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> But our looming weight makes us vulnerable, vulnerable to viruses that were once isolated deep in forests and mountains, but are now bumping into humans, vulnerable to climate change, vulnerable to armies fighting over scarce resources. The lesson of Toba the Supervolcano is that there is nothing inevitable about our domination of the world. With a little bad luck, we can go too.

I'm personally more inclined to think we are less vulnerable than ever before.

I doubt any virus would wipe out an entire population. An infectious agent spreads better among a numerous population, but as it kills its hosts, the population becomes smaller, which slows the infection rate. So there is negative feedback here, and I doubt that can lead to a total extinction of the host species. Not to mention that we have modern medicine now, and that we understand how viruses work.

Climate change is an issue, but I have hard times imagining how it could wipe out all human beings. Worse case scenario, I guess, would be a sharp decline in agricultural production. So hunger riots and stuff. But even that would at worse reduce the population until a new equilibrium is reached. And I don't see that equilibrium to be at 0.

Nuclear war is a serious threat. But it's not like it would destroy the surface of the Earth or anything. It would provoke a nuclear winter though. I suppose a nuclear winter is about as bad as a volcanic winter is, or worse. Again, the main difficulty would be a sharp decline in food production. And that also would require a new population equilibrium to be reached.

IMHO human beings, nowadays, can deal with an awful lot of contingencies. We can predict them, we can store resources, we can plan ahead...

There really is a case to make about the idea that humans will survive a mass extinction. Annalee Newitz wrote a book about it[1]

1. https://www.amazon.com/Scatter-Adapt-Remember-Survive-Extinc...

Canticle for Liebowitz is a novel on that topic.

I'm not sure "humans will not go totally extinct" is any more comforting than the cliche of "We'll not destroy the earth, it'll be fine, it's human's that'll be wiped out" there's definately the opportunity for a lot of people to have a very bad time. Even worse than the bad times that large segments of the planet are experiencing right now.

No matter how bad times large segments of the planet are experiencing, there have been worse times. Meaning:almost all of the past was worse than it is today.

At https://ourworldindata.org/ you can find tons of data, info-graphics and articles from various (respectable) sources backing that claim. That's not meaning that things are all rosy yet - just meaning that they have been worse in the past!

I feel like people use the current ok state of humanity and the phrase "it's been worse!" to block out a completely unrelated statement, "it might get worse".

I never said that we not better make sure that it stays that way.

If I see someone mentioning the "current, miserable state of the world" I have to object and correct their skewed view (which is not of the present but of a wrongly remembered or romanticized past that serves as incorrect baseline for the comparison!).

I think it's not so much a rosy view of the past, but a fear-filled view of the present.

I did a quick poll of my FB feed, and about 60% of my "friends" felt that the present was worse than the past. Despite all the evidence saying that it's not.

I'm also not afraid of isolated viruses in desolate places. They have limited gene pool and no humans to practice with. It's incredibly unlikely that such virus would randomly be very very good at targeting humans, but also very very bad at staying super sneaky when on a human host.

The optimum strategy for virus is not to kill. It's to stay unnoticed and spread. And the best way to stay unnoticed is not to cause any symptoms ever.

HIV is scary because it's not very good at staying unnoticed. But it's also very bad at spreading too. Same goes with anthrax and pretty much every other deadly virus/bacteria. They typically are optimized for other mammals and therefore they suck at both staying unnoticed and targeting humans.

HIV has actually gotten much better at co-existing with its human hosts over the last few decades.

As a species we're still part of the food chain, we depend upon plants and animals to survive, and we're full of microorganisms. Some of the long lasting consequences of the Chernobyl disaster in this respect are quite worrying - https://www.smithsonianmag.com/science-nature/forests-around....

IMO the only thing that could extinguish humanity is AI (possibly extra-terrestrial AI).

Other events (if in the next decades) that might kill billions of humans:

- meteorites.

- super volcanoes.

