[HN Gopher] On the trail of the Denisovans
___________________________________________________________________
On the trail of the Denisovans
Author : georgecmu
Score : 23 points
Date : 2024-03-02 15:01 UTC (7 hours ago)
(HTM) web link (www.nytimes.com)
(TXT) w3m dump (www.nytimes.com)
| goles wrote:
| https://archive.is/TXTdK
| rhelz wrote:
| No doubt there are many, many other varieties of humans which
| we'll never know about because we'll never find any bones.
|
| What chilling is that shows very clearly that humans can go
| extinct. In fact, humans go extinct all the time: 50,000 years
| ago, we shared the earth with at least 5 different varieties of
| humans (Homo Neanterthalensis, Homo Denisova, Homo Naledi, Homo
| Florensiensis, and Homo Luzenenensis). Probably also some late
| surviving populations of Homo Erectus and Homo Rudolfensis.
| Almost certainly more we'll never know about.
|
| Since the last ice age we've been dropping like flies. In fact,
| we're the only humans left. And what with climate change,
| accidental nuclear war, or the singularity looming, we are
| arguably in a more precarious position than we've ever been.
| huytersd wrote:
| Humans have never had the numbers they've had right now. It
| would be very hard to eradicate 8 billion individual organisms.
| Simon_ORourke wrote:
| What do you mean hard? I do this all the time with some
| bleach and a scrubbing brush.
| huytersd wrote:
| Global scale bleach events are rare.
| AndrewKemendo wrote:
| This offered me a good laugh. Thank you.
| account-5 wrote:
| We're trying our best though.
|
| EDIT: for those downvoting, I'd like to discuss why you don't
| agree. I mean, climate change, war, etc. What else can you
| call it?
| echelon wrote:
| No amount of climate change short of Venusian runaway
| heating will scour the earth of humans.
|
| If we launch all of our nukes, we might collapse
| civilization, but even that would likely leave humans
| around. We might get stuck in our gravity well for a long
| time, though.
|
| Whatever makes us go extinct will either be cosmic or
| something we haven't invented yet.
| account-5 wrote:
| I think the amount of climate change that kills off our
| food or the atmosphere we breath might do it.
| huytersd wrote:
| An appropriate virus would do it. Spread through the air,
| 5 year incubation rate, 90%+ mortality would do it.
| rhelz wrote:
| // venusian runaway...//
|
| We cool our bodies by sweating, a process which ceases to
| work at about 95 degrees at 100% humidity, or 115 degrees
| at 50% humidity. Its been estimated that an average
| temperature of above 122 degrees F would kill off all
| mammalian life on the planet.
|
| Currently the earth is warming at about 1/3rd of a degree
| F per decade.
| echelon wrote:
| Seeing how the summer mean daily maximum in my city is
| 95.8 deg F and the mean humidity averages 80%, I think we
| already cross your threshold frequently. It hasn't killed
| us yet. I would frequently go running in the afternoon
| during "heat stroke" days. I love that weather. Hot and
| humid summers are personally invigorating. I grew up with
| them. I'd like to see your sources.
|
| > Currently the earth is warming at about 1/3rd of a
| degree F per decade.
|
| Every decade our technological capability increases
| dramatically. We're already working on climate
| engineering. Nothing here will extinct us.
| rhelz wrote:
| // I'd like to see your sources //
|
| See the July 19, 2022 Issue of the Scientific American,
| "How Hot Is Too Hot for the Human Body?"
|
| // I would frequently go running //
|
| Recall, it's 95 degrees at 100% humidity. The more humid
| the air, the less sweat will evaporate. I don't care if
| you are Jesus Christ Usane Bolt Superstar, above 95
| degrees at 100% humidity, if you run long enough you will
| get heatstroke.
|
| // Nothing here will extinct us // Extinction has
| happened to every other species of Homo. Every. single.
| one. I wonder how many of them accurately predicted when
| and why they would go extinct....
| echelon wrote:
| I spent fifteen minutes in a 112 deg F shower today [1]
| at presumably near total humidity. I do this all the
| time, and that isn't even hot.
|
| I was born and live in heat, so when I hear cold climate
| SF denizens say the end is nigh, I have to chuckle.
