Ken Fabian

Above - Should have been "achievable" not "achievement". I need to proofread before posting. I think over-population is a more intractable problem than decarbonising energy; I think we can educate and make contraception available and encourage but not regulate, not without costs that go beyond merely economic. Doing the best we can for the population we have and expect to have has to continue, even at risk of failure but the trade offs between the economic development that makes fertility a choice and resource constraints that make overpopulation a problem... is a problem.

Availability of education, healthcare and contraception with a minimum of basic needs being met seems to be the most effective way to reduce population growth. Reducing population deliberately takes us into crimes against humanity territory - and almost inevitably means preferentially reducing numbers of people who aren't like us. Even schemes involving random selection are bound to include exceptions, for people like us. Problems like global warming being framed as overpopulation problems leads to presumptions of either solutions being unachievement (so don't bother) or else that anyone who is genuine must inevitably support policies that promote or lead to tyrannical control over people's lives (so must be opposed). Whereas I think it is more correctly framed as a dirty energy problem - so that when our primary energy is zero emissions even high populations with high energy use will have low emissions. It doesn't make solutions easy but it doesn't make them unachievable or tyrannical.

A rise in the total atmospheric water vapor content due to warmer air holding more water vapour is being monitored and is occurring but relative to ocean volume it isn't nearly enough to counter the effects of warming on sea levels. A doubling of atmospheric vapor would be about 25mm of sea level, at current rates of change maybe 5 years worth, but that much increase hasn't happened and isn't expected. If anything increase in water vapor is happening slower than expected. But the most significant effect in climate change terms is the water vapor feedback, that effectively amplifies the warming from other causes - because water vapor is a greenhouse gas and warmer air takes up and holds more of it. A bit of warming increases water vapor content and that causes more warming.

Other apes have fur from birth until sexual maturity; having fur during the juvenile stage isn't a secondary sexual characteristic but would be a normal juvenile trait. Not having it is the peculiarity. The furlessness doesn't go away with puberty. But it could be a delay or missing out of an earlier growth stage than that. When puberty starts does appear to vary between populations - the duration of the furless childhood stage might change but otherwise it looks like the same pattern of long hair on head and only fine vellus hairs elsewhere is universal. And yes, Heterochrony, including Neotony - changes to timing, rate and duration of growth - has been suggested as involved in furlessness and I'm inclined to agree, but it looks more complicated than just that. The gain in follicular nerve supply doesn't appear to be a consequence of a change in timing. Going by Montagna it sounds like it is an exceptional change, but I'm not sure anyone knows; I'm not sure we'll see the kinds of comparative anatomy that Montagna did, that included examination of human and animal skin samples, repeated or extended. Maybe genetics will end up telling us to what extent the factors that affect the size of the hair shafts affected the nerve supply - and what was the result of other evolutionary changes.

It would be very odd for a trait that appears to offer no special advantage and considerable disadvantage except in exceptional circumstances would be selected for repeatedly in widely different environments and result in all populations evolving the exact same trait, all very recently, all since speciation. I would expect it to be expressed with significant variation in separate human population if that were so but it isn't; it seems to be a trait that has effectively been unvarying - irrespective of how varied adult hairiness is (a secondary sexual characteristic) childhood furlessness is universal. A trait shared universally by all members of a species will almost certainly go back to common ancestors. I think we really do have greater sensitivity than related apes - and by implication, than our shared ancestors. I can't prove that of course. Doing experiments with chimps and bonobos to compare to humans to determine relative sensitivity seems difficult but doable - they are our best stand-in for our common ancestors but that can't deliver certainty. The late Mr Montagna seems to have thought the sensory sensitivity of human skin via hairs/hair follicles was exceptional. My own experience is of high sensitivity - but that is subjective. That so many people fail to notice the difference between the sensations from hairs and sensations from direct skin contact and appear to believe they add nothing at all is maybe a question for Psychology. Arriving at any definitive conclusions is probably expecting too much - I don't claim to have any, barring being confident that we can rule out sexual selection because... the furless child. I have some hopes that delving into DNA might shed light on it.