- any combination of them.

There is nothing else that could happen for real that would harm humanity to a catastrophic degree.

> Other events (if in the next decades) that might kill billions of humans: > > - meteorites.

No asteroid large enough to kill billions of humans is likely to impact Earth in this century. After that, it's likely that humanity will be so advanced that it'll be able to either mitigate or deter an impact of any magnitude.

An overlooked possibility imho would be a catastrophic population decline[1]. Basically women not having children anymore. Japanese style, only worse.

It's difficult to imagine it leading to extinction, since there will always be groups, at the very least religious groups, who will keep having babies. But still, it wouldn't take much of a cultural change for it to expand to all women.

Not saying it's plausible, but to me in terms of population dynamics it's at least as much of a concern as climate change (by this I mean that I believe reproductive behavior will have more impact on demography than climate change).

1. https://en.wikipedia.org/wiki/Population_decline

There is _massive_ evolutionary pressure going against this. To the extent that not wanting to have children is at all genetic, it will disappear from the gene pool within a few generations.

That the desire to "not want to have children" (especially among women) exists at all is caused by the sexual revolution (contraceptives), which changed who had children from "people who desired sex" to "people who desired to have children."

Maybe contraceptives are a dead-end against which evolution can't do much.

Maternal instinct exists : it pushes a woman to keep her offspring alive at all cost. I suppose it also makes women yearn for having a baby to take care of. But apparently, having just one is enough for them. Maybe two, but they seem to be content with no more than that.

What makes a woman pregnant in the first place is the sexual impulse of the male. That sexual impulse is the primary way nature gets animal organisms to reproduce. With contraceptives, males can satisfy that sexual impulse without creating new offspring. How will nature induce highly-intelligent animals to make an offspring if the sexual intercourse is no more sufficient? It's hard to imagine how genes could intervene high enough on cognitive functions to induce a thought such as "I must have intercourse with this women without contraception because I want children".

It could be an evolutionary dead-end.

Paternal instinct, and women who like sex, exist too.

Well, no rule is written in stone. What you talk about could be a consequence of the fact that men and women are more or less built the same way after all. Kind of like why men have nipples, even if they are useless to them.

My point remains anyway : even if there was a perfect symmetry in gender roles, parenting instinct would be what makes parents desire to have at least one offspring and keep it alive at all cost, but what would drive them to have more than two would be sexual impulse.

There exists a desire to have children in a household amongst some people both male and female just because it can be fulfilling and nice.

Yes, but as I wrote this desire doesn't seem to be enough to renew generations.

I don't understand : we are in the middle of the biggest population explosion in the history of the world and at the back end of a century of government programs aimed at reducing childbearing...

Most of the population explosion is behind us. Many developed countries have sub-replacement fertility, and it seems to be a trend followed by developing countries.

"As of 2010, about 48% (3.3 billion people) of the world population lives in nations with sub-replacement fertility."[1]

1. https://en.wikipedia.org/wiki/Sub-replacement_fertility

But it's not genetic

It's culture and education

Complex behavior can be and often is genetic. A great example of this is the vastly different behavior of the zebra and lion when in close company with zebras. The zebra will engage in herd behavior, whereas the lion will try to eat one of the zebras. No amount of socialization can alter these behavioral patterns.

I can tell you that my wife and I both knew long before we were anywhere near adults that we wanted families. You know how some people know that they want to be a fire fighter or a police officer when they grow up? I knew I wanted to have a bunch of kids. The story is more or less the same for her. And my wife and I both grew up on the left, where the attitude toward having children varies from something you do after you have your career sorted to outright anti-natalism.

> . A great example of this is the vastly different behavior of the zebra and lion

We're not zebra and lions

> knew long before we were anywhere near adults that we wanted families

peer pressure is strong in our society

family is a motivation to stay alive for many

> I knew I wanted to have a bunch of kids.

