American botanist George Washington Carver did not invent peanut butter, though he reputedly discovered 300 uses for peanuts and hundreds more for soybeans, pecans, and sweet potatoes.

32. Most diamonds are not formed from highly compressed coal. More than 99% of diamonds ever mined have formed in the conditions of extreme heat and pressure about 90 miles (140 km) below the earth's surface. Coal is formed from prehistoric plants buried much closer to the surface, and is unlikely to migrate below 2 miles (3.2 km) through common geological processes. Most diamonds that have been dated are older than the first land plants, and are therefore older than coal. It is possible that diamonds can form from coal in subduction zones and in meteoroid impacts, but diamonds formed in this way are rare and the carbon source is more likely carbonate rocks and organic carbon in sediments, rather than coal.

33. There is no scientific evidence for the existence of "photographic" memory in adults (the ability to remember images with so high a precision as to mimic a camera), but some young children have eidetic memory. Many people have claimed to have a photographic memory, but those people have been shown to have good memories as a result of mnemonic devices rather than a natural capacity for detailed memory encoding. There are rare cases of individuals with exceptional memory, but none of them have a memory that mimics a camera.

34. Toilet waste is never intentionally jettisoned from an aircraft. All waste is collected in tanks which are emptied on the ground by toilet waste vehicles. Blue ice is caused by accidental leakage from the waste tank. Passenger trains, on the other hand, have indeed historically flushed onto the tracks; modern trains usually have retention tanks on board and therefore do not dispose of waste in such a manner.

35. In people with eczema, bathing does not dry the skin and may in fact be beneficial.

Alcoholic beverages do not make the entire body warmer. The reason that alcoholic drinks create the sensation of warmth is that they cause blood vessels to dilate and stimulate nerve endings near the surface of the skin with an influx of warm blood. This can actually result in making the core body temperature lower, as it allows for easier heat exchange with a cold external environment.

37. Exposure to a vacuum, or experiencing uncontrolled decompression, does not cause the body to explode, or internal fluids to boil. (However, fluids in the mouth or lungs will boil at altitudes above the Armstrong limit.) Instead, it would lead to a loss of consciousness once the body has depleted the supply of oxygen in the blood, followed by death from hypoxia within minutes.

38. Shaving does not cause terminal hair to grow back thicker (more dense) or darker. This belief is due to hair which has never been cut having a tapered end, whereas after cutting the edge is blunt and therefore thicker than the tapered ends; the cut hair appears to be thicker and feels coarser due to the sharper, unworn edges. The shorter hairs being less flexible than longer hairs also contributes to this effect.

39. Mental abilities are not absolutely separated into the left and right cerebral hemispheres of the brain. Some mental functions such as speech and language (e.g. Broca's area, Wernicke's area) tend to activate one hemisphere of the brain more than the other, in some kinds of tasks. If one hemisphere is damaged at an early age, these functions can often be recovered in part or even in full by the other hemisphere (see Neuroplasticity). Other abilities such as motor control, memory, and general reasoning are served equally by the two hemispheres.

40. Researcher Andrew Wakefield claimed a connection between vaccines and autism and autism spectrum disorders. Repeated attempts to reproduce the results by other researchers later showed that there is indeed no connection between the two and his research was ultimately shown to have been manipulated.