|
| I took a look at your source [2]. I'll have to read the
| underlying literature. The way this is presented to a lay
| audience doesn't make it clear if they're controlling for
| acclimation. I'm not educated in physiology beyond an
| undergrad class, so I'm not sure if their measure is a
| good proxy.
|
| It'll take sixty years to raise the temperature two
| degrees, after which I'll probably be dead. It'll take
| centuries to push into dangerous ranges. I think we're
| already building the tech to deal with this, and very
| little growth is exponential. This is going to be yet
| another sigmoid. And in geologic times, just noise.
|
| I will say I am worried about loss of species diversity.
| But I'm more worried about a lack of cheap energy to fuel
| our ascendent climb to the next stages. And more worried
| about nukes.
|
| As far as green tech goes, I've always been worried about
| particulate matter in the air leading to cardiopulmonary
| diseases. So it's not a bad thing and I've never once
| been against it.
|
| What I am concerned about is that we're teaching Gen Z
| and Gen Alpha to just give up. Go look at /r/GenZ and all
| the threads about climate - these kids are just giving up
| on life because of these memes. In reality, their lives
| will not be impacted by climate change whatsoever. We're
| scaring them to death and their entire generation is
| experiencing trauma because of this.
|
| We do need to control these systems, and we do need to
| protect ecosystem biodiversity, but this hysteria is
| ridiculous.
|
| [1] I just measured the water temperature.
|
| [2] https://www.scientificamerican.com/article/how-hot-
| is-too-ho...
| rhelz wrote:
| // I spent fifteen minutes in a 112 deg F shower...I
| spent fifteen minutes in a 112 deg F shower //
|
| Did you measure your body temperature? Were you able to
| cool yourself by sweating, or was your body temperature
| monotonically rising?
|
| Recall, it is recommended that you go to a doctor if you
| have a fever of over 103 degrees, and over 108 degrees
| you risk brain damage.
|
| Soaking some nice heat into your sore muscles in a
| 20-minute shower is one thing; but 24/7 your body is
| absolutely, positively not able to cool itself down is
| quite another.
|
| // They don't control for so many things, let alone
| acclimation. //
|
| Hey man, I gave you a source as requested. Whether or not
| evaporating water can cool down a body of a certain
| volume and surface when that body is internally
| generating heat--that isn't a matter of acclimation, its
| a matter of thermodynamics.
|
| // after which I'll probably be dead // And why think
| about extinction after I'm dead, eh? :-) But far before
| 60 years passes, you'll find yourself in the age
| demographic for which death from hot weather is a risk.
| The body's ability to thermoregulate degrades as we get
| older, alas...
|
| // worried about a lack of cheap energy // Wind farms are
| already cheaper to build than coal-fired plants. And if
| you factor in all the externalities, fossils fuels don't
| even come close to being a cheap source of energy.
|
| // we're teaching Gen Z and Gen Alpha to just give up...
| this hysteria is ridiculous // Worrying about how the
| media affects "kids these days" is a normal, expected
| part of the aging process :-) ....maybe, perhaps, the
| thought that Gen-Z and Gen-X are just giving up is a bit,
| well, I won't say hysterical, but perhaps a bit
| hyperbolic? And inasmuch as they are going to be here
| longer than we are, they do have a bit more of a stake in
| the future than we do.
| cgh wrote:
| War? We live in one of the most peaceful times in human
| history.
| polishdude20 wrote:
| Wonder if there's a structure of ours that's akin to the
| pyramids. But like, something that would last millennia.
| blamazon wrote:
| Hoover dam? Svalbard seed vault?
| klyrs wrote:
| Open pit mines seem to be a pretty good candidates for this.
| They're pretty much the opposite of a structure, but I can't
| imagine them looking "natural" even thousands of years from
| now. I can imagine one or two getting overgrown, but ones in
| desert areas like Utah could last until the next deep ice
| age.
| polishdude20 wrote:
| Yeah I guess you can look at ancient craters from meteors
| or volcanos to see how it would look.
| klyrs wrote:
| Can we? I'm not under the impression that those were ever
| terraced[1] like open-pit mines. But come to think of it,
| terracing itself qualifies as a megastructure[2]. Where
| the Long Now clock is an offbeat art project, rice
| paddies are crucial for nutrition for a great many people
| and they've already been around for at least 2 millenia.
