A new study of genetic patterns among modern Europeans lends support to a novel theory that starting 9,000 years ago early farmers spread from the Middle East all across Europe, transmitting a common language along with the new agricultural techniques.

The conventional theory holds that languages like English, French, German and Iranian are all related because a warlike people speaking the tongue ancestral to all the Indo-European languages over a period of time occupied all of Europe and imposed their language on the conquered. Skeptics who found this idea implausible proposed a different theory based on the known spread of agriculture across Europe: that as the early agriculturists moved year by year in search of new lands, they carried their language with them.

The new study, though not decisive, is better news for the agriculture theory than the conquest theory. By analyzing proteins from people at more than 3,300 sites across Europe, scientists have found that certain genes become progressively less common in going from southern Turkey, near where agriculture originated, toward northern Europe.

This genetic gradient is presumably the sign of an original population whose genes were diluted as it moved out and intermarried with the hunter-gatherer populations in its path. The migration routes suggested by the genetic gradient show a strong statistical correlation, according to the new study, with the spread of agriculture as known from the archeological record. They also match nicely with, though they do not prove, the agricultural theory. In contrast, if the conquest or rapid-migration theory was true, a genetic study would expect to find the genes more consistent throughout the Indo-European-speaking parts of Europe.

The analysis, which is reported in today's issue of the British journal Nature, was undertaken by Dr. Robert R. Sokal, Dr. Neal L. Oden and Chester Wilson of the State University of New York at Stony Brook.

The correlation established by the scientists suggests that genetic and cultural change moved in tandem from Turkey through the Balkans, proceeding northwestward as the new agricultural techniques enabled populations to grow and continually seek more land.

This hypothesis was first proposed some years ago by Dr. Luca L. Cavalli-Sforza and Dr. Robert J. Ammerman of Stanford University, who argued that agriculture was transmitted by the physical movement of people, not as an exchange of information.

Their theory that agriculture was diffused by people was recently taken up by Dr. Colin Renfrew, an archeologist at Cambridge University in England, as support for his iconoclastic theory that Indo-European languages were disseminated in Europe not by conquerors from what is today the Ukraine, as the dominant view among experts has held, but as a cultural adjunct to the spread of agriculture. New Investigation Planned

Dr. Sokal, an evolutionary biologist, said in an interview that the new findings "are consistent with Renfrew's theories." If they had turned out not to be, he said, "then Renfrew's hypothesis would collapse."

There is wide agreement among scientists that agriculture began in the Middle East about 10,000 years ago, probably in what is now Israel and Jordan. Archeological evidence has established the routes and timing of the spread through Europe, but not the manner of spreading.

One possible mode of spread, called cultural diffusion, would leave few genetic traces. In this mode, Dr. Sokal said, farmers "would tell their neighbors, 'I have a better way of making a living: You put seed in the ground, and you have more food than you have by running around and picking up berries.' "

According to the model devised by Dr. Ammerman and Dr. Cavalli-Sforza, on the other hand, it happened this way: Once people had domesticated food plants, food supplies increased dramatically and the human population zoomed. Soon the population outgrew the capacity of existing fields to supply its needs. Faced with the need to expand the food supply again, the farmers cleared more land, with sons and daughters moving onto their own plots upon coming of age. In this way, they believe, the agricultural frontier advanced. A Form of Gentrification

The hunter-gatherers who stood in the path of the advance "suffered a process of gentrification -- or even yuppification -- from the east," Dr. J. S. Jones of University College, London, wrote in a commentary in Nature.

"It is easy," he said, "to imagine the complaints of the archers (or stone-throwers) as the incomers with their newfangled ways, high-technology imports and braying voices moved in on what had been a rural idyll." But whatever clashes between old and new Europeans took place, he wrote, "they were not enough to act as barriers to mating."

The study by Dr. Sokal and his colleagues shows that modern Europeans "still reflect the migrations of ancient farmers who spread from the Middle East," Dr. Jones wrote.

But adherents of the conquest theory of language spread do not accept any setback from the new study. While agriculture did spread across some parts of Europe as a result of migration, "it is more complicated than that," said Dr. Marija Gimbutas, an archeologist at the University of California at Los Angeles, a leading exponent of the conventional view about the spread of Indo-European languages.

In some areas of Spain, France and eastern Europe, she said, the idea of farming was successfully transmitted even though there was no migration of farmers into the region.

As for the Renfrew hypothesis on the spread of language, she said, "it is not acceptable."

"It is counter to all that we know about the Indo-Europeans," she said, adding that she based this assessment on, among other things, archeological evidence and comparative linguistic studies.

Map: "Charting Frontiers Of Ancient Agriculture" Boundaries of the spread of agriculture in Europe, at intervals of several centuries. Lines approximate routes of farmers' migration. Numbers are years before present. (Source: Nature) (pg. A10)