On Being A Tube Worm

This is only going to involve a bit of light zoölogy.

That illustration above, of a polychæte worm called Chætopterus, looks quite fierce and jagged. In fact these animals are entirely innocuous to humans and we rarely encounter them, but I have at times become inordinately focussed on them. Although this is not really about them, they’re worth considering, so I’ll go into a bit of detail.

Any number of species of animal sit around all the time not doing very much, particularly in the sea and to a lesser extent in the much harsher environment of freshwater rivers, lakes and ponds. There’s no particular reason to single Chætopterus in this respect. It just happens to be one of those countless animals whose lifestyle involves doing very little other than filtering food out of water. The picture shows such a worm in a state it would rarely be in while alive, because in its burrow its chætæ would be lying flat against its sides, and they are by no means sharp or offensive weapons. It lives in a mucus-lined U-shaped burrow in mud or sand, although some of them live under rocks. The middle section has fans which draw sea water down towards them and the front makes a bag of mucus in which a bolus of food is formed, which it passes down its back towards its mouth. The current it creates also enables it to breathe, just as a fish’s gills exchange dissolved gases in a current. It’s completely blind, but oddly it also glows blue when disturbed. Any consciousness it has does not include the luminescence, so it can’t perceive that it does this and there’s no possibility of it being a signal between individuals of the same species. There are a couple of small species of crab who tend to share its burrow and they can’t live anywhere else.

Really, the point is not the animal itself, as it’s only one of many sessile organisms who do nothing but filter feed on the bottom of bodies of water. In some cases this is extreme, in the sense that they actually live kilometres down on the abyssal plains of the oceans, but on the whole their lives seem quite simple compared to our own. They just suck and eat. In the case of Chætopterus they also have separate sexes, but even simultaneous hermaphrodites generally benefit as a species from combining their gametes with other individuals. It is worth asking how a sexual animal that just lies there all day can reproduce and whether this contributes to the richness of their life experience. Females release a chemical which stimulates the males to release sperm, which in turn stimulates the females to release eggs. In both cases this is done by rupturing the body wall, so in a sense both sexes explode with pleasure, and we might imagine this as orgasmic. The gametes then combine in the water, becoming planktonic larvæ, most of whom are presumably eaten, possibly by adults of the same species. Being a tube worm is not like being human. The presumed death of the parent worms conveniently gets them out of the way for the next generation, preventing them from hogging resources such as food and substrate, and is pretty normal for thousands of animal species. It means that they are all absentee parents and orphans, and they substitute parental care with prodigious physical reproduction.

It seems to be an easy life. It also seems to be the kind of life which, if lived by a human being, would lead to our swift demise. There are trivial ways in which this is true: for instance, obviously no human is going to live very long buried in the seabed trying to breathe water. However, on the whole it’s a very inactive life, and although there are overuse injuries, often acquired by athletes, humans more often suffer as a result of physical inactivity or disuse: “use it or lose it”. In the richer parts of the planet, many health problems are associated with not doing very much physically, although the situation is very different in the global South, and has historically been elsewhere. Yet there are many animals who do best when left alone.

In a way, the life of a polychæte worm buried in silt all her adult life is idyllic. On the other hand, harnessing the probably instinctive taboos humans have about mucus, what she’s “actually” doing is very similar to picking her bogies and eating them, because the dust we inhale which gets trapped in our nostrils by the mucus and is then sometimes disposed of by people “picking their nose and chewing it” as the song has it, is how she keeps body and soul together. An odd thought in a way, and also a disgusting one. She also lives in a tube of congealed mucus. There’s another question here. Is this tube to be considered part of the animal’s body or is it just a container? Also, if it’s the latter, it could be considered to be clothing for worms in a way, so humans are not the only clothed species, although caddis fly larvæ cases are a lot closer to what we do.

