by Vaclav Smil
Highest fertility rate in the world is 7.5 in Niger, rates have been declining globally but especially so in wester cultures
South Korea went from a fertility rate of 6 to <2 in 30 years
Replacement rate is 2.1 to account for females who don't survive to fertility age
If rates drop below 1.5, it is very hard to reverse
In 1950, 40% of the population lived in countries with fertility rates above 6 and the mean rate was 5
Now 5% of the population does and the mean is 2.6
75% of births between 2020 and 2070 will be in Africa
Infant mortality rate in the 1800s was 25% in the US, now it's 0.5%
For every $1 invested in vaccination, $16 is saved in healthcare cost and lost wages / productivity due to illness and death
The first vaccine was for smallpox in the 1700s
In 1985 there were 400k cases of polio, in 2000 there were 100
In 1850, life expectancy in the US was 40, now it's 79
Humans have a profound ability to moderate our body temperatures through sweating, we sweat more than any other animal. This allows us to run long distances during hot days. Humans are not the fastest or most efficient runners, but we are the most persistent.
Cities: