Earth-sized planet found in Proxima Centauri's habitable zone

[Guardsman Bass]

Assuming the current population growth might be a little off. Population growth rates have declined a bit slower than expected, but they have declined considerably from their highs in the 20th century. If the developing world (where virtually all of that population growth is happening, especially subsaharan Africa) gets richer and more prosperous, I'd only expect that growth rate to shrink further.

[Rhadamantus]

The number of people that could live in the solar system is less than the number than could live in the solar system+alpha centauri.

Are you fucking illiterate or something?

You keep completely ignoring everybody's points and saying, "lol population growth". Once, again: life is not an RTS. Harvested resources don't go into a magic universal pool that can be accessed from anywhere, and collecting X pieces of gold doesn't let you magically upgrade to the next technology level. If Alpha Centauri were colonized, that population would be COMPLETELY AND FUNCTIONALLY SEPARATE FROM THAT OF THE SOLAR SYSTEM. It would have precisely 0 economic impact on the Solar System (notwithstanding the cost of sending the expedition out to begin with).

Are you an idiot? No where have I suggested shipping resources from the Alpha Centauri system. I suggested a colonization, which might use the resources there. And then use them to build habitats there.

[Alyrium Denryle]

The number of people that could live in the solar system is less than the number than could live in the solar system+alpha centauri.

You missed his point. It would take, at best, a century to get there if we went balls-deep with a fusion drive and a small payload. We are nowhere near the point of a generation ship.

There is simply no practical way to exploit that star system. There is a fuckton of empty space and resources in just this solar system, and much more accessible to boot. Direct economic gain is not the argument you want to make.

The correct argument is that it would be Fucking Awesome and we should go there because We Can (in the not unforseeable future). There is nothing practical about it. We go because we want to.
?

You underestimate exponential growth. The highest number I've seen for possible solar population is 10^22 people (starlift the sun, and slowly turn it into habitats). Assuming the current population growth rate, it'd take us 4000 years to fill the solar system. If we go with a more reasonable estimate, it'd take just 1700 years.

I am a god damned biologist, no. I dont. Do you have any idea how many people 10^22 people is? 10,000,000,000,000,000,000,000

That is ten sextillion people.

Humans also do not operate on an exponential curve. Our population growth follows a sigmoid curve. Our population growth is already leveling off because our response to increased life-expectancy and reduced child mortality is to reproduce less. By the time we start thinking about space colonization seriously, we'll basically have a net growth of 0. That might increase a bit when a new area is colonized but it wont be anywhere near what it is now.

Just.. sit the fuck down.

[Rhadamantus]

You missed his point. It would take, at best, a century to get there if we went balls-deep with a fusion drive and a small payload. We are nowhere near the point of a generation ship.

There is simply no practical way to exploit that star system. There is a fuckton of empty space and resources in just this solar system, and much more accessible to boot. Direct economic gain is not the argument you want to make.

The correct argument is that it would be Fucking Awesome and we should go there because We Can (in the not unforseeable future). There is nothing practical about it. We go because we want to.
?

You underestimate exponential growth. The highest number I've seen for possible solar population is 10^22 people (starlift the sun, and slowly turn it into habitats). Assuming the current population growth rate, it'd take us 4000 years to fill the solar system. If we go with a more reasonable estimate, it'd take just 1700 years.

I am a god damned biologist, no. I dont. Do you have any idea how many people 10^22 people is? 10,000,000,000,000,000,000,000

That is ten sextillion people.

Humans also do not operate on an exponential curve. Our population growth follows a sigmoid curve. Our population growth is already leveling off because our response to increased life-expectancy and reduced child mortality is to reproduce less. By the time we start thinking about space colonization seriously, we'll basically have a net growth of 0. That might increase a bit when a new area is colonized but it wont be anywhere near what it is now.

Just.. sit the fuck down.

Human population growth might also be slowing down because of resource limitations. Furthermore, the particular factors that apply to humanity do not neccesarilly apply to all aliens.

