biology zoology blog benno meyer rochow sneeze

The Science behind Sneezing

Have your handkerchief handy

Have you noticed that most of the words related to the “nose” start with the letters ‘n’ and ‘sn’? Apart from nose, nares, nostril, and nasal you’d find snot, snort, sniff, snuff, snore, snooze, snub-nosed and, of course, sneeze. The most common reason advanced for why people (and other animals) sneeze is that the act of sneezing removes an irritant or obstruction in the nasal passage. Suffering from hayfever (my children used to have fun chasing me around in the garden with flowers in their hands) I once counted that I was sneezing forty times in a row  – and that was not at all because of an obstruction in my nasal passages (or looking into the sun, which is said to trigger sneezing in some people). So, what goes on?

The allergic reaction to pollen like the one that made me sneeze is probably one of the commonest reasons of sneezing in humans. But it’s complicated, for it involves an oversensitivity reaction in which substance P (cf., my earlier blog) is increased in the nasal epithelium together with other neuropeptides like, for example, calcitonin (cf. also old blog). These and the release of antibodies and histamine by the body’s immune system to the perceived threat posed by the inhaled pollen, lead to the hypersensitivity reactions (e.g. nose and eye itch). All these in conjunction with neurotrophic factors stemming from the allergy, target neuronal fibres like chemo- and pain receptors and those sensing itch, which then send the information to the trigeminal ganglion. The trigeminal nerve that serves also the cheek and orbital region of the face then instructs the sneezing centre in the brain’s medulla to take action.

Action means that effector neurons should become active. Those involved with breathing make sure that deep inspirations occur prior to the sneeze and that the eyes and the glottis close, before through an increase of the pressure in the lungs the glottis suddenly opens and releases in an explosive action air and fluid droplets through mouth and nose. The pressures involved in a sneeze can be 176 mm Hg, which would be one tenth of the pressure of a tyre of a small car or one third of the pressure penguins generate to poop. During a sneeze thousands of tiny droplets of liquid are released up to a metre and sounds accompanying a sneeze can vary from faint to deafening.

People who own a dog or a cat know that their pets may occasionally sneeze spontaneously or when you tickle their nose or when they smell irritating chemicals. The same holds true for humans and I for one avoid the perfume sections of the department store because the odours there could make me sneeze. The sneezing that accompanies a cold is usually related to a mucus build-up in the nasal passages that the sneeze tries to remove. The Galapagos iguana and some marine birds sneeze to remove salt crystals that have accumulated in the nasal passage and need to be flushed out.  All vertebrate animals with lungs and a connection between the nose and the pharynx (that excludes the fish) are said to have ‘choanae’ (= internal nares) and can sneeze. The nose of a fish consists of two nasal openings for the inflow and two for the outflow of the water. Located between in and outflow nares is the olfactory epithelium with its odour sensitive cells. Thus, looking at the head of a fish you will see 4 nasal openings and not just two as in all terrestrial vertebrates. Sneezing in fish is therefore not possible.

Antarctica is a good place for people with pollen allergies. Although you can get cold there, you are not likely to ‘catch a cold’ there, but on one of my trips to the icy continent my friend and colleague Taka Hariyama sneezed (dust does exist in some areas of Antarctica). He sneezed once and seemed happy, exclaiming joyfully “only once!”. I was puzzled why he stressed “only once”, until I learned that ‘sneezing once’ suggests to a Japanese that someone is saying good things about the ‘sneezer’, but that sneezing twice means the opposite. Yet, what it means to sneeze 40 times in a row I don’t want to know.

© Dr V.B. Meyer-Rochow and, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and with appropriate and specific direction to the original content. 

Keep on Dreaming

But did Blondie and Aerosmith ever dream about insects?

I knew a Chinese girl who told me that she often dreamt about snakes and that the dreams frightened her. But I love to dream and my dreams never frighten me. It’s like entering a parallel world: you can be in unusual places, experience otherworldly adventures, solve scientific problems and, like Alice in Wonderland, meet strange creatures. The few dreams I’ve had in which insects appeared were pleasant ones, like finding a new and fantastic species of weevil with moss growing on its back or discovering an insect so small that one could hardly see it without a magnifying glass. And yet there are apparently people who encounter insects in their dreams that frighten them just like the snakes did in the dreams of my Chinese friend. I suggested to her that I could try to replace the snakes in her dream with ants or perhaps flies, but she did not like that idea.

By chance I came across a 2012 paper in the journal “Insects” by Barrett Klein, who wrote about people that had dreams about insects. Interpreting dreams that contain insects in them is a controversial issue and I guess the quotation by Barrett Klein attributed to James Horne that “Sometimes it can be difficult to say who is fantasizing more, the dreamer or the dream ‘interpreter’” is not too far off the mark. Often the interpretation depends on who dreamed what about the insect. Farmers, for example, dreaming about locusts are more likely to be worried about their crops and nasty people than others who will connect grasshoppers with a sense of freedom and enlightenment and fun.

When flies, fleas and lice occur in a dream anxieties, frustrations, fears and sorrow may be behind it, but dreams in which butterflies play a role are frequently linked to creative thinking, romantic encounters, and feelings of happiness. Dreams of bees and wasps are difficult to interpret as they could signify positive things like wealth, good luck and success and an ability to meet challenges , but also that trouble and dangers lie ahead and that fear and sickness may take over and that there are enemies to get to the dreamer. Unsurprisingly, beetles, representing the by far most species-rich order of insects, can, on the one hand, be part of pleasant dreams in which the beetles may be linked to success and positive images (ladybird beetles are so cute) or, on the other hand, may feature I dreams in which they are seen as harbingers of loss, death and destruction (carrion beetles and dung rollers perhaps).

It has been noted that the insect dreams of children aged between four and six years of age reflect the children’s  situation of being small and weak, basically powerless and it has been documented that insect and snake phobias were more prevalent in the female students’ than in the male students’ dreams, based on studies that had involved several Canadian universities. The great enthusiast of dream interpretations, Sigmund Freud, recounts and explains several cases in which psychological problems of people manifested themselves in their dreams containing a variety of insects.

Being well aware that (at least) mammals other than humans also dream as behavioural observations and encephalographic brain recordings have shown, one cannot help but think, if their dreams might not occasionally also feature insects. And going a step further one might even wonder if sleeping insects themselves not only dream, but would then have dreams about those annoying humans. 

© Dr V.B. Meyer-Rochow and, 2020.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and with appropriate and specific direction to the original content.

biology zoology blog benno meyer rochow rats as food

Rats on the Plate and on your Palate

“If you can’t beat them, eat them!”

When I lived in Japan, I knew I had mice in my apartment. They had found my chocolate and had torn holes into the cover and eaten some: you could see their toothmarks. I also saw some quite regularly when I happened to enter the kitchen at night and switched on the light. But it weren’t the mice that made me seek a different flat, it was when I had rats in my bedroom! These clever, but not exactly charming rodents, must have resided behind the cupboard in the wall and on four occasions traps I had placed around my bedroom caught one of them. There are people who love rats and keep them as pets and in many parts of Asia credit is given to the rats’ intelligence, their adaptability and hardiness and even temples (e.g., the Karni Mata) dedicated to rats exist in India, because Hindus believe that a rat had helped to carry Lord Ganesh around the world. And there are many people who’d claim that there was nothing more delicious than rat meat on your plate, rat fried or roasted, or rat as a stew or casserole. —>—>