Even up to 1900s the average life expectancy was 31 years. Many factors resulted in short life span but what mattered for many communities was early marriages to maintain a population that could function as an organized society i.e. to farm and manufacture and secure and so on.
It is not for us to judge those marriages. We should only judge our own affairs with women and children in our own households, not what those millions of people did centuries back.
Source: https://en.wikipedia.org/wiki/Life_expectancy
| Era | Life expectancy at birth in years |
Life expectancy at older age |
|---|---|---|
| Paleolithic | 33 | Based on the data from recent hunter-gatherer populations, it is estimated that at 15, life expectancy was an additional 39 years (total 54), with a 0.60 probability of reaching 15.[11] |
| Neolithic | 20 [12]-33 [13] | |
| Bronze Age and Iron Age[14] | 26 | |
| Classical Greece[15] | 28 | |
| Classical Rome[16] | 20–30 | If a child survived to age 10, life expectancy was an additional 37.5 years, (total age 47.5 years).[17] |
| Pre-Columbian North America[18] | 25–30 | |
| Medieval Islamic Caliphate[19] | 35+ | Average lifespan of scholars was 59–84.3 years in the Middle East[20][21] and 69–75 in Islamic Spain.[22] |
| Late medieval English peerage[23][24] | 30 | At age 21, life expectancy was an additional 43 years (total age 64).[25] |
| Early Modern England[14] | 33–40 | |
| 1900 world average[26] | 31 | |
| 1950 world average[26] | 48 | |
| 2010 world average[27] | 67.2 |