- land meats were all but banned in Japan for centuries prior to Perry's ultimatum, encouraging the development of alternatives in flavor and nutrition like natto and katsuobushi
- geographically, Japan had less access to land crops (even wheat was not common!) and more access to fish and seaweed than Korea
Here's my five minute lunchtime hypothesis: it's because the heart is on the left. As human behavior demanded increasing precision from the hands, being a little farther from the heartbeat was a slight advantage.
Here’s my multiple years of anatomy classes response: the heart isn’t on the left. The aorta is, sure, but the vena cava is on the right. Also people with situs inversus (essentially all organs flipped laterally from
“normal”) aren’t obviously more prone to left-handedness.
I’ve wondered ever since fourth grade (where an anatomical model in a corner of the classroom always made it clear that the heart is centrally located) how the vernacular conception of the heart as located on the left originated and persisted.
Your post finally made it click for me – the aorta extending to the left gives the superficial impression of that being the heart’s location because it’s easier to feel the heartbeat through the skin, versus the more deeply embedded vena cava on the right.
Presumably this means, evolutionarily, greater vulnerability on the left, predisposing the left hand to shielding duties, leaving the right to more dexterous tasks like spearing. The cardiological hypothesis of right-handedness holds!
> Also people with situs inversus (essentially all organs flipped laterally from “normal”) aren’t obviously more prone to left-handedness.
I feel like this isn’t really an argument against the theory. If right handedness did evolve because of heart position, a later genetic mutation to have the heart on the opposite side wouldn’t suddenly undo the previous evolution towards right handedness.
Why are you assuming situs inversus, which occurs in species with no handedness (or, indeed, hands) came after handedness?
The argument is that the selection bias was towards precision and the hypothesis was that precision is influenced by heart position (which is, still, in the middle in humans)… individuals with situs inversus would be more precise in the left hand, thus if the causal hypothesis is correct AND the argument holds then there should be a selection bias that would result in a correlation between situs inversus presence and left-handedness.
In the end I don’t believe either the argument or the hypothesis hold even as much water as I can in either hand.
It might be hard to eliminate confounding factors depending on when the research was done. A lot of people in my generation were still dissuaded pretty heavily from writing with their left hands. I'm not entirely convinced anymore as a lay person that "handedness" is a real, distinct phenomenon that's primarily genetically determined or a result of the organization of the brain. It's equally possible that it's a learned preference and that the way the brain organizes around it is as a result of the preference's impact on how you have to solve problems with your preferred hand in a society that preferences right-handedness.
Not disagreeing that handedness is probably unrelated to heart position.
But why would situs inversus somehow be tied to this at all? If there's a gene that favors right-handedness, it's not like it would somehow "choose" left-handedness because the individual has their internal organs flipped.
Genes don’t favor (or not favor), but if a natural selection bias for precise dexterity exists AND heart lateral orientation affects dexterity precision THEN those with flipped lateral orientation should exhibit more dexterity in the left hand, thus they should be naturally selected for because of the same bias.
Now, I’d seriously doubt there’s any evidence whatsoever for the assumed selection bias in the first place, never mind any causal relationship between fine motor control and heart asymmetry, but the selection bias should apply to both flips of the anatomical mirror.
The heart is asymmetrical, but it’s in roughly the center of the chest. The left auricle and ventricle are larger muscles because they’re pumping through the descending aorta to the extremities, that’s the systemic circulatory branch, the plumbing for which is also largely to the right, while the right are pumping into the lungs alone as part of the pulmonary circulatory branch. The left lung (right on those with situs inversus) has two lobes and basically accommodates the extra muscle mass on its side of the heart, but if you really want to kill someone you stab them through the sternum, kind of dead center, not where they hold their hand when performing patriotism.
even this is wrong, a penetrating weapon aimed for the heart is applied below the sternum at roughly the positionof the 3rd shirt button, and thrust upward at shallow angle topass behind the manubrium, and is then levered into a pommel upward position so as to lacerate the heart
First, that’s because you want to keep your weapon, which implies you don’t really want to kill the killee. I’m assuming a half inch drill, and I’m leaving it powered up and spinning.
