What human adaptation may enable us to live more sustainably by understanding and copying the ways in which nature has sustained itself for billions of years, despite major changes in environmental conditions?

Complex brain.

Explanation:

The cranial capacity of Homo sapiens are responsible for their successful adaptation on earth. They have the cranial capacity of around 1400cc.

The major environmental conditions has changed but the complex human brain has helped him to sustain and understanding the nature. Humans are successful to sustain on this earth due to their complex brain.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.