I’ve been thinking about reciprocity lately—how it holds relationships together. How partnerships end if one or the other takes more than gives. How wars start over lack of reciprocity—disrespect, seizing land, taking resources. How contracts aren’t successful and trades don’t work unless each party gives as good as it gets.

In other words, taking and giving in equal measure is the only sustainable practice in human relationships, whether interpersonal or international.

But then I’ve been thinking about how reciprocity is key in our relationship with the Earth too. At bottom, our ecological crisis boils down to one simple fact: humans are taking more than we’re giving back to the Earth.

For instance, we take oil out of the rock, and instead of making something of it that nourishes other life forms or enriches the soil, we make things out of it—plastic, CO2-releasing fuels, fertilizers, pesticides—that over their lifespan take more out of the soil or water or air than they contribute.

How did the Earth survive for billions of years and prepare an atmosphere conducive to life? By every species giving as good as it gets. By a system of exchange in which every part of the whole contributes as much as it uses. One species’s waste is another species’s fuel.

Who gets it?

• Plants: They take in carbon dioxide and produce oxygen.
• Animals: Just the opposite. They take in oxygen and produce CO2.
• Ecologists: They always think in terms of the whole ecosystem—how each part contributes and uses resources in balance with all the others.
• Indigenous peoples: They’ve been teaching their children for millennia that reciprocity with the earth is the bottom line for survival.
• Real estate agents: They know that a good deal is one in which the buyer and seller both go away happy. And that the only fair trade is an equal trade.
• Religious folks: They developed the Golden Rule in all its forms. Receiving as much as we give—it’s how everyone wants to be treated.
• Adam Smith: Yes, the father of capitalism himself talked about responsibilities as well as rights—something his economic progeny forgot in the nineteenth century when they permanently severed economics from ethics.

Who doesn’t get it?

• Plastics manufacturers and users: That’s us—every one of us. We’re putting into circulation a product whose end-of-life does not fuel some other life form but instead endangers the soil, the oceans, and all kinds of animals.
• Banks that shell out astronomical bonuses: They’re unsustainable because not based on reciprocity—unless you want to argue that bank execs are contributing a value in either goods or services equal to their bonus. And I can’t think of anyone who does. In fact, in a time of recession when labor is plentiful, wages (according to the law of labor supply and demand) should go down. Something’s definitely fishy here.
• Those who deal in natural resource extraction: Because the value of a healthy, functioning ecosystem is beyond measuring, any treaty or trade that places a number value on natural resources is by definition not reciprocal and therefore not in the long run sustainable. Think clear-cut logging, mining, and just about every trade agreement between industrialized and developing nations.
• Coal-mining companies that blast the tops off mountains AND the people who rely on the energy they produce: Again, all of us. Destroying ecosystems is the definition of unsustainable, rooted in a lack of reciprocity both with the people who live near those mountains and more generally between humans and the earth.
• Buyers of nonorganic food: Guilty here. Fossil-fuel-intensive agriculture is the epitome of nonreciprocal relations with the earth—and is therefore unsustainable.

It looks to me like humans are the only species capable of such radically nonreciprocal relations. We’re the only ones who can forget so spectacularly that we have to give in equal measure with getting.

Which is why our systems of education, religion, ethics, business—you name it—in this time of ecological and economic crisis must turn toward helping humans remember reciprocity.

Reciprocity—it’s the only sustainable practice. In ecology, in trade, in friendship. Reciprocity is the meeting place between economics and spirituality.

Reciprocity is, quite simply, the only way to hand down to our children a world conducive to life.

Reciprocity is the bottom line for survival.