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Malthusian-past suviving-kids

Historically, many societies had two surviving kids per Woman. This is consistent with the Malthusian model, in which one would expect surviving kids to be around the rate of replacement.

	c 1300	c 1800	Surviving kids
Norway	0.40	0.88	2.095
Southern Italy	4.75	7.9	2.061
Franced	17	27.2	2.056
Englandb	5.8	8.7	2.049
Northern Italy	7.75	10.2	2.033
Iceland	0.084	0.047	1.930

Since the average women will give birth to 5-7 kids this means that the majority of children did not survive to adulthood.

The observation that the birth rate exceed the rate of population growth inspired Malthus to formulate his model & would subsequently inspire Darwin to formulate the idea of natural selection.

From Darwin’s autobiography:

“In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work.”

The idea of natural selection is practically baked in to the malthusian model since the birth rate exceed the num of surviving kids, only some will survive and some sort of selection will occur.

This just shows how exceptional large families were back in the days. Having six surviving children on average like the Amish do today or like it was in many developing countries for a few decades after WWII is only possible under modern conditions.