Second, note that what you don’t do when trying to hit the heart is aim left.
not only smaller but having 2 lobes rather than 3, the left lung is possessed of a featureknown as the cardiac "notch" an involution of the lobe that corresponds to the larger left ventricle of the heart.
Wikipedia on Situs Inversus (visceral organs are mirrored, heart on the right, liver on left) [0], mentions mixed results regarding handedness. There would be a load of other confounding factors here and I know nothing about medicine.
Situs inversus ("dextrocardia") is a rare disorder. What I postulated is a (very) small selective advantage leading to a neurological mechanism evolving over generations, not a direct line from the heart to handedness during development. Anyway, the effect would be very slight, and even if it did exist, it could have gone away later, but dexterity would have been baked in at that point (see also the ocular blind spot).
That's a long time hypothesis of mine as well, but I think it stems from being stung or bitten by venom. If venom is injected into the bloodstream, it is desirable to be injected as far away from the heart as possible.
Some centimeters might not sound much, but over millions of years, the cumulative effect might be that 1% of human population every 10.000 years gets genetically optimized to hold their heart at a more protective spot.
Handedness is probably not (often) captured in healthcare records, but I'm wondering if epidemiologists could mine insurance claims (or some other data rich resource) to see if there's a correlation with serious outcomes (death, hospitalization, etc.) from venom and handedness.
That's a good idea, a very good idea actually, but I wonder about it's effectiveness due to a very small total number of snake bites nowadays, compared to the past.
Hundreds of thousands years in the past, hominids lived into much more tropical areas than today and there are a lot more spiders, scorpions, lizards and snakes in these warm places. It makes sense that insects and especially reptiles pushed the evolution of mammals in certain directions and the positioning of the heart in the human body might be one of them.
Today people live a much different lifestyle than having to deal with insects and reptiles all day long. I don't know if it is possible to decipher the past from today's data.
There is also a bias for how babies are held [1]. It holds even with left-handers. Holding a baby's head near the mother's heart helps the baby get to sleep. Which means the baby doesn't cry (and attract predators) and also gives the parents more time to sleep at night.
It also allows right-handed mothers to do something with their dominant hand while cradling the baby in that position.
I wonder why you're getting downvoted? Even if it turns out you're completely wrong it's still an interesting point and something I never even considered before.
Sometimes I think people downvote me because they're frustrated that I didn't engage further. After twenty years of Internet discussions, I'm a little burned out and I tend to fire and forget.
Most high-entropy alloys contain expensive metals so the primary domain of interest has mostly been as a coating for other metals. Recently there has been some work on AlCrMnFeNi, which is the cheapest composition I've seen by far.
The production case for a stronger stimulant is weaker. Heroin is a really complicated molecule. It is only made from a natural precursor. Meth can be made by two major pathways, and P2P can be made by at least four off the top of my head. It was the fentanyl equivalent for cocaine. For anything else, you balance the increased complexity of synthesis with any increase in potency.
>On top of that battery prices have been plummeting too so that now Solar + battery is cheaper than other options like Nuclear and especially Gas.
I'm a little bit sad that pumped hydro doesn't get more attention in the discussion. It might be too late for it to matter, with improvements in battery prices and ongoing lithium discoveries. But that only underscores the fact that it should have been allowed to matter twenty years ago. Utilities have slow-walked solar all around the world because of concerns about the grid stability, which has been well within the reach of pumped hydropower to fix since many years ago. In fact major pumped hydropower projects were mostly carried out in the United States during the nuclear power optimism era.
It is a little destructive to construct pumped hydro reservoirs. But it generally isn't as damaging as a conventional hydroelectric dam. The reason lies in the source of the water. In a conventional dam, you need a lot of water flowing in from up high, so you dam a major river near its lower cataracts. This disrupts the migration of fish and animals along the river and impacts the whole ecosystem of the rather large drainage basin upstream, and disrupts the migration of fish. But when a closed-loop pumped storage reservoir is created above an existing lake, usually a much less important stream is selected. Its immediate valley is still inundated, but the area of effect is much less. It does tend to prolong the use of the existing dam, but we are already preserving basically all existing dams.
It might still be appropriate in some places where imports are less affordable like Latin America or it might appeal to protectionists in the West. In general, hydro is usually cheap.
