Alice wants something done and pays Bob to do it. Bob subcontract to Carol, who subcontracts to David. David doesn't do it or botches it. Alice is upset and sues Bob. Bob says "It isn't my fault, sue Carol instead". What happens?
What looks to me to be the sensible solution is that Bob petitions the court to have Carol added to the suit, but Bob can't be removed from the suit unless Alice agrees. Carol then has David added to the suit. Assuming that Alice wins, David is liable, but if he cannot or will not pay, Carol has to pick up the tab, and failing that Bob. Alice gets paid so long as Bob, Carol and David collectively can come up with the awarded penalty.
Does the law actually work like this? Alternatively, Alice sues Bob who has to pay. Then in a separate suit, Bob sues Carol for Bob's penalty plus legal costs. Then Carol sues David, by which time a decade has passed and legal costs have dwarfed Alice's original damage.
(In the case in hand, Alice is the plumber, the "something done" was removing the decals, Bob is the dealer Alice dealt with. The rest of the chain only occurs in this case if the exporter who the dealer sold to had some obligation to the dealer to remove the decals - probably not the case here.)
Worth is determined by what people will pay for it;
No, worth is the maximum of what the owners are willing to sell for and what non-owners are willing to pay. That nobody else is offering $1M per year does not obligate the owners to accept that offer, if they place a greater value on the land. Nor does it matter why the value the land - whether for spiritual reasons, or because they think they can hold out for a better deal.
Consider the Airbus A350: First proposed to customers September 2004. Launched Dec 2006 (i.e. Airbus commits to building it.) First flight June 2013. First commercial service Jan 2015. Airliners have long gestation periods. If I'm wrong (which I'd be happy to be) and this idea really does have wings, it still very unlikely to fly before 2030.
I predict this won't happen. The cost of the system, in weight, complexity, ground support and possibly safety I think will outweigh the benefits for all but a few niche markets, which wouldn't be able to support the massive investment required to bring it to market.
A rather smaller example was that Boeing tried to sell the idea of 777s with folding wing tips, so they could use then-current terminal gates (for which the 777 wingspan was too large.) Nobody took them up on it.
However, I am not an airliner engineer. I'd be happy to be proved wrong.
Airline pilot training has a huge emphasis on 'debugging'. Twice a year (I think - not 100% sure) they have several days of simulator training/testing where sadistic trainers throw dozens of complicated failure scenarios at them.
Airliner safety has improved hugely in recent decades. (The USA recently went over a decade without a passenger jet airliner crash either on USA soil or USA flagged carrier.) New technology has played a large part, yet the proportion of crashes due to pilot error has remained about constant - i.e. improvements in pilot training and performance has kept pace with the safety improvements from technology.
Improvements can be (and are) made to pilot training, guided by investigations like this one.
It sounds like a precarious business model. Everyone prefers lithium batteries. So long as lithium prices are high enough, you can find a market for cheaper inferior batteries. But high lithium prices will lead to higher lithium production and prices likely coming back down. In building a sodium battery plant, you're gambling on lithium price being sufficiently high most of the time for several decades into the future.
The picture changes if you can make the sodium batteries as good as lithium for at least some market niche, or if your battery plant can easily switch between lithium and sodium (which seems fairly likely.)
OK, that is a start at understanding the nature of cricket commentary. Now imagine how relevant the commentary would be if instead of 90 minutes (or whatever it is) they had to keep talking for five days.
I've shown the claim is implausible, not impossible. I'd be interested to see what evidence there is to support it.
I don't see the need for the claim from an evolutionary point of view: there is no reason I am aware of to suppose that current tides are insufficient to drive organisms to evolve into terrestrial niches.
What happened 4 billion years ago is not the point - the claim was made in the context of the 'conquest' of the land by multicellular life, which was only about 0.5 billion years ago (not 1 billion, as I used in my analysis, and so tides were likely only about 15% higher then.) I agree that tidal conditions were very different four billion years ago, and that my linear extrapolation would not apply so far back.
10% (for a billion years, or 5% for 500 million) is a small enough change in distance that we wouldn't expect the recession rate to have changed a lot over that time. This is a somewhat weak point in my argument - the recession rate of the moon is largely dependent on how many Bay of Fundys there are in the world, so the current rate may not be typical. However the argument is strong enough to place the burden of proof on those making the claim: you claim an effect an order of magnitude greater than simple analysis allows for. Show evidence for these tides, or a well founded model which predicts these tides (at the required time.)