[Alyrium Denryle]

You underestimate exponential growth. The highest number I've seen for possible solar population is 10^22 people (starlift the sun, and slowly turn it into habitats). Assuming the current population growth rate, it'd take us 4000 years to fill the solar system. If we go with a more reasonable estimate, it'd take just 1700 years.

I am a god damned biologist, no. I dont. Do you have any idea how many people 10^22 people is? 10,000,000,000,000,000,000,000

That is ten sextillion people.

Humans also do not operate on an exponential curve. Our population growth follows a sigmoid curve. Our population growth is already leveling off because our response to increased life-expectancy and reduced child mortality is to reproduce less. By the time we start thinking about space colonization seriously, we'll basically have a net growth of 0. That might increase a bit when a new area is colonized but it wont be anywhere near what it is now.

Just.. sit the fuck down.

Human population growth might also be slowing down because of resource limitations. Furthermore, the particular factors that apply to humanity do not neccesarilly apply to all aliens.

No. That is not why. If it were, population growth would be lowest in sub-saharan africa. Instead, it is highest there, and population growth lowest in Northern Europe and Japan.

Humans do it that way because birthing offspring is physiologically expensive and raising them is time consuming and drains resources that could be used for other things. When we can (because we expect to live a long time and our kids wont die before hitting the age of 10), we tend to delay reproduction until we are optimally situated (barring accidental pregnancy). This maximizes our ability to actually raise our offspring and potentially gives them a competitive edge against others. We sacrifice quantity for quality.

In places with poor resources, low life expectancy, and high child mortality, people reproduce quickly and often. Largely as a biological insurance policy against malaria and starvation. Kind of like how shoebill storks lay two eggs but only raise one chick most years. One is an insurance policy against early mortality in the other chick and in a really good year two can be raised. In most years they let the other chick starve to death or be killed by its sibling.

How are aliens even relevant here? Are you expecting to be in a war of attrition with them soon?

[Ziggy Stardust]

Are you an idiot? No where have I suggested shipping resources from the Alpha Centauri system. I suggested a colonization, which might use the resources there. And then use them to build habitats there.

You said:

Colonizing Alpha Centauri would triple our resources, and therefore our possible population. More people means faster technological progress.

You are clearly implying a relationship between Alpha Centauri's resources and Sol's resources. A colony on Alpha Centauri would be completely and functionally independent from Earth unless FTL is involved. Period. So it doesn't triple "our resources", and it has no bearing on technological progress on Earth (except for that necessary to launch the expedition in the first place). If this wasn't what you meant to say, why didn't you say so two pages ago, after multiple people (not just myself) chastised you for that implication?

[Rhadamantus]

Are you an idiot? No where have I suggested shipping resources from the Alpha Centauri system. I suggested a colonization, which might use the resources there. And then use them to build habitats there.

You said:

Colonizing Alpha Centauri would triple our resources, and therefore our possible population. More people means faster technological progress.

You are clearly implying a relationship between Alpha Centauri's resources and Sol's resources. A colony on Alpha Centauri would be completely and functionally independent from Earth unless FTL is involved. Period. So it doesn't triple "our resources", and it has no bearing on technological progress on Earth (except for that necessary to launch the expedition in the first place). If this wasn't what you meant to say, why didn't you say so two pages ago, after multiple people (not just myself) chastised you for that implication?

I would have thought it was clear that the new people would live in Alpha Centauri.

[Rhadamantus]

I am a god damned biologist, no. I dont. Do you have any idea how many people 10^22 people is? 10,000,000,000,000,000,000,000

That is ten sextillion people.

Humans also do not operate on an exponential curve. Our population growth follows a sigmoid curve. Our population growth is already leveling off because our response to increased life-expectancy and reduced child mortality is to reproduce less. By the time we start thinking about space colonization seriously, we'll basically have a net growth of 0. That might increase a bit when a new area is colonized but it wont be anywhere near what it is now.

Just.. sit the fuck down.

Human population growth might also be slowing down because of resource limitations. Furthermore, the particular factors that apply to humanity do not neccesarilly apply to all aliens.

No. That is not why. If it were, population growth would be lowest in sub-saharan africa. Instead, it is highest there, and population growth lowest in Northern Europe and Japan.

