Compulsive Hoarding

A disorder with ancient roots?

I think we all know some people who are ever so ready to throw away something they no longer fancy or to discard some item if a newer version is available. But we may also know people, who behave in exactly the opposite way: they never throw away anything but keep and store and guard even things that no longer seem useful. That kind of behaviour can be compared to what is termed “hoarding” and, if compulsive, it is now considered a mental disorder of the “obsessive-compulsive” nature. But is it an atavism, a re-surfacing of an ancient trait with roots in the animal kingdom as suggested by Sandro René Pinto de Sousa Miguel, Rodrigo Ligabue-Braun of Porto Alegre in Brazil, akin to narcolepsy and quadripedalism in humans, which have also been linked to atavisms?

Hoarding, especially of food but occasionally also of material or other items, is certainly common in the animal kingdom and helps individuals survive lean periods. And immediately La Fontaine’s famous poem “La cigale et al fourmi” that I had to learn as a pupil during my High School French lesson, comes to mind. Indeed, there are several examples of invertebrates that store or cache food or, in the case of leaf cutter ants, even collect and tend inedible leaves to grow on them edible fungi. Honey bees are so successful (unlike the equally social hornets) and survive the winter, because they prepare and store food for the cold season. Although not usually overwintering, spiders, too, can often be seen in summer to keep numerous wrapped-up insect prey in their orb-webs for later use.

More obvious hoarders are found amongst our feathered friends and some of them behave seemingly intelligently when they attempt to hide food items and then firstly look around to make sure no other bird observes where they hide their treasures. A behaviour such as this has been reported from Corvus corax ravens by the Austrian researchers T. Bugnyar and K. Kotrschal and also the Eurasian jay Garrulus glandarius by the Cambridge University scientists E.W. Legg and N.S. Clayton. North American woodpeckers are less selfish and establish food stores that are accessible to other wood peckers, but whether shrikes like Lanius collurio allow other shrikes to access the insects, and even small mice and lizards, they store on thorns in the open, I do not know. However, policing food stores such as these, which are visible and in the open would be quite a task. Besides, hoarders with multiple caches (to reduce pilferage) run the risk of forgetting some of their troves, and in the case of forgotten and buried seeds, help spreading trees. A special facet of hoarding is that, which is represented by the New Caledonian crow Corvus moneduloides that bends twigs into hooks to extract grubs from wooden trunks with and then hides and hoards these precious tools.

Proverbial hoarders are the hamsters. It has been reported that European hamsters of the species Cricetus cricetus may have many kg of grain (up to 60 kg !) in their nests  – and it’s all for themselves (and their offspring). Packrats and squirrels, too, are well known hoarders and beavers establish food stores that can be used by anyone of their family. Some of the best-studied mammalian hoarders are shrews, especially a species by the name of Blarina brevicauda from the northeastern region of North America. To survive the winter they collect and cache food items in their burrows that can contain seeds and dry fruit, invertebrates and even small mice. It was this species of shrew that the Brazilian researchers, mentioned above, compared obsessive human hoarding with to suggest that the latter was an atavism going back to ancient evolutionary roots. The problem is, human hoarders more often than once, not just hoard food, but inedibles like coins, stamps, toys, clothes, buttons etc., and some are even known to hoard and guard some really weird and useless things like used underwear, smelly socks, cigarette buds, etc. Do animals do that also? Well, in the Statistical Manual of Mental Disorders, 5th edition (DSM-5) such behaviours in humans are now classified as a mental disorder. Maybe it’s risky then to mention I collect coins with animals on them.

© 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.

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Chicken Eggs

Is there anything you did not yet know about them?

We used to keep chicken in New Zealand and it was my job every morning to collect their eggs and turn them into fried or poached eggs, boil them hard or soft, or serve them as scrambled eggs with some chives added to them. At that time, I frequently came across some abnormalities which excited my children (but not my Indian Brahmin wife, who never consumed eggs, fish or meat). Most interesting to them were the occasional eggs with two egg yellows, but even though all this happened many years ago, I remember all of the exceptional eggs I came across at that time. This morning, however, I had an egg with an abnormality I’d never seen before. The egg (like all fresh eggs do) sank nicely to the bottom of the pot, was boiled for 5 min, held briefly under cold water and then carefully de-shelled. You’d normally find an “air space” on the egg’s blunt end, but in this egg the air space was under the egg’s “equator”!

It was this incident this morning which made me look up some of my old notes on egg abnormalities that I (and others like a 19th century character with the beautiful name Wilhelm v. Nathusius-Königsborn) had encountered when studying eggs and their shells. First of all there is the egg’s shape, which can vary from almost spherical to torpedo-shape, but usually is -well, ‘egg-shaped’. I loved the occasional egg with a wrinkled appearance as if it had gone through the washing machine, but my children felt it was too odd and avoided it. I, on the other hand, felt these eggs were particularly tasty. Once I had a longish egg with no bilateral symmetry that looked as if bent. And then there is, of course, the occasional egg with little sand-like protrusions, i.e. calcium carbonate pimples on the shell’s surface. After the war (WWII that is) and not from our chickens, I had once received an egg with no hard shell at all, a case that suggests the hen had received insufficient (or too much) calcium or was stressed. However, if fresh and there’s nothing wrong with them, such eggs can be eaten just like eggs with white, brown or even greenish shell colours. A lot of such shell, shape and colour abnormalities reflect an unbalanced diet,  stress, hen’s age or even sickness, but some  -especially the shell colours- are genetically fixed.

Cracking an egg open can give you the surprise of not only finding one, but two or even more yellow egg yolks, but finding no yellow at all may surprise you the most!  Such eggs are known as fart or wind eggs and were once thought to be those of roosters. In fact, it’s the very young or very old hens that are likely to produce yolkless eggs. On one occasion I found a complete little egg with its own shell inside another and, of course, much bigger egg with its own shell. Apparently, this can be caused by an egg reversing its course in the egg tube or oviduct and getting packaged into a newer egg. However, it’s not a big problem: when fresh, both are edible. Also edible, when fresh, are unsightly eggs that exhibit blood patches near or in the yolk. The blood stems from vessels that carry yolk-building material to a hen’s ovary.

There are in rare cases chicken egg abnormalities that I myself during the time we kept chickens had thankfully never been confronted with. A nematode worm known as Ascaridia galli can occur in eggs laid by hens that suffer from a high parasite load. The twisted whitish bands in the egg white that are attached to the yolk and hold it in place are a normal component of eggs and must not be confused with such worms. Certainly more worrying are microbes like Mycoplasma synoviae (which alter the shell surface, cause thinning and increased shell translucency) and Salmonella enteritidis. The latter can enter damaged eggs or may even occur in clean, intact shelled eggs as a result of infections of the reproductive tissue of laying hens. However, it doesn’t show up as an egg abnormality and you won’t notice it until you start vomiting, develop a fever, stomachache, and diarrhoea. But then it’s too late and you had better decide – if you feel like eating an egg again-  to purchase your next carton of eggs from a different supplier who only sells fresh eggs kept not above 20℃ (Salmonella loves temperatures around 30℃).

© 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. 

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Internal Sunglasses

Some birds appear to have sunglasses

Although I myself did not have to wear glasses (except perhaps sunglasses) until I turned 55, millions of people on Earth may view this simple ‘tool’ to improve the resolving power of their eyes as one of the greatest inventions ever made. Photographers, microscopists, and opticians can tell you that the aperture of an optical system not only controls the amount of light admitted (and thus the brightness of the image you see) but also the resolving power of the system. —>—>