ON the high Andean plains near Lake Titicaca, at 12,500 feet above sea level, every five to 10 years a severe drought comes along, parching the adobe villages scattered through the fields, then twisting and curling the leaves of the crops. At such times, Indian peasants in the village of Chatuma split into two groups, one searching along the shores of the lake, the other among the hills. They are after an ancient remedy, the only one they know of that may break the severity of the drought. Peasants here call it ``the marriage of the frogs.'' Once a group has captured a male frog from the lake, the people begin playing music, carrying the frog in a procession until they arrive where the other group waits on top of a dusty hill, holding the frog's captive bride. The tiny nuptial couple is placed together, then surrounded with serpentine colored streamers. A solemn ceremony is performed and the frogs are betrothed.
As in their own marriage customs, the peasants believe the male frog will bring to his parched-hill bride a dowry, which in his case can be only one thing. It is the frog's most precious possession, one that neither he nor the peasants can do without: water from the lake.
The tradition is only one of many from a time before the Spanish conquest. For two American scientists who have completed three years of study here, several such traditions are the reason for one of the greatest problems in the high Andes - chronic hunger and starvation.
``In the highlands of Peru, Indian agricultural technology has been changed from thousands of years of tradition only by the Spanish conquest,'' says John Kusner, who along with Roland Bergman is studying traditional Andean agricultural techniques for the National Geographic Society.
The two scientists say that, by using a controlled land-swapping procedure that would consolidate a peasant's fields, using animal dung as fertilizer, and raising more animals, peasants can double or even quadruple their food production, using only the resources they already have.
``What you basically have is a pre-conquest agriculture based on the Inca hoe along with some medieval Spanish introductions such as the wooden plow and horse,'' says Mr. Kusner.
For the most part, peasants on the highlands continue to live as they have for millennia - in isolated adobe and grass-roofed villages, with no electricity, sewage, or running water. Despite their cultural stability, however, more and more peasants are faced with an increasingly desperate situation: They can no longer produce enough food.
In certain years hunger becomes so acute that peasants have been known to practice infanticide, while older children are sometimes sold as servants in the cities. The going rate for a 14-year-old child, the two scientists found, can be as little as a 50-pound sack of corn.
Applying the principles of agronomy - the scientific management of land, soils, crops, animals, and time - as a standard against which to measure the peasant's traditional agricultural techniques, the two researchers set out to see how efficient the peasants' present food production actually was. They measured 7,780 fields, produced 28 detailed maps, and compiled data onto 120 floppy computer disks.
``The peasant's cumulative agricultural efficiency is so appalling,'' says Dr. Bergman, ``that our amazement is how these people even survive at all.'' Because inheritance and marriage traditions continually fragment and scatter a peasant's fields over numerous villages, the average peasant spends three-quarters of his day walking between fields that sometimes measure less than a few square feet.
Even worse, peasants here traditionally don't use fertilizer - although fertilizer in the form of llama and alpaca dung lies abundantly about them. Instead, the scientists found, the peasants were using a pre-medieval fallow system in which up to 90 percent of their land is fallow at any given time. Blind tradition, then, seemed to be leading the peasants increasingly into agronomic self-destruction. But it hadn't always been that way.
``Under the Inca Empire you had a well-managed, self-supporting system that produced continuous food surpluses,'' Kusner says. ``Inca surpluses used to carry the nation over several years of poor harvests.''
Since the Inca state owned all land, when a peasant died his land immediately reverted to the empire. The landholdings were thus reconsolidated and made agriculturally more efficient. A system of raised fields, terraces, and artificial lakes, on the other hand, was employed to overcome the often-disastrous turns of weather.
When the Spanish conquistadors arrived in 1533, however, their interest was in gold, not agriculture. The Incas' time-tested methods were abandoned.
Armed with their data from the first detailed study ever to be carried out on the Andean highlands, Bergman and Kusner are applying to the United Nations Development Program for a grant that would allow them to carry out their recommendations.
At a time when government aid programs have dried up and past high-technology applications have failed, Bergman and Kusner say their simple solutions could help solve the hunger problem currently besetting the high Andes of Bolivia and Peru.