Their children were presumably furless when humans left Eastern Africa. (I prefer that to hairless, because hairs are still there, just smaller... and with better nerve supply). That every human child is furless in modern humans means it is a homologous trait that goes back to (at the least) the emergence of homo sapiens as a species. Montagna, approaching it from comparative anatomy asked - Furlessness - the furless child - was part of homo sapiens first. Variations like that greater adult hairiness came later. If it is beneficial to adults it will be beneficial to children. Furred animals pretty much all have furred young. Smaller body size usually means greater heat loss and susceptibility to cold and human babies are especially vulnerable. Also more susceptibility to overheating - which would be more pronounced without the furlessness in combination with greater ability to sweat for cooling. Do children make more internal body heat than adults? They are often very active. Mistermack mentioned lion cubs dying from cold during wet weather - but having fur that is soaked and stays wet may be a greater risk for hypothermia than having no fur. Similar to wet clothing raising hypothermia risk. I think it's a case of sometimes it will be a benefit and sometimes it won't. Humans - and our hominid ancestors - were better capable of finding fixes and workarounds than any other species.

@mistermack - I am not disagreeing that fire and shelter and maybe clothing too would have been important to the success of early furless hominids, and ever since. It could be a significant reason the furless trait could be sustained rather than taken back out of the gene pool even if, for a time, for some reason or reasons, it was a common variant. The timing isn't entirely clear but fire use goes back at least that far. Evidence of early shelter making is harder to establish, but very possible, even very likely they were used very early on. A maybe on clothing because shelter and fire would probably be sufficient in a warm climate - as is the case with modern humans, including well outside the warm tropics going by Australian Aborigines, who often wore little more than versions of loincloths, with kids going naked most of the time. Animal skin cloaks and wraps were used in colder places in cold conditions. Oiling the skin of children in Winter was apparently practiced in some colder regions too - I surmise for being water repellent to reduce cold from prolonged time being wet. It is the use of these as the primary cause for evolving furlessness that I disagree with. But not vehemently; I expect multiple factors at play, not all at the same time. I think there are some sub-questions that might be answered - was it a progressive loss of fur over many generations? Or was it a distinct furless variant - furless individuals born to furred parents via specific mutation - that swept through the population because it gave survival advantage? Was it sexual selection for attractiveness or natural selection for survivability? Or a dominant genetic mutation that gave no advantage but was survivable, that induced clever tool making problem solvers to rely on and develop better shelter and clothing, that gave a thermo-regulatory advantage far beyond what any fur, even seasonally shedding, can deliver? And there is still the gain in sensory sensitivity of hairs in humans to explain, that has nothing to do with thermo-regulation. I had thought maybe the sensitivity gain was "spandrel" - the hair shaft size shrank but the follicular nerve supply of much larger hairs remained. Except that Montagna's comparative anatomy makes clear there is a significant increase over what the (larger) hair follicles of related apes have. It may be invisible but that looks as profound a difference between us and our primate relatives as being visibly furless is. I think not progressive fur loss - because... the furless child. There is no - or very little - variability of furlessness in childhood and if it were a trait subject to incremental change it ought to show variation. Not sexual selection because... the furless child; furlessness has to already be in place in children for preferentially choosing youthful, pre-pubescent furlessness in a sexual partner.

@mistermackDepends on the climate, surely. Keeping active by day, huddling together by night would do in milder climates. Hominids have been clever tool users and problem solvers for a very long time - even dragging vegetation over themselves can provide insulation. But, yes, clothing and shelter and fire may well have preceded furlessness and made it easier to cope with when it happened and perhaps those were used or known but not used all the time; furlessness could make their use more of a necessity. But I don't see how they would lead to the evolution of the furless child; where is the selective advantage? I think just not needing fur to keep warm when fur does provide significant benefits - even if not all the time - isn't going to be enough for a species to lose it. As an aside I've heard it said that hiking in cold, wet conditions without clothes is less likely to result in hypothermia than wearing wet clothes; my own experience hiking in swimming shorts in the rain seems to support that - like swimming, as long as I kept moving I wasn't cold - but I haven't done that outside a mild climate or in extreme conditions.

