Also, in a world where elephants/mammoths can be reliably (and cheaply) cloned and bred, ivory would become about as valuable as beef,
But we could achieve the same tomorrow simply by impaling any person caught with any ivory on a stake at the entrance of the airport where they're found. The screams and groans of the impaled criminals would depress the price of ivory just as well, and need no more than (1) political will, (2) trained sniffer dogs, and (3) stick sharpening. One of those requirements is difficult - but whether it is more difficult than cloning large animals from multi-millennia - degraded DNA is a very open question.
(The idea that ivory owners would not be found at airports is dead in the water. Ivory is a "prestige" material, so will be owned in large part by rich idiots. Rich idiots cannot avoid flying as part of their showing of of their sex organs (wallets). Therefore ivory owners can efficiently be found by targetting airports, which are already configured for sniffer dogs and searching. If ivory becomes as "prestige" a product as radium-laced toothpaste (yes, a genuine product) and the price collapses appropriately, then it ceases to be worth poaching or keeping and selling. Which is the desired outcome.)
They only went extinct because we arrived as an invasive species and killed them all ourselves.
Do you have some data to support this assertion? In particular, something to support your claim that the mammoths on the Siberian island of Wrangel - the last to die out - actually had any contact with humans in the time before this population going extinct? Any evidence at all of humans being on Wrangel Island before 3000 BCE, when these mammoths died out.
The Earth has had Egyptian Pyramids longer than it has not had mammoths.
You are conflating two different times. While the (non-avian, see signature) dinosaurs were around, oxygen levels were within a few percent of our present atmospheric levels, though CO2 was at times considerably higher. Over 100 million years earlier however, in the Carboniferous period (Pennsylvanian/ Mississippian if you speak EN_US), the first insects were sometimes much larger than present insects and oxygen levels were up to about 30%.
Personally, I blame the fungi. When they learned how to decompose lignin (the stuff that makes wood tough), the accumulations of undecomposed land-plant debris got digested back into carbon dioxide (which went into limestone) and absorbed a large amount of the oxygen. This change in the carbon cycle had measurable effects in the stable-isotope carbon composition of the oceans, which we can see in authigenic minerals in marine sediments.
But those two atmospheres were further apart in time than we are from the last of the ammonites, or the Chixulub impactor.
Well, the bond strength is much the same. But the CO doesn't release from the haemoglobin anything like as rapidly or easily as O2 does.
A standard figure from diver training is that if you have a cigarette (with say 20ppm, 0.002% of CO) before you dive, you'll start your dive with about 5% of your blood's haemoglobin content inactivated by being bound to CO. If you're a regular smoker (more than a couple of fags a day) then you'll typically have 5-10% of your haemoglobin bound by CO and it'll take several days of non-smoking to clear that binding.
Teach kids in a language that is not only clean and easy to learn, but also one that they can take home and mess around with if they're interested.
Then teach them another language. Then another.
Because if there is one thing that is a certainty in the working lifetime of the next generation of students who learn to code (out to 2080~2090, if we continue using the current calendar - which I'm not betting for or against), then that certainty is that they'll need to use multiple different languages. Sometimes for good reasons, like language design ; other times for crap reasons like a PHB's addiction to BuzzWord Bingo.
To put things into perspective, if I'd stayed on to a 3rd year of computing science (instead of doing years 3 and 4 in geology), then I might have learned to use C, but I could not have used C++, because it didn't exist ; BASIC was dead when I was a student, and the IBM PC still cost around 6 month's income. Bill Gates had recently brought QDOS from (what's his name) and was re-badging it as MS-DOS.
How many comedy series from Britain can you name that made it past their second season?
H2G2
Just a Minute (that's on series... I'm not exactly sure - somewhere in the 40s). ISIHAC is of comparable vintage and has survived the death of it's anchorman reasonably well.
Now, if you'd specified British comedy DRAMA series, you'd have a stronger point. Though I sometimes find the Archers to be utterly hilarious, and I'm sure it's deliberate.
A valid comment would have been "wait, how big is the earthquake sample? how large is the increase in intensity?, could it be just random variation?". There is no way to answer those questions,
The sample of earthquakes (note : "sample", not "population") showing this effect is of "great earthquakes", not all earthquakes. But when they extend their analysis to M5.5 quakes the correlation disappears. There have been a dozen "great earthquakes" in instrumental history.
