simple. its called the industrial revolution
people used to die more frequently from infant deaths, disease, infection, or something similar that modern science has been able to prevent.
The percentage of the children born in London who died before the age of five decreased from 74.5% in 1730-1749 to 31.8% in 1810-1829.[22]
It is important to note that life expectancy rises sharply in all cases for those who reach puberty. A pre 20th Century individual who lived past the teenage years could expect to live to an age close to the life expectancy of today.
people live longer because they are healthier. if the food was so bad this would not be the case. hello?