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8642Re: [ANE-2] population growth

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  • Ariel L. Szczupak
    Jul 3, 2008
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      At 03:40 PM 7/3/2008, Niels Peter Lemche wrote:

      >We are talking about a traditional society with traditional health
      >care. And a death rate among children of, say between 50 and 90%.

      I don't know what "traditional" means in this context.

      We know that human biology results in exponential growth (aka
      Malthusian) in "ideal" reproductive conditions (both environmental
      and social). I seem to recall that for humans the yearly growth rate
      figure (in ideal conditions) is somewhat above 5%. We also have hard
      data about populations in the present and near past which can be used
      to create models.

      And everything we know indicates that "static populations" are either
      a myth or extremely rare exceptions. When I first looked into how ANE
      population estimates were done (and was shocked), "common wisdom" had
      it that static populations could exist in primitive societies, e.g.
      the Amazonian tribes - but then the towns/cities in the Xingu region
      were discovered making these "stable size" societies something
      temporary (historically).

      I haven't seen anything that supports single-number population
      estimates for historical periods (i.e. more than one or two
      generations) being meaningful. All that I've seen (and to a certain
      degree researched) indicates that such numbers are simply pseudo-science.

      Note that archeological population estimates are different. They are
      based on material evidence from which a carrying capacity is
      calculated - i.e. a number that represents the maximal, or sometimes
      optimal, number of people that could be supported by the physical
      evidence that was discovered. I have many misgivings about specific
      archeological ANE population calculations I have seen, but at least
      the numbers, correct or not, are meaningful. But these capacity
      numbers become meaningless when they are turned into historical
      population numbers representing a century or more.

      Note also that mathematical averages are of course possible. The
      general process seem to be "sawtooth" like. I.e. an exponential
      growth (aka geometric, as opposed to linear growth) followed by a
      steep decline. These numbers can be averaged, but such averages
      remove the "sawtooth" aspect, making them practically meaningless
      from an historical point of view.

      I don't have quick access to my notes from back then, but a quick web
      search shows that the resources available online today on this
      subject are huge, and anyone interested can find a lot with just few

      Instead, two quick examples.

      Does "the medieval population of Europe was X" have an historical
      meaning? It was thought so when I was in school, but check:


      It's the growth/decline processes that have historical meanings, not
      some number for the entire period (or some sub period).

      And re tradition ...

      The understanding of the sawtooth aspect of historical population
      sizes is far from new, and indeed "traditional" :)

      2 Samuel 24:9 [KJV]: "And Joab gave up the sum of the number of the
      people unto the king: and there were in Israel eight hundred thousand
      valiant men that drew the sword; and the men of Judah were five
      hundred thousand men."

      2 Samuel 24:13 [KJV]: "... shall seven years of famine come unto thee
      in thy land? or wilt thou flee three months before thine enemies,
      while they pursue thee? or that there be three days' pestilence in
      thy land? ..."

      1.3 million "arm bearers" implies a general population of about 3-4
      million. Has "greater Canaan" a "carrying capacity" of 3-4 million
      people, given the 10th cbc material culture? My personal opinion is
      that it does, but that's beyond the scope of this message. However,
      wether the numbers are correct or not, this passage shows an
      understanding of the process and lists three of the most common
      causes for the decline part in the sawtooth (climate/environment, war
      and plague, with the 4th being emigration) with their associated
      (very steep) rates of decline.

      Personal note - what an amazing book. [And in case anyone wonders,
      I'm an atheist]

      >Furthermore, I do not care if the numbers can be corrected, as long
      >as the way they are calculated remains the same. We can also discuss
      >the way of calculating numbers. No problem.

      I don't understand the above.

      What I'm trying to say is that while "carrying capacity" is a
      meaningful number, representing the population during an historical
      period (more than 1-2 generations) by a single number is not.

      If I recall correctly, a population growth rate of below 1% per year
      (a number that includes everything - births, deaths, arrivals &
      departures) is considered to be temporary (leading either to a
      quicker rate or to a decline). In real-life conditions rates above 2%
      per year are considered "quick". So let's see what happens in this
      range for a large village of 1000 people during a century (rounding to tens).

      1% growth rate:

      25 years - 1280. 50 years - 1640. 75 years - 2110. 100 years - 2700.

      1.5% growth rate:

      25 years - 1450. 50 years - 2110. 75 years - 3050. 100 years - 4430.

      2% growth rate:

      25 years - 1640. 50 years - 2690. 75 years - 4420. 100 years - 7240.

      I.e. a difference of 1% in the growth rate results in a difference of
      almost 270% in the size of the population after 100 years. That
      difference grows to 720% after 200 years, 1920% after 300 years and so on.

      These numbers have historical implications. E.g. if the calculated
      carrying capacity is 2000 people, you know that whatever the growth
      rate was, there was an historical event, at least one, that dropped
      the population level during that period. If the calculated carrying
      capacity is 10000 but you have no archeological evidence of the
      village becoming a town, you again can infer an historical event. Etc.

      And while growth rates and carrying capacities are meaningful
      numbers, determining them for specific locations or areas, in
      specific time periods, is far from trivial. And as the example above
      shows, choosing the wrong growth rate to model some historical
      period, wrong by a fraction of a percent, can result in computed
      populations sizes that are very far from the historical ones.

      For example, we know that Pontius Pilate had water brought to
      Jerusalem from springs near Hebron. Was it because the carrying
      capacity of the local water resources was reached, or was it because
      of a lifestyle that increased the quantity of water needed per
      person? Can the volume of the local water resources be evaluated for
      that period? What is local in that respect? Herod could have had mule
      trains bring water from nearer springs, e.g. Ein Yahel, Ein Karem,
      Abu Gosh, etc. And if these can be answered - can a number
      representing a yearly volume of water be translated into a number of people?

      Why water? because I think that it's safe to assume that food was not
      a factor in determining the carrying capacity of Jerusalem during the
      Herod or Pontius Pilate reigns. Why this period (which is short
      enough for a population size to have meaning)? Because of all the
      estimates that floated around during the Talpiot Tomb fiasco. If an
      argument could be made that the water carrying capacity of Jerusalem
      was reached during Pontius Pilate's reign, and if that could lead to
      a "water volume into number of people" calculation, then maybe we'd
      have a figure with some reasonable likelihood.

      Population estimates are not my thing, though I was sidetracked into
      them at one time. So I'm off this topic. The moral for me was to
      ignore population sizes for historical periods as meaningless, and
      not to accept carrying capacity or growth rate figures without
      checking carefully how they were reached. YMMV.


      [100% bona fide dilettante ... delecto ergo sum!]

      Ariel L. Szczupak
      AMIS-JLM (Ricercar Ltd.)
      POB 4707, Jerusalem, Israel 91406
      Phone: +972-2-5619660 Fax: +972-2-5634203
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