Archive for the ‘fitness’ Category
kin selection – some fascinating stuff
Canto: So we’ve done four blogs on Palestine and we’ve barely scratched the surface, but we’re having trouble going forward with that project because, frankly, it’s so depressing and anger-inducing that it’s affecting our well-being.
Jacinta: Yes, an undoubtedly selfish excuse, but we do plan to go on with that project – we’re definitely not abandoning it, and meanwhile we should recommend such books as Tears for Tarshiha by the Palestinian peace activist Olfat Mahmoud, and Goliath by the Jewish American journalist Max Blumenthal, which highlight the sufferings of Palestinian people in diaspora, and the major stresses of trying to exist under zionist monoculturalism. But for now, something completely different, we’re going to delve into the fascinating facts around kin selection, with thanks to Robert Sapolski’s landmark book Behave.
Canto: The term ‘kin selection’ was first used by John Maynard Smith in the early sixties but it was first mooted by Darwin (who got it right about honey bees), and its mathematics were worked out back in the 1930s.
Jacinta: What’s immediately interesting to me is that we humans tend to think we alone know who our kin are, especially our extended or most distant kin, because only we know about aunties, uncles and second and third cousins. We have language and writing and record-keeping, so we can keep track of those things as no other creatures can. But it’s our genes that are the key to kin selection, not our brains.
Canto: Yes, and let’s start with distinguishing between kin selection and group selection, which Sapolsky deals with well. Group selection, popularised in the sixties by the evolutionary biologist V C Wynne-Edwards and by the US TV program Wild Kingdom, which I remember well, was the view that individuals behaved, sometimes or often, for the good of the species rather than for themselves as individuals of that species. However, every case that seemed to illustrate group selection behaviour could easily be interpreted otherwise. Take the case of ‘eusocial’ insects such as ants and bees, where most individuals don’t reproduce. This was seen as a prime case of group selection, where individuals sacrifice themselves for the sake of the highly reproductive queen. However, as evolutionary biologists George Williams and W D Hamilton later showed, eusocial insects have a unique genetic system in which they are all more or less equally ‘kin’, so it’s really another form of kin selection. This eusociality exists in some mammals too, such as mole rats.
Jacinta: The famous primatologist Sarah Hrdy dealt something of a death-blow to group selection in the seventies by observing that male langur monkeys in India commit infanticide with some regularity, and, more importantly, she worked out why. Langurs live in groups with one resident male to a bunch of females, with whom he makes babies. Meanwhile the other males tend to hang around in groups brooding instead of breeding, and infighting. Eventually, one of this male gang feels powerful enough to challenge the resident male. If he wins, he takes over the female group, and their babies. He knows they’re not his, and his time is short before he gets booted out by the next tough guy. Further, the females aren’t ovulating because they’re nursing their kids. The whole aim is to pass on his genes (this is individual rather than kin selection), so his best course of action is to kill the babs, get the females ovulating as quickly as possible, and impregnate them himself.
Canto: Yes, but it gets more complicated, because the females have just as much interest in passing on their genes as the male, and a bird in the hand is worth two in the bush…
Jacinta: Let me see, a babe in your arms is worth a thousand erections?
Canto: More or less precisely. So they fight the male to protect their infants, and can even go into ‘fake’ estrus, and mate with the male, fooling the dumb cluck into thinking he’s a daddy.
Jacinta: And since Hrdy’s work, infanticide of this kind has been documented in well over 100 species, even though it can sometimes threaten the species’ survival, as in the case of mountain gorillas. So much for group selection.
Canto: So now to kin selection. Here are some facts. If you have an identical twin your genome is identical with hers. If you have a full sibling you’re sharing 50% and with a half-sibling 25%. As you can see, the mathematics of genes and relatedness can be widened out to great degrees of complexity. And since this is all about passing on all, or most, or some of your genes, it means that ‘in countless species, whom you co-operate with, compete with, or mate with depends on their degree of relatedness to you’, to quote Sapolsky.
Jacinta: Yes, so here’s a term to introduce and then fairly promptly forget about: allomothering. This is when a mother of a newborn enlists the assistance of another female in the process of child-rearing. It’s a commonplace among primate species, but also occurs in many bird species. The mother herself benefits from an occasional rest, and the allomother, more often than not a younger relation such as the mother’s kid sister, gets to practice mothering.
Canto: So this is part of what is called ‘inclusive fitness’, where, in this case, the kid gets all-day mothering (if of varying quality) the kid sister gets to learn about mothering, thereby increasing her fitness when the time comes, and the mother gets a rest to recharge her batteries for future mothering. It’s hopefully win-win-win.