Our catalogues of quakes of M5.5+ are essentially complete for the last half century. Chalk that one up to the global test-ban treaty - a nuclear blast of Hiroshima or smaller size will produce a quake of M3 or higher.
Many people have been trying to find correlations between the occurrence of earthquakes and the occurrence of other phenomena which might possibly give predictive ability for earthquakes, and they've been trying (scientifically and less scientifically) for somewhat more than a century.
No-one has had significant success up to this date - this result barely makes it to significance with a corpus of relevant earthquakes of only a dozen or so. And the (putative) discovery of this weak signal is likely to mean that any other signals in the data set (several million earthquakes) are even weaker and of even lower significance.
Which won't really happen IMO until we are mining asteroids.
for which we're likely to need robots on the Moon to extract rocket fuel from the polar regolith, for which we'll need large acreages (well, hectares or square kilometres) of solar cells at several locations (to keep the power on through the local night at some of the power stations) and the cables to link power stations to processing plant (1km of 30A cable with 250VAC insulation would weigh around 1/4 tonnes, mostly copper ; this is not trivial).
In short, you need that supply chain. Or you need to hump every kilo of that material from Earth to your first industrial site and then build your supply chain.
2 points (because it's been a long day and it's bedtime for me.
(1) At some point, there will be an astronomical body on a collision course with the Earth. If you like the idea of the planet you (or your descendants, should you choose to have any) being hit by a megatonne - equivalent event at random, without anyone doing anything about it, that's your choice. But I would think that the process of developing then necessary technologies in good time to deploy them if needed, is a fairly good investment. (As an aside, any and all of the credible techniques for terraforming Mars would require this technology. Terraforming Venus, not so much. But increasing the number of planets open to impact simply increases the likelihood of an impact, and therefore of the benefits of developing and practising moving asteroids.
I do agree with you on the comparative benefits of moving factories to materials versus materials to factories. But either needs reaction mass at your departure point, so at some point, someone is going to have to move that reaction mass to the departure point - near Earth. The seemingly dissimilar problems converge - move some (quite significant) masses of material into near-Earth space.
(2) in terms of radiation, just choose to tolerate the risk, and/or bring a tiny shielded rad bunkerLets look at some numbers. If you can fit a single astronaut into a sphere 1.5m in diameter without them going insane (note the "if" - as a caver (EN_US: spelunker], I'd find a week in a 1.5m chamber wearing. Your level of claustrophobia is likely to be different, but is unlikely to be lower than mine.), and you accept half the protection that the atmosphere gives, then you're talking on the order of (4/3)*pi*(R^3-r^3) cubic metres (for 'r' ~0.75 and R ~ 5.75m) of water ice, or an approximately similar mass of lead, concrete, steel, whatever. I make that a smidgin under 800 cubic metres of water ice, or 800 tonnes. If you do your shielding with steel (specific gravity ~7) then the volume reduction reduces that mass to more like 80 tonnes. In comparison with the estimate of the mass of the "starter kit" of between 12 and 40 tonnes... well that's clearly an option that needs much more detailed analysis. Which is precisely what Dr Metzger's paper is about. (Just to point out something important - water ice can be re-used for either drinking or reaction mass with a heater ; to re-use steel similarly would require rather more tooling. You can even drink water ice, shit it out into a bag and put it back outside the ship and use it as radiation shielding.)
I didn't say "children", I said "embryos". And a lot more sperm and unfertilised eggs, all carefully categorised so that you can breed up colonists with appropriate properties.
Volunteers were not being looked for.
Anyone who did get shipped (if some form of reliable "cold sleep" could be developed, which is a very big if) would effectively be on a one-way ticket to never seeing anyone they know for the rest of their life. And precious little chance of any other contact either - a birthday message 20 or 30 years late, perhaps. Anyone who was shipped would be a convict of some sort, convicted of a crime that would attract a penalty of life exile without parole or visitors. In the event that you live in a barbarous country that still uses execution, you're legal system probably has not thought much about what level of crime that would be, since it would be far more expensive than killing them. (A "cruel and unusual punishment" too.) But some people would probably qualify - and I'd suspect political offenders (say - the survivors of the 2001-09-11 plot) would be the ones in the frame.
Which would mean that you'd need either a volunteer overseer of whose political loyalty you had mathematically zero doubt (that's another big ask of reality) or you'd need a sufficiently well programmed supervising computer. And surveillance, big style. Surveillance to make the nastiest denizens of modern TLAs drool with lust.
