New evidence, an old question: How ancient are America's Indians?

A decade ago, conventional archaeology recognized no human traces in North America much older than 12,000 years. Now there is evidence that goes back four times as far. Some of it may even extend 100,000 years beyond that.

This has vindicated the faith of such radicals as the late Louis S.B. Leakey, who believed paleoindians to be far older than had been imagined. However, such conclusions depend critically on interpretation of bits of stone or bone as having been worked into tools by human hands. Such findings tend to be controversial. The antiquity of the sites is not in question.But are the stone or bone fragments found there really human artifacts?

As Dennis Stanford of the Smithsonian Institution, Robson Bonnichsen of the University of Maine, and Richard E. Morlan of the National Museum of Man in Ottawa pointed out recently in the journal science, some of the best sites have produced no direct evidence of a stone tool tradition.But they have yielded bone fragments that suggest a well-developed technology for making bone tools. The problem has been to convince skeptics that humans, not some other animal, cracked the bones.

One way to do this is to try to recover the ancient toolmaking skill and demonstrate that the bone fragments found can be identified as tools and most likely were produced by human agency. This is what the three archaeologists have done, using the bones of a female African elephant name Ginsberg which died at Boston's Franklin Park Zoo a few years ago.

Extensive experiments in bone toolmaking were carried out at the National Zoological Park Conservation Research Center at Front Royal, Va., in March 1978 and at the Ottawa museum in March 1979. The three scientists now report that "not only are bone flakes simple to produce, but they are also effective butchering tools."

hey found that the fresh bones fractured in distinctive patterns unlike the fracturing of old, well-weathered bone. These are the same patterns exhibited by the ancient bone chips. This is important for it strongly indicates that the bone flakes found at such important sites as Old Crow Flats in the Canadian Yukon Territory are indeed human artifacts.

These experiments follow up earlier work by Binnichsen and others in which cattle bones were used. However, the elephant bones are closer to the kind of material, such as mammoth bones, with which the paleoindians would have worked. As binnichsen, Stanford, and Morlan note, such bone tools could be made rapidly at a butchering site, enhancing the mobility of these early hunters.

Commenting in this is his recent book "American Genesis," Jeffrey goodman, director of Archaeological Research Associates Inc. of Tucson, Ariz., says: "The Old Crow people lived in and adapted to one of the most challenging environments. Considering the great technical skill and knowlegedge required to meet this challenge, it would be a great mis take to call these very early Indians "primitive."