Jacinta: Yes, there are negatives and positives to altruistic behaviour, but according to Hamilton’s Rule, r.B > C, kin selection favours altruism when the reproductive success of relatives is greater than the cost to the altruistic individual.
Canto: To explain that rule, r equals degree of relatedness between the altruist and the beneficiary (aka coefficient of relatedness), B is the benefit (measured in offspring) to the recipient, and C is the cost to the altruist. What interests me most, though, about this kin stuff, is how other, dumb primates know who is their kin. Sapolsky describes experiments with wild vervet monkeys by Dorothy Cheney and Robert Seyfarth which show that if monkey A behaves badly to monkey B, this will adversely affect B’s behaviour towards A’s relatives, as well as B’s relatives’ behaviour to A, as well as B’s relatives’ behaviour to A’s relatives. How do they all know who those relatives are? Good question. The same researchers proved this recognition by playing a recording of a juvenile distress call to a group of monkeys hanging around. The female monkeys all looked at the mother of the owner of that distress call to see what she would do. And there were other experiments of the sort.
Jacinta: And even when we can’t prove knowledge of kin relations (kin recognition) among the studied animals, we find their actual behaviour tends always to conform to Hamilton’s Rule. Or almost always… In any case there are probably other cues, including odours, which may be unconsciously sensed, which might aid in inclusive fitness and also avoiding inbreeding.
Canto: Yes and It’s interesting how this closeness, this familiarity, breeds contempt in some ways. Among humans too. Well, maybe not contempt but we tend not to be sexually attracted to those we grow up with and, for example, take baths with as kids, whether or not they’re related to us. But I suppose that has nothing to do with kin selection. And yet…
Jacinta: And yet it’s more often than not siblings or kin that we have baths with. As kids. But getting back to odours, we have more detail about that, as described in Sapolski. Place a mouse in an enclosed space, then introduce two other mice, one unrelated to her, another a full sister from another litter, never encountered before. The mouse will hang out with the sister. This is called innate recognition, and it’s due to olfactory signatures. Pheromones. From proteins which come from genes in the major histocompatibility complex (MHC).
Canto: Histowhat?
Jacinta: Okay, you know histology is the study of bodily tissues, so think of the compatibility or otherwise of tissues that come into contact. Immunology. Recognising friend or foe, at the cellular, subcellular level. The MHC, this cluster of genes, kicks off the production of proteins which produce pheromones with a unique odour, and because your relatives have similar MHC genes, they’re treated as friends because they have a similar olfactory signature. Which doesn’t mean the other mouse in the enclosure is treated as a foe. It’s a mouse, after all. But other animals have their own olfactory signatures, and that’s another story.
Canto: And there are other forms of kin recognition. Get this – birds recognise their parents from the songs sung to them before they were hatched. Birds have distinctive songs, passed down from father to son, since its mostly the males that do the singing. And as you get to more complex species, such as primates – though maybe they’re not all as complex as some bird species – there might even be a bit of reasoning involved, or at least consciousness of what’s going on.
Jacinta: So that’s kin selection, but can’t we superior humans rise above that sort of thing? Australians marry Japanese, or have close friendships with Nigerians, at least sometimes.
Canto: Sometimes, and this is the point. Kinship selection is an important factor in shaping behaviour and relations, but it’s one of a multiple of factors, and they all have differential influences in different individuals. It’s just that such influences may go below the level of awareness, and being aware of the factors shaping our behaviour is always the key, if we want to understand ourselves and everyone else, human or non-human.
Jacinta: Good to stop there. As we’ve said, much of our understanding has come from reading Sapolsky’s Behave, because we’re old-fashioned types who still read books, but I’ve just discovered that there’s a whole series of lectures by Sapolsky, about 25, on human behaviour, which employs the same structure as the book (which is clearly based on the lectures), and is available on youtube here. So all that’s highly recommended, and we’ll be watching them.
References
R Sapolski, Behave: the biology of humans at our best and worst. Bodley Head, 2017
https://www.britannica.com/science/animal-behavior/Function#ref1043131
https://en.wikipedia.org/wiki/Kin_selection
https://en.wikipedia.org/wiki/Eusociality
On cramp, sensation and pain
hard to find a non-athletic-looking image of leg cramp
In recent times I’ve been suffering from cramp, usually in bed in the early mornings, almost always in the calf but sometimes in the foot, around the toes but sometimes at the back of the foot, and invariably on the left leg. So all of this leads to a great variety of thoughts and anxieties. What is cramp? What causes it? Can it be cured or prevented? Why only on the left side? Why now and not in the past? Will it keep getting worse? How to describe the sensation? What’s the difference between a description of a sensation and the sensation itself? Can pain be measured? Can it be distinguished from pain response?