I seem to recall that orcas generally avoid hunting other dolphins and whales unless other food is scarce.
And on the other flipper, the English translation of the Portuguese (or was it Spanish?)word for orcas was got wrong. They shouldn't have translated it as "killer whales", but as "whale killers". Because killing whales is a routine part of the diet of some pods. And others, as noted below, specialise in salmon. And others in seals.
Short version : social predators are variable. Very variable. And often flexible.
Given that dolphins routinely attack and kill (but not often eat) harbour porpoises - at least the Scottish pods - then there doesn't seem to be a lot of "cetacean lives matter" activity in the marine mammal part of the world. Similarly, the number of monkeys killed for bush meat rather argues against there being a "Primate non-aggression pact".
Both Mars and Europa show strong evidence of having liquid water,
Mars shows evidence of having had abundant water in the past. Whether it has significant liquid water at surface these recent gigayears remains a very open question. Europa has almost certainly got around 3 times the volume of liquid water as Earth has. Whether it has sufficient geological overturn in it's rocky core, or in it's icy shell, to move energy into that water and potentially drive metabolism, is a question for the modellers, with slowly improving constraining data from our exploration efforts at the moment.
Lovelock's argument is considerably different to your oversimplification. (I've read a couple of his books - even found on which is signed by him in a 2nd-hand bookshop.)
Lovelock thinks that life would maintain homeostasis away from thermodynamic equilibrium.
Thermodynamic equilibrium is stable too, on human time-scales, so observing a stable environment itself is not indicative of life. That's why the big efforts over the last few years to verify and quantify the patchy reports of atmospheric methane on Mars. And then to understand if it's a product of geology, or of life.
My guess is that humanity won't have a lot of interest in artificially seeding life unless it's with the express purpose of terraforming planets for later habitation by humanity
By the time the first human wakes up in a system not controlled by the Sun, they will look at the idea of living on a planet like you'd suggested an evening of recreational goat buggery. The seed population would have spent their entire life - for generations - living on ships in deep space, and will know that their ancestors (if they know anything of their ancestors) had lived in space ships for generations. They might (if the people setting up the mission chose to tell them) know that the first humans lived on planets, and they might know of the difficulties of managing such an unmanaged ecology, compared to the designed ecology of the ships life support.
Even if there's nothing more complex than worms to start with, how many hundreds of millions of years do you suppose it would take our bacteria to evolve to that complexity?
About 20 units of a hundred million years each. If you take the "chain of beads" fossils as evidence of the very earliest of (infaunal) "worms". They pre-date the Ediacaran - possibly. But the odd thing is that if thy were infaunal (living by burrowing through mud), they didn't do much about disturbing the bedding of most of the sedimentary rocks known of that age. So, maybe they were an experiment that failed.
"Worms" are a lot more complex than most people give them credit for. Certainly more complex than early metazoans.
The other thing of course when it comes to transport large numbers of colonists,
What are the comparative costs of shipping a couple of kilos of embryos and frozen eggs & sperm (from tens of thousands of donor, voluntary or not) compared to shipping a single human (80kg) plus their life support system ( a few dozens of tones, hydroponics, pumps, filters, etc).
No. you'd not ship colonists. You'd ship embryos and when you get to the destination set about converting your travel ship to an industrial base, and building artificial wombs and "nursery robots" to rear the colonists to maturity. (Incidentally, this gives the opportunity for thorough-going indoctrination.) Then you set on with building your new colony. Plenty of stored genetic variation in the liquid nitrogen, and in your artificial society you encourage people to think it is a sin to indulge in natural childbirth. Hell, you might even want to make heterosexuality an unspeakable sin, for better population control.
Proving that a potentially habitable rock does not have it's own indigenous life is not simple. We've been trying to answer that question on Mars for 40 years, and there's only a year-or-so time of flight between here and there.
And indeed that is the ethic that NASA are applying by thoroughly sterilising their equipment before sending it to Mars. We'd have to do the same to the human explorers too, if they arrive before our robots have done a really convincing job of looking for the slightest hints of Martian life.
Or maybe, only 1 in 4 of the sub-fossils had adequate preservation of detectable bacterial fragments.
Just for starters : they were looking at microbe fragments preserved in teeth - because these are some of the most decay-resistant bits of the entire body. But for 1665 I wouldn't be astonished if most people who went into the ground for any reason had either badly-eroded teeth (grit in bread) or badly-rotted teeth (caries), or just plain no teeth. If the enamel from a tooth had worn off in life to expose the dentine or tooth pulp, then any bacteria found in there could have come into the tooth at some time post burial. Likewise if there were a caries pit in the tooth, it's a potential entry point for post-mortem bacteria.