1 billion years ago the Earth had 100 to 1,000 foot tides as the Moon and the Earth were much closer
My initial response is "I don't think so." My second response is to calculate, so here goes: Current distance to moon = 384,400 km = 4 x 10^8m Current rate of increase in distance to moon = 3.8 cm/year = 4 x 10^-2 m/year. If this rate were constant over a billion (10^9) years, then a billion years ago the distance to the moon was 4 x 10^-2m/year*10^9year = 4 x 10^7 m closer, or 10% closer. Tidal effect strengths are inverse-cube in distance, so a billion years ago, lunar tides would have been about 30% larger than now.
This doesn't come close to "100 to 1000 foot tides."
Not only that, but without the moon, Earth's day would not be even close to 24 hours. (Lunar tides over billions of years have modified the length of the day.) Think how inconvenient that would be! I think you're on to something.
As seen from the moon, the Earth is only about two degrees across, so the proportion of projectiles blocked by it would be miniscule. Even that small effect is reduced (possibly beyond zero) by 'gravitational focusing': projectiles which come towards the moon from the direction of the Earth which would otherwise have missed can be deflected by Earth's gravity such that they hit. (And this happens more often than projectiles that would have hit being deflected so they miss.)
Here is a paper I found on gravitational focusing.
Antimatter and matter react in the same way with photons, so in the wildly unlikely event that you could produce and collect an observable quantity of anti-mercury and then observe it, it would look like mercury.
This is a quibble, but non-volatile RAM has only been the Holy Grail since about 1970. Prior to that, magnetic core memory was the standard RAM technology and is non-volatile. (To quibble the quibble, for a short period of time Williams tubes were the state-of-the-art (indeed, only) RAM, and they are volatile. Alan Turing played with Williams tubes.)
What I was trying to get at was that if a section of DNA performs some useful function, even if we don't know what it is, it'll tend to be preserved...
Yes.
Would such cyclic shifts meaningfully affect the assumptions underlying the multiple mutation rate?
I'd expect it to be a very minor effect. I'm not aware of anyone getting worried about this. It is a matter of statistics: if you're comparing 100,000 DNA sites, you don't care much if 50 of them behave weirdly in some fashion. If you successfully target 'junk' DNA for the comparison, it is not an issue.
A related effect is convergent evolution. Say two species of bacteria each colonize high temperature environment. Then certain mutations which are favoured in high temperature will likely occur in both of them. When we compare their DNA, this can make it look like they are more closely related than they really are. This is more of an issue in morphology (Darwin's finches, for example, or cormorants, which look very similar all around the world but turn out often not to be closely related) but it can happen at the DNA level too.
OK, Jane has evidence for the absence of a certain class of gorilla (highly visible gorillas.) She has placed constraints on the properties of any gorillas in the town (that they not be highly visible.) She can't say anything useful about presence or absence of ninja gorillas.
Let me see if I understand. By measuring over a long period, we're measuring the long term rate of mutation survival after applying selection pressure, and that could be noticeably different than the raw rate of mutation. Is that a correct summary?
Yes, that is correct. The technical term for 'mutation survival' is 'fixation'. A mutation is 'fixed' once the entire population carries it. It is 'extinct' (unsurprisingly) when it no longer exists in the population. When it exists in part of the population it is 'segregating'.
There are huge amounts of DNA that have no known purpose and appear to be junk. This is over 98% in humans, but varies a lot between organisms. The junkness of this is under debate. My feeling is that much of it really is junk, but some of it has a function we don't yet understand. (Also, sometimes the function is simply "we need a certain amount of space between these two bits of non-junk". This has a clear purpose, but is 'junk' in that the DNA letters don't matter.)
This particular experiment is about mitochondrial DNA which has very little 'junk', and that which it does have probably at minimum has something like 'need this amount of space' function.
Yes, scientists do like using 'junk' DNA for phylogeny (making family trees of organisms) because it is (we think) not subject to selection. On the other hand, you need to find the corresponding junk regions in all your critters and sequence them. It is easier to identify corresponding genes, and often someone else (who cared about the genes themselves) has done the sequencing work for you. Often the choice is doing phylogeny on genes using only a computer, when phylogeny on junk DNA requires samples and a molecular biology lab. Another issue is time scale: the junk DNA mutates faster, so it is good for closely related species (e.g. 'apes') but for distantly related species (e.g. 'vertebrates') you need highly conserved sequences (genes). The junk DNA will have mutated so much that it is all noise, no signal.