Humans do it that way because birthing offspring is physiologically expensive and raising them is time consuming and drains resources that could be used for other things. When we can (because we expect to live a long time and our kids wont die before hitting the age of 10), we tend to delay reproduction until we are optimally situated (barring accidental pregnancy). This maximizes our ability to actually raise our offspring and potentially gives them a competitive edge against others. We sacrifice quantity for quality.

In places with poor resources, low life expectancy, and high child mortality, people reproduce quickly and often. Largely as a biological insurance policy against malaria and starvation. Kind of like how shoebill storks lay two eggs but only raise one chick most years. One is an insurance policy against early mortality in the other chick and in a really good year two can be raised. In most years they let the other chick starve to death or be killed by its sibling.

How are aliens even relevant here? Are you expecting to be in a war of attrition with them soon?

Aliens are relevant because this was about the fermi paradox.

[Alyrium Denryle]

Human population growth might also be slowing down because of resource limitations. Furthermore, the particular factors that apply to humanity do not neccesarilly apply to all aliens.

No. That is not why. If it were, population growth would be lowest in sub-saharan africa. Instead, it is highest there, and population growth lowest in Northern Europe and Japan.

Humans do it that way because birthing offspring is physiologically expensive and raising them is time consuming and drains resources that could be used for other things. When we can (because we expect to live a long time and our kids wont die before hitting the age of 10), we tend to delay reproduction until we are optimally situated (barring accidental pregnancy). This maximizes our ability to actually raise our offspring and potentially gives them a competitive edge against others. We sacrifice quantity for quality.

In places with poor resources, low life expectancy, and high child mortality, people reproduce quickly and often. Largely as a biological insurance policy against malaria and starvation. Kind of like how shoebill storks lay two eggs but only raise one chick most years. One is an insurance policy against early mortality in the other chick and in a really good year two can be raised. In most years they let the other chick starve to death or be killed by its sibling.

How are aliens even relevant here? Are you expecting to be in a war of attrition with them soon?

Aliens are relevant because this was about the fermi paradox.

...

...

How? Now, I just went back and checked, I dont see any prior discussion in here regarding the Fermi Paradox, and I fail to see how population growth is relevant with respect to it. So you are just back-pedaling.

But lets humor your stupidity.

You will have a rather hard time finding a sentient species that follows an exponential growth trajectory for a lot of reasons. Not the least of which is the fact that r selected species (those that follow exponential growth curves) tend to be fast breeders with short lifespans and little to no parental care. When they are animals instead of plants, they are typically small and the potato chips of nature (which is why they follow an exponential growth curve, they try to out-breed predation which is what regulates their population instead of resource limitations). Most are dumb as a post Even when they are not dumb as a post, their lifespans are too short to do a whole lot of conceptual learning, even if they were notionally capable of it.

You cannot learn what you need to learn to put a spacecraft into orbit if your lifespan is only five years.

You might *might* get something like an ant colony where a queen lays hundreds of thousands of eggs that hatch into non-sapient larvae that are cared for by long-lived sapient workers. You might get something like that. But if they are big they are going to be regulated by an actual carrying capacity instead of predation and if they are regulated by a carrying capacity they follow a sigmoid growth curve.

I could teach a semester course in population ecology. But I am not going to do that here.

[Flagg]

An intelligent species that didn't build anything we could detect with radio telescopes could be sitting around Proxima Centauri and be utterly unknown to us.

A civilization even a century more advanced than us would probably have fusion drives. Those would be detectable from a distance of a 100 ly. We've seen nothing.

Still doesn't preclude a civilization up to modern/near-modern technological development.

Your argument also seems to presume that their is a set path, set levels of technological development that all civilizations will follow.

Must have played too much 'Civilization'. But you're right. And I blame those idiotic 'from ape to man' charms.

[Flagg]

No, it's not. That trillion dollars would have to come from somewhere - we can't even all agree that people deserve to not starve to death, and you want to spend a huge sum of money on something that will accomplish exactly no practical aims and will take centuries?

