If you don't have good medical care the average age of the people in your country is less

So, when you see countries with the average age being 10 to 15 years old you know basically two things about that area or country.

1. the people are very poor and relatively uneducated.

2. There is not good medical care, good food or pure water so people die very young. 

You also know that these places will be pretty much wiped out in the future by Global Climate changes because they likely won't have the resources to survive what is coming regarding flooding and droughts and storms of various kinds.

So, the darker the color the more likely these people will be wiped out this century without outside help.

This is regarding the population age map in the previous article.

Also, if the age average of the  population is 10 to 15 you also know that since there is no social welfare there that people have a lot of children partly to help work in the fields, help support them and also take care of them when they grow old because there is no social welfare system in place in that country or area.

However, having a lot of children is generally counterproductive in preventing human extinction (at least at this time in world history) because we already have 7.9 billion people here on earth.