we get asked and give our answers.

One that's come up for a long time is: as we make the world healthier, is the population going to get so big that feeding everybody and maintaining the environment is going to be impossible?

Here we can see a chart that looks at the total world population over the last several hundred years, and at first glance this is a bit scary.

We go from less than a billion in 1800, and then 3, 4, 5, 6 and 7.4 billion where

we are today is happening even faster.

So, Melinda and I wondered whether providing new medicines and keeping children

alive, would that create more of a population problem?

What we found out is that as health improve, families choose to have less children

and this effect is very, very dramatic.

We find that in every country of the world, this is repeated.

The population growth goes down as we improve health.

So, we've taken that chart that shows the global population growth

and we've actually extended it out all the way to 2100.

And we can see that instead of continuing, it actually flattens out .

Another way to see that is through this rate of population growth.

And you can see that in the 60s that reached a pretty high number,

over 2% per year, and it's now come way, way down.

Now, 11 billion people is still a lot, but the good news is that the faster we improve

health, the faster family size goes down.

And so, we can feel great about saving those lives.