On the trail of the Denisovans
nytimes.com
nytimes.com
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.
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?
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.
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.
> 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.
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....
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...
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.
First, you've got those folks who are in deep denial about how much we've utterly fucked our climate, i.e. "don't look up, just vote down!" Included in this group are those who think/feel "things got better over the past 100 years, so the next 100 years must be better too!"
Then you've got the astroturfers who are paid to minimize any discussion of climate disaster for whatever reason; governments, political movements, oil companies, etc. I see those in comments on the larger newspapers, they swarm in and state contradictory "facts" that confuse people and shut down discussion.
Personally, after the experience of COVID-19, the inability of governments to give up the easy money from oil etc, and the lack of reaction to extreme weather events, I think humanity is utterly doomed. If anyone survives, I don't think there will be more than a couple million people left at the end of this century.
People talk about "oh we'll just do X, Y, and Z to fix things" while forgetting that we'll have to do those things while dealing with:
Ecosystem and food supply collapse.
Resource wars.
Massive refugee migrations.
Worsening climate.
Do we also air condition the farms?
Even if that were possible, humanity has shown that we will only do something worldwide when we're absolutely forced to. We will not be able to do that while dealing with the disasters that come with global climate catastrophe and ecological collapse.
A refresher in thermodynamics is in order here....thermal energy is...energy, which is a conserved quantity. Heat doesn't just disappear. An air conditioner cools the inside air by making the outside air hotter.
And (thermodynamics strikes again) it also creates yet more waste heat in the process.
// if people are free //
Doesn't matter how free people or the markets are, thermodynamics is for real. We are not air-conditioning our way out of this.
The best counterargument to the population trend argument is that we're in the midst of a Wile E. Coyote period. Along with that though one still needs to account for:
- What's different about weapons today versus say 1970s?
- Why climate change, despite being a serious (and to be clear: actual risk), isn't amenable to solutions like the Montreal protocol that've succeeded in the past?
But sure the Montreal protocol and even the response to COVID 19 shows what can be accomplished should everyone work together. But it wasn't too late in either case then, and they were easier to solve. Today's weapons are definitely scarier than 1970s weapons.
Either way, I wasn't attempting a definitive list with my two items and "etc", I'd consider overpopulation as big a threat as climate change, the fact it's increasing each year is part of the problem.
I believe that would be after you've run off a cliff but before gravity has noticed.
The sibling reply expressed this as well. Wile E. runs off a cliff, the forward momentum keeps gravity in check but only for a short time.
The fact that human population continues to grow isn't by itself sufficient evidence that there are no existing parallel, possibly embryonic, trends developing that'll change that later. The period where both of these are true would be similar to when Wile E. is no longer on solid ground and hasn't yet fallen. It's a temporary and (on a relative basis, which could exceed human lifespan for sufficiently complex or slowly moving trends) brief period.
To be clear, I don't think it's an accurate view of where we are today. On the other hand, had the changes we've seen since 1970s not come to pass, it'd be harder to say. (An example that is climate change specific is the exponentially decreasing cost curve for solar energy.)
> Either way, I wasn't attempting a definitive list with my two items and "etc"
So long as the focus is on the definitive then IMHO there is value in looking hard here. Otherwise, why bother?
> Today's weapons are definitely scarier than 1970s weapons.
Can you say more?
[1] https://www.dreamstime.com/stock-photography-bingham-kenneco...
[2] https://en.wikipedia.org/wiki/Rice_Terraces_of_the_Philippin...
Open pit mines will fill with water. The sides will collapse. In the desert, they will fill with dust. Deserts often have flash-floods following thunderstorms. They might remain recognizable as hollows, but not much more.
The Bingham mine has had collapses in 2013 and 2021:
https://blogs.agu.org/landslideblog/2021/06/04/2021-bingham-...
https://blogs.agu.org/landslideblog/2013/04/30/analysing-the...
https://blogs.agu.org/landslideblog/2013/05/06/analysing-the...
There was a similar collapse recently at the Çöpler Mine in Turkey...
https://eos.org/thelandslideblog/copler-mine-1
https://eos.org/thelandslideblog/copler-mine-2
https://eos.org/thelandslideblog/copler-mine-3
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.
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.
Good luck getting them to adopt your useless ass in the post-apocalypse.
https://en.wikipedia.org/wiki/Permian–Triassic_extinction_ev...
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.
Minoans went from the thriving trading center of the Mediterranean with written language as old as Egyptian Hieroglyphics to seemingly irrelevant for a while during the Bronze Age because volcanic eruptions seemed to have turned the air they breathed to poison. Not to mention places allegedly hit by the fall of volcanic ash whose remains are so far deep we only speculate they lived there.
I’m really hoping this is a ironic literary reference to “How I learned to stop worrying and love the bomb”
https://en.wikipedia.org/wiki/IUCN_Red_List_of_extinct_speci...
And homo cyberneticus will do it to us.
Those were pre-human ancestors, but humans aren't special, we are just animals that are more destructive than any species that came before us.
Hubris will likely play a large role in any possible future human extinction event. E.g., doing nothing to curb climate change because we are "smart" and invincible and/or god(s) wouldn't allow things to get that bad, a deadly pathogen develops resistance to all antibiotics because of free-feeding antibiotics in factory farming animal flesh, we use nuclear weapons in conflict X believing it will not escalate (George "Baby" Bush, "I want nuclear weapons I can use" [actual quote]), a pathogen intentionally developed to both spread quickly and be extremely deadly (because we can), that somehow... "no one could ever foresee the possibility..." escaped the lab-- or maybe it will be a large meteor impact wiping out humans (and other large animals) across the globe like a kid stomping on an ant hill.