Yeah I though I knew as well, much like I thought I was going to be an astronaut

Now I'm a grown up man, in charge of his life, and I know I don't care about a family

And it's not the gene's telling me, I still think about having a legacy, a mini me persisting my DNA but I know that it's just a legacy from the past where a man without a family to support wasn't a real man.

That's it, education and culture

If reproducing was such a strong genetic trait, men on heart would have been billions centuries ago

The truth is kids are family support, the more societies get rich, the less people make children

It's scientifically proven, poor need kids not for reproduction but for elderly support

Poor also make a lot of children because in poor societies kids die more easily

For all of human evolution except the last 50 years, so 6,997 out of the last 7,000 generations, the drive to have sex was synonymous with the drive to have children. Then we invented birth control. Now evolution will select for people who have a desire to have children, separate from their desire to have sex.

The idea that complex behavior can be caused by genes in animals, but somehow not in humans is incorrect. People point to culture as if it is some magical force that makes people do things, but the human ability to create and interact with culture is itself the result of genes. After all, zebras and lions don’t have culture.

And you missed my point: I grew up in a culture that did not value having children. Having children was considered an after thought, something to be done after you had attended to your career. Growing up, I only knew one family with 4 children. They were considered the weird religious family. Yet I have known since I was 12 or 13 that I wanted to have a large family, even though I grew up in a culture that would look down their noses at a family of 4 or more children.

And the argument that poor people have lots of children for financial reasons doesn’t hold up any more. It did when most people were farmers, but the poor in the developed world are no longer farmers and I don’t think there’s any way to argue that children are a net financial benefit to them.

> the drive to have sex was synonymous with the drive to have children.

that's not true!

It's not even the main drive for many apes and monkeys…

> The idea that complex behavior can be caused by genes in animals, but somehow not in humans is incorrect

But I didn't say that

I said we are not those animals and don't live by the same rules

The complex behaviour of catching a mouse in a cat is genetic

Should humans behave the same when they see a mouse?

> I grew up in a culture that did not value having children.

Oh that's even more powerful

Youth rebellion

Do exactly the opposite that your parents and people around you are doing

> And the argument that poor people have lots of children for financial reasons doesn’t hold up any more

It does now more than ever

Now that globalization is taking a lot of poor countries out of poverty

Just watch Hans Rosling's talks

If the drive to have sex and the tremendous pleasure that results from it are not for making offspring, then how did they evolve?

> then how did they evolve?

Easy: being on top of the food chain allowed us to evolve our relations beyond having an offspring

Those having more satisfactory relations formed groups that we now call families up to the point where sex today is mostly recreational

basically pleasurable sex gave us mate choice just like a bird chose the best dancer or a lioness the stronger male

pleasure instead of strength in the long run made happiness a goal in our modern societies instead of simply domination

we don't have sex just in some period of the year

we enjoy sex just like we enjoy eating or having fun

For a cat or a dog sex is not pleasurable, it's just a relief from heat, but we call it rape.

Citation needed - obviously culture and education have an enormous impact on how humans live, but given that other animals are driven to reproduce, it shouldn't be a surprise that we are also.

When child survival increases, kids per family decrease at an enormous rate down to one kid per family


> There is _massive_ evolutionary pressure going against this. To the extent that not wanting to have children is at all genetic, it will disappear from the gene pool within a few generations.

This is only the case if the selection pressures which humans in the developed world are facing stay the same. Since they seem to be tied to our technological development, I think there is a good argument to be made that these selection pressures will intensify as we breed resistance to them. My personal theory is that the increasing addictiveness (see the PG essay on this[0]) of modern life is why people are having less children. I don't see that trend changing.

I do think there's a good chance that technological renunciation and voluntary cultural isolation of some sort are the best solution to this problem for people who are naturally susceptible to the addictiveness of modern life.