1 in 4 bodies yielding usable results doesn't sound at all bad to me.
Incidentally, euipment failure wouldn't be an issue. You do the fieldwork one month. 6 months later, you get to "doing" the skeletons and decide which ones have teeth suitable for DNA work. Then you apply for a grant for the DNA work - if it's granted, you cut the teeth decided upon and extract your samples. Put them in liquid nitrogen while you're working on the other teeth in the sample. Then send them off to who-ever is doing your testing. If their equipment is having a bad hair day, then it might take 3 months to get the results instead of 2 months, or they farm it out to another lab.
They're not walking around with a Tricorder and a guy in a red shirt, zapping a bone sticking out of the mud and saying "Yersinia pestis!"
Slashdot Mirror
If I were you, I'd look up what happened in Greek mythology to people who expressed hubris.
But we could achieve the same tomorrow simply by impaling any person caught with any ivory on a stake at the entrance of the airport where they're found. The screams and groans of the impaled criminals would depress the price of ivory just as well, and need no more than (1) political will, (2) trained sniffer dogs, and (3) stick sharpening. One of those requirements is difficult - but whether it is more difficult than cloning large animals from multi-millennia - degraded DNA is a very open question.
(The idea that ivory owners would not be found at airports is dead in the water. Ivory is a "prestige" material, so will be owned in large part by rich idiots. Rich idiots cannot avoid flying as part of their showing of of their sex organs (wallets). Therefore ivory owners can efficiently be found by targetting airports, which are already configured for sniffer dogs and searching. If ivory becomes as "prestige" a product as radium-laced toothpaste (yes, a genuine product) and the price collapses appropriately, then it ceases to be worth poaching or keeping and selling. Which is the desired outcome.)
Do you have some data to support this assertion? In particular, something to support your claim that the mammoths on the Siberian island of Wrangel - the last to die out - actually had any contact with humans in the time before this population going extinct? Any evidence at all of humans being on Wrangel Island before 3000 BCE, when these mammoths died out.
The Earth has had Egyptian Pyramids longer than it has not had mammoths.
Personally, I blame the fungi. When they learned how to decompose lignin (the stuff that makes wood tough), the accumulations of undecomposed land-plant debris got digested back into carbon dioxide (which went into limestone) and absorbed a large amount of the oxygen. This change in the carbon cycle had measurable effects in the stable-isotope carbon composition of the oceans, which we can see in authigenic minerals in marine sediments.
But those two atmospheres were further apart in time than we are from the last of the ammonites, or the Chixulub impactor.
A standard figure from diver training is that if you have a cigarette (with say 20ppm, 0.002% of CO) before you dive, you'll start your dive with about 5% of your blood's haemoglobin content inactivated by being bound to CO. If you're a regular smoker (more than a couple of fags a day) then you'll typically have 5-10% of your haemoglobin bound by CO and it'll take several days of non-smoking to clear that binding.
Then teach them another language. Then another.
Because if there is one thing that is a certainty in the working lifetime of the next generation of students who learn to code (out to 2080~2090, if we continue using the current calendar - which I'm not betting for or against), then that certainty is that they'll need to use multiple different languages. Sometimes for good reasons, like language design ; other times for crap reasons like a PHB's addiction to BuzzWord Bingo.
To put things into perspective, if I'd stayed on to a 3rd year of computing science (instead of doing years 3 and 4 in geology), then I might have learned to use C, but I could not have used C++, because it didn't exist ; BASIC was dead when I was a student, and the IBM PC still cost around 6 month's income. Bill Gates had recently brought QDOS from (what's his name) and was re-badging it as MS-DOS.
H2G2
Just a Minute (that's on series ... I'm not exactly sure - somewhere in the 40s). ISIHAC is of comparable vintage and has survived the death of it's anchorman reasonably well.
Now, if you'd specified British comedy DRAMA series, you'd have a stronger point. Though I sometimes find the Archers to be utterly hilarious, and I'm sure it's deliberate.
Suspicious that no-one has mentioned the Chinese, who are just as capable of cloaking their operations in layers of false flags as anyone else.
You'll be able to find some good ones at Carstairs. You're going to be real popular with the big boys there.