[1] https://www.scientificamerican.com/article/human-ancestors-n...
The linked article talks about the human bottle neck 900,000 years ago, that's almost a million years, but well short of 900 million.
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.
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.....
FWIW this study suggests that Neanderthals and modern humans might have had very different approaches to language: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766443/ Neanderthals and modern humans both evolved to make sophisticated vocalizations, but it's possible that the Neanderthals had 10000 words yet only a few ways to join them in simple sentences. (E.g. what if Neanderthals couldn't ask questions, only state disagreements?) In particular we know that humans can have local brain damage leading to near-total disability in using language while still being able to comprehend language, so you could see ancient hominids being "as smart as modern humans" in terms of general problem-solving - building tools, administering medicines and performing surgeries, long-term planning around food - but having profound blocks in language that prevented them from forming larger societies. Neanderthals tended to live in small family groups, whereas almost every modern human hunter-gatherer lives in a much larger tribe (absent war or disaster).
But IMHO it applies just as well when trying to show that Neanderthal’s language was super different from ours. We know virtually nothing about the evolution of language in our own species, let alone another species.
They were different for sure, but the fact that we regularly mated with and formed families with Neanderthals and their first few generation generations means to me that the difference wasn’t that much. I’d go so far as to that absent any reason to believe otherwise, the default presumption should be that we’d be close to equals with them in these matters.
To be clear there's only genetic evidence of admixture, not any evidence that humans and Neanderthals actually coexisted as families. Mating between humans and Neanderthals definitely wasn't "regular" since there's not actually very much neanderthal DNA in modern humans. Maybe we had an enormous number of infertile children, but I don't think human hunter-gatherers would survive that since rearing and raising a child is so costly.
In particular there's very good reason to suspect that we didn't form families with Neanderthals in the way you are suggesting[1]:
> No evidence of Neanderthal mitochondrial DNA has been found in modern humans. This suggests that successful Neanderthal admixture happened in pairings with Neanderthal males and modern human females. Possible hypotheses are that Neanderthal mitochondrial DNA had detrimental mutations that led to the extinction of carriers, that the hybrid offspring of Neanderthal mothers were raised in Neanderthal groups and became extinct with them, or that female Neanderthals and male Sapiens did not produce fertile offspring. [...] As shown in an interbreeding model produced by Neves and Serva (2012), the Neanderthal admixture in modern humans may have been caused by a very low rate of interbreeding between modern humans and Neanderthals, with the exchange of one pair of individuals between the two populations in about every 77 generations.
Even if it was 1 pair in 5 generations, that's simply not high enough to suggest a strong common humanity based on admixture alone. Pulling this all together, I don't think there's any real evidence that humans and Neanderthals co-parented or had any other real integration between their societies. There was just occasional admixture.
I am sure there's a paper somewhere but I've never read anyone actually rule out what is IMO the simplest explanation: Neanderthal men occasionally raped modern human women and the child was raised among modern humans (the reverse situation explains why children with Neanderthal mothers and modern human fathers would have been raised among Neanderthals).
[1] https://en.wikipedia.org/wiki/Interbreeding_between_archaic_...
There is not much evidence, but it's going too far to say there's no evidence. The evidence is their genetic heritage in us. There are many ways that that genetic heritage could have got there, ranging from rape to adoption to romeo-and-juliet style romances. The genetic admixture is evidence for all these routes.
// IMHO the simplest explanation: Neanderthal men occasionally raped modern human women //
That's one way it could happen, but we don't have anywheres near enough evidence to conclude that was the only way it happened, or even that it was the most common way it happened. All other hypothesis are still on the table.
And, certainly the first generation hybrids were welcomed in human families. Don't forget, in the Pleistocene, there was no such thing as being alive without being a member of a family.
This also led to the notion of a shared culture across many individuals that can adapt much more quickly than genetic evolution.
(Unless I misunderstand, of course.)
The author squarely blames Homo Sapiens for wiping out the other hominins, pointing out how many other large species seemed to go extinct as soon as we arrived someplace new, even long before the Agricultural revolution.
50,000 years ago, something changed . Maybe it was an increased capacity for abstract thought, but if so, that was a software and not a hardware development, because we had the same anatomy for 300,000 years. If we could implement the software, I don’t see why the Neanderthals couldn’t have done so, as they had even bigger brains than we do.
So maybe the abstract thought hardware was there for a long time before we got culturally coordinated enough to use it with full effectiveness to organize large groups capable of outcompeting Neanderthals.
It's far more chilling to me that people ascribe value to genetic lines outside that ascribed by living, breathing people.
the last ice age was ~12,000 years ago. the latest evidence for any of these other branches of humans is 3x that many years ago. on the contrary, the human population has skyrocketed since the last ice age
There is no "homo denisova". They're called Denisovans.
Svante Pääbo refused to give them a Latin name or declare them a species because he thinks it's pretentious.
[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.
East and South Asians, and Native Americans have higher Neanderthal DNA than Europeans.
hybrids are usually unlikely to be able to reproduce but its not impossible depending on how distant they were, and we simply dont have enough evidence to deny they could have
so it could have been neanderthal-denisovan hybrids that went across asia for all we know
It seems like it would answer so many questions.
siberia i doubt though, and probably not neanderthals
>In Tibet, Dr. Huerta-Sánchez and her colleagues have found a Denisovan gene that helps people survive at high altitudes
Can't it be simply convergent evolution?
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-Sánchez, et al.
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"!
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.
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.
This nobel winner’s lecture on the topic goes into the genetic details and covers how they make the more general conclusions