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What percentage of people are alive today?

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Re: What percentage of people are alive today?

#31

Post by petercooper »

Not to detract from the insight but:

Until very recently life expectancy at birth hovered between 20 and 35 years, but in the past century it has risen to 67 years

Most of this increase has been due to a precipitous crash in infant mortality, rather than a soaring increase in the median life expectancy. For example, even in the 1500s it seems a well-to-do Englishman (who lived a somewhat more hazardous life medically than even today's poor) had an average life expectancy of 71 if he made it as far as 21: http://apps.business.ualberta.ca/rfield/lifeexpectancy.htm

Re: What percentage of people are alive today?

#32

Post by ellyagg »

btilly wrote: post #15
tel wrote: post #9

Am I the only one absolutely terrified by that number? Malthus wasn't wrong in principle, just in timescale. It's clear that technologies have improved Earth's human carrying capacity, but I don't know any method to claim that an S-shaped curve isn't inevitable. It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

You are not alone. If you want to get more scared, read http://www.amazon.com/Collapse-Societies-Choose-Fail-Succeed... . Interestingly from the population statistics alone it is possible to make an argument about the total likely future number of humans that will live. There is debate about whether the reasoning is correct, but it is at least suggestive. See http://en.wikipedia.org/wiki/Doomsday_argument for more.

I don't think the Doomsday Argument is that interesting. It may be trivially true, but it doesn't tell us anything interesting or predictive. All it says is that the chronology of human existence is too complicated for us to calculate. That being the case, our working assumption can only be that we're at the midpoint of our species population line. But, keep in mind that this estimate is really, really horrible, it's only virtue being that it's better than all the others.

If someone gave you a trick coin, and you didn't know which side was favored, you'd have to assume 50/50, even knowing that you were certainly wrong. Knowing that one side is weighted doesn't give you any interesting information for one toss.

If you follow the arguments for and against the DA, it's clear this isn't about a well-defined statistical argument, but immediately devolves into qualitative arguments about our survivability. The optimists say, well, based on the average extinction rate it's extremely unlikely we'll die in And that's fine, because we need to argue about and introspect on the longevity of species, but brainteasers like the DA don't further it in any meaningful way.

Re: What percentage of people are alive today?

#33

Post by yummyfajitas »

reasonattlm wrote: post #24
tel wrote: post #9

Am I the only one absolutely terrified by that number? Malthus wasn't wrong in principle, just in timescale. It's clear that technologies have improved Earth's human carrying capacity, but I don't know any method to claim that an S-shaped curve isn't inevitable. It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

Malthus was wrong in principle. He didn't understand human action or economics, and that misunderstanding remains very common. See: http://www.fightaging.org/archives/2006/09/overpopulation.ph... "Common Malthusianism - the idea that a given resource (such as living space or food) will run out in the future based upon extrapolation of present trends - stems from fundamental misunderstandings about economics, human ac…

"Common Malthusianism" is a strange name to apply to a claim Malthus didn't make. Malthus didn't attempt to extrapolate current trends, he merely pointed out (correctly) that there will eventually be a limit to productivity. From "An Essay on the Principles of Population":

We may be quite sure that among plants, as well as among animals, there is a limit to improvement, though we do not exactly know where it is. It is probable that the gardeners who contend for flower prizes have often applied stronger dressing without success. At the same time, it would be highly presumptuous in any man to say, that he had seen the finest carnation or anemone that could ever be made to grow. He might however assert without the smallest chance of being contradicted by a future fact, that no carnation or anemone could ever by cultivation be increased to the size of a large cabbage; and yet there are assignable quantities much greater than a cabbage. No man can say that he has seen the largest ear of wheat, or the largest oak that could ever grow; but he might easily, and with perfect certainty, name a point of magnitude, at which they would not arrive. In all these cases therefore, a careful distinction should be made, between an unlimited progress, and a progress where the limit is merely undefined.

He then observed the tendency of humans to reproduce until the limits of their environment are reached and concluded that poverty will be the terminal state of humanity.

Malthus was merely wrong on this empirical point - humans are willing to voluntarily stop reproducing under certain cultural and economic circumstances. These circumstances involve modern levels of economic productivity, technologies (birth control) invented 100 years after his death, and western cultures. He wasn't wrong on principle, he merely lacked the data we have today.

Re: What percentage of people are alive today?

#34

Post by radu_floricica »

btilly wrote: post #15
tel wrote: post #9

Am I the only one absolutely terrified by that number? Malthus wasn't wrong in principle, just in timescale. It's clear that technologies have improved Earth's human carrying capacity, but I don't know any method to claim that an S-shaped curve isn't inevitable. It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

You are not alone. If you want to get more scared, read http://www.amazon.com/Collapse-Societies-Choose-Fail-Succeed... . Interestingly from the population statistics alone it is possible to make an argument about the total likely future number of humans that will live. There is debate about whether the reasoning is correct, but it is at least suggestive. See http://en.wikipedia.org/wiki/Doomsday_argument for more.

Scared? I remember distinctly the book ended with a "cautious optimism".

Yes, it points out a lot of potential problems, and makes it obvious that societies _do_ fail, and that we're not yet above that rule, but I wouldn't call it scary.