It seems more likely to me that use of clothing was a response to being furless rather than inducing furlessness - a parental response to their furless children suffering from cold perhaps. It is certainly possible the use of clothing and shelter and fire came before the loss of fur and gain in sensory sensitivity but I don't see how it would lead to evolving furless children. I have dogs that are very pleased to wear warm jackets in winter but I don't expect dogs to evolve furlessness as a consequence. There has been more going on than reduced hair size. Skin has gotten tougher and makes more perspiration and gained (variably) resistance to UV. Hairs gained sensory sensitivity. Seems unlikely they happened simultaneously or for the same reason. Abebe Bikila famously won back to back Olympic Marathons with bare feet. I don't see any fundamental problem with running long distances without shoes. Australian desert Aboriginals traveled long distances in harsh conditions without footwear but I'm not aware of persistence hunting as a usual hunting method. Sneaking up on prey and using spears or hunting boomarangs seems more usual. Chasing down wounded prey no doubt happened - but I expect marksmanship would be criticised; a few times and young hunters would learn the worth of taking prey down quickly, to avoid all that chasing after them. African Bushmen however, are noted for long distance running and persistence hunting - the Kalihari Desert is a unique and challenging environment. More usually a variety of hunting methods were used, from snares and traps to ambushes at water holes or river crossings (which the Kalihari doesn't have). But I also have some reservations about reliance on persistence hunting of large prey as the primary source of high protein food, but conceivably at some extreme bottleneck - where the very survival of the species was in doubt such as due to extreme anf persistent drought - it may have been so... if an ability to sweat profusely had already developed and overlapped with individuals having loss of fur. There are some furry primates that sweat a lot.

Only the adults have more (as in larger) body hairs. The children are as furless as children everywhere else. I think that is a significant observation that has been largely overlooked in developing plausible explanations for how we got to be a furless ape. It tells us that greater adult hairiness within some groups must have evolved later than the childhood furlessness that is universal across our species. All the variations of hairiness in adults, barring perhaps some dimorphic (male vs female) differences, would have arisen after speciation. If I could write academic style papers I would address this, along with the sensory function of hairs - "hairlessness" itself is in my view better framed conceptually as a developmental trait and might be better described as a furless childhood condition than as a species with furless adults. Which means any hypothesis for childhood furlessness based on sexual selection has serious problems; how does choosing a less hairy adult mate lead to children having no fur? The childhood furlessness has to pre-exist for sexual selection to be able choose less hairiness in adult mates.

Yes, I am inclined to think that there were times and circumstances where being able to keep going in hot conditions would be significant and other times and circumstances where having reduced exposure to parasites would be significant. I don't think it will be down to any one thing except perhaps the presence of a furless mutant variant at the right time. But then it could be the other way around - that body hairs staying small was driven by parasite - and parasite borne disease - avoidance and the increase in sweat glands came later and turned it into a significant heat dissipation advantage. Susceptibility to extant parasite borne disease and the presence of mutations that reduces it would have a very strong selective effect, even within a single generation; the furless mutant types, despite the problems - with the problem solving, tool using capacity to work around the problems

And I'm intrigued by the evolution of a significant gain in sensory sensitivity in humans via those changes to patterns of hair growth. Enough to wish I could write something publishworthy about it. Having small hairs means it takes less to disturb them. Being effectively sparse - hairs not laid against each other - means there is less dampening of their movement should something deflect or vibrate the hair shafts. That was my initial thinking for why my body hairs seemed so especially sensitive - able to feel the air vibrations off a fly that does a close pass, without any physical contact. Or to notice an Australian Paralysis Tick bumping hairs on it's way up my leg, enough look and pick it off before it dug in. Anyone who said body hairs serve no useful purpose hasn't avoided the painfully itchy bites of an Australian Paralysis Tick. Clearly not 100% effective, but there's that ability to get so deep in concentrated thought as to ignore our senses; maybe our ancient ancestors paid more attention. On the other hand having very sensitive hairs make busy, buzzy flies almost unbearable; they prompt humans to take significant actions, besides swipe and swat and swear. Anything that can provoke children to screams of "get it off me, get it off me!" is not a functionless leftover. As an aside - or even more aside - I even wonder if the most common sensations hairs make being irritation is a subconscious part of the appeal of body hair removal. It was a few years before I encountered William Montagna's "Evolution of Human Skin" and learned that human hair follicles, no matter where or how small, are especially rich with nerves in comparison to the hairs of other extant apes - more like the vibrissa, the dedicated feeler hairs than their ordinary hairs - If nothing else, this seems relevant to any ecto-parasite hypothesis for how we got the particular patterns of hair growth that humans do.

