5 ms·
> One day, scientists might be able to successfully mimic the expansion of the interstitial space that does the mental janitorial work so that we can achieve ma
by wging 13y ago
> One day, scientists might be able to successfully mimic the expansion of the interstitial space that does the mental janitorial work so that we can achieve maximally efficient round-the-clock brain trash pickup.
We can ask the same question the article poses initially about why we still sleep. Why hasn't this evolved yet? What are the disadvantages of this 'always-GCing' approach? In a best-case scenario, it might just be some sort of historical limitation that no longer applies* (just as our tendency to get fat is a result of an approach to resource conservation that made sense in the ancestral environment, where food was scarce and opportunities to feed intermittent, but does not in modern civilization, where food is nearly always available). In a less appealing scenario there might be some tradeoff that causes us to think less efficiently when this interstitial space expands.
[*] The extra fluids have to come from somewhere, which would mean they're not available for other tasks. Similarly, digestion is expensive--blood flows to the intestines after a meal, and if this is to happen then (since in the short term, you have a fixed amount of blood) it's less available for fueling your muscles. (And if you force yourself to be active right after a meal there's contention for these finite resources. Ever go for a run right after eating?)
Though perhaps there's less fluid involved here than there is with the intestines.
- hindsightbias 13y agoMy theory is it has to do with the eyes. The optical input capacity of a human per day has just got to be an incredible stress on the brain.
- CaveTech 13y agoThen blind people wouldn't need nearly as much sleep, and I don't believe that to be the case.
- eruditely 13y agoMaybe it depends on what type of blind people?
- PakG1 13y agoConsider that blind people often have their other senses enhanced by the body to compensate for the lack of sight. Perhaps it balances out.
- FreeFull 13y agoI think there has been a study where it was found that the senses aren't actually enhanced, but they just pay more attention to them.
- beagle3 13y agoOptic nerves carry thousand to millions of times more information than either audial or touch (e.g. Compare AAC to H264 per second). Even much enhanced, other senses don't provide even remotely as much information.
- JunkDNA 13y agoI suspect it's tied to metabolic limitations. It's likely difficult for the brain to provide enough energy to support higher order functions and also do this cleanup efficiently at the same time.
- ggreer 13y agoEvolution is actually quite horrible at engineering. Since it can only hill-climb, we end up with ridiculous designs stuck in local maxima. Evolution made video cameras out of jelly, a breathing tube that must be crammed full of solid foods every few hours, and (as Neil deGrasse Tyson put so delicately) a sewage plant next to an amusement park. No organism ever evolved radio communication, or the ability to transmit nerve signals faster than 0.000001c. Still, why 8 hours of sleep instead of 2? The best explanation I've heard is famine resistance. Sleep conserves energy; until recently, humans were calorie-limited. Also, there's probably an advantage to remaining quiet and still in the dark, when human eyesight is at its worst and predators roam.
- sampo 13y ago> there's probably an advantage to remaining quiet and still in the dark, when human eyesight is at its worst and predators roam. That's a bit too anthropocentric view. Also other animals sleep, even nocturnal animals.
- ars 13y agoWorms sleep too - and they don't have brains that need cleaning.
- sampo 13y agoWikipedia suggests that also in nematodes, "sleep is necessary for changes in the neural system". http://en.wikipedia.org/wiki/Sleep_%28non-human%29#Invertebrates http://en.wikipedia.org/wiki/Sleep_%28non-human%29#Invertebr...
- count 13y agoWhy take human engineering out of 'evolution'? Biological evolution developed our brain and manipulative appendages, which were then used to make better video, comms, etc. Humans, and everything we do, are still 'naturally evolved', by definition.
- 13y ago
- jessriedel 13y agoPhilosopher Nick Bostrom makes the same argument more generally and detailed here: www.nickbostrom.com/evolution.pdf We shouldn't expect easy congitive enhancement through drugs unless there is a strong reason it wouldn't have been advantageous in the ancestral environment that doesn't matter now (e.g. much higher calorie usage).
