10 ms·
Nocturnal bottleneck
- allemagne 4y agoWere some of these adaptations a major factor in mammals largely surviving K-T?
- rolph 4y agoits more like K-T was a bottleneck and those adaptations carried through the selection regime
- allemagne 4y agoHow certain can we be that that's the case? Seems like thermo-regulation and burrowing in particular could have been helpful traits in the immediate and long-term aftermath of the asteroid impact
- rolph 4y agothe mammalian traits you speak of were the default mamalian due to pressure from the dinosaurs existence, they could not compete so survied in a compressed niche. when the dinosaurs failed to survive the bottleneck at the KT boundry, the mammals were in a position to weather it out and expand niche into a landscape devoid of most large dinosaur lineages, this was followed up with mammalian diversification founded on the small cynodont plan. this is all a tale of the fossil record and the principle of superposition
- eru 4y agoWhat is the principle of superposition in this context?
- eru 4y agoI don't think mammals largely survived K-T? What's the evidence for that? (Some mammals survived, definitely, the evidence for that is that we are here.)
- Gravityloss 4y agoThis explains a lot.
- paganel 4y agoIt sure does. Not that scientific but maybe a little on topic, I'm just reading a book about the memoirs of past Soviets leaders, and at some point Khrushchev is complaining how Stalin had an almost all nocturnal life, how for him 2AM was still "an early hour". Afaik Churchill was also a very nocturnal man. I'm wondering what other past leaders were in the same category as Stalin and Churchill when it comes to their night life.
- zdragnar 4y agoIt was probably the only time they could get anything done without constant interruption. In a past life where I was a lead of a larger team, I would have a fair chunk of my work day devoted to mentoring and meetings, and spent a few hours late in the evening doing actual programming work.
- sho_hn 4y agoThis is me, too. I start work relatively late, because it gives me a few hours of uninterrupted, productive work past "EOB" when everyone else fades out and the meetings are over.
- wizofaus 4y agoI'm actually seriously worried my current role is going to end up like that. The annoying thing is that the meetings are actually quite important and useful too (undoubtedly some of them could be shorter). But I know it's not inevitable as I did manage to avoid it in previous roles as a principal engineer, just not sure how now!
- pmontra 4y agoDid they pay you to both program and lead the team? I realized that I didn't have any time left to program one week after I was given the lead of a small team. Meeting customers and the sales team to get requirements, design, explain to the team, check for progresses, etc. I could have been writing code at night but it was clear that my company didn't expect me or anybody else in my position to do that. I was writing code at night anyway, but on my own projects.
- 420official 4y agoThe bit on the photolyase DNA mechanism[1] is really interesting [1] https://en.wikipedia.org/wiki/Photolyase https://en.wikipedia.org/wiki/Photolyase
- Metacelsus 4y agoYeah, adding photolyase to humans is high on my genetic engineering wishlist.
- axg11 4y agoThis would presumably only be useful if expressed in the skin?
- cestith 4y agoI've always had a sneaking suspicion humans, like many other modern mammals, may be best thought of as variable among crepuscular, diurnal, matutinal, and vespertine.
- deleted 4y ago[deleted]
- Joker_vD 4y agoWhy not just call that, I dunno, nychthemeral?
- cestith 4y agoThat has among its meanings "lasting 24 hours" and also "a changing of day to night, back, or both". A single human is not likely to be equally active the whole 24 hours. Although I do know of some people who basically nap around the clock and don't sleep in an extended block, they seem to be a rare exception. It seems like a decent word to stretch a little into this use of the idea that members of a species may have different familial, social, or individual circadian activity. I hesitate to do that though, because I'm unaware of it being used that way to date and it seems it could be difficult in such a context to differentiate it from established meanings of the word.
- Joker_vD 4y agoWell, it won't become an established use until people start using it with this meaning: and you personally can help with that!
- wizofaus 4y agoGlobal warming might well gradually force us back again to a semi-nocturnal/ underground existence too. Bring on the night...
- prichino 4y agoGlobal warming is so 2010... It's climate change
- wizofaus 4y agoIPCC still use both terms, at least, they were last year: https://www.ipcc.ch/2021/08/09/ar6-wg1-20210809-pr/#single-content-1 https://www.ipcc.ch/2021/08/09/ar6-wg1-20210809-pr/#single-c... I wrote "global heating" first but it still feels weird to me.
- eru 4y agoExtremely unlikely. https://en.wikipedia.org/wiki/Economic_impacts_of_climate_change#Aggregate_impacts https://en.wikipedia.org/wiki/Economic_impacts_of_climate_ch... says that the best available studies foresee global GDP dropping between 0% - 20% from climate change (compared to no climate change). Given that this happens against a backdrop of normal, regular economic growth, people in the future will still be richer than people today. And approximately everyone today who can afford aircon (and needs it) gets aircon, rather than turning nocturnal.
- eyelidlessness 4y agoGiven that this happens against a backdrop of most of human habitation being below sea level, I think GDP projections are probably an awful estimation of human impact.
- bratbag 4y agoReading that link, those estimates are based upon us keeping temperature increases below 3 deg. In which case most human habitation will be fine. It also means that analysis is not a good one to quote without qualifiers about 'controlled climate change'
- trhway 4y ago>placental mammals were mainly or even exclusively nocturnal through most of their evolutionary story, starting with their origin 225 million years ago, and only ending with the demise of the non-avian dinosaurs 66 million years ago. i guess we're lucky that dinosaurs didn't evolve IR vision (not that it wasn't impossible given that snakes did get IR sense).