Well, we've spent about two trillion dollars on the war in Iraq, and that hasn't really accomplished anything practical. I don't know about you but I'd rather have an interstellar mission than a war.

And so would I. But the Iraq War was supposed to cost much, much less than that, and was supposed to achieve practical ends. Don't be obtuse.

Sarcasm, not just for teenagers anymore!

[Flagg]

For a society even somewhat more advanced than us, that's cheap for the opportunity to colonize an entire solar system.

Why bother? It will most likely be an extremely long time yet before the Solar System is tapped out, and it's not like the Alpha Centauri colony is going to be sending stuff back in a timely fashion (if at all), so the investment is a total loss from the perspective of the the investing entity. A sufficiently wealthy civilization might do some interstellar exploration out of curiosity, and you might even have eccentric space quadrillionaires doing colonization as a 'because we can' vanity project, but I don't think it's a given that interstellar colonization will be of huge interest.

Asteroids, comets, and super-volcanos. Just the first most probable reasons to expand across our solar system.

[Rhadamantus]

No. That is not why. If it were, population growth would be lowest in sub-saharan africa. Instead, it is highest there, and population growth lowest in Northern Europe and Japan.

Humans do it that way because birthing offspring is physiologically expensive and raising them is time consuming and drains resources that could be used for other things. When we can (because we expect to live a long time and our kids wont die before hitting the age of 10), we tend to delay reproduction until we are optimally situated (barring accidental pregnancy). This maximizes our ability to actually raise our offspring and potentially gives them a competitive edge against others. We sacrifice quantity for quality.

In places with poor resources, low life expectancy, and high child mortality, people reproduce quickly and often. Largely as a biological insurance policy against malaria and starvation. Kind of like how shoebill storks lay two eggs but only raise one chick most years. One is an insurance policy against early mortality in the other chick and in a really good year two can be raised. In most years they let the other chick starve to death or be killed by its sibling.

How are aliens even relevant here? Are you expecting to be in a war of attrition with them soon?

Aliens are relevant because this was about the fermi paradox.

...

...

How? Now, I just went back and checked, I dont see any prior discussion in here regarding the Fermi Paradox, and I fail to see how population growth is relevant with respect to it. So you are just back-pedaling.

But lets humor your stupidity.

You will have a rather hard time finding a sentient species that follows an exponential growth trajectory for a lot of reasons. Not the least of which is the fact that r selected species (those that follow exponential growth curves) tend to be fast breeders with short lifespans and little to no parental care. When they are animals instead of plants, they are typically small and the potato chips of nature (which is why they follow an exponential growth curve, they try to out-breed predation which is what regulates their population instead of resource limitations). Most are dumb as a post Even when they are not dumb as a post, their lifespans are too short to do a whole lot of conceptual learning, even if they were notionally capable of it.

You cannot learn what you need to learn to put a spacecraft into orbit if your lifespan is only five years.

You might *might* get something like an ant colony where a queen lays hundreds of thousands of eggs that hatch into non-sapient larvae that are cared for by long-lived sapient workers. You might get something like that. But if they are big they are going to be regulated by an actual carrying capacity instead of predation and if they are regulated by a carrying capacity they follow a sigmoid growth curve.

I could teach a semester course in population ecology. But I am not going to do that here.

My literal first comment was about the Fermi Paradox. Two, Octupi are r-selective species, and they're intelligent. Also, humans used to be substantially more r-selective. Third, the ant colony would follow a sigmoid curve only until they expanded into their solar system. Then it'd be exponential again.

[Simon_Jester]

Various octopus species have existed for millions of years. If they're sapient, as in not just "smart" like a dog is smart but smart like humans are smart... that leads to three possibilities.

One is that it's a coincidence that sapient octopuses* and sapient humans would evolve on the same planet at almost exactly the same time. This is very unlikely.

The second is that octopuses have existed for millions of years and never invented tools or technology. This suggests that sapient octopuses never will develop technology, and that species like our hypothetical sapient octopus may exist all over the galaxy... but not colonize other planets or provide us with any signs of their existence, unless we go over to look for them.