@mistermack - Fire was also used to drive prey animals towards hunters and burning of dry grass and vegetation around camps was done to make them safe from wildfires. That kind of burning also results in fresh green plant growth as the area recovers and that attracts grazing (prey) animals.

An ongoing interest of mine has been what is usually (misleadingly) named human hairlessness - notably smaller hairs that leave human skin exposed and visible over most of the body, which is so different to related apes and primates. But it also comes with a greatly increased follicular nerve supply ie increased sensory sensitivity of those hairs. That is not a visible trait but is something subjectively experienced, presumably by every human barring those that for some reason have no body hairs, or they don't have nerve connections. How furlessness (I prefer that term) evolved has been an ongoing puzzle that has engaged the minds of many serious contributors to science but the greater puzzle to my mind has been how so many people attempting to explain it could entirely overlook that sensory function - many to the point of claiming our fine body hairs serve no useful function at all, despite living immersed in the sensations they provide. Busy, buzzy insects, puffs of breeze, slide of cloth as we move, close passes by hard objects - sensory awareness of them is a useful function. I have a picture in my mind of Charles Darwin in short sleeves, deep in thought and unthinkingly swiping at annoying flies tickling the hairs on his arms as he composes the line "No one supposes that the nakedness of the skin is any direct advantage to man: his body, therefore, cannot have been divested of hair through natural selection." Which I think is both false - he admits as much in his response to a naturalist named Belt who did suppose that by suggesting ease of finding and removing skin parasites as an advantage - and an example of "not even wrong" type of wrong; it casts the question as one of the advantages of absence of hairs, when hairs are not absent, but are small with high sensory sensitivity. That capacity for such deep thought and concentration that we can lose awareness of our senses has to be unusual in the animal kingdom - I do that too - but that so many people who were seriously attempting to understand how human furlessness evolved could have such a big blind spot is intriguing.

The false perception that we are perceiving and thinking and acting in the present when there is actually a significant time lag has intrigued me - a little bit, or maybe a lot of predictive power needs to be involved in doing that.

If we had evidence of an advanced technological society out there messaging them our accumulated knowledge including descriptions and examples of the human genome might make sense, otherwise I think it would be like building pyramids - it will impress humans whilst they are still around but won't actually result in life after extinction. It may have some societal benefits so long as the effort doesn't cost too much.