The cramps I suffer from are clearly not the same thing as those experienced by footballers near the end of a go-for-broke cup final, when they crumple in a heap of agony and have to be massaged back to life by a team-mate, an exercise which also seems to involve a stretching of the afflicted muscle. I’ve heard this has to do with a lack of oxygen getting to the muscle when it’s being strenuously exercised. I don’t know if I’ve ever experienced that kind of cramp (does it feel different?) but I do recall getting a sharp pain in the abdominal region, referred to by others as ‘the stitch’, when, either during a football game or a school run, I exercised myself beyond my level of fitness – which was very easily done. That pain, however, was qualitatively different from the cramps of today. It didn’t feel muscular.
So now to what the pundits say. First, on ‘stitch’, this BBC health and fitness website has it that ‘most scientists believe the pain is caused by a reduction of blood supply to the diaphragm, causing it to cramp’. It’s certainly common in long-distance runners, but as I recall – and it’s been a long time since I’ve been silly enough to bring on that particular pain – it felt very different from the leg cramps, more like an organ pain, of the stomach perhaps, or the duodenum (I’ve no idea). If it is a muscular cramp, it’s an indication that these cramps can feel very different from each other.
It hasn’t taken me long to realise that the science of cramps isn’t particularly well-developed. Though perhaps that’s a bit unfair – better to say that it’s not settled, due largely to its complexity. Some cramps, though surely not mine, are caused by muscle fatigue, while others are caused by a lack of electrolytes, or it could be a combo.
So what are these electrolytes? Salts, acids and bases mostly, which become ionised in solution when an electric current passes through it. The major electrolytes in our body are calcium, sodium, magnesium, potassium, phosphate and chloride.
Okay, I’ve got it slightly wrong. These electrolytes, or ‘lytes’ as the pundits call them, dissolve in any ‘polar solvent’, such as water, and separate into cations and anions. I learned a bit about this at school but I’ve forgotten. Basically the dissolved lytes become ionised, I don’t know why, becoming either positively charged (having fewer electrons than protons, making them cations), or negatively charged anions (with more electrons than protons). These anions and cations disperse more or less uniformly through the fluid, making it electrically neutral. But when an electric potential (something very complicated, but I think it basically means an electric charge) is applied to the fluid, the cations gravitate (surely the wrong word!) to the electron-rich electrode, the anions to the … other one.
What does this mean for cramp sufferers? Fuck knows, but I think it means that if you don’t have enough of these lytes, for whatever reason, you don’t get this ionisation happening and that’s bad for your body. Anyway, we’ve all presumably heard of these probably bogus electrolyte-bearing drinks that are advertised as a salvation for athletes, of which I’m very obviously not one, but it does seem possible that I’m a bit light on my lytes. What I’m doing here is engaging in a bit of deductive reasoning a la Sherlock Holmes. If you eliminate all the impossibles, whatever’s left, however improbable, is probably true, or something like that.
So… my cramps are definitely not caused by hyperflexion (flexing of a muscle beyond normal limits), or by hypoxia (deprivation of oxygen at the tissue level). Nor is it likely to be a complication of pregnancy (I wish). I don’t want to think about it being symptomatic of kidney or thyroid disease (I feel otherwise healthy), but they’re extreme improbabilities that might need to be looked at later. Three other conditions are highlighted on the fabulous Wikipedia: hypokalemia, hypomagnesemia and hypocalcaemia. Careful inspection from the astute reader should render these terms intelligible. They refer, bien entendu, to a, presumably chronic, lack of potassium, magnesium and calcium, respectively (the aforementioned lytes). A quick glance at the symptoms of these three conditions suggests to me that they can be relegated to the bottom section of the list of probable causes. Often they result from the use or overuse of prescription medication. I don’t take any.