And both of those possibilities assume octopuses are sapient, which is far from certain, just as it is not certain whether elephants or dolphins are sapient. In all three cases, we're stuck with the awkward question of how and why sapience would evolve in the absence of tool use. In the case of elephants and dolphins, which are social organisms, there is at least part of an explanation- interaction between organisms in the same social group drives higher intelligence. But there is no such explanation for the octopus.

Moreover, both of that the sapient octopus species are fast breeding ones, which is possible but also uncertain. "Octopus," like "rodent," is a wide category of physically very different animals. Not all rodents are fast-breeding r-selective organisms; the order Rodentia includes creatures as diverse as the field mouse and the capybara. Not all octopuses have r-selective to be either.

In conclusion: IF octopuses are an example of a sapient r-selective species, and that is not likely, then they are also an example of a sapient species that will likely never develop tool use and never colonize the stars. Not an example we want to imitate.
________________________

*Octopuses, not octopi, unless we are holding this conversation in Latin, which only Alyrium is qualified to do out of the people participating in this discussion.

---

Moreover, nothing in your argument negates Alyrium's actual point, which is that humans do not breed exponentially. Human population growth looks a little like an exponential in some parts of the curve, under some conditions, but it is not. Because raising human children is extremely labor-intensive. Raising large numbers of children per family for generation after generation takes a very heavy toll. Traditional (primitive) societies tend to deal with this by drafting all women to act as childcare staff at all times whether they like it or not, but this is not a practical solution for an interstellar colony. Supporting the colony in the short run is likely to require the labor of nearly everyone present, and if someone is not needed to support the colony, they will not be sent on a starship across interstellar distances.

There will not be enough people available with nothing to do for us to make plans based on the assumption that a space colony's population will grow rapidly. Moreover, populations on Earth will not grow exponentially, either, because human populations tend to level off after a few generations no matter what you do. We do not have the set of drives and impulses that make it 'normal' for us to support four or six or ten children per adult breeding couple, even if it becomes economically practical for us to do so.

---

And if you think humans used to be "r-selective," you don't actually know what r-selection means. Which is not uncommon among people who stopped paying attention after high school biology; I used to not know what it means too.

R-selection refers to species that don't even try to raise their children, or which grow extremely quickly so that infancy is a very short process.

Human infants are among the most helpless infants of any living species, with perhaps the exception of baby birds. Human children remain physically and mentally unable to perform even basic tasks necessary to keep a group of humans alive, until the age of about ten, or in modern societies fifteen to twenty. Humans practice childcare on a scale totally unknown among almost any other living species, for this very reason.

This has literally always been true. It never changed. While humans in the past may have had higher birth rates, it was not because we were adopting r-selective reproductive strategies. It was because k-selective strategies still require you to have enough children that 2.1 or more of them survive to reproductive age and have children themselves!

"R" and "K" selection don't talk about how many children are born per mother. They talk about whether a species spends the balance of its effort on raising children, or on giving birth to more of them. Humans have always been balanced in favor of raising children, as illustrated by the fact that mothers in hunter-gatherer societies spend only a small fraction of their time pregnant, compared to a large fraction of their time caring for an infant. And the fact that we spend nine months in gestation, but are physically helpless until the age of three or four at the earliest, forces k-selection in humans' evolutionary environment. A mother hunter-gatherer who has an infant to take care of cannot feasibly care for a second until the first one grows big enough to keep up with the nomadic tribe. And many hunter-gatherer groups practice infanticide for this very reason.

[Alyrium Denryle]

Aliens are relevant because this was about the fermi paradox.

...

...

How? Now, I just went back and checked, I dont see any prior discussion in here regarding the Fermi Paradox, and I fail to see how population growth is relevant with respect to it. So you are just back-pedaling.

But lets humor your stupidity.

You will have a rather hard time finding a sentient species that follows an exponential growth trajectory for a lot of reasons. Not the least of which is the fact that r selected species (those that follow exponential growth curves) tend to be fast breeders with short lifespans and little to no parental care. When they are animals instead of plants, they are typically small and the potato chips of nature (which is why they follow an exponential growth curve, they try to out-breed predation which is what regulates their population instead of resource limitations). Most are dumb as a post Even when they are not dumb as a post, their lifespans are too short to do a whole lot of conceptual learning, even if they were notionally capable of it.