I don't think I am missing the point. Globally, seagrasses appear to be on par with global rainforests in terms of carbon uptake and, like them, are being lost, not gained. Comparison to Amazon alone rather than global rainforest is misleading. Also Carbon going into ocean sediments is relatively small in the global carbon cycle scheme of things. Carbon going into vegetation, whether on land or marine requires ongoing and enduring gain in biomass; without the assurance it is unduring it remains iffy. I think zero emissions is a prerequisite to the possibility, without assuring it - whilst failure at zero emissions seems likely to assure that it won't stay put. And I don't think it has been shown that enhanced seagrass growth is easier than terrestrial vegetation and soil carbon or that biomass gain wherever it is is a cost effective and scalable way to draw down atmospheric CO2, no matter how tantalising the quoted numbers look. I see preventing their loss, ie stopping them being an emissions source - as both the higher priority and as the prerequisite to achieving a rebound, as are significant emissions reductions. The changes that global warming are causing represent significant threats to that "thousands of years" of sequestration - e.g. marine heatwaves, which shallow waters, ie seagrasses, are at most risk of, have already seen large areas suffer die-backs that saw years of becoming emissions source before recovery. It isn't clear that the recovery brought them back to net CO2 negative or that their survival as sinks can be counted on. No matter that in theory they offer opportunity to draw down CO2 I remain doubtful about achieving recovery equal to past losses without success at achieving zero emissions first. Becoming a significant drawdown of CO2 beyond that - becoming an emissions solution that can lessen the requirements for reducing fossil fuel burning - looks unlikely to me, so I am inclined to object when it is presented as a solution. It isn't any more than Amazon re-forestation is a solution. I see building low/zero emissions energy - emissions reduction - as the most effective action we can take on global warming. It looks necessary to preventing seagrass ecosystem losses as well as enabling potential for any ongoing draw down. How to pay for enhancing seagrass ecosystem carbon draw-down? Mostly emissions offsets are the likely funding source but I am not a fan of carbon offsets; the financing of them, including seagrass management by such means is going to present ongoing challenges starting with preventing abuse of such schemes that includes their role in excusing and justifying ongoing emissions and delay. If we do indeed reach zero emissions other kinds of funding will be needed… well, I don't think we can seriously begin without alternatives to carbon offsets to fund it. It has to be not just subsidised but protected against the variety of human impacts, from inappropriate and excessive fishing to protected against global warming itself that are threatening their viability. I am doubtful of fishing industries being sufficiently supportive of seagrass protection; it may get in principle support but my observation of industry responses to protected no-fishing zones is that they tend to object, often fiercely, rather than support, irrespective of science based evidence of overall benefits to fish stocks. At the individual fishing business level any reduced access - to prevent damage from trawling, anchoring and overfishing, which rate high as threats - will be opposed; having them pay for managing those areas as well seems even more likely to be opposed. This isn't objecting for the sake of argument, it is me attempting to be pragmatic; I am seeing a necessary priority of preventing their degradation and loss and most of all by actual emissions reductions.

The moderating effects on atmospheric CO2 of healthy seagrasses are way short of being a global warming solution. Even if losing more of them will add to the climate problem (the loss of them as sink makes them a CO2 source) I'm not sure how we can greatly enhance their habitats and health, even to the point of retaining as sink what exists before it is lost. Preventing further loss seems the clear priority. Locally as adaptation ( eg to reduce erosion from sea level rise) there may be efforts at enhancing their growth. But climate change itself is probably a negative influence on seagrass health, undermining the likelihood they will "hold carbon for thousands of years". We need more emphasis on emissions reductions through growth of low emissions energy as an element of preserving sea grass health. Not sure ocean floor coverage gives a valid comparison of seagrass effectiveness, although human intervention may be more effective for enhancing seagrasses than for other things that contribute to carbon sedimentation in oceans - being shallow and coastal vs open ocean.

So much depends on what is deemed sin and what isn't, where the rewards and punishments of post life eternity (including the punishment of Hell, according to some but not all) have no half measures; it is all bliss or all unendurable suffering, which seems excessive and unjust when no clear direct instructions were supplied to everyone everywhere and just missing out is deemed Hellworthy. There is no repenting if people don't think it is sin - which I'm told means falling short as much as committing crimes (but a Not-Fundamentalist Christian). It isn't even clear which failures are entrance to heaven level sins. Is ignoring global warming as revealed by seeking understanding of the world and of the consequences of our action through science a sin? For Christians to deny it looks like open denial of the reality made by God, something which can be recognised by the use of observation, intelligence, reason used honestly and shared freely - using "God given gifts". Some very important principles that are often highly regarded by religion have to apply for science to work - honest observation, accurate record keeping, seeking true understanding, sharing knowledge freely with no bearing false witness or making false accusations. Global warming surely is a case where there are consequences for actions in the real world that are not lifted from humanity by repentance, but only by actions in the real world; more like sins of the fathers being heaped upon their children unto eternity - or at least far enough beyond the lifetimes of people now living that it may as well be eternity. Religious people really need to lift their game and apply better standards to what they choose to believe. I've heard the good of religion - that doesn't require religion btw - described as Loving Kindness. Generosity of spirit and so on. From Without it looks like lots of them are falling way short.