- thriftwy 4y agoIR does not work for warm-blooded creatures. You will be jamming your own IR vision with heat coming from your body. That, or having eyes on beanstalks. And archosaurs were at least partly warm blooded.
- eru 4y agoEven 'cold blooded' creatures warm up when they move around a lot, or when they bask in the sun.
- it_was_cool 4y agoWhich part is the "bottleneck"? Is it the idea that at one point nearly all mammals were nocturnal and that it became advantageous for some to transition to diurnal since there was less competition for resources during the day?
- rolph 4y agothe bottleneck was a global ecosystem level of selection. dinosaurs pressured the mammals to stay small, hide in burrows, and roam at night. dinosaurs, and a lot of other things came to an abrupt end, the basal mammals survived in thier bunkers with hoards of seed, and were relieved of selective pressure, thus diversified in thier traits this is when mammalian diurnalism made a big comeback so they could now compete among fellow mammals radiate and expand niche into the estate of the late dinosaurs
- exolymph 4y agoPath dependence is neat!
- FredPret 4y agoWhat a wild thought that our ancestor was a mousey thing that hid in a hole, terrified of the giant dinosaurs and falling asteroids, and survived only because it had the Jurassic mouse equivalent of a Costco habit while completely failing to suspect that its distant children will one day rule the planet.
- vhold 4y agoI think it's a genetic trait diversity bottleneck? Mammals almost all went in the direction of nocturnal adaption and a lot of adaptions useful during the day were lost over time.
- Qem 4y agoLike, mammals are very vulnerable to skin cancer. We lost some traits reptiles have that makes them cope better with UV.
- sfink 4y agoThis makes me speculate if intelligence was enabled by the slop available from nocturnal animals becoming diurnal. As in, perhaps intelligence would be much harder to achieve in a step by step fashion, but the adaptations to night living left some things on the table that enabled a random walk to intelligence: richer sensory input, and more energy available for processing that input. And perhaps faster and more flexible outputs. If intelligence hadn't come about, presumably evolution would have pushed things back towards faster / extreme sized (smaller or bigger) / more streamlined, basically repopulating the non-mammalian design points. (Note that by "intelligence" I'm not referring to human intelligence, just the basic form of using mental processing power to facilitate survival. Which is not specific to mammals, nor necessarily strong in all mammals.)
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- tomjakubowski 4y agoI like the theory. If true, it's another example of the virtue of leaving some slop in your systems.
- elevaet 4y agoThis is extremely tangential and speculative, but I've always thought ancient practices of sacrifice served as slop, or a safety margin. When times are lean, you can leave a little less food for the gods and do a little more praying.
- yakubin 4y agoOr become a priest and eat the offerings.
- eru 4y agoOctopuses and corvids are plenty smart, more than comparable to most mammals. Not sure they had a nocturnal bottleneck in their evolution? So that is probably not required. Looking at plenty of relatively dumb mammals, I don't think the nocturnal bottleneck is sufficient either. Of course, it might be a more complicated correlation than just sufficiency / necessity.
- tejtm 4y agothe environment limited some traits and allowed for others; you (most likely) have three flavors of color cones in your eyes not four like birds(dinosaurs) and replies because the having more rods (B/W low light sensitive) was better suited to night survival. On the other hand our brains do not (usually) have a bone partition between the two halves because we did not need to sleep with one eye open underground.
- elevaet 4y agoYes, apparently chickens (and other birds) really can sleep one half of their brain at a time. In chickens, the ones roosting on the edge of the flock keep their outside eye open and sleep the other side of the brain.
- anubiskhan 4y agoDolphins and whales as well https://www.scientificamerican.com/article/how-do-whales-and-dolphin/ https://www.scientificamerican.com/article/how-do-whales-and...
- russellbeattie 4y agoI'm an absolutely incurable night owl. My theory is it must be an inherited trait, which is passed through the generations at random, and was first developed for a reason. For thousands of years, maybe longer, my forebears protected the rest of the tribe at night so everyone else could sleep peacefully and then go hunting or farming during the day. We were probably the ones that domesticated the wolf, I'd bet, as that makes sense. They'd be the ones coming around the campfires at night. And we'd say, hey buddy, want this juicy elk bone? In return for saving civilization, we're now persecuted by people who think 8 a.m. is a good time to start school.
- Zekio 4y agoI'm the exact same, and I've thought about the same theory, especially since I sleep way better during the day than at night.
- desmosxxx 4y agoThat's what finally got me to come to terms with my extreme night owl shift. When I get up earlier than 9am (using light therapy etc), I get anxiety/panic attacks and have a hard time sleeping more than 6 hours. My natural schedule is sleeping around 5am - 1pm and I sleep like a baby and feel great.
- russellbeattie 4y agoHa! That's just about my perfect schedule as well, though for practicality I try to make sure I'm winding down by 3:00 am so I can get up before noon. In college I'd regularly go get breakfast before heading to bed and marvel at the morning people around me. My sleep shifts about an hour later every week, so that last week or so before it flips back is pretty tough, especially during the winter. Waking up at like 4 or 5 pm is definitely not good. I still need light!
- sixQuarks 4y agothank you for your service
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- baybal2 4y ago
- INTPenis 4y agoBut how many social mammals are nocturnal? Seems to me that when mammals began moving and living in social groups they could watch out for each other like those cute meerkats.
- yakubin 4y agoFirst social nocturnal species of mammals that come to my mind are hyenas and beavers. But it does seem that most social mammals are diurnal.
- Cenk 4y agoMore details in this paper, “The nocturnal bottleneck and the evolution of activity patterns in mammals” (OA): https://oa.mg/work/10.1098/rspb.2013.0508 https://oa.mg/work/10.1098/rspb.2013.0508