Anyway, life longetivity must be mainly improved by modern medicine and safe foods.
But, it's not better to rely on modern medicine to extend our lives. It would be better to do so by focusing on factors below as Harvard School of Public Health says.
・Eating a healthy diet
・Exercising regularly
・Keeping body weight
・Consuming alcohol in moderation
・Never smoking
But, for people who feel strong stress when keeping these rules, I wonder if they really extend their life expectancy.
The next research would be relationship between stress and healthy life.