What does <negative> mean in the context?
I understand the whole, but do not understand the part.
For many people — including many scientists — 'nature' is defined by a negative: it exists where people do not. Nature lies outside the urban and agricultural realms, in regions of Earth where natural processes are unimpeded. Nature is where fallen logs rot and acorns grow, wildfires turn woodlands into meadows, and barrier islands shift with the currents — all without human interference. By extension, this definition suggests that nature is best protected by keeping humans far away, so that it can continue to run itself.
But there is a serious problem with this view. If nature is defined as a landscape uninfluenced by humankind, then there is no nature on the planet at all. Prehistoric peoples changed their surrounding ecosystems, whether by installing orchards in the Amazon or — according to one increasingly accepted theory — by hunting many large mammals to extinction in North America. And modern humans are changing the global environment even more profoundly, whether through planet-wide climate change, or by the worldwide movement of synthetic chemicals through the food chain. Today there is no place untouched by man