The inevitable issue of consciousness arises. As a panpsychist, I am going to say that of course this species is conscious. There’s even a central nervous system including a brain. Some polychætes, notably peacock worms, react a hundred times faster than we can, which makes them superior in that one respect. I don’t know if this is true of parchment worms (which is what they’re called because of the texture of their tubes) as they don’t seem to need to respond so quickly to a stimulus. Their companion crabs use their burrows to hide from predators, so it’s probably quite a dull life from that perspective too. Nonetheless they can sense the pheromones in the water, seem to make some kind of decision as to when to release them, also choose when to move the lump of food and mucus towards their mouths and do something which results in them glowing blue when they’re threatened, although that could in theory be passive. There also seems to be some awareness of the passage of time, or of the right conditions coming about, in the female initiation of the reproductive sequence. However, thinking of our own puberty, although there is a correspondence between life events and hormonal changes, they aren’t, at least straightforwardly, under conscious control. The endocrine system has parallels to the nervous system and even uses some of the same compounds such as adrenalin, but only one appears to involve consciousness clearly. All that said, maybe there’s a shadowy, or not so shadowy, consciousness within our endocrine and immune systems, and maybe they’re even linked to what we think of as our nervous system-based consciousness. After all, almost nobody who remembers or experiences it would say puberty doesn’t pack an emotional punch, and this is just one example of a hormonal event, albeit a near-universal one.

The SF writer Philip K. Dick introduced the concept of “zebra”. Based on the idea that zebra stripes are a form of camouflage, which they probably aren’t, PKD conjectures that although we may be aware of camouflage which works well to fool other species into not noticing particular organisms, there could also be a successfully camouflaged entity which completely deceives all human beings. Although it’s almost impossible for this to be a scientific possibility, because the idea is that it is in principle impossible to observe this entity, nothing seems to rule it out, and there’s also an element of humility in the idea that we humans may be as subject to being deceived as any other animal. There are very clear examples where we know we’re being fooled some of the time, as with the likes of flatfish and cuttlefish who can change colour and hide themselves visually, and the way cricket chirps seem to come from a different direction than the actual cricket is a similar happenstance, but the rational possibility exists that there could be something we will never see or know about. Our sensory world is quite restricted in various ways, notably due to our practically non-existent sense of smell, and it seems feasible that a dog, for instance, would be able to smell our fear or a change in odour when we get certain types of cancer. We don’t know what tricks or senses are possible which are not available to us. Hence what are the chances that, just as Chætopterus glows blue when threatened, presumably scaring off some potential predators, we also have an adaptation which serves a function for us but of which we are completely unaware, even in principle? It needn’t be something particularly exotic. Maybe we emit an aversive odour when we’re afraid which deters predators, and dogs can smell it but are not averted.

Carefree lives are probably rare, and I’m thinking of all animal lives here, possibly more than that. I was clearing up some lumber earlier and a spider fled across one of the planks. I think it would be a failure of empathy to deny she was afraid. Whether that’s actually so is another matter, but the benefit of the doubt should be exercised on most occasions. If you see an animal of whatever size or phylum moving as fast as they can away from an obvious threat, it makes sense that that’s how they’re feeling. I could go on, but I won’t. The observation was once made to me that in the past, every human adult’s life involved being afraid, hungry and tired almost all the time, and the same still applies to the rest of the animal kingdom. I’m not entirely sure this is true of humans because they were on top of things, but it does occur to me that childbirth and parenting of small children at least seems to resemble that more closely than most of the rest of human life in an industrial or post-industrial society for most White able-bodied wealthy (etc) humans.

There used to be a pair of wood pigeons which nested in a sycamore tree outside our house. During discomfortable conversations with Sarada I used to look at them and imagine they had an easy, simple, happy relationship raising chicks and letting them free into the adult world. They came back at least once. Then it became clear that the sycamore was sending roots under the neighbours’ house and causing damage, and it was deemed that the tree be felled. This was not while they were nesting in it, but it occurred to me that they might return to their haunt the next year and find it gone, so their life wasn’t really as blissful as all that, thanks partly to us. Probably most of a wood pigeon’s life is nasty and miserable. The average lifespan of the species in the wild is three years, but they can live for more than seventeen in captivity, demonstrating the difference between potential and reality. A house mouse can be expected to live an average of eighteen weeks but could live to be a year and a half. I don’t know if these figures are skewed by infant mortality. This was probably never true of humans or their childhoods would have to have been a lot shorter than they generally are, but it shows how hard life generally is.

