And these different trends would tend to be consistently upwards rather than random, because we are consistently trying to improve such things? (Though the families one would probably still be random)
I’m not sure we do consistently try to improve these things. Nutrition, yes. But lead exposure got appreciably worse between WWI and 1970-1975, at least in the UK & US, and shrinking families is a manifestation of the demographic transition, which is only semi-intentional.
And these different trends would tend to be consistently upwards rather than random, because we are consistently trying to improve such things? (Though the families one would probably still be random)
I’m not sure we do consistently try to improve these things. Nutrition, yes. But lead exposure got appreciably worse between WWI and 1970-1975, at least in the UK & US, and shrinking families is a manifestation of the demographic transition, which is only semi-intentional.