You cannot learn what you need to learn to put a spacecraft into orbit if your lifespan is only five years.

You might *might* get something like an ant colony where a queen lays hundreds of thousands of eggs that hatch into non-sapient larvae that are cared for by long-lived sapient workers. You might get something like that. But if they are big they are going to be regulated by an actual carrying capacity instead of predation and if they are regulated by a carrying capacity they follow a sigmoid growth curve.

I could teach a semester course in population ecology. But I am not going to do that here.

My literal first comment was about the Fermi Paradox. Two, Octupi are r-selective species, and they're intelligent.

Yes, yes you did. In a way that has nothing to do with population growth.

Octopuses (that is the proper plural, even in latin Octopi is not the proper plural) are just odd. They are r-selected and intelligent, but their lifespans are too short for the sort of learning required for civilization and because they die before they are able to care for offspring, they cannot achieve cultural information transfer. Every octopus--even if they were fully sapient--would have to reinvent the proverbial wheel.

If they did evolve in such a way that they have longer lifespans and could raise offspring, the number of offspring they raise would necessarily drop. This is because octopuses die from starvation after a HUGE energy expenditure on egg-laying. They starve to death caring for many many eggs in the hope that a few survive to adulthood. Making that not be the case would mean caring for fewer eggs, probably carrying them around with them or going ovoviviparous. Oh, and they would need to evolve 2nd order theory of mind, which is rather difficult for an animal that is decidedly non-social.

If they did that, they would be k-selected.

If they are sapient and r-selected, they (or an analogous alien species) wont reach the stars. If they somehow do eventually go to the stars, they will have to evolve toward k-selection.

Also, humans used to be substantially more r-selective.

No. We were not.

This is an exponential curve



This is a sigmoid curve



Notice how they look similar in the middle?

We are, right now, entering the point in a sigmoid curve where the rate of growth decreases and population starts leveling off.

Third, the ant colony would follow a sigmoid curve only until they expanded into their solar system. Then it'd be exponential again.

Because carrying capacity would be increased. Holy shit! It is still not an exponential growth curve. They would still be a K-selected species. Try again.

[Simon_Jester]

Uh, Alyrium...

A question. Wouldn't any species whose maximum practical population is limited by some kind of carrying capacity look like a sigmoid, regardless of their reproductive selection strategy?

Or do you get a fundamentally different sort of curve (say, a boom-bust-crash cycle) with r-selection in an environment with limited carrying capacity?

...

I may not know biology that well, but I know calculus. You get sigmoid curves when the rate of population growth is proportionate to the existing population, times the amount of empty space left for that population to expand into.

Now, humans (excellent examples of k-selection) don't deliberately breed less as they near carrying capacity; the birth rate seems to have to do with other factors.

Do those "other factors" or analogous ones simply not come into play when dealing with animals like rabbits or other fast-breeders?

[Rhadamantus]

No. We were not.

This is an exponential curve



This is a sigmoid curve



Notice how they look similar in the middle?

We are, right now, entering the point in a sigmoid curve where the rate of growth decreases and population starts leveling off.

There's a reason people used to have 8 kids.

[Napoleon the Clown]

There's a reason people used to have 8 kids.

Because most of the kids didn't survive childhood! People didn't pop out a bunch of kids and then walk away from them, they popped out a bunch of kids and buried most of them because they caught some horrible disease and died, or fell off a horse and broke their neck, or some other fate. Humans care for their young, to a greater extent than most species.

Christ, can't you just admit you were wrong about something? Without modern medicine and technology people tended to die very young. Childhood mortality rates are the biggest factor in how much greater the life expectancy is now than it was a few centuries ago. Or even just one century ago. If you survived to adulthood, you stood a reasonable chance of seeing your sixties or seventies.

Oh, and birth control helps to avoid having that many kids. Most people don't want to have eight little hellspawn running around underfoot.

