Nobody knows the exactly the number of people who lived on earth in 100 years
Abouriginals have lived in Australia for many thousands of years. :)
Historical evidence shows that Ice Age people lived there 18,000 years ago.
200 years
There have been people that lived way past 100 but on average its 80 years.
They were the people who lived many years before us.
Methusaleh, the oldest person recorded, lived for 969 years and so, according to what is written in the Bible, no-one lived longer than a thousand years.
About 200-220 years
Two words... fossil records. There are fossils all over the planet - which can be electronically 'dated' - showing that people have lived for thousands of years.
The world is 4.5 billion years old. There has been billions of people who have lived and died since the first humans.
The people who lived in it thousands of years ago.
The Anasazi.