Did mediaeval people stink? Was Walt Disney’s body cryonically frozen? Are bats really blind? Do we have only five senses?
We continue the by now well-established series of myth-busting articles. Every Friday, I take ten common beliefs, myths, urban legends or misconceptions, and in a few paragraphs each, debunk them.
It’s fun, and it offers good exercise for our critical thinking faculties. So let’s get started.
1. The Amazon rainforest is the lungs of the planet
As long as I can remember, I’ve heard that the Amazon rainforest, the largest in the world, is “the lungs of the Earth”. The Amazon, they say, produces about 20% of the oxygen in the atmosphere.
Since the atmosphere contains about 21% oxygen, and the lower limit for human safety is 19.5%, anything that threatens the Amazon’s oxygen production, like deforestation or wildfires, therefore threatens our ability to breathe – or so the story goes.
This not only overstates the importance of the Amazon. The truth is startling: the Amazon could vanish tomorrow, and we’d still be breathing just fine.
The origin of the 20% number is unclear, but it is wrong. It may derive from the fact that the Amazon represents perhaps 20% of terrestrial photosynthesis (it’s probably closer to 15%), but that doesn’t mean it accounts for 20% of all atmospheric oxygen.
Yet the 20% number is repeated as received wisdom by news media, politicians, and celebrity environmentalists.
The true “lungs of the Earth” are oceanic phytoplankton, which account for at least 50% of all atmospheric oxygen (and is also by far the most important carbon dioxide sink in the world).
Taking this into account, the Amazon is responsible for between 6% and 9% of all the oxygen produced by photosynthesis.
Then we need to account for the fact that trees consume about half the oxygen they produce at night through respiration. What is left over is mostly consumed by the microbes responsible for the decomposition of plant matter.
Yadvinder Malhi, an ecosystem ecologist at Oxford University’s Environmental Change Institute, draws the inevitable conclusion: “The net [oxygen] effect of the Amazon, or really any other biome, is around zero.”
Virtually all of the free oxygen produced by photosynthesis each year is promptly consumed by living things, fires and decomposition, according to Scott Denning, professor of atmospheric science at Colorado State University.
All of the excess oxygen in the atmosphere – the 21% – is produced not by today’s photosynthesis, but was built up over geological timescales by phytoplankton.
The difference between phytoplankton and terrestrial plants is that they produce oxygen while alive, but then sink to the sea floor, which is often oxygen-poor. There, it is broken down by anaerobic microbes, instead of their oxygen-consuming counterparts.
Anaerobic decomposition, which also occurs in places like peat bogs, is the only way organic matter decomposes without consuming the very oxygen it produced by photosynthesis in the first place. This is the source of buried gas, oil and coal.
That process is where the excess oxygen that built up modern atmospheric oxygen levels came from.
The Amazon rainforest provides important ecosystem services, including cooling the climate, but it has nothing whatsoever to do with the oxygen we breathe.
2. Eating garlic is a mosquito repellent
We all know someone who unashamedly eats garlic at every opportunity, and makes elaborate claims about its great many benefits, from warding off vampires (and anyone else that might have wanted a kiss), to preventing a range of dread diseases.
Among them is that garlic is, supposedly, a mosquito repellent. These insects won’t go after garlic-infused blood, they’ll say, sitting around the braai swatting away mosquitos.
Taxpayers of Uncle Sam’s have generously funded research work by four people who are highly qualified in pathology and pathogenesis, and who conducted a randomised, double-blinded, placebo-controlled crossover study to get to the bottom of the matter.
Alas, “[t]he data did not provide evidence of significant systemic mosquito repellence.”
Joe Conlon, technical advisor for the American Mosquito Control Association, told ABC News that while eating garlic is not helpful, “if you take garlic and squeeze it on your skin, that portion of your skin will be repellent to mosquitoes for about 20 to 40 minutes”.
Whether the repellent effect is limited to mosquitos we’ll leave as an exercise for the reader.
3. Walt Disney’s body was cryonically frozen before he died
Everyone has heard that Walt Disney, the famed animator who died on the morning of 15 December 1966, was one of the first, if not the first, person to have their body cryonically frozen in the hope that medical science would one day be able to revive him and cure his terminal cancer.
While it is possible that Disney might have read about cryonics, which was a fringe topic in the speculative literature of the 1950s and 1960s, there is no contemporary evidence that he did, or that he ever expressed any interest in the subject.
The only people who have claimed that Disney was interested in life extension, immortality, or having his body frozen, are two disreputable biographers who not only have proved to be unreliable and sensationalist on other matters, but also cite no primary sources for their claims.
There is, however, paperwork to certify that Disney was cremated two days after his death.