[Alyrium Denryle]

Uh, Alyrium...

A question. Wouldn't any species whose maximum practical population is limited by some kind of carrying capacity look like a sigmoid, regardless of their reproductive selection strategy?

Or do you get a fundamentally different sort of curve (say, a boom-bust-crash cycle) with r-selection in an environment with limited carrying capacity?

Boom and bust cycles typically, plus they are limited by predation. Population growth curves are only the nice steroetypical ones we see in isolation from other factors like predation. Strictly speaking a K selected species can boom and bust as well if their generation time is long enough to overshoot their carrying capacity, but those are usually damped oscillations that stabilize at K eventually.

I may not know biology that well, but I know calculus. You get sigmoid curves when the rate of population growth is proportionate to the existing population, times the amount of empty space left for that population to expand into.

Now, humans (excellent examples of k-selection) don't deliberately breed less as they near carrying capacity; the birth rate seems to have to do with other factors.

Do those "other factors" or analogous ones simply not come into play when dealing with animals like rabbits or other fast-breeders?

In biological terms, we have a phenotypically plastic response to the likelihood of child survival. We ramp up reproductive effort when our offspring are likely to die, and scale it back when they are not likely to die. Carrying capacity does not enter into that.

There's a reason people used to have 8 kids.

Yes moron. It has already been discussed. Half of them died in early childhood.

[Rhadamantus]

There's a reason people used to have 8 kids.

Because most of the kids didn't survive childhood! People didn't pop out a bunch of kids and then walk away from them, they popped out a bunch of kids and buried most of them because they caught some horrible disease and died, or fell off a horse and broke their neck, or some other fate. Humans care for their young, to a greater extent than most species.

Christ, can't you just admit you were wrong about something? Without modern medicine and technology people tended to die very young. Childhood mortality rates are the biggest factor in how much greater the life expectancy is now than it was a few centuries ago. Or even just one century ago. If you survived to adulthood, you stood a reasonable chance of seeing your sixties or seventies.

Oh, and birth control helps to avoid having that many kids. Most people don't want to have eight little hellspawn running around underfoot.

Having 8 kids because most died is a lot more r-selective.

[Broomstick]

No it's not, dumbshit. The mere fact humans usually have just one child at a time indicates we're k-selective, not r. Shut the fuck up and listen to the guy who is actually a biological scientist.

[Sky Captain]

At some point technology could come where launching interstellar expedition no longer is expensive or difficult compared to total scientific and engineering knowledge base, material and energy resources available to civilization or even wealthy individuals or organizations.

Imagine autonomous factories in space that can gather required resources from asteroids and replicate to achieve necessary industrial base to build starship with little to no human oversight. If AI and self replicating technology is involved current economic model no longer works. Building a starship could be as simple as send the instructions, AI controlled robots do the rest.

[Simon_Jester]

Having 8 kids because most died is a lot more r-selective.

You keep using that word. I do not think it means what you think it means.

R-selection is not about "have many kids, hope some survive." It is about "put minimal effort into any one child, hope some survive." For example, a fish might lay a LOT of eggs. Like, hundreds of them. Most of those fish eggs wind up as caviar for some marine predator, and the fish won't even know or care it's happened. But as long as two or three of them hatch into little minnows that actually grow up into reproductive-age fish, the fish "wins" from an evolutionary point of view.

Because two living, breeding-age offspring per mother is enough to maintain a population somewhere close to replacement rate. Three provides insurance.

How do I explain this better?

Hmm... let me analogize...
___________________

The difference between r-selection and k-selection is like the difference between spamming people and writing essays.

Let's extend that analogy to talk about human reproduction. You're writing term papers for college. You MUST write two good term papers to pass, and three to get a good grade. If you only write one, you've failed the semester. Crappy pseudo-papers don't count, you MUST produce good, solid papers.

Now, producing a good term paper takes time. You cannot spam term papers; at a bare minimum you need to be up all night the day before it's due putting in hours of reading and organizing and typing. There is literally no way to create a term paper in ten minutes, try to make two hundred of them, and turn them all in in the hopes that one or two will be good enough.