Re: What percentage of people are alive today?

#35

Post by kalid »

petercooper wrote: post #31

Not to detract from the insight but: Until very recently life expectancy at birth hovered between 20 and 35 years, but in the past century it has risen to 67 years Most of this increase has been due to a precipitous crash in infant mortality, rather than a soaring increase in the median life expectancy. For example, even in the 1500s it seems a well-to-do Englishman (who lived a somewhat more hazardous life medically…

Exactly. One of my pet peeves is the misconception that a life expectancy of 35 means a normal adult somehow drops dead at that age. (And leads to arguments like "Oh, don't eat a paleo diet, cavemen only lived to 35").

Socrates lived to 71 in ancient Greece. Yet you know him for being a philosopher, not for living 2.5x the average age (like living to 200 today -- you'd think that'd make a fuss).

Re: What percentage of people are alive today?

#36

Post by scott_s »

georgieporgie wrote: post #28

I thought that 'humans', as in, you would see one and say, "yeah, that weird looking guy over there," went back about 2.2 - 2.3 million years. http://en.wikipedia.org/wiki/Human_evolution Populations would have been small, but an extra 2.1 million years is a long time.

From that, The dominant view among scientists concerning the origin of anatomically modern humans is the "Out of Africa" or recent African origin hypothesis, which argues that Homo sapiens arose in Africa and migrated out of the continent around 50,000 to 100,000 years ago, replacing populations of Homo erectus in Asia and Homo neanderthalensis in Europe. Scientists supporting an alternative multiregional hypothesis argue that Homo sapiens evolved as geographically separate but interbreeding populations stemming from a worldwide migration of Homo erectus out of Africa nearly 2.5 million years ago.

The difference is that the species that we call Homo sapiens - us - is on the order of 100,000 years old.

Re: What percentage of people are alive today?

#37

Post by scott_s »

tel wrote: post #9

Am I the only one absolutely terrified by that number? Malthus wasn't wrong in principle, just in timescale. It's clear that technologies have improved Earth's human carrying capacity, but I don't know any method to claim that an S-shaped curve isn't inevitable. It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

Historically, colonization has had little impact on the size of the population that sent them. And even if it improved the lives of the people who left, it had no impact the lives of the people who stayed.

Re: What percentage of people are alive today?

#38

Post by wulczer »

kalid wrote: post #35
petercooper wrote: post #31

Not to detract from the insight but: Until very recently life expectancy at birth hovered between 20 and 35 years, but in the past century it has risen to 67 years Most of this increase has been due to a precipitous crash in infant mortality, rather than a soaring increase in the median life expectancy. For example, even in the 1500s it seems a well-to-do Englishman (who lived a somewhat more hazardous life medically…

Exactly. One of my pet peeves is the misconception that a life expectancy of 35 means a normal adult somehow drops dead at that age. (And leads to arguments like "Oh, don't eat a paleo diet, cavemen only lived to 35"). Socrates lived to 71 in ancient Greece. Yet you know him for being a philosopher, not for living 2.5x the average age (like living to 200 today -- you'd think that'd make a fuss).

And he died condemned to death and executed, too! So he could have lived happily for many more years.

Re: What percentage of people are alive today?

#39

Post by lotharbot »

tel wrote: post #9

Am I the only one absolutely terrified by that number? Malthus wasn't wrong in principle, just in timescale. It's clear that technologies have improved Earth's human carrying capacity, but I don't know any method to claim that an S-shaped curve isn't inevitable. It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

The vast majority of natural populations that I've looked into have s-shaped population growth without any particular unpleasantness; as population nears its carrying capacity, birth rate naturally tapers off, leading to near-zero population growth. Humanity appears to be in the tapering-off stage of this already (since around 1980), and I don't see any reason to presume there will be unusually high levels of conflict or tragedy as that tapering-off process continues.

The typical Mathusian "overpopulation" argument (based on a shallow misreading of Malthus) is not that we'll have an S-shaped population growth curve, but an A-shaped one -- that we'll have population grow out of control, and then come crashing back down through some massive tragedy (akin to the Kaibab Deer population [0]). The A-shaped scenario is reasonably unlikely for humans.

[0] http://depts.alverno.edu/nsmt/youngcc/research/kaibab/story3...

Re: What percentage of people are alive today?

#40

Post by hugh3 »

wulczer wrote: post #38
kalid wrote: post #35

Earlier quoted context omitted.

Exactly. One of my pet peeves is the misconception that a life expectancy of 35 means a normal adult somehow drops dead at that age. (And leads to arguments like "Oh, don't eat a paleo diet, cavemen only lived to 35"). Socrates lived to 71 in ancient Greece. Yet you know him for being a philosopher, not for living 2.5x the average age (like living to 200 today -- you'd think that'd make a fuss).

And he died condemned to death and executed, too! So he could have lived happily for many more years.

Xenophanes of Colophon supposedly lived to 95. Pyrrho of Ellis lived to 90, and Democritus to 109. On the other hand, Epimenedes is supposed to have lived to the age of 154 or 290 depending on whom you believe, so take these numbers with a grain of artery-clogging sodium chloride.
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