But the thing is, maybe life for humans is supposed to be hard. Not for us that nice cosy mucus-coated burrow in the mud. Something about our very existence might have to be difficult for us to live at all. When I consider our granddaughter, I’m acutely aware that she is happy and carefree much of the time, or so I imagine, but thinking back at my own childhood I can remember that at the age of ten I traced back what I worried about and found that worry had been my constant companion for as long as I could remember. That might be me of course, but I don’t think childhood is the happiest time of most people’s lives, or rather, I don’t think childhood is usually happy. It might be that adulthood has more potential for happiness but maybe it doesn’t get realised. Nor do I think poverty is the sole culprit here because many wealthy people are thoroughly miserable, not necessarily because of their wealth but because that’s what life is like. On the other hand, maybe that’s just what we’re supposed to believe because human life could be a whole lot better but it isn’t, though not because of non-human influences.

They shoot horses. I don’t honestly believe it’s kinder to do so because there are examples of horses who were able to recover from serious limb injury, but it is also true that to a considerable extent a horse is a running being, and not being able to do so is psychologically and physically injurious. Humans need to be good at being human, but it isn’t always clear what that involves. We don’t, then, benefit from living in slimy holes on the sea bed, but what do we benefit from?

I’m not totally clear what I’m getting at here. Maybe I should’ve thought about it a bit longer, or maybe you can tell me.

Stripy Horses Or Plain Zebras?

Yes, I know what’s happening in the Ukraine. This is what’s stopped me from blogging. Before I get going on this subject, I want to explain why I haven’t said much about it. The truth is that my limited knowledge of the matter leads me to fear saying anything which might turn out to be ill-judged or crass. We all know it’s happening. My response to it, like many other issues, is to engage in what I hope is a helpful manner but also to recognise that there is a lot else going on in the world at all times, and there’s a rôle for escape. For what it’s worth, I’m thinking about Putin’s odd association between a country with a Jewish leader and Nazism, and the psychological influence being a long-term leader has on the person in that position. Even so, I am going to talk about zebras.

There’s a saying in medicine that if you hear the sound of hooves, you should conclude it’s horses and not zebras, which obviously makes more sense in Europe than in certain parts of Afrika. One of the shortcomings of my cognitive style is that I will tend to think of zebras more than horses and then wonder why everyone else hasn’t thought of that. In the context of medical diagnosis, this might mean I’m more likely to think someone has Lewy Body Dementia than Alzheimers or Paget’s Disease of Bone than arthritis. This is, however, self-correcting and doesn’t constitute a huge problem, because in herbalism one can address more than one possible diagnosis at once without necessarily doing harm. Also, it isn’t my job to diagnose, which is a responsibility legally enshrined in particular offices, none of which are mine. That said, I do need to have a firm grasp of disease processes to address them.

But this is not the other blog, so I’ll broaden that to something which is in fact relevant to the current Eurasian situation. If a first-language reader of a language with a Latin script such as English sees a page of Cyrillic text and is mindful of the adage that if you hear hooves, expect horses, they’re quite likely to presume that the passage is Russian rather than, say, Ossetian. However, Cyrillic has been used to write a wide variety of languages and it may not be Russian. This, of course, would arise in the case of the Ukrainian language, since a cursory glance from someone unfamiliar with the details of the differences might think the text was Russian. This is part of the Universal Declaration of Human Rights in Ukrainian:

Всі люди народжуються вільними і рівними у своїй гідності та правах. Вони наділені розумом і совістю і повинні діяти у відношенні один до одного в дусі братерства.

And this is the same in Russian:

Все люди рождаются свободными и равными в своем достоинстве и правах. Они наделены разумом и совестью и должны поступать в отношении друг друга в духе братства.

For the record, in English this reads:

All human beings are born free and equal in dignity and rights. They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood.