I was thinking it is light source that passes through an exoplanet atmosphere too - ones that from our angle don't transit their parent star. It was a thought, but I hadn't thought it through - telescopes less good that that will probably be able to detect them and directly observe atmosphere lit by the parent star's light and get relevant chemical information from it.

I expect this type of observation and analysis of exoplanet atmosphere is the most likely way we will detect signs of life outside our solar system. Impressive to do so with a planet and star so far away. Not going to find life on this specific planet though, unless it is very different to life as we know it. And the method will be limited to planets that transit between the parent star and our solar system. I don't know if it could become possible to use more distant starlight that way, ie not confined to light from the parent star - seems unlikely, but not so long ago detecting any exoplanets seemed unlikely.

I did a quick look to affirm my recollection that it mostly a problem of human senses and the nausea and discomfit from the mismatch between what our sense of balance is saying and what our other senses say. Sounds a lot like the spinning sensation from lying down drunk on alcohol. I expect actually moving around and adapting our motions to such an environment isn't the problem, the problem is people feel ill. Whilst actual conditions can't be tested there have been attempts to mimic some of the effects using centrifuges and rotating spaces on Earth. A few different conclusions cited at http://www.artificial-gravity.com/Dissertation/2_2.htm - eg - @Gian - I did watch some of the vid starting from the point you picked out. Sorry, not going to watch the whole 30+ minute video (a synopsis would be good) but what I did watch made no mention of the role of the sense of balance (vestibular/inner ear), only more direct sensations of changing directions and strengths of pseudo gravity. Did I miss it or is it absent? It would be a serious omission - it wasn't hard to find references to the disorientation and nausea as one of, if not the most significant problem for human occupants.

My understanding is this an issue with the human inner ear, the motion/balance detection part. There is a difference and mismatch between the perceptions of motion, where eyes and other senses say one thing - that you are within a motionless space - but the inner ears are detecting rotation and that becomes disorienting and nauseating. Those little stones in those ear canals - the semi-circular canals - will keep giving the sensation of rotation and being unbalanced unless the rotation is slow enough.

Ending corruption would be up near the top of my list, both the illegal "hard" corruption where appropriate laws exist but bribery, threats and inducements assures no prosecutions and the legal "soft" corruption where undue influence assures appropriate laws are weak or don't exist at all. I suspect that without corruption a lot of problems would be easier, with more resources (money) to use for them. I think we would see more actions taken around issues where vested interests have successfully evaded responsibility and accountability eg global warming would be dealt with more effectively.

Which makes me wonder what we are arguing about - since that is what I have repeatedly been saying. I think this is incorrect - convection requires a difference in density (and gravity... or an acceleration like a centrifuge provides); different density due to temperature difference is just the most common, but having a different mix of gases with a different density will do it. Hydrogen, being lower density, will make convection. My citing the velocity of hydrogen molecules at 0 C was what I found and was intended as illustrative of the high velocity of gas molecules, far exceeding what gravity will do. I should add that doesn't mean I think hydrogen molecules will be bouncing off the walls and floor in a fraction of a second - they will run into other molecules along the way and how fast it disperses depends on (iirc) mean free path. Read my posts and you will find I spoke of other mechanisms all along. It looks more like you being hung up on diffusion, as if it were inconsequential. It isn't. I don't see how that reveals anything different than what I have been saying. Sure, the hydrogen in the bucket will be displaced faster by bulk gas movement (convection) than it could by diffusion. Not sure I am reading it correctly but a table of properties of Hydrogen (here) has convection (bouyant velocity) at 1.2 - 9 m/s - a lot faster than diffusion velocity of under 2 cm/s, but 2 cm/s is still significant in this hypothetical - the convection won't persist for long but diffusion will - from ceiling to floor of a 3m high space in a few minutes. Which won't be to homogeneity - I am assuming for the first molecules arriving? Sethoflagos or someone else likely knows better than me. Most of it will settle temporarily at the top but diffusion will happen from the moment the lid is removed. Do it in zero gravity without convection and the hydrogen will disperse faster than plain air - because hydrogen molecules move faster and that makes them disperse faster. The specific air molecules of plain air will disperse (and be exchanged by Brownian Motion), without changing concentrations.