Until now, "grow or die" has pretty much summed up capitalism. A company that only maintains its present output and profitability will be outgunned by young, flexible, hungry upstarts. Not just in business, either. Larger, expansionist and innovative conglomerations of states and countries out-match smaller ones — the United States is a case in point, as are the European Union and OPEC. (One reason the USSR stagnated is that it never really got beyond being a giant gas pump.)

But — a big but — exponential expansion is an evolutionary dead end. At some point, growth will meet the limits of available resources, whether we're talking water, coal, oil or arable land. It happened here with the redwoods — cut them down faster than they re-grow and your logging business is doomed. (In 1900, 400 lumber mills were operating in the North Coast.) Atlantic cod, same difference. Have you seen photos of Delhi lately? Nothing to see but smog from coal-fired power stations and vehicle exhaust fumes. Same with Beijing and Jakarta, huge cities awash in their own waste. Easter Island was a subtropical broadleaf forest before early inhabitants cut down all the trees. Global population is growing (1 billion in 1800, 6 billion in 2000, currently over 7 billion) and per capita power use is increasing, leading to the rise of everything "bad": pollution, carbon dioxide levels, ocean acidity, air and water temperature, environmental destruction, species extinction ... you know the litany by now.

All of which stands the grow-or-die mantra on its head. Mindless growth — what we're presently engaged in — is a dead end. It's more like grow-and-die. Not today or tomorrow, but inevitably; a sustainable future depends on our ability to downsize, on all fronts.

Jumping to a cosmic perspective for a tangential moment, conventional wisdom was that we might be able to detect remote alien civilizations from their energy-use signature. In 1964, Russian physicist Nikolai Kardashev defined three types of civilizations: Type I uses all the energy resources of its own planet; Type II captures the total energy of its star; Type III utilizes the energy output of its entire galaxy ("Thinking Outside the Galaxy," Jan. 29, 2015). In tune with the times, Kardashev assumed grow-or-die when thinking about extraterrestrial life. Now we're starting to realize that exponential energy use is a losing strategy — whether for Kardashev's alien life occupying an entire galaxy or, more mundanely, for a little planetary civilization like ours.

If unlimited growth and profligate energy use dooms a civilization, what ensures long-term survival? In a word, sustainability. Here on Earth, we're starting to develop the tools and strategies to allow us to stay happy and engaged without wrecking the planet and drowning in our own waste. For instance:

Downsizing. Everything's getting smaller and more energy-efficient, from smart phones and personal medical probes to electric bikes and immersive virtual reality glasses.

Transportation. Self-driving vehicles operated by Uber-like companies will make most private cars obsolete, while telecommuting (think: telepresence, avatars) will minimize the need to go to the office in the first place.

Population. Sociologists have found that girls' education — especially in third-world countries — is the fastest way to encourage smaller families toward the goal of slowing and eventually reversing population growth.

Media. Movie theaters, and tree-based books, newspapers and magazines are giving way to personal, stay-at-home digital experiences.

Energy. Cheap, high-efficiency, roof-mounted solar cells will soon enable us to lessen our dependency on huge power stations.

Barry Evans (barryevans9@yahoo.com) is ready to downsize, starting with his sock drawer.