Since I’m much more familiar with Russian than Ukrainian, having abortively attempted to learn it in the late 1970s and early ’80s CE, the first text looks foreign to me, and in particular its use of the letter “i” seems very incongruous. The two languages are quite similar, and I wonder if the differences would be perceived as a little like those between Scots and English. That is, is there a tendency for Russian speakers to regard Ukrainian as merely a dialect of Russian? Historically there has been. This might sound quite abstruse in the setting of the conflict, and I’m aware too that many Russians won’t consider this war as done in their name, but it does impinge on English media in one particular aspect: the name of the capital city.

I’ve long considered the name of the capital of the Ukraine to be «Киев», but in fact that is the Russian version. The Ukrainian, and therefore correct, name of the city is «Київ», and at this point I’m also wondering about Ukrainian punctuation – do they use guillemets like Russian or something more like inverted commas? The Romanisation of the name is now “Kyiv” in English, whereas it has formerly been written “Kiev”, the Russian pronunciation. Is it important to focus on this with all the other stuff going on? Well, probably. The spelling and pronunciation of placenames in the Ukraine has remained stubbornly Russian in the international news media even though the country became independent from Russia in 1991 and the name of the capital was officially changed in 1995. This politicises the name. It once again reminds me of Scottish placenames, which in that case is further complicated by the presence of the Gàidhlig language and its nationwide promotion by the Scottish government. Speaking of which, when I laboriously ploughed through a Russian tweet yesterday (not “labourious” – there’s another one), I found myself, as I often am, reminded of Q-Celtic languages in the dual pronunciation of many of the consonants, leading me to feel very much, once again, that they could really benefit from being written in Cyrillic script. But it ain’t gonna happen is it? Another illustration of the politics of scripts.

But this post wasn’t supposed to be about the Ukraine but horses, asses and zebras. Note that I put horses first in that list. Conceptually, we often have a tendency to separate marked from unmarked concepts in our language and thought, so I clearly regard horses as the unmarked concept in that list. Also, asses are apparently less exotic than zebras to me. There is some justification for that because a zebra, visually speaking, is literally marked, but there are other aspects to this. For instance, in Western Eurasia, where I live, horses are more familiar and widespread than zebras, and this is basically down to human exploitation of them. Historically, the exploitation of horses is vastly important and the domestication of the horse is a necessary pre-requisite to that. I feel unqualified to comment on the issue of veganism and horses because I’m aware of disparate views and my own encounters with them are somewhat limited, though also a lot more extensive than the average contemporary Western urbanite because I grew up in the country, used to hunt sab and have been on a lot of demos with mounted police present. It’s odd to think that up until a little over a century ago, these animals would’ve been an everyday part of life for most people in these isles regardless of where they lived.

I’m aware also that I’m thinking rather in terms of a binary opposition between zebras and horses rather than a ternary one between horses, asses and zebras. I can’t help thinking, though, that zebras and asses have a lot in common compared to zebras and horses, such as their tails and manes being more similar. I don’t have a firm impression of how large zebras are either, and I’m aware that there are three species of them and just talking about “zebras” generically is fairly vague.

But the question I’m working up to is this (actually there are two): Is a horse a plain zebra, or a zebra a stripy horse? It could equally well be, is a donkey a plain zebra or a zebra a stripy donkey? I should probably also explain why I’ve been calling them asses. The reason for this is that donkeys to me seems to refer to the domesticated species, but there are two other species of ass who are wild. I’m not being frivolous here, incidentally. My question is, are the extinct ancestors of today’s equines primitively stripy or primitively plain? Or did they have a different appearance than either of these? It seems to me that we assume in many pictures of prehistoric equines that they were primarily plain, although some have stripy portions of their coats. When we do this, are we being “horse-centric” or is it based in science? Are zebras the unusual ones? How could we find out?

The other question also sounds nonsensical but isn’t: is a zebra black with white stripes or white with black stripes? This doesn’t seem to make sense until you see one of the unusual individual zebras who are the other way round than usual, and at that point you realise that it is in fact normally a particular way round. Right now, I can’t remember which. But this is a secondary point.

