Through the middle of the 19th century, the US and other nations in the Americas approved of plantation slavery. Looking back at such horrors, it is easy to ask: What were people thinking? Yet, the chances are that our own descendants will ask the same question, with the same incomprehension, about some of our practices today. Here are three contenders for future moral condemnation.

The institutionalized and isolated elderly. Nearly two million of America's elderly are warehoused in nursing homes, out of sight and, to some extent, out of mind. Some 10,000 for -- profit facilities have arisen across the country in recent decades to hold them. Other elderly Americans may live independently, but often they are isolated and cut off from their families. Is this what Western modernity amounts to -- societies that feel no filial obligations to their inconvenient elders?

Industrial meat production. Of the more than 90 million cattle in our country, at least 10 million at any time are packed into feedlots, saved from the inevitable diseases of overcrowding only by regular doses of antibiotics, surrounded by piles of their own excrement. In the European Union, many of the most inhumane conditions we allow are already illegal or will be illegal soon.

Let's not stop there, though. We will all have our own suspicions about which practices will someday prompt people to ask, in dismay: What were they thinking, even when we don't have a good answer, we'll be better off for anticipating the question.

The environment. Of course, of these the most obvious candidate for condemnation is our wasteful attitude toward the planet's natural resources and ecology. Desertification, which is primarily the result of destructive land-management practices, threatens a third of the Earth's surface; tens of thousands of Chinese villages have been overrun by sand drifts in the past few decades.