Now I’m starting to run out of possible causes, and I don’t want to complicate the problem too much. Actually the best advice I’ve read so far on the Wikipedia website is this: Stretching, massage and drinking plenty of fluid, such as water, may be helpful in treating simple muscle cramps. Obviously they don’t include wine as a useful fluid in these circs. That may be my downfall – alcohol tends to dehydrate, which is negative in itself but also seems implicated in cramping. It narrows the blood vessels (hypoxia enfin? the blood vessels oxygenate the muscles don’t they?), which is probably what gives that headachey hungover feeling I sometimes have in the morning. It also causes a build-up of lactic acid, another probable cause of cramping. I’m beginning to feel that a few small adjustments, such as drinking some water before bed-time, avoiding excessive alcohol intake, and keeping the muscles of the lower leg warm (cramping always seems more excruciating in winter) might be enough to solve my problems, which are only minor after all.
So that’ll do me, all that philosophical stuff about the nature of pain will have to wait for another day. I need to hydrate and keep warm, firstly, and I’ll see how that helps as winter is coming.
exercise is medicine
I read recently that regular moderate exercise sloshes up the blood, washing immune cells from vessel walls. This brings those cells back into the mainstream so to speak, where they can be more effective in combating infection. It makes no small difference – a simple study in which 500 adults were tracked for 12 weeks found that those who engaged in regular aerobic exercise sessions were found to suffer considerably less from upper respiratory tract infections – precisely my personal area of concern. Levels of immune cells in the blood double during exercise.
There’s also good news in this for those of us who couldn’t become gym junkies no matter how hard we tried. Too much exercise (but that means quite a lot) can undo all the good by raising levels of cortisol, noradrenaline and other stress hormones, which alter immune cell functioning. Stress, though, is another one of those complex indicators of health. Mild bouts of stress can be healthful, again boosting blood levels of immune cells. So don’t relax too much, but don’t overdo it.
Even so, exercise helps with everything, and that’s something worth promoting because the recommended dose of exercise isn’t being swallowed by the majority of people in the west. Of course we’ve always kind of known about the benefits of exercise, but the hard evidence has really been coming in lately. A really interesting study was published in the Lancet in 1953, at a time when the rising incidence of heart attacks was becoming a worry. It compared bus conductors to bus drivers on London’s busy double-deckers. The conductors, who spent much of their working day running up and down steps, had half as many heart attacks as their driver colleagues. This landmark study has of course been followed by many others that have confirmed the positive effects of exercise in reducing the incidence of stroke, cancer, diabetes, liver and kidney disease, osteoporosis, dementia and d barkepression.
So what exactly is the goldilocks zone for exercise? Well, anything is better than nothing, and most of us know we’re not doing enough. I’m not quite a senior citizen yet, but studies have been done with the elderly requiring them to do 40 minute walks three times a week, which is hardly strenuous. I catch a tram to work, which requires a ten-minute walk each way, and then a five minute walk each way to my workplace – 30 minutes a day, five days a week, though it would doubtless be better if those 30 minutes were continuous, and if I didn’t dawdle much of the time. The benefits of such a regime have been shown through before-and-after brain imaging. Expansion of the hippocampi, either through the growth of new brain cells, or greater synaptic connectivity, and a restoration of long-distance connections across the brain.
Mental exercise shouldn’t be forgotten either. It has been known for a couple of decades that intellectual stimulation can provide a kind of ‘cognitive reserve’ which can buffer us against the kinds of physical brain deterioration typical of Alzheimer’s and other forms of dementia, but clearer proofs of this have been gathered recently. Magnetic resonance imaging of Alzheimer’s sufferers has caught the goings-on in the brain while cognitive tasks are being performed. Highly educated people – brain workers if you will – are better able to develop alternative neuronal networks to compensate for damaged areas. I would assume though that it’s not so much about education but about brain usage. Keep tackling new things. Keep using your brain in new ways. And your body for that matter.
Cognitive reserve is now seen as a real thing, and has been pinpointed as residing in the dorsolateral prefrontal cortex, a key area for learning, short term memory, attention and language. Increased activity in this area suggests flexibility in thinking and problem solving. Information processing efficiency is also a key to a healthy brain. Having a high IQ, something I’ve often been sceptical about in the past, is an indication of information processing efficiency, even if the information is often culturally specific. It appears that physical brain deterioration, from Alzheimer’s, stroke and and other causes, can be fended off by compensating neural network development and increased information processing efficiency in certain people, until the deterioration becomes too great to be compensated for, after which things tend to go downhill very rapidly. By the time the symptoms of Alzheimer’s appear in such people, the physical damage is already well advanced.
A major message from all this is that you should try to develop lifestyle habits involving physical and mental exercise. Always a work in progress.
I note that one of the in terms these days is ‘hat tip’ (h/t), so h/t for this piece to New Scientist, the collection, edition 3: a guide to a better you.