Equines are members of a declining clade, that of odd-toed ungulates or perissodactyls. This order’s heyday was back in the earlier part of the Cenozoic and includes the largest land mammal ever, the Indricotherium, which shows convergent evolution with the giant sauropod dinosaurs of the Mesozoic. Nowadays there are the relatively widespread equines, the rhinos and the tapirs, and so we’re in the peculiar position of having a small order with one or two extremely populous species, namely the donkey and horse, a couple in the middle and a relatively large number of species who are largely recently extinct because of us, or severely endangered for the same reason. However bad the domestication of the horse and donkey may have been for individual members of those species, it’s turned out to be good for their survival as species.

Domestic zebras don’t happen. This is because they don’t meet six criteria making a species suitable for this, which incidentally humans may have done themselves – we may ourselves be domesticated. These criteria are that they must:

• Eat food that’s easily available where humans live.
• Reach maturity quickly.
• Don’t panic easily when startled.
• Be docile.
• Breed easily in captivity.
• Have a social hierarchy.

Zebras only conform to some of these. For instance, they do graze like horses but they’re quite aggressive. They’re unpredictable and have been known to attack humans. The same is true of horses but to a much lesser degree. This seems like a good adaptation for resisting being dominated by other species, such as ourselves, but ironically it seems to have led to them becoming much rarer than horses, or perhaps staying at a similar level of population for longer. Remarkably, one of the effects of domestication is often that the animals resulting have black and/or white patches, so the fact that zebras aren’t but are still black and white is interesting.

One problem with working out whether they were primitively striped or not is that fossil horses are of course just bones and teeth on the whole. I’m not aware of either frozen or tar pit equines, although they may exist, so the problem is they tend to be fossilised in such a way as not to preserve skin or hair. There’s another issue too. It may not be a question of stripes versus plain so much as the distribution of the stripes or the presence of other patterns. There are melanistic zebra foals with white spots on a black background, as it were. It seems there could be several ways of working out what happened when.

Zebras are stripy for a reason and the question arises of what selective factors might have led to this. Perhaps surprisingly, it doesn’t seem to be connected to protection from large predators. They can be smelt by lions and other carnivores from further off than the stripes would make a noticeable difference to their appearance. It’s thought that the real reason is to confuse biting insects, which is also the cause of their tail anatomy, which acts as a fly swatter. Asses have the same kind of tails. Therefore, is it possible that the stripiness or otherwise of an equine could be related to their tail anatomy? Not entirely, since asses are not striped, but horses are the ones with divergent tails and zebras and asses both have the original in that respect. However, these are only two of a dozen and a half theories about this.

Just to answer the question of whether zebras are black with white stripes or the other way round, zebra skin is black and it’s an adaptation for some of their coat to appear white, so they are black with white stripes rather than the other way round. This becomes evident when you see a zebra who is striped as a “negative” of the common type, because they actually look like white animals with black stripes. There are also three living species of zebras with slightly different skin patterns: Grévy’s, Mountain and the Plains Zebra. They’re in a subgenus referred to as Hippotigris, and there are two others, the asses in the unsurprisingly named Asinus – these have three living species, two of whom are Eurasian and one Afrikan. Finally, there’s the horse itself, presumably in a subgenus called Equus, and although there are two subspecies of these, namely the tarpan and Przewalski’s horse, the latter has a different number of chromosomes, so I don’t understand why it’s considered the same species. European horses, now extinct, were also a separate species, and some of these were piebald, as can be seen in cave paintings. Przewalski’s horse and the ancestors of modern domesticated horses diverged during the last Ice Age, roughly in Crô-Magnon times. It may be that the tarpan and Przewalski’s horse are the same species and horses a separate one.

