The other 72% is still a result of human activities!
A lot of it has to do with human activity.
How many human activities can you say that about these days?
On the first two days they saw no sign of any human activity.
A number of them have no clear association with human activity.
After all, most human activities have some impact on the environment.
There is evidence of human activity in this area going back 5000 years.
As a result, social scientific knowledge of society will actually change human activities.
Rather few human activities seem to have their main point merely in themselves.
It also studies the effects of human activity on the environment.