Is there a way to measure the mutation rates for different sites in the overall genome of a given organism, so that: (a) we can determine if some regions are actually junk because mutations to them do not affect organism fitness
Yes, if we have diverse organisms and a good alignment of their DNA, we can look for 'junk' regions by how much mutation occurs where. (Actually it tends to be the other way around - we see islands of conserved sequence, and deduce therefore that they have a function. This isn't how genes are detected, as there are more sensitive gene-specific ways of doing this.)
and (b) can distinguish between the rate of mutation and the rate of mutation survival?
Only I think by comparing mutation rates over pedigree time scales (a few generations) with mutation rates over long time scales - which is what this paper addresses.
No, the paper has nothing about epigenetics. They are looking only at mitochondria which I believe is not affected by epigenetics. I don't think mitochondria can function without all of their genes. They are actually looking directly at the DNA - the mutations really did happen, because they are observing them at the most fundamental level. There is nowhere for them to 'hide'.
The experiment covers about 50 generations. (Or, more accurately, they are piggybacking off an existing experiment that has been running for 50 generations.)
So this seems to just be another study showing the trickiness of using that 'clock'.
I agree except for the word "just". Yes, very much one of the things they are saying is that the molecular clock may have quirks, and failing to account for them will lead to error. (Whether this quirk is one which can be accounted for accurately isn't addressed in this paper, they are trying to establish that the quirk does in fact exist.) But it is more interesting that that, being a pedigree study over a large number of generations, and having a well documented case of paternal leakage. The only pedigree study I've been involved in was over a single generation.
I think you're talking about punctuated equilibrium, which is about phenotypic change (change in body shape/size/colour/function etc.) I think punctuated equilibrium is somewhere between controversial and discredited, but it is not my field so I'm not sure.
In this case, we are talking about evolution at the level of DNA, which is commonly thought to be a continuous process with rate being nearly constant. https://en.wikipedia.org/wiki/... The limitations of the molecular clock are what are being argued about in the academic debate that this paper is part of.
Slashdot Mirror
Alice wants something done and pays Bob to do it. Bob subcontract to Carol, who subcontracts to David. David doesn't do it or botches it. Alice is upset and sues Bob. Bob says "It isn't my fault, sue Carol instead". What happens?
What looks to me to be the sensible solution is that Bob petitions the court to have Carol added to the suit, but Bob can't be removed from the suit unless Alice agrees. Carol then has David added to the suit. Assuming that Alice wins, David is liable, but if he cannot or will not pay, Carol has to pick up the tab, and failing that Bob. Alice gets paid so long as Bob, Carol and David collectively can come up with the awarded penalty.
Does the law actually work like this? Alternatively, Alice sues Bob who has to pay. Then in a separate suit, Bob sues Carol for Bob's penalty plus legal costs. Then Carol sues David, by which time a decade has passed and legal costs have dwarfed Alice's original damage.
(In the case in hand, Alice is the plumber, the "something done" was removing the decals, Bob is the dealer Alice dealt with. The rest of the chain only occurs in this case if the exporter who the dealer sold to had some obligation to the dealer to remove the decals - probably not the case here.)
Furthermore this is not news - it was uncontroversial when I studied astronomy 25 years ago.
As I'm unwilling to do battle with the Forbes website, I don't know whether TFA has anything new to add to this.
Worth is determined by what people will pay for it;
No, worth is the maximum of what the owners are willing to sell for and what non-owners are willing to pay. That nobody else is offering $1M per year does not obligate the owners to accept that offer, if they place a greater value on the land. Nor does it matter why the value the land - whether for spiritual reasons, or because they think they can hold out for a better deal.
Consider the Airbus A350: First proposed to customers September 2004. Launched Dec 2006 (i.e. Airbus commits to building it.) First flight June 2013. First commercial service Jan 2015. Airliners have long gestation periods. If I'm wrong (which I'd be happy to be) and this idea really does have wings, it still very unlikely to fly before 2030.
I predict this won't happen. The cost of the system, in weight, complexity, ground support and possibly safety I think will outweigh the benefits for all but a few niche markets, which wouldn't be able to support the massive investment required to bring it to market.
A rather smaller example was that Boeing tried to sell the idea of 777s with folding wing tips, so they could use then-current terminal gates (for which the 777 wingspan was too large.) Nobody took them up on it.
However, I am not an airliner engineer. I'd be happy to be proved wrong.
This is an uninformed and incorrect opinion.
Airline pilot training has a huge emphasis on 'debugging'. Twice a year (I think - not 100% sure) they have several days of simulator training/testing where sadistic trainers throw dozens of complicated failure scenarios at them.
