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.

Adolf Hitler and the Scrotum

A Discussion about Testicles

Some colleague in Australia wanted to know from me once what my view was on Adolf Hitler’s condition of ”having had only one ball” (= one testicle). I knew nothing about this, but later learned that many people believed that to be true. And so it was (in a way), for according to a report by Prof. Peter Fleischmann in 2015, based on the medical records of Hitler’s health, the man had suffered from an undescended right testicle. Medically this does not mean he had only one testis; it only means that just one was externally visible. Surgically, of course, it is sometimes necessary to remove one (or even both) and historically eunuchs, men in other words who for whatever reason were bereaved of their testicles, come to mind. I remember having read once that some tribal people practiced the ritual removal of one testicle, but despite a thorough investigation involving internet search engines, I could not locate the source of that information and wonder if a reader can perhaps help and find evidence in support of that claim. However, what is well documented is that in most men the left testicle is bigger than the right one and that the Greeks of the antiquity (wrongly) believed that sons were “made” by the right and girls by the left testicle.

Anyway, I want to devote this blog to the structure that males cannot be without: their testes (also known as testicles). If men can be fertile with just one testicle externally visible (whether the other is missing altogether or simply undescended as in Hitler’s case), why do these structures in most but not all mammalian males, dangle on the outside of the body in their little scrotum bag? Amongst bats, insectivores and rodents it is common to find that the testes migrate from the inside of the body into a scrotum during the mating season; afterwards they move back to their hidden location inside the body. But elephants and other mammals known as Afrotheres, which also include elephant shrews, tenrecs, aardvarks, hyraxes, sea cows and several extinct groups, all possess testes that never  – not even during the mating season –  become externally visible and constantly remain hidden and protected inside the male’s body. In whales the testes are permanently internal and that would probably make sense if one considers hydrodynamic drag and having to swim with a dangling scrotum.

A widely accepted theory, for which good experimental evidence exists, postulates that higher internal body temperatures are damaging to the spermatozoa. But this does not square with the examples of species given above that don’t have an externally placed scrotum with testicles in them. Besides, if temperature is so deleterious to sperms, why do all bird species have their testicles inside their bodies, even a bird’s body temperature is usually higher than that of a mammal? The discovery of “testicle descent genes” in the Afrotheres species has recently been announced. This suggests that during evolution these genes either mutated or were inactivated and consequently prevented that the testes descended in Afrotheres. But did their spermatozoa suffer or become damaged? It doesn’t look like that and it seems that protecting the sperm-making structures from physical damage was of greater concern than preventing effects that the higher internal body temperature might possibly cause. Could, therefore, the evolutionary older testicular descendence have had a different function?

That is possible, because in species that exhibit a seasonal testicular “out-and-inward” migration, the appearance of a voluminous scrotum could be a sexual signal, especially if combined with an attractive colour. A permanent display of maleness through externally visible testicles could have been the reason why in most mammalian species the testes are not retained inside their bodies. In humans, following ejaculation, testes are sometimes temporarily retracted into the body cavity: a case of an atavism? An echo from the past? Or a sign of what is still to come?

© 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.

A Bit of Philosophy on Movement, Motion, and the “Mirror Neurons”

One of my graduate students’ fathers was a Professor of Philosophy and in most Anglo-Saxon countries a doctorate, obtained in whatever subject it may be, is usually called a PhD (which stands for Doctor of Philosophy). You might call this a quirk of history, going back to antiquity when Greek mathematicians, scientists, healers and thinkers were all “philosophers”. Anyway, if you hope a conversation with a philosopher will help you find answers to questions you carry in your mind, you are likely to be in for a disappointment and may leave the philosopher with more questions in your mind than you had before. Perhaps that is the function of philosophy: to make you question what is real and what isn’t and to make you think what makes “you” to be “you”. Bonjour Monsieur René Descartes: Cogito ergo sum!

Anyway, my conversation with a philosopher dealt with movement and motion, which I thought was the straightforward action of something being in the process of changing its position from one place to another. But that assumes, so the philosopher, that a moving object occupies successive positions ever so briefly while it is moving. But it is impossible to ‘count’ such positions as there would be infinitely many. It’s not like an old movie, in which separate pictures in quick succession create ’movement’. If I’d argue that one could say an object decreases its distance from one place to another while “on the move”, the philosopher would argue that a moving object has no definitive starting point. Moreover he’d point out that while the Earth rotates, we all move all the time and he made me think of sitting in a moving train watching a fly flying from one seat to another. Motion is indeed “philosophy”!

However, biologically motion and rest, we agreed, are different modes of a moved body, but to visibly move a part of the body, muscle fibres need to be activated to contract by signals from a nerve cell: a neuron. Now imagine you wave to someone you don’t know, what happens? Most likely that person will wave back. A child, playing happily, upon observing another unrelated child cry is very likely to begin to cry too and attendants of a meeting in which the speaker repeatedly touches his ear may also begin to touch their ears. This copycat phenomenon is due to so-called ‘mirror neurons’ in the brain that were discovered by Di Pellegrino et al. and Rizzolatti in 1992. The mirror neuron system has evolved at seemingly different rates in and among species and involves hand and mouth visuo-motor and audio-vocal mirror neurons in different regions of the brain (more precisely for those who want to know: the superior temporal sulcus, the pre-motor cortex, the inferior parietal lobe). Interestingly, neurons of the premotor cortex apparently distinguish between hand-made movements (which they mirror) and tool-made movements (which are not mirrored).

The purpose for which these mirror neurons have evolved seems to facilitate communication between individuals of the same or at least related species (monkeys and humans, for example). It has also been postulated that mirror neurons play a role in the development of empathy and to imagine another person’s state of mind. Mirror neuron systems may be involved in dance routines, sports, speeches in which gesticulations are involved, etc. and it has been postulated that in sufferers of autism the mirror neuron system may be impaired. However, conflicting data on this hotly debated issue do not currently allow a definitive conclusion. Whether mirror neurons exist in insects and are, for instance, involved during the migratory phase of locust hoppers when the action of one individual jumping forward is followed by other nymphs nearby, is a possibility, but hasn’t yet been investigated. For mammals and birds, however, there is no doubt that mirror neurons are present and I wonder: Was that perhaps the reason why our dog always began to runaround when our children started running up and down our yard and the reason why our children were trying to lap up milk from a plate like our cats did?

© 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.