The first person to be cryonically preserved is actually one Dr James Hiram Bedford, who died of renal cancer on 12 January 1967, almost a month after Disney died.
According to PBS, Disney’s daughter, Diane, wrote in 1972: “There is absolutely no truth that my father, Walt Disney, wished to be frozen. I doubt that my father had ever heard of cryonics.”
We might also add that the notion of reviving frozen bodies, even if they were preserved in a manner that avoids the most obviously damaging effects of freezing, is so remote as to be implausible. In an article for MIT Technology Review, Michael Hendricks, a neuroscientist and assistant professor of biology at McGill University, explains why cryonics is a “false science”.
4. Andy Warhol said, “In the future, everyone will be world-famous for 15 minutes”
The phrase “everyone gets their 15 minutes of fame” is supposed to originate with Andy Warhol, the iconoclastic artist who in the 1960s worked at the intersection of pop culture, celebrity, advertising, and artistic expression.
Warhol never said this, however.
The phrase, or something like it in French, predates Warhol by over a century.
It became associated with Warhol when it appeared on the programme for his 1968 exhibit at the Moderna Museet in Stockholm, Sweden. The director of the museum, Pontus Hultén, tasked Olle Granath with producing the programme and provided a box of source material.
In an essay for the museum, Granath recalls what happened: “After a couple of nights of reading and taking notes I delivered a script to Pontus and awaited his reaction with great anticipation. ‘Excellent,’ Pontus said when he called me, ‘but there is a quotation missing.’ ‘Which one?’ I said. ‘In the future, everyone will be world-famous for 15 minutes,’ Pontus replied. ‘If it is in the material I would have spotted it,’ I told him. The line went quiet for a moment, and then I heard Pontus say, ‘If he didn’t say it, he could very well have said it. Let’s put it in.’ So we did, and thus Warhol’s perhaps most famous quotation became a fact.”
5. Lightning never strikes twice
Lightning, it is said, never strikes the same place twice.
This statement epitomises the strange relationship intuition has with statistical reality. Perhaps because lightning strikes are viewed as very rare, the chance that two would occur in the same place is assumed to be extra rare.
Lightning strikes on people are indeed rare. By one estimate, only about 2 000 people are struck by lightning worldwide each year. That makes your chance of being struck by lightning in any given year about 0.000025%, or about one in four million.
Statistically, that would make the chance of being struck twice 0.00000000000625%, or one in 16 000 000 000 000 (16 trillion). So it would be reasonable to say that lightning isn’t likely to strike the same person twice (unless they don’t learn from their experience).
However, lightning does like to strike in very particular places. It seeks out conductive materials in high places. It not only can strike the same place twice, but it is very likely to do so.
That is why we don’t want to be caught in the open during thunderstorms, and certainly not holding umbrellas or sheltering under trees. We do, by contrast, want to be indoors, surrounded by a Faraday cage of plumbing and wiring (and perhaps a lightning conductor) to direct the current harmlessly away from us and into the ground. (We do not want to be in the shower, however.)
Proof positive that lightning can and will repeatedly strike the same place can be found at skyscrapers like the Empire State Building in New York. Its antenna is struck by lightning about 25 times every year, or once a fortnight.
6. Bats are blind
Bats famously use echolocation to navigate in the dark, and to hunt if they are insectivores. They produce high-pitched sounds or clicks, and detect their echoes to create an auditory “image” of the world around them.
This, and their largely nocturnal behaviour, produced the myth that bats are blind. “Blind as a bat,” goes the phrase.
The thing is, bats aren’t blind. Only about half of all bats use echolocation at all, and all bats can not only see, but often prefer visual to sonic information.
Bats that feed on fruit or nectar tend to have particularly sharp vision, and can often see well into the ultra-violet spectrum. Even insectivores, however, tend to use a combination of echolocation and visual feedback to hunt.
7. Richard Nixon was impeached
Richard “Tricky Dicky” Nixon was a Republican president of the United States from 1969 until he infamously announced his resignation on national television in 1974, elevating his vice president, Gerald Ford, to the presidency for the remainder of his term.
He is often associated with unpopular actions in the Vietnam War, such as carpet-bombing North Vietnamese and Khmer Rouge positions in Cambodia without the consent of Cambodia’s leader, and with the Watergate scandal, which exposed a campaign of dirty tricks and sabotage against his opponents in the Democratic Party.
Often forgotten are his efforts to bring the Vietnam entanglement to an end, his establishment of the Environmental Protection Agency and the Occupational Health and Safety Administration, his rapprochement with both the Soviet Union and China, and the fact that he won re-election in 1972 with a historic landslide victory over George McGovern.
It is widely believed that the Watergate scandal led to Nixon’s impeachment. It did not. He resigned before he could be impeached.