If your term paper writing conditions are comparable to the conditions faced by a Stone Age hunter-gatherer mother, the sequence goes like this:

You are trying to write your papers during party week. There are loud, drunken idiots crashing around your dormitory, and the library, and everywhere else at the university. Also, your computer is a six year old relic that crashes if someone looks at it cross-eyed. You try to write a paper. Someone trips over the power cord, your computer goes out. Your save file is gone. You curse a blue streak, because you just wasted an hour on that. You gather up your notes and try again. Two hours later, the machine crashes. Try again. Ninety minutes later, a drunk staggers by and spill beer all over your notes. And your keyboard. Computer shorts out. You borrow a friend's computer. This time you type it up correctly! You print it out. Then you take it back to your dorm... and some reckless idiot driving by too fast outside splashes your paper with mud from a mud puddle. Oh, and your friend's gone to sleep and shut down their computer, so now you have to find YET ANOTHER way to get this done...

See, the thing is, you are still using a "k-selective" strategy (work on ONE paper at a time, work hard on each paper). But most of your potential 'term papers' were destroyed or aborted long before you got to use them. So you wound up 'giving birth' to four papers, each of which got worked on for an extended time, and all of which were failures.

No matter how many times you have to repeat this strategy in order to turn out two or three good term papers, you have NOT started spamming papers. Your strategy is not, and can never be, that of spamming papers, and if you ever tried to do that you would fail. Because term papers, like human babies, cannot be brought to term successfully via spamming techniques. It's biologically impossible.

[Napoleon the Clown]

There's a reason people used to have 8 kids.

Because most of the kids didn't survive childhood! People didn't pop out a bunch of kids and then walk away from them, they popped out a bunch of kids and buried most of them because they caught some horrible disease and died, or fell off a horse and broke their neck, or some other fate. Humans care for their young, to a greater extent than most species.

Christ, can't you just admit you were wrong about something? Without modern medicine and technology people tended to die very young. Childhood mortality rates are the biggest factor in how much greater the life expectancy is now than it was a few centuries ago. Or even just one century ago. If you survived to adulthood, you stood a reasonable chance of seeing your sixties or seventies.

Oh, and birth control helps to avoid having that many kids. Most people don't want to have eight little hellspawn running around underfoot.

Having 8 kids because most died is a lot more r-selective.

R-selective is when little to no care goes into offspring, regardless of their survival! Humans have always put a shitload of care into our young because, aside from possibly marsupials, our infants are the least developed upon being shat forth into this world. Ignore those goddamn awful shows you see where some kid grows up in the wild instead of dying. Those are bullshit. If humans were to adopt an r-selective child-rearing method humans would go extinct.

Replacing what dies isn't r-selective. It doesn't mean that you're not putting effort into your offspring.

[Rhadamantus]

Because most of the kids didn't survive childhood! People didn't pop out a bunch of kids and then walk away from them, they popped out a bunch of kids and buried most of them because they caught some horrible disease and died, or fell off a horse and broke their neck, or some other fate. Humans care for their young, to a greater extent than most species.

Christ, can't you just admit you were wrong about something? Without modern medicine and technology people tended to die very young. Childhood mortality rates are the biggest factor in how much greater the life expectancy is now than it was a few centuries ago. Or even just one century ago. If you survived to adulthood, you stood a reasonable chance of seeing your sixties or seventies.

Oh, and birth control helps to avoid having that many kids. Most people don't want to have eight little hellspawn running around underfoot.

Having 8 kids because most died is a lot more r-selective.

R-selective is when little to no care goes into offspring, regardless of their survival! Humans have always put a shitload of care into our young because, aside from possibly marsupials, our infants are the least developed upon being shat forth into this world. Ignore those goddamn awful shows you see where some kid grows up in the wild instead of dying. Those are bullshit. If humans were to adopt an r-selective child-rearing method humans would go extinct.

Replacing what dies isn't r-selective. It doesn't mean that you're not putting effort into your offspring.

Ok. I did not know that, and I admit I was wrong.