The sample of earthquakes (note : "sample", not "population") showing this effect is of "great earthquakes", not all earthquakes. But when they extend their analysis to M5.5 quakes the correlation disappears. There have been a dozen "great earthquakes" in instrumental history.
Our catalogues of quakes of M5.5+ are essentially complete for the last half century. Chalk that one up to the global test-ban treaty - a nuclear blast of Hiroshima or smaller size will produce a quake of M3 or higher.
If you want the paper, try this link.
No-one has had significant success up to this date - this result barely makes it to significance with a corpus of relevant earthquakes of only a dozen or so. And the (putative) discovery of this weak signal is likely to mean that any other signals in the data set (several million earthquakes) are even weaker and of even lower significance.
I see the traditional Slashdot disease of not reading the fucking article before commenting stupidly hasn't cured in the last week.
for which we're likely to need robots on the Moon to extract rocket fuel from the polar regolith, for which we'll need large acreages (well, hectares or square kilometres) of solar cells at several locations (to keep the power on through the local night at some of the power stations) and the cables to link power stations to processing plant (1km of 30A cable with 250VAC insulation would weigh around 1/4 tonnes, mostly copper ; this is not trivial).
In short, you need that supply chain. Or you need to hump every kilo of that material from Earth to your first industrial site and then build your supply chain.
(1) At some point, there will be an astronomical body on a collision course with the Earth. If you like the idea of the planet you (or your descendants, should you choose to have any) being hit by a megatonne - equivalent event at random, without anyone doing anything about it, that's your choice. But I would think that the process of developing then necessary technologies in good time to deploy them if needed, is a fairly good investment. (As an aside, any and all of the credible techniques for terraforming Mars would require this technology. Terraforming Venus, not so much. But increasing the number of planets open to impact simply increases the likelihood of an impact, and therefore of the benefits of developing and practising moving asteroids.
I do agree with you on the comparative benefits of moving factories to materials versus materials to factories. But either needs reaction mass at your departure point, so at some point, someone is going to have to move that reaction mass to the departure point - near Earth. The seemingly dissimilar problems converge - move some (quite significant) masses of material into near-Earth space.
(2) in terms of radiation, just choose to tolerate the risk, and/or bring a tiny shielded rad bunkerLets look at some numbers. If you can fit a single astronaut into a sphere 1.5m in diameter without them going insane (note the "if" - as a caver (EN_US: spelunker], I'd find a week in a 1.5m chamber wearing. Your level of claustrophobia is likely to be different, but is unlikely to be lower than mine.), and you accept half the protection that the atmosphere gives, then you're talking on the order of (4/3)*pi*(R^3-r^3) cubic metres (for 'r' ~0.75 and R ~ 5.75m) of water ice, or an approximately similar mass of lead, concrete, steel, whatever. I make that a smidgin under 800 cubic metres of water ice, or 800 tonnes. If you do your shielding with steel (specific gravity ~7) then the volume reduction reduces that mass to more like 80 tonnes. In comparison with the estimate of the mass of the "starter kit" of between 12 and 40 tonnes ... well that's clearly an option that needs much more detailed analysis. Which is precisely what Dr Metzger's paper is about. (Just to point out something important - water ice can be re-used for either drinking or reaction mass with a heater ; to re-use steel similarly would require rather more tooling. You can even drink water ice, shit it out into a bag and put it back outside the ship and use it as radiation shielding.)
Volunteers were not being looked for.
Anyone who did get shipped (if some form of reliable "cold sleep" could be developed, which is a very big if) would effectively be on a one-way ticket to never seeing anyone they know for the rest of their life. And precious little chance of any other contact either - a birthday message 20 or 30 years late, perhaps. Anyone who was shipped would be a convict of some sort, convicted of a crime that would attract a penalty of life exile without parole or visitors. In the event that you live in a barbarous country that still uses execution, you're legal system probably has not thought much about what level of crime that would be, since it would be far more expensive than killing them. (A "cruel and unusual punishment" too.) But some people would probably qualify - and I'd suspect political offenders (say - the survivors of the 2001-09-11 plot) would be the ones in the frame.
Which would mean that you'd need either a volunteer overseer of whose political loyalty you had mathematically zero doubt (that's another big ask of reality) or you'd need a sufficiently well programmed supervising computer. And surveillance, big style. Surveillance to make the nastiest denizens of modern TLAs drool with lust.
H means a 5mm hole punch. Your Imperial 6.3mm punches won't do.
