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Comment by petercooper | Hacker News Reader

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

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Here are a couple posts questioning the impact of infant mortality on ancient lifespan estimates, http://santafereview.com/chronicle/2011/02/01/ancient-mortal..., http://www.wonderquest.com/LifeSpan.htm both referencing this paper, http://www.animalsimulation.org/index.php?option=com_content....

A few statistics from the paper are the mean lifespans of the Kings of England and Scotland between 1000 and 1600 were about 50. This was also about the mean lifespan of people at court. In a monastic population studied only 5% lived past 45 and excavations of anglo-saxon cemeteries dated at 600-1000 CE found no one older than 45.

I still don't understand why the average is used instead of median (or average of data between the first and third quartile), when people talk about life expectancy. It leads to misconceptions.

(A) It fits into peoples agenda.

(B) Most people know almost nothing about statistics. Even those who use it on a every day base. Honestly, I'm afraid, I'm not really an exception.

I think if you have to guess between human evilness and stupidity the latter is more likely, right?

Most people know almost nothing about statistics. Even those who use it on a every day base.

The same could be said of English.

Not every poster here calls English his or her first language. If you send me corrections, I very much appreciate it.

"on an everyday basis." <shared in the spirit of learning and mutual respect. Not snark>

Aside from the fact that more than half of the people in the world actually don't know anything about English, what does that have to do with..anything?

I do claim to be at least moderately familiar with the language, and have no idea why you're quoting that line.

Because it is the correct measure for the question at hand. In a steady state population, life expectancy at birth times the rate of births gives you the number of people alive, and equally number of people alive divided by average length of life gives you the number (or rather, rate) of individuals born, which is what you need if you want to know how many individuals have ever been born. The maths gets a bit mor complicated with a dynamic population size, but the principle is the same. The median would be completely useless for this.

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.

Yeah, and Noah reportedly died at 950, so I'd definitely take these numbers with a drop of hemlock :)

Go back far enough in history and numbers get even less believable, just think of Methuselah.

It should be noted that there is some difference between history and scripture. Though, history doesn't know everything either.

Zeno of Elea got ever so close to 60 but never quite made it.

All true, though, as far as I know, hunters and gathers who manage to survive childhood still die quite early, no? [1] They appear very healthy but thats partly because there are pretty much no grand parents. I might be wrong about this.

Also, a diet high in animal protein might make you very fit but it is thought to be a cause for cardiovascular disease [2]. Actually, afaik, this is the reason why government still gives out these fat making, carbohydrate rich, diet recommendations [3]. They might make you obese, but on the other hand, if you might live a sportive life just to suddenly die of a heart attack.

[1] I can't recall if it was Diamond, Kevin Kelly in "What Technology Wants", Campbell in "The China Study" or someone else, who wrote about this. Can anyone back or correct this? [2] This, Im sure you will find in "The China Study" by Campbell [3] Lustig and also Taubes in "Good Calories, Bad Calories"

Nutrition isn't the only issue. Hunter-gatherers have a much higher chance of a violent death; not just because of the risks of hunting, but because tribal warfare drafts the majority of able-bodied men. Even the ritualized warfare commonly used among present-day hunter-gatherers is likely to cause deaths.

http://en.wikipedia.org/wiki/War_Before_Civilization

Christopher Ryan [1] denies this.

So which of my down voted post above was bullshit? I'd like to learn.

[2] http://www.psychologytoday.com/blog/sex-dawn/201103/steven-p...

Christopher Ryan's blog post is low on examples, compared with that Wikipedia page about the book...

>>About 90-95% of known societies engage in war. [Etc.]

This is a sensitive subject for people with (political) axes to grind, so I'd prefer better references for the claim that Pinker is totally non serious?

(I was surprised to see that Eskimos had extermination wars?! You would think the population density made organised conflicts impossible?)

Edit: Clarity.

You might be right. I still think its worth reading. I still tend to prefer Christopher Ryan's point of view but this might change. Also, Pinker is afaik not a professional expert on anthropology [1].

[1] http://en.wikipedia.org/wiki/Pinker

Pinker quoted an expert. Or not?

If the research consensus in the field really was different, Ryan would have pointed that out gleefully -- with many more references. Since Ryan didn't do that, he is either dishonest or ignorant. Either way, he can be ignored.

Also, there has been much more man to man violence in the past. Its been an exponential decrease since the beginning of man. Stephen Pinker had a TED talk about this http://www.ted.com/talks/steven_pinker_on_the_myth_of_violen....

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