There used to be a fourth subgenus: Amerihippus. Unsurprisingly, these are American, and in fact horses originally evolved in North America although they died out before Columbus. Once again, the presence of horses and their possible domestication in America might have made a huge difference to the course of history, but of course nobody knows if their temperament was more like zebras or horses and asses, and of course whether they were striped, plain or something else. There are Pre-Columbian native figurines of horses. It used to be thought that American horses were wiped out during the last Ice Age, but in fact they seem to have survived it. Genetic studies have shown that there were horses unrelated to those introduced by Spanish settlers in North America, and only two years after Cortez arrived, there were people on horseback in the Carolinas, even though meticulous paperwork recorded that none of the horses brought by the Conquistadores had escaped or been otherwise lost. There is a political element in the idea that American horses died out in the Ice Age, because it makes it seem that anything worthwhile was introduced by the Europeans. However, this does still raise the question of why horses seem to be so much more important in Eurasian cultures than Native American, and also makes me wonder if their ancestors had always been in America. Native American dog breeds are remarkable in that although they are still of the same appearance and behaviour as the breeds present before the Europeans, they are actually now entirely descended from Old World dogs. How this happened is a mystery. Native American horses today can have curly or very long manes compared to Old World horses. They are also sometimes piebald. More remarkably, some of them have slightly stripy legs! This, I think, is a clue.

The other hypotheses regarding zebra stripes include the idea that they create cooling convection currents by forming alternating hot and cold strips of air, that they help zebras recognise each other and that they’re warning colouration for what are apparently quite aggressive animals. If these situations apply to North America at the time the ancestors of today’s Afrikan zebras left, it’s feasible that they were already striped.

It’s said that the reason for the long manes and hairy tails of horses is connected to the North American climate. If this is so, it would be expected that their ancestors wouldn’t have had these before it became quite so harsh. It seems that the cold of the Ice Ages led to horses evolving these features, and in fact Przewalski’s horses have spikier manes than the more familiar horses, although their tails are still similar. As mentioned previously, the Palæarctic and Nearctic zoögeographical realms are sometimes united into a single Holarctic realm, consisting of North America and Eurasia, and the mammalian and other fauna of this vast region, comprising fifteen percent of the planet’s land surface excluding Antarctica, is shared between the two continents, such as wolves, bears, formerly woolly mammoths, beavers and so forth. However, of course there are differences – coyotes spring to mind very close to being wolves but not quite – and the question arises of whether the North American horses are the same species as Eurasian horses. I presume that if they couldn’t breed true, this would’ve been noticed by now, so the alternatives seem to be that native North American horses are either hybrids with Eurasian horses with some North American horse DNA, just as some Homo sapiens have Denisovan and/or Neanderthal DNA, or that the horses in question have always been two subspecies. The former possibility is particularly interesting because of the presence of faintly striped legs among them. If this is from a separate species of native North American horse hybridised with Eurasian horses, maybe that species was more obviously striped.

I’ve largely ignored asses in all this, which is probably a mistake. I do have the impression, and it’s just a hunch, that asses and zebras are closer to each other than zebras and horses. One reason I think this is that there are native Afrikan asses but no native Afrikan horses. Zebras are smaller than horses at around a dozen hands and weigh from 250 to 450 kilos. Adult plains zebras can be as little as ten hands and Afrikan wild asses actually slightly larger. It’s easy to get hypnotised by the apparently central, “standard” equines we’re familiar with in Europe and ignore a possible alternate route of zebra ancestry.

So, to conclude, this is what I think, and this isn’t based on genetics. It’s scientifically established that equines are essentially American animals. Incidentally, there also used to be native South American horses which I’ve ignored for the purposes of this post. The original members of Equus had coats of various colours and patterns, including piebald, black and different shades of brown. Some of these had faint stripes, and these traits were widely distributed through the first species of the genus, Equus simplicidens, also known as the American zebra and found in Idaho, Texas and presumably other places. They’re supposed to have looked like this (the one on the left):

I don’t know what the reasoning behind the idea that the American zebra was striped is. I do know that the apparently most basal population of humans, the San, has considerable genetic variation in skin tone so my conclusion is that the American zebra was probably quite variable but had a brown and fawn striped variety. I also wonder if the South American horses were a lot more like zebras due to living in similar climates to today’s Afrika south of the Sahara.