Airliner safety has improved hugely in recent decades. (The USA recently went over a decade without a passenger jet airliner crash either on USA soil or USA flagged carrier.) New technology has played a large part, yet the proportion of crashes due to pilot error has remained about constant - i.e. improvements in pilot training and performance has kept pace with the safety improvements from technology.
Improvements can be (and are) made to pilot training, guided by investigations like this one.
It sounds like a precarious business model. Everyone prefers lithium batteries. So long as lithium prices are high enough, you can find a market for cheaper inferior batteries. But high lithium prices will lead to higher lithium production and prices likely coming back down. In building a sodium battery plant, you're gambling on lithium price being sufficiently high most of the time for several decades into the future.
The picture changes if you can make the sodium batteries as good as lithium for at least some market niche, or if your battery plant can easily switch between lithium and sodium (which seems fairly likely.)
Israel is fighting an existential war of self defense.
Yet if I put a different hat on, I see Palestine fighting an existential war of self defense.
But organic LEDs are good for you and the environment, because chemical fertilizers and pesticides aren't used to make them.
OK, that is a start at understanding the nature of cricket commentary. Now imagine how relevant the commentary would be if instead of 90 minutes (or whatever it is) they had to keep talking for five days.
I've shown the claim is implausible, not impossible. I'd be interested to see what evidence there is to support it.
I don't see the need for the claim from an evolutionary point of view: there is no reason I am aware of to suppose that current tides are insufficient to drive organisms to evolve into terrestrial niches.
What happened 4 billion years ago is not the point - the claim was made in the context of the 'conquest' of the land by multicellular life, which was only about 0.5 billion years ago (not 1 billion, as I used in my analysis, and so tides were likely only about 15% higher then.) I agree that tidal conditions were very different four billion years ago, and that my linear extrapolation would not apply so far back.
10% (for a billion years, or 5% for 500 million) is a small enough change in distance that we wouldn't expect the recession rate to have changed a lot over that time. This is a somewhat weak point in my argument - the recession rate of the moon is largely dependent on how many Bay of Fundys there are in the world, so the current rate may not be typical. However the argument is strong enough to place the burden of proof on those making the claim: you claim an effect an order of magnitude greater than simple analysis allows for. Show evidence for these tides, or a well founded model which predicts these tides (at the required time.)
1 billion years ago the Earth had 100 to 1,000 foot tides as the Moon and the Earth were much closer
My initial response is "I don't think so." My second response is to calculate, so here goes:
Current distance to moon = 384,400 km = 4 x 10^8m
Current rate of increase in distance to moon = 3.8 cm/year = 4 x 10^-2 m/year.
If this rate were constant over a billion (10^9) years, then a billion years ago the distance to the moon was 4 x 10^-2m/year*10^9year = 4 x 10^7 m closer, or 10% closer. Tidal effect strengths are inverse-cube in distance, so a billion years ago, lunar tides would have been about 30% larger than now.
This doesn't come close to "100 to 1000 foot tides."
Not only that, but without the moon, Earth's day would not be even close to 24 hours. (Lunar tides over billions of years have modified the length of the day.) Think how inconvenient that would be! I think you're on to something.
As seen from the moon, the Earth is only about two degrees across, so the proportion of projectiles blocked by it would be miniscule. Even that small effect is reduced (possibly beyond zero) by 'gravitational focusing': projectiles which come towards the moon from the direction of the Earth which would otherwise have missed can be deflected by Earth's gravity such that they hit. (And this happens more often than projectiles that would have hit being deflected so they miss.)
Here is a paper I found on gravitational focusing.
Antimatter and matter react in the same way with photons, so in the wildly unlikely event that you could produce and collect an observable quantity of anti-mercury and then observe it, it would look like mercury.
This is a quibble, but non-volatile RAM has only been the Holy Grail since about 1970. Prior to that, magnetic core memory was the standard RAM technology and is non-volatile. (To quibble the quibble, for a short period of time Williams tubes were the state-of-the-art (indeed, only) RAM, and they are volatile. Alan Turing played with Williams tubes.)
I could have spent the effort debating the creationists. This was much more fun.
What I was trying to get at was that if a section of DNA performs some useful function, even if we don't know what it is, it'll tend to be preserved...
Yes.
Would such cyclic shifts meaningfully affect the assumptions underlying the multiple mutation rate?