| As times get lean, I can imagine pilfering the Long Now
| clock for parts; but those rice paddies will only gain
| importance.
|
| [1] https://www.dreamstime.com/stock-photography-bingham-
| kenneco...
|
| [2] https://en.wikipedia.org/wiki/Rice_Terraces_of_the_Ph
| ilippin...
| AlbertCory wrote:
| There's a good book, _The World Without Us_ that goes into
| great detail on what would happen if humans disappeared.
| fredsmith219 wrote:
| The other species are gone because we eliminated or out
| competed them. Even with climate change we're in no danger of
| extinction
| slashdev wrote:
| This. It would take something truly catastrophic to make
| humans extinct now that there are so many of us on every part
| of the globe.
|
| Climate change won't cut it, neither would total nuclear war.
|
| Even if you had something like an impact big enough to
| superheat the entire atmosphere, enough humans might survive
| inside buildings, basements, subways, etc to carry on.
|
| Modern civilization though is a lot more fragile. It's
| possible to blast us back to pre-industrial times and the
| easy to access resources are mostly gone. It's not clear that
| we could bootstrap a second industrial revolution easily.
| Cacti wrote:
| eh. you underestimate global thermonuclear war.
| philipkglass wrote:
| Global thermonuclear war would destroy technological
| civilization, but even now there are small groups of
| pastoralists and hunter-gatherers in remote regions who
| use only muscle power and do not need factory
| manufactured goods. Uncontacted tribes [1] would go on
| living much as usual if a nuclear war depopulated
| industrialized regions.
|
| There would be some increase in mortality among remote
| tribes as radioactive fallout from a large scale nuclear
| war drifted down globally, but that wouldn't be enough to
| cause human extinction.
|
| [1] https://en.wikipedia.org/wiki/Uncontacted_peoples
| bryanlarsen wrote:
| OTOH our garbage and wreckage will provide a lot of
| resources. For example there may not be any easily
| accessible copper deposits, but there are a lot of wires to
| scavenge. No easily accessible fossil fuels, but the amount
| of plastic in garbage dumps makes them a fossil fuel
| source.
| nicklecompte wrote:
| To be clear I don't think anthropogenic climate change will
| cause human extinction. But a terrible series of volcanos
| could absolutely turn Earth into a colder Venus for, say, a
| couple hundred years - pelagic vertebrates and certain
| microbes would be ok, but I am not sure humanity would
| survive more than a few generations, even in underground
| sci-fi bunkers.
|
| https://en.wikipedia.org/wiki/Permian-
| Triassic_extinction_ev...
| slashdev wrote:
| It would have to be worse than the previous volcanic
| extinction events, which were massive. It's not clear the
| Earth can even do that anymore.
| nicklecompte wrote:
| > It's not clear the Earth can even do that anymore.
|
| This is a good point, but the event wouldn't need to be
| more volcanic so much as that volcanism would need to
| ignite more carbon-containing materials - naively I would
| expect there to me more "fuel" in the Earth than there
| was 300m years ago.
| Anotheroneagain wrote:
| We are at an imminent threat of extinction.
| Cacti wrote:
| We are? You have evidence for this?
| Anotheroneagain wrote:
| Yes. The near future will decide if and to what extent
| the life on Earth will survive because of what those
| madmen did.
| mistrial9 wrote:
| here are some non-human species "we eliminated" in Latin
| naming system
|
| https://en.wikipedia.org/wiki/IUCN_Red_List_of_extinct_speci.
| ..
| arp242 wrote:
| Also the population for many of these earlier humans was much
| much lower. It's hard to give accurate population counts for
| many of these earlier humans - we don't know all that much
| about Denisovans - but for Neanderthals the total population
| was in the tens of thousands.
| shrimp_emoji wrote:
| https://en.wikipedia.org/wiki/Competitive_exclusion_principl...