[0]: http://www.paulgraham.com/addiction.html

Based on what I've read, pre-agricultural people nursed their children until the age of 4 or 5 when they could keep up with the tribe on foot, which limited the birth rate. The explosive growth in population we have had for the last few thousand years dates to the agricultural revolution, when we settled down in one place which allowed women to wean their children sooner and have more. So in a sense the absence of birth control is the new and unusual phenomenon here. If you look at ratios of sexual activity to pregnancies human beings are extreme outliers- we clearly are evolved to use sex for bonding first and reproduction second, so the idea that birth control is going to change our behavior through selection pressure seems wrong.

A data scientist would say we are overfitted to sex.

IMO the problem today is https://en.wikipedia.org/wiki/Human_overpopulation.

I can not imagine that lack of babies could ever become a problem for humanity until humans decide to build humans so that the "natural human species" dies out.

The solution for the aging population:

- Automation.

- Biochemical solutions and genetic engineering to remain/become capable. Replacement of natural body parts by machine body parts.

> IMO the problem today is https://en.wikipedia.org/wiki/Human_overpopulation.

Worrying about overpopulation is short-sighted. Also, no matter what kind of problems overpopulation brings, it's hard to imagine how that could lead to extinction, which is what we were discussing.

Overpopulation is frequently the cause of steep popuation decline (90+%) in ecology due to input resource depletion and the building of toxins that are the end products of that species metabolism.

Pollution and resource scarcity are the obvious limits that can send population numbers off a cliff.

Overpopulation is a problem right now. I mentioned overpopulation as reply to the fear of too few babies.

I hope that poverty and the culture to have as many children as possible will not exist anymore after 2030 CE.

I would view the comfortable lives of humans in the developed world as a very peculiar circumstance, not as something which will persist as the norm. Life expands to consume all available resources. Humans are part of the lineage that we call life. That we are poorly adapted to modern life is just a temporary state of affairs. Though many people are opting out of large families, not all are. And the people who aren't are the future of the species.

That doesn't kill people, just cause them to not be born - and won't happen in the next few decades anyway.

Grey goo and engineered bio-weapons?

At space there are some pan-galatic killers, nearby supernovas (no idea where is the closest candidate), and a black hole could always cross our path without any warning.

A black hole crossing our path would give plenty of warning, assuming it approaches significantly slower than the speed of light.

The effect of a black hole's gravity on distant objects is exactly the same as the effect of any other object with the same mass. It would disturb Kuiper belt objects that everyone's watching very carefully these days, affect the orbits of the outer planets as it moves closer, and bend light around its event horizon in a very obvious way.

Whether we can do anything about it, of course, is a different problem.

What about pandemics? (Either natural or engineered.)

We're pretty good at disease control, see eg. the recent ebola outbreak. An outbreak of anything dangerous would be quickly contained. There are no organizations with the capacity to surreptitiously produce, distribute and release an infection agent broadly enough that it might kill in the billions before being contained.

That basically leaves the US or Russia (the only countries with the capacity to do so) arbitrarily deciding to nuke most cities in south Asia.

I'd give China more of a chance than Russia, actually. They have more resources. (But perhaps less willingness than Russia: China is doing very well with the status quo.)

I don't think China has the nuclear warhead stockpile to kill 1 billion+ people. Wikipedia says "Current stockpile (usable and not): ~260" which means each would have to kill 3.8 million, which basically means delivering each perfectly into a major city. That's a non-trivial operation to put it mildly.

That said, I don't see any objective (rational or otherwise) of either country that would be advanced by such an attack. And again, we're talking about an attack that will kill 1B+ people, not just any nuclear attack -- that's a different story. Still low probability, but at least there are semi-rational objectives that could motivate it.


Oh, I didn't mean to imply the Chinese had enough stockpiles. I meant they have a big enough economy to rapidly build up their nukes (or invest in bioweapons etc), should they decide to.

Possible in theory but IMO too unlikely; especially for a natural disease.

With regard to climate change: We know the danger is real and thus humanity adapts to prevent the worst.

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