- d23 13y agoI don't have the will to read a 40 page pdf at the moment, but my initial reaction to that argument is that evolution is not perfect and does not produce the same results in all species. Some animals hibernate for months, while some sleep much less time than we do. Not to mention that it seems like a cop out that avoids any possibility of progress through technology. Why should we expect an easy cure to syphilis in a drug if evolution has not found one? I don't know, but penicillin still works pretty darn well.
- jessriedel 13y agoIn fact, you shouldn't have expected an easy cure to syphilis. It's a dramatic exception. The vast, vast majority of problems the body has are not easily solved by a simple chemical. This is born out by the tremendous difficulty of finding effective drugs which don't carry unacceptable side effects.
- deleted 13y ago[deleted]
- ronaldx 13y ago> (just as our tendency to get fat ... I suggest that the tendency to get fat is protecting us as a species on an evolutionary scale. It's unwise to believe we could ditch that just because we haven't needed it for the last 2 generations or so: evolution cares little about a 2 generations scale.
- arrrg 13y agoNice job anthropomorphising evolution. Unfortunately that path leads to ruin. Evolution has no foresight. Evolution can’t predict the future. Evolution is firmly rooted in the here and now. Doing something now (or not doing something now) because of a prediction of the future is something only humans can do, not evolution. Evolution knows no future.
- ronaldx 13y agoWhat I claim is that this iteration of humans have survived catastrophic black swan events in the past, and that catastrophic black swan events will happen in the future (in a very-long-term, i.e. evolutionary, timeframe). Living humans don't have any reasonable concept of that, but evolution does have a memory of that[0]. I trust evolution to cover us for this type of future event better than I trust human prediction. Being rooted in the here and now is something I would ascribe to humans before evolution: humans typically think as individuals on a time scale of 100 years - whereas if something has not been needed for 100 years, this does not illustrate that it is no longer of evolutionary importance. [0] You can claim I am anthropomorphising here (but not in the earlier comment), but this is sometimes called an analogy, and is an accepted way of using the English language to describe concepts in a clear and simple way. Please ask any geneticist to translate this into evolutionary terminology if you remain unsure.
- thaumasiotes 13y agoEvolution knows no future, but it still makes sense to talk about evolution being prepared for a possible future. In particular, what ronaldx is saying is quite close to the accepted explanation for sexual reproduction. Sex produces, and maintains, a great deal of variety within the population that you won't see in an asexually reproducing one. It also imposes a very large penalty to the speed at which the population can grow (males, roughly half of any sexual population, cannot reproduce at all). It is felt that, historically, sexual populations have been so much more able to weather changing circumstances, because of the variability that their lifestyle ensures, that it must have outweighed the susbstantial reproductive penalty -- since sexual organisms have taken over virtually every ecological niche in the world. And this is for an adaptation the entire purpose of which is to guard the population against the future. In summary: variability in the gene pool is a form of future protection, and one that has been specifically selected for. Be careful before you shout "fallacy!"
- sorbits 13y ago> […] why we still sleep. Why hasn't this evolved yet? A number of animals can put one half of the brain to sleep while the other half remains alert¹. As for eliminating sleep or shortening it; for such “trait” to evolve there would (beyond being physically possible and the proper mutations having occurred) need to be an advantage that would cause more individuals with the trait to survive (and pass on their genes). Considering that we have been sleeping in trees and caves, and in groups, there’s probably not a significant larger chance of someone requiring less sleep to make it through the night. ¹ http://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep http://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep
- rtpg 13y agoalternatively, the genes that allow for this would just need to be the dominant ones, the recessive ones that we have now being just the result of a lot of bad luck.
- fauigerzigerk 13y agoI could well be completely coincidential. It may not affect the rate of procreation at all. Another possibility is that sleeping conserves resources, because we don't burn as many calories while asleep.