Today, we try to create a new food. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Historian Warren Belasco tells how we tried to solve world hunger fifty years ago. We'd gone into WW-II badly shaken by the "dust bowl" droughts of the mid-'30s. We came out of it anxious about an emerging Asia, with new political power and a huge population. Malthus's old message rang in our ears: population rises exponentially while the food supply can rise only linearly.

Today, birth control has slowed or even reversed population growth in all but poor countries where women are denied education. But in 1950 the forces aligned against birth control were formidable. It seemed that our only hope (and only a temporary hope at that) was to radically improve our food supply.

Most of the arable land was already under cultivation. The new plant geneticists and biochemists were finding ways to improve crop yields. But that was only incremental gain. We needed some as-yet-unmined resource. That resource appeared to be the vast oceans, which cover three quarters of the Earth.

The severest need was for new sources of complete protein, and a remarkable plant source showed up in the late 1940s. It was an algae called chlorella. Compared with other plants, scientists expected it to convert twenty times as much solar energy into protein and to yield fifty times as many pounds of protein per acre. Dried chlorella was half protein and rich in other nutrients.

All this was any journalist's dream. A watery slime promising to feed the millions. Scientists' hopes outran their caution. The true manna for feeding the hungry was here at last.

Making algae edible was the problem that kept getting swept under the rug. While scientists complained that people needed to "transcend their irrational attachments to a few inefficient higher plants," plankton soup was being tried out in a Venezuelan leper colony. People who tried to eat algae talked about the Gag Factor. Promoters finally stopped talking about eating the vile stuff directly. They began talking about adding it to other foods.

Then economics caught up with it. An algae farm required a huge capital investment. Algae production was delicate and unstable. Promoters acknowledged that it cost more than conventional plant foods, but they thought costs would drop. Then grain became more abundant and less costly, while a new gourmet movement swept the country. We wanted coq au vin, not minimal fuel for our bodies.

So our fascination with algae burgers and plankton soup blew away like summer smoke. Hydroponics lingered only in science fiction. But algae might yet be resurrected as a food source. For terrible hunger does stalk the earth. Today, feeding the world's six billion people is as much a problem of distribution as it is of shortage. But, sooner or later, I fear, we really will need some kind of edible manna to keep our bodies nourished.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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Belasco, W., Algae Burgers for a Hungry World? The Rise and fall of Chlorella Cuisine. Technology and Culture, Vol. 38, No. 3, July 1997, pp. 608-634.

Chlorella is commercially available today. For more on chlorella, see the following websites or search your own browser for more information: http://www.taiwanchlorella.com/

I am grateful to Tom DeGregori, UH Economics Department, for his valuable additional counsel.