To date, the only US presidents who were impeached by Congress were Andrew Johnson in 1868, Bill Clinton in 1998, and Donald Trump, first in 2019 and then again in 2021. All were saved from being removed from office by narrow votes in the Senate.
8. Humans have five senses
When I went to school, I was taught in biology class that humans have five senses: sight, hearing, touch, taste, and smell.
That information, however, was more than 2 300 years out of date. It was drawn from Aristotle’s book, De Anima (“On the soul”), written in 350 BCE. This is the same guy who thought perception, cognition, and emotion occurred in the heart and not the brain.
Yet we still talk about a “sixth sense” as something mystical that involves “extra-sensory perception”.
It isn’t easy to say just how many senses humans do have, since it depends very much on how you define them.
We can sense balance, for example, so the vestibular system ought to be considered one of the senses. We are aware of the action of many of our organs – the beating of our heart, our breathing, our digestion – which can be described as the sense of interoception. We can sense where our body parts are in space, called proprioception. We can sense temperature, both of our bodies, and in the environment. We can sense pain, but it is hard to say whether something so general could be called a sense.
Whether it is 10, or 12, or 20 is a matter of definition, but humans clearly have more than five senses, and Aristotle really shouldn’t be taught as modern biology anymore.
9. Four tastes can be distinguished with different parts of the tongue
Another factoid that comes from primary school biology is the notion that the tongue is divided into sectors, each of which is responsible for sensing one of four different tastes: sweet, sour, salty and bitter.
This idea originates with a book by Edwin Boring, a Harvard psychologist, written in 1942, in which he misinterprets a doctoral dissertation by Dirk P. Hänig he translated from German, Zur Psychophysik des Geschmackssinnes (The Psychophysics of Taste).
Although receptors for all tastes are distributed all across the tongue, Hänig had drawn some charts suggesting that different parts of the tongue were marginally more sensitive to particular tastes. Boring converted that into a map of the tongue in which different regions were suggested to be responsible entirely for particular tastes.
That misunderstanding somehow made it into school curricula and popular knowledge, and has stuck there ever since.
A grave omission from the tongue map is, of course, the fifth taste, which the Japanese call umami, and which we might describe as savoury. None of the other four tastes account for savoury flavours.
The simplistic division of taste into four or five types doesn’t account for the almost infinite variation in tastes we experience, and the “tongue map” that places only four of them in specific zones is – not to put too fine a point on it – wrong.
10. People stank in the Middle Ages
Since the advent of hot and cold running water, we have become used to a very particular kind of bodily hygiene, which relies heavily on daily baths or showers.
In the past, it was not a trivial undertaking to draw a bath, and it certainly wasn’t a daily routine, so we imagine the past as an era in which offensive body odour was just a fact of life.
This is to a large extent false, however. People in the past weren’t that much different from us. They weren’t any less intelligent, nor any less attuned to pleasant and unpleasant experiences.
Before indoor plumbing, individual baths were fairly rare for most people. It was costly, in terms of fuel, time and effort, to draw water and heat it for a bath in which the entire body could be submerged.
However, communal bathing was fairly common. Maintaining public baths was far more economical.
Many people bathed in rivers or lakes, when they had access to them.
Almost all people had what we now call “dry basins”, which are wash stands with a ewer of water and a ceramic or wooden bowl for washing. That they didn’t take immersive baths or showers did not mean that they did not wash themselves frequently.
Another very important difference (discussed in fascinating detail in this video) was that clothing was designed very differently. People would wear several layers, and the innermost layer almost always consisted of linen garments that covered the full body. Linen absorbs moisture and oils from the skin, and rubs the skin clean, reducing the problem of body odour. Linen underclothes were washed frequently, keeping the skin clean and protecting the outer clothing layers.
Of course, in the past far more people lived in abject poverty, so we can expect that odour issues would arise among them just like they do among the poor today, especially after strenuous labour.
But while pre-modern people couldn’t aspire to today’s standards of hygiene, they were certainly not indifferent to cleanliness. They were very aware of the health risks that attended filth, and attributed various diseases to “bad air” or “miasma”.
Many writers, among them doctors, extolled the virtues of personal hygiene. Washing hands, face, head, feet, armpit and privates frequently, or even daily, was widely recommended, and washing before meals was routine.
Various preparations, including oils, wine, vinegar, and wood-ash soap, were used to clean the body, and powders and perfumes kept moisture and body odour at bay.
Personal hygiene practices were certainly different during the Middle Ages, simply because of a lack of access to facilities like running water that we take for granted today. Different doesn’t mean absent, however. People back then cared about their appearance, smell, comfort and cleanliness just as much as we do today.
[Image: Lightning strikes the antenna atop New York’s Empire State Building about 25 times per year. Image: supplied.]
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