| hunglee2 wrote:
| it's possible to have a more positive take on this - those
| species did not go entirely extinct, as their genes continue
| live on within many of us - and thus we carry their legacy as
| much as we do for homo sapien. We might even speciate again one
| day, should genetic populations isolate again for a time
| lordnacho wrote:
| That's what I understood as well. In a way, they live on with
| us because they are part of the same species. We know that we
| have bred with Neanderthals. Why aren't they just considered
| a branch of humanity? It's normal for some designs to die out
| in favour of others. Slightly stocky humans with bigger
| brains. If you met one, I wonder what you'd think in
| comparison with, say, a person from another culture?
| softg wrote:
| >Since the last ice age we've been dropping like flies. In
| fact, we're the only humans left.
|
| I was under the impression that was our doing. All of these
| human varieties were outcompeted by homo sapiens who replaced
| them. Modern humans don't need to worry about another hominid
| taking their place because we're the last one standing.
| shakezula wrote:
| We're so good at it we're going to outcompete ourselves in
| fact
| rhelz wrote:
| It's one possible theory, and no doubt, at the very least, it
| was part of the reason they died. But that's not the only
| smoking gun.
|
| E.g. For at least 200k years, we can tell by fossils from the
| middle east that we made many attempts to spread to Europe,
| but were always pushed back. Fun fact: Neanderthals actually
| had substantially bigger brains that we do today (their
| average size was about 1400-1500ccs. Subtract the volume of a
| tennis ball from that and you'll get the average size of our
| brains today). Neanderthals were smart, tough, mofos.
|
| So what changed 50k years ago which finally let us succeed?
| Well, the climate was warming from the last ice age, and
| Neanderthals were very much cold-adapted hominids. Their
| short, stocky legs and heavy muscular arms were great at
| sneaking through the woods and stabbing a deer with a spear,
| but when the climate changed the woods disappeared, those
| short legs, hauling a very heavy upper-body musculature, were
| not so good at running the deer down on a plain.
|
| Honestly, we have no real definitive answer to why we are
| here and they aren't. Like anything else, probably it was a
| complicated process in which lots of factors--including dumb
| luck--played a role.
|
| For about 4 million years, the earth was very hospitable to
| all kinds of species of Homo--we find their bones, in a
| kaleidoscope of shapes and sizes, all over the old world.
| Since the last ice age, however, Homo has been having a
| really rough time of it. And we are the only humans left.
|
| If you were locked in a room with 10 people, and one by one
| they started to disappear, when you were the only one left,
| you might wonder whether it would happen to you too.....
| allendoerfer wrote:
| The fact, that I am sitting here slacking off, reading
| something some dude wrote on the other side of the world
| just because he had nothing better to do and wanted to
| enjoy and share his own thoughts, takes away the fear of
| imminent extinction of my species.
| temp0826 wrote:
| Fun to think about. Maybe they were bigger and stronger,
| which forced us to actually be more clever and start to use
| our smaller but still very capable brains to accomplish
| stuff. I don't know if there were actually interactions
| between the different species, but I sure wouldn't want to
| fight a neanderthal without a plan or some tools.
| verisimi wrote:
| > In a new review paper, anthropologists tally all of the fossils
| that have been clearly identified as Denisovan since the first
| discovery in 2010. The entire list consists of half a broken jaw,
| a finger bone, a skull fragment, three loose teeth and four other
| chips of bone.
|
| Right... is that enough? Then:
|
| > "What we have found out about Denisovans is that, from a
| behavioral perspective, they were much more like modern humans,"
| said Laura Shackelford, a paleoanthropologist at the University
| of Illinois.
|
| How can anyone make those sorts of leaps, on the basis of a tooth
| and some bone chips?
|
| > Dr. Shackelford said findings like these raised the possibility
| that Denisovans and modern humans coexisted and interacted for
| tens of thousands of years -- though whether they communicated is
| unclear. "That's really going down the rabbit hole," Dr.
| Shackelford said.
|
| What he's saying is we can't tell if these purported species
| communicated, on the basis of what seems to me to be super
| lightweight evidence. He said "communicate"!
| WalterBright wrote:
| How does one tell a skull fragment is a different species?
