This morning I read Mysterious marks on Ice Age cave art may have been a form of record keeping in science News.

The marks left in a cave 25,000 years ago illustrate the wisdom of early hunter-gatherers. Even then, these people were knowledgeable about their environment and respectful of nature's cycles; understanding that taking too much from one place could lead to decline. Nowadays, we can look back at this example as an invitation for modern civilization to take up sustainable living practices—regenerating our resources instead of simply consuming them without thought or consequence.

I spend a lot of time thinking about the question, how do we mimic regeneration in our cities? We have to ask, What can we learn from Earth’s earliest environmentalists? A lot.