I'd expect it to be a very minor effect. I'm not aware of anyone getting worried about this. It is a matter of statistics: if you're comparing 100,000 DNA sites, you don't care much if 50 of them behave weirdly in some fashion. If you successfully target 'junk' DNA for the comparison, it is not an issue.
A related effect is convergent evolution. Say two species of bacteria each colonize high temperature environment. Then certain mutations which are favoured in high temperature will likely occur in both of them. When we compare their DNA, this can make it look like they are more closely related than they really are. This is more of an issue in morphology (Darwin's finches, for example, or cormorants, which look very similar all around the world but turn out often not to be closely related) but it can happen at the DNA level too.
OK, Jane has evidence for the absence of a certain class of gorilla (highly visible gorillas.) She has placed constraints on the properties of any gorillas in the town (that they not be highly visible.) She can't say anything useful about presence or absence of ninja gorillas.
Let me see if I understand. By measuring over a long period, we're measuring the long term rate of mutation survival after applying selection pressure, and that could be noticeably different than the raw rate of mutation. Is that a correct summary?
Yes, that is correct. The technical term for 'mutation survival' is 'fixation'. A mutation is 'fixed' once the entire population carries it. It is 'extinct' (unsurprisingly) when it no longer exists in the population. When it exists in part of the population it is 'segregating'.
There are huge amounts of DNA that have no known purpose and appear to be junk. This is over 98% in humans, but varies a lot between organisms. The junkness of this is under debate. My feeling is that much of it really is junk, but some of it has a function we don't yet understand. (Also, sometimes the function is simply "we need a certain amount of space between these two bits of non-junk". This has a clear purpose, but is 'junk' in that the DNA letters don't matter.)
This particular experiment is about mitochondrial DNA which has very little 'junk', and that which it does have probably at minimum has something like 'need this amount of space' function.
Yes, scientists do like using 'junk' DNA for phylogeny (making family trees of organisms) because it is (we think) not subject to selection. On the other hand, you need to find the corresponding junk regions in all your critters and sequence them. It is easier to identify corresponding genes, and often someone else (who cared about the genes themselves) has done the sequencing work for you. Often the choice is doing phylogeny on genes using only a computer, when phylogeny on junk DNA requires samples and a molecular biology lab. Another issue is time scale: the junk DNA mutates faster, so it is good for closely related species (e.g. 'apes') but for distantly related species (e.g. 'vertebrates') you need highly conserved sequences (genes). The junk DNA will have mutated so much that it is all noise, no signal.
Is there a way to measure the mutation rates for different sites in the overall genome of a given organism, so that: (a) we can determine if some regions are actually junk because mutations to them do not affect organism fitness
Yes, if we have diverse organisms and a good alignment of their DNA, we can look for 'junk' regions by how much mutation occurs where. (Actually it tends to be the other way around - we see islands of conserved sequence, and deduce therefore that they have a function. This isn't how genes are detected, as there are more sensitive gene-specific ways of doing this.)
and (b) can distinguish between the rate of mutation and the rate of mutation survival?
Only I think by comparing mutation rates over pedigree time scales (a few generations) with mutation rates over long time scales - which is what this paper addresses.
No, the paper has nothing about epigenetics. They are looking only at mitochondria which I believe is not affected by epigenetics. I don't think mitochondria can function without all of their genes. They are actually looking directly at the DNA - the mutations really did happen, because they are observing them at the most fundamental level. There is nowhere for them to 'hide'.
The experiment covers about 50 generations. (Or, more accurately, they are piggybacking off an existing experiment that has been running for 50 generations.)
Viruses meet all the requirements needed for evolution to apply to them.
So this seems to just be another study showing the trickiness of using that 'clock'.
I agree except for the word "just". Yes, very much one of the things they are saying is that the molecular clock may have quirks, and failing to account for them will lead to error. (Whether this quirk is one which can be accounted for accurately isn't addressed in this paper, they are trying to establish that the quirk does in fact exist.) But it is more interesting that that, being a pedigree study over a large number of generations, and having a well documented case of paternal leakage. The only pedigree study I've been involved in was over a single generation.
I think you're talking about punctuated equilibrium, which is about phenotypic change (change in body shape/size/colour/function etc.) I think punctuated equilibrium is somewhere between controversial and discredited, but it is not my field so I'm not sure.
In this case, we are talking about evolution at the level of DNA, which is commonly thought to be a continuous process with rate being nearly constant. https://en.wikipedia.org/wiki/...
The limitations of the molecular clock are what are being argued about in the academic debate that this paper is part of.