| verisimi wrote:
| Via DNA, it says. But I can't get to the bottom of why DNA
| analysis is considered to be solid, when there are examples
| of it being quite flawed, eg with these twin sisters:
|
| https://www.youtube.com/watch?v=Isa5c1p6aC0
|
| Someone said that these consumer outfits are known to be
| trash - but I presumed that all DNA tests would end up going
| to the same labs, and those labs would use the same
| principles to test.
|
| There is quite a big question for me about the validity of
| DNA as evidence, when it is possible to show how some tests
| fail.
| Tagbert wrote:
| Automatic genetic testing in a commercial lab is not the
| same thing as controlled analysis by anthropologists and
| geneticists.
| verisimi wrote:
| Are you arguing that adding an anthropological
| interpretation over the top of the automatic testing adds
| value? Or that it is a fudge to make the automatic
| testing fit whatever criteria are required?
| jvanderbot wrote:
| I think the argument was that mass produced testing is of
| lower quality than top scientific labs dedicating all
| their expertise on a specific sample or two.
| shakow wrote:
| They are not the same process at all. Commercial
| ``automated'' kits only genotype you, i.e. look at a
| couple thousands of well known SNPs to put you in the
| group you share more with. Resolution is low,
| extrapolation is virtually impossible, but it's cheap and
| fast, and Uncle Joe can claim his 15% Italian ancestry.
|
| Work like those done on these denisovan is a whole other
| can of worms, which is still a very vibrant field
| (https://en.wikipedia.org/wiki/Ancient_DNA) - at least it
| was when I left it a couple years ago. The main
| difference being that it's trying to sequence as much of
| the genome as possible, using the better preserved DNA
| molecules, typically in the teeth or some places in the
| skull. Then it's dozen of hours of menial work by
| specialized worker using protocols light-years ahead of
| what is done for the commercial kits.
|
| To make a good ol' HN car comparison, it would be like
| saying that because some chain carshop once screwed your
| head gasket change, there is no way anyone could ever
| restore a Cobra.
| kjkjadksj wrote:
| Those kits are genotyping you. For these ancient dna
| analysis they are performing whole genome sequencing which
| is a different technology.
| Tagbert wrote:
| Morphology and genetics
| baerrie wrote:
| https://youtu.be/g4F6BlD8mZs?si=iszAW6tgxH3oUWy1
|
| This nobel winner's lecture on the topic goes into the genetic
| details and covers how they make the more general conclusions
| kgeist wrote:
| The article says:
|
| >In Tibet, Dr. Huerta-Sanchez and her colleagues have found a
| Denisovan gene that helps people survive at high altitudes
|
| Can't it be simply convergent evolution?
| rhelz wrote:
| Anything is possible, but it would kind of be like finding two
| pc-clones, both which contained a copy of MS-DOS, and
| concluding that each was independently programmed.
|
| For the kinds of arguments which scientists use to support
| these claims, see "Altitude adaptation in Tibetans caused by
| introgression of Denisovan-like DNA" by Emilia Huerta-Sanchez,
| et al.
| kryptiskt wrote:
| It would be weird to have the same DNA sequence from convergent
| evolution, since even if evolution converged on exactly the
| same protein (unlikely as that may be), most amino acids in the
| sequence can be represented by several different DNA triplets
| and there is absolutely no reason why it should converge on the
| same triplets.
| profsummergig wrote:
| Because Neanderthals were discovered in Europe, people think
| Neanderthal DNA is a marker of European ancestry.
|
| East and South Asians, and Native Americans have higher
| Neanderthal DNA than Europeans.
|
| Source: https://images.app.goo.gl/Q1JLpT6MqiubCHq18
| MilStdJunkie wrote:
| There's a non-zero chance that many of the asiatic H. Erectus[0]
| found during the late 19th and early 20th century are, in fact,
| Denisovans or their relatives, but were recovered in a period
| where our ideas about human migration were quite different from
| today's . . and _long_ before genetic analysis[1]. When the
| remains are examined in their entirety, the variations are quite
| extreme, with brain sizes ranging from near-ape to practically
| modern.
|
| [0] i.e., Java Man [1] Revealing peoples like the Andaman
| islanders as having a high proportion of non-Sapiens non-
| neanderthal DNA, something that would fit into a 19th century
| anthropology not at all.
___________________________________________________________________
(page generated 2024-03-02 23:00 UTC)