Anyone can install batteries anywhere at a fairly minimal local fire risk.
A dam is a major mechanical structure which if it fails will straight up obliterate downstream towns, and as such requires a numerous specialized engineering designs and on going maintenance to retain basic safety.
There have been two hydroelectric power plant failures in the United States in the last fifty years, and one near miss. This is among hundreds of dams many of which have operated for more than a century.
A pumped-storage dam also doesn't increase the area subject to flooding. If the upper dam fails, it flows into the lower lake. This can potentially be a design consideration. It's not like a greenfield hydropower dam.
If you want to play the rare catastrophic risk card, battery fires can release highly toxic hydrogen fluoride. But the damage of climate change is far greater than the very small risk from either dams or batteries, which is preventable in both cases with proper maintenance and monitoring. I think the tail risk question is moot, honestly.
Homelessness and visible homelessness need to be distinguished here. The large majority of homeless people are not the ones you notice on the streets. Most try to be discreet. Some have jobs. A person who lives in their car is considered homeless.
The best measure to reduce homelessness is to provide timely support for people who are being evicted from their homes before they lose their jobs (which they might still have) and before their mental health deteriorates. This is the point at which assistance is most effective. You have heard the saying, "an ounce of prevention is worth a pound of cure". Such programs have been applied to great effect in e.g. London.
The way to respond to people who have experienced chronic homelessness with complications is different and more difficult.
The Simon Community where I live went around the city one December and counted how many rough sleepers there were. I forget the exact figure but it was less than 100. Meanwhile there were thousands classified as homeless due to being in temporary accomodation. And this is a part of the UK well known for having a homelessness problem.
>This is likely the worst issue humanity will be facing over the next 50 years, even more than climate change.
Tangent, I know, but the climate change horizon is very long, much longer than 50 years. For example, a common projection is that the sea level will rise by almost one meter by 2100. This is already an unpleasant forecast. But it will continue to rise: under a 2 C warming scenario, sea levels reach (median prediction) 2.7 meters above the 2000 levels in 2300, which would be catastrophic. 2300 may seem far away, but it will come.
The current estimate is that we need to eliminate emissions this century and we will thereafter still need to do mitigation and removal to undo the damage, or extant coastal settlements will be destroyed. It is a very long process. See e.g.:
Do you know what the timelines are for demographic collapse? Similar and much worse, who will need the coastal cities if our trends continue. AND they have NO way have being undone AT ALL after the previous hundred years of trends set in.
>Venice was run by very old men. It was common for the Doge to be in their 80s. Meanwhile, many of their neighbors had kings who were very young, sometimes teenage boys.
But those kings were (legally) absolute monarchs, while Venice was (somewhat) a republic. This isn't a trivial distinction. The young kings of the various Carolignian successors also tended to inherit their titles when their fathers were killed, while Venice occupied a highly defensible geographic location (a swamp) which supported institutional continuity.
Most of South America has worked like this for decades. Hydropower is king even in Venezuela. It's altruistic on their part, but it may have reduced their long-term economic growth. Viewed in terms of GDP per capita, South America is a laggard. But if you change the denominator and look at GDP per kWh (energy intensity) they are surprisingly close to the rich world.
There is a hidden upside to all this hydro: it could potentially be upgraded to pumped storage and support a massive expansion of solar and wind. However, no SA country has such a forward-looking energy policy.
Do you have a source for GDP/kWh? Last time I was curious I dumped some raw stats (copied from wikipedia) into excel and venezuela was among the bottom three. I recall being surprised that there wasn't any strong correlation between GDP/kWh and any other obvious metric like technological development, population, land size, climate, etc.
If someone is willing and able to pay, they have a source of money. If they aren't allowed to buy something, that control should be applied at the level where they get the money. If the child is using an adult's credit card, responsibility lies with the adult. If children need to have their own credit cards, the obvious point of control is the credit card itself.
But also, most porn is ad-supported, pirated or free. Directly paid content is a small fraction. So all of this is moot for porn.
- land meats were all but banned in Japan for centuries prior to Perry's ultimatum, encouraging the development of alternatives in flavor and nutrition like natto and katsuobushi
- geographically, Japan had less access to land crops (even wheat was not common!) and more access to fish and seaweed than Korea
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