Asked by: Jacob Hackett, Swadlincote
Males have slightly higher mortality rates for subtle genetic reasons as well as war and occupational hazards. To offset this, we have evolved a slight male bias of 110 boys born for every 100 girls. This gap gradually narrows as you move up through the age groups to reach a 1:1 ratio around reproductive age. The ratio of men then continues to fall to around 79:100 after age 65.