The current human population is about 7.5 billion (when I was a kid, it was more like 5 billion). Right now, the population is doubling about once every 64 years. If it continues to double at that rate, and humans don’t colonize other worlds, then you can calculate that, less than 3000 years from now, the entire earth, all the way down to the core, will be made of human flesh.
Have not learned about the four stages of human population growth rule