And on the other flipper, the English translation of the Portuguese (or was it Spanish?)word for orcas was got wrong. They shouldn't have translated it as "killer whales", but as "whale killers". Because killing whales is a routine part of the diet of some pods. And others, as noted below, specialise in salmon. And others in seals.
Short version : social predators are variable. Very variable. And often flexible.
Given that dolphins routinely attack and kill (but not often eat) harbour porpoises - at least the Scottish pods - then there doesn't seem to be a lot of "cetacean lives matter" activity in the marine mammal part of the world. Similarly, the number of monkeys killed for bush meat rather argues against there being a "Primate non-aggression pact".
Mars shows evidence of having had abundant water in the past. Whether it has significant liquid water at surface these recent gigayears remains a very open question. Europa has almost certainly got around 3 times the volume of liquid water as Earth has. Whether it has sufficient geological overturn in it's rocky core, or in it's icy shell, to move energy into that water and potentially drive metabolism, is a question for the modellers, with slowly improving constraining data from our exploration efforts at the moment.
Lovelock thinks that life would maintain homeostasis away from thermodynamic equilibrium.
Thermodynamic equilibrium is stable too, on human time-scales, so observing a stable environment itself is not indicative of life. That's why the big efforts over the last few years to verify and quantify the patchy reports of atmospheric methane on Mars. And then to understand if it's a product of geology, or of life.
By the time the first human wakes up in a system not controlled by the Sun, they will look at the idea of living on a planet like you'd suggested an evening of recreational goat buggery. The seed population would have spent their entire life - for generations - living on ships in deep space, and will know that their ancestors (if they know anything of their ancestors) had lived in space ships for generations. They might (if the people setting up the mission chose to tell them) know that the first humans lived on planets, and they might know of the difficulties of managing such an unmanaged ecology, compared to the designed ecology of the ships life support.
About 20 units of a hundred million years each. If you take the "chain of beads" fossils as evidence of the very earliest of (infaunal) "worms". They pre-date the Ediacaran - possibly. But the odd thing is that if thy were infaunal (living by burrowing through mud), they didn't do much about disturbing the bedding of most of the sedimentary rocks known of that age. So, maybe they were an experiment that failed.
"Worms" are a lot more complex than most people give them credit for. Certainly more complex than early metazoans.
What are the comparative costs of shipping a couple of kilos of embryos and frozen eggs & sperm (from tens of thousands of donor, voluntary or not) compared to shipping a single human (80kg) plus their life support system ( a few dozens of tones, hydroponics, pumps, filters, etc).
No. you'd not ship colonists. You'd ship embryos and when you get to the destination set about converting your travel ship to an industrial base, and building artificial wombs and "nursery robots" to rear the colonists to maturity. (Incidentally, this gives the opportunity for thorough-going indoctrination.) Then you set on with building your new colony. Plenty of stored genetic variation in the liquid nitrogen, and in your artificial society you encourage people to think it is a sin to indulge in natural childbirth. Hell, you might even want to make heterosexuality an unspeakable sin, for better population control.
Proving that a potentially habitable rock does not have it's own indigenous life is not simple. We've been trying to answer that question on Mars for 40 years, and there's only a year-or-so time of flight between here and there.
Same for Europa and Callisto.
Just for starters : they were looking at microbe fragments preserved in teeth - because these are some of the most decay-resistant bits of the entire body. But for 1665 I wouldn't be astonished if most people who went into the ground for any reason had either badly-eroded teeth (grit in bread) or badly-rotted teeth (caries), or just plain no teeth. If the enamel from a tooth had worn off in life to expose the dentine or tooth pulp, then any bacteria found in there could have come into the tooth at some time post burial. Likewise if there were a caries pit in the tooth, it's a potential entry point for post-mortem bacteria.
1 in 4 bodies yielding usable results doesn't sound at all bad to me. Incidentally, euipment failure wouldn't be an issue. You do the fieldwork one month. 6 months later, you get to "doing" the skeletons and decide which ones have teeth suitable for DNA work. Then you apply for a grant for the DNA work - if it's granted, you cut the teeth decided upon and extract your samples. Put them in liquid nitrogen while you're working on the other teeth in the sample. Then send them off to who-ever is doing your testing. If their equipment is having a bad hair day, then it might take 3 months to get the results instead of 2 months, or they farm it out to another lab.
They're not walking around with a Tricorder and a guy in a red shirt, zapping a bone sticking out of the mud and saying "Yersinia pestis!"