According to the sources, life expectancy in 1700 varied depending on the country and social class. For most of human history, life expectancy has been short, perhaps 25 years for our hunter-gatherer ancestors and only 37 years for residents of England in 1700. Excluding child mortality, the average life expectancy during the 12th–19th centuries was approximately 55 years. However, if a person survived childhood, they had about a 50% chance of living 50–55 years, instead of only 25–40 years. In Massachusetts, colonists who reached the age of 50 could expect to live until 71, and those who were still alive at 60 could expect to reach 75. In medieval England, life expectancy at birth for boys born to families that owned land was a mere 31.3 years. However, life expectancy at age 25 for landowners in medieval England was 25.7. This means that people in that era who celebrated their 25th birthday could expect to live until they were 50.7, on average — 25.7 more years. It is important to note that life expectancy is a population-level statistic that reflects the conditions and experiences of a huge variety of people with very different health conditions and behaviors, some who die at very young ages, some who live to be over 100 years old, and lots whose life spans fall somewhere in between.