3 ms·

I'm no scientist, but I'm skeptical. The claims in the article are: 1) All of the Ashkenazi Jews alive today can trace their roots to a group of about 330 peop

I'm no scientist, but I'm skeptical. The claims in the article are: 1) All of the Ashkenazi Jews alive today can trace their roots to a group of about 330 people who lived 600 to 800 years ago 2) These people lived 25 to 32 generations ago, and their descendants grew at a rate of 16% to 53% per generation 3) Today there are more than 10 million Ashkenazi Jews around the world, including 2.8 million in Israel I just can't believe the growth rate. It's astronomical. Especially in times before modern medicine, with wars, plagues, pestilence. Especially considering that the Nazis alone killed millions of Jews before/during WWII. Also Jews were/are relatively widespread in Europe. Even before WWII there were populations that were separated by thousands of miles. Until recently it wasn't easy to migrate thousands of miles. There were already people in most places, it was hard to travel, it was often dangerous to travel. I dunno. I'm just going by intuition here, and as we know that is something that is often (usually?) wrong when it comes to things outside of our normal experience. But I believe that there were considerably more than 330 Ashkenazi Jews in the middle ages.

maxerickson 12y ago
Historically, there was nothing extraordinary about having 3-5 (or more) children. 5 children gives you a high rate of population growth even if you have quite some early mortality. Also, it is a case of exponential growth, so you get a multiplier of up to 25,000 (from 1.5^25). Or 400,000 from 1.5^32. I guess it isn't really that simple, but that explanation is at least useful for enhancing intuition.
- PhantomGremlin 12y ago
  Fair enough. Exponential growth can be pretty amazing. But think of it this way. Let's say the total population of Europe was 20,000,000 at some point in the middle ages in the countries from where the Ashkenazi Jews originated (corresponding to the time that there were 330 Jews). [1] This is a very crude estimate, as the population certainly varied a lot. So you're telling me that those 330 Jews out-competed 20,000,000 gentiles to such an extent that, before the Nazis and WWII, there were (perhaps) 10,000,000 Jews in Europe? That growth seems very high. My guess would be 20,000,000 people overall in the middle ages means at least 20,000 Jews (0.1% of total). But if there really were only 330 (really only 165 couples?) then they certainly had a knack of "getting it done"! This implies that Jews were much more adept than the general population at "survival", reproducing in each generation regardless of all the droughts, wars and plagues. One other explanation would be that the 330 starting number is accurate but corresponds to an earlier period of time, maybe 2,000 years ago, not 600 to 800 years ago as the article claims. [1] http://en.wikipedia.org/wiki/Medieval_demography http://en.wikipedia.org/wiki/Medieval_demography
  - maxerickson 12y ago
    The Ashkenazi Jews were part of the population decline: http://www.nature.com/ncomms/2014/140909/ncomms5835/fig_tab/ncomms5835_F4.html http://www.nature.com/ncomms/2014/140909/ncomms5835/fig_tab/... So you wouldn't want to compare the ~300 to your peak population estimate. Getting it done was very common in those times. People had lots of children.
    - PhantomGremlin 12y ago
      Ok, my fault for just reading LA Times article and not following the Nature link. The figure you link to really makes clear the bottleneck and the subsequent exponential growth. I'll read the Nature article and see if I can gain a better understanding.

maxerickson 12y ago

Historically, there was nothing extraordinary about having 3-5 (or more) children. 5 children gives you a high rate of population growth even if you have quite some early mortality. Also, it is a case of exponential growth, so you get a multiplier of up to 25,000 (from 1.5^25). Or 400,000 from 1.5^32. I guess it isn't really that simple, but that explanation is at least useful for enhancing intuition.

PhantomGremlin 12y ago
Fair enough. Exponential growth can be pretty amazing. But think of it this way. Let's say the total population of Europe was 20,000,000 at some point in the middle ages in the countries from where the Ashkenazi Jews originated (corresponding to the time that there were 330 Jews). [1] This is a very crude estimate, as the population certainly varied a lot. So you're telling me that those 330 Jews out-competed 20,000,000 gentiles to such an extent that, before the Nazis and WWII, there were (perhaps) 10,000,000 Jews in Europe? That growth seems very high. My guess would be 20,000,000 people overall in the middle ages means at least 20,000 Jews (0.1% of total). But if there really were only 330 (really only 165 couples?) then they certainly had a knack of "getting it done"! This implies that Jews were much more adept than the general population at "survival", reproducing in each generation regardless of all the droughts, wars and plagues. One other explanation would be that the 330 starting number is accurate but corresponds to an earlier period of time, maybe 2,000 years ago, not 600 to 800 years ago as the article claims. [1] http://en.wikipedia.org/wiki/Medieval_demography http://en.wikipedia.org/wiki/Medieval_demography
- maxerickson 12y ago
  The Ashkenazi Jews were part of the population decline: http://www.nature.com/ncomms/2014/140909/ncomms5835/fig_tab/ncomms5835_F4.html http://www.nature.com/ncomms/2014/140909/ncomms5835/fig_tab/... So you wouldn't want to compare the ~300 to your peak population estimate. Getting it done was very common in those times. People had lots of children.
  - PhantomGremlin 12y ago
    Ok, my fault for just reading LA Times article and not following the Nature link. The figure you link to really makes clear the bottleneck and the subsequent exponential growth. I'll read the Nature article and see if I can gain a better understanding.