The question of our human origins is a very old one, in any sense of that word. It is, as our myths and religions show, as old as human history. Its answering forces us to search far back to the distant evolutionary past. But whether within myth, religion or science, the debates provoked by this question have, more often than not, had two persistent features: the evidence on which the arguments turn has been scanty and the tenor of these arguments has been heated.

So far as biology is concerned, the questions have been greatly refined since the beginning of the 20th century. How, when and where did man branch off from the higher mammals? By what criteria, indeed, do we determine the appearance of man? These two questions are closely related, for the criteria chosen may affect the answers to how, when and where. Until recently, the only evidence available came from a single source -- fossil bones -- and was not only sparse and quite literally fragmentary, but also geographically widespread, ranging from Europe to China to Kenya and Ethiopia.

But recently, a new form of evidence has emerged that will undoubtably shed light on these vexed questions. It comes not from the dead past, but from the living present. For some time now, new techniques have enabled us to compare immune reactions and blood proteins between animal species. But now we can even compare the genetic material by mapping the genetic strands of DNA. Throughout evolutionary history, DNA has remained remarkably stable--it has had to. But even minor molecular changes can provoke major anatomical, or functional, differences. And it is concluded that the more similar their molecular maps of genetic material, the more closely two species are related.

Perhaps even more remarkable is the evidence that comes from the mitochondria, small organelles inside all cells which, according to present theory, were once free-living organisms, but which, eons ago, took up residence in the cells of other living organisms. When their host cell divides, so too do the mitochondria, but so insulated are they from all external influences that, as John Gribbin and Jeremy Cherfas write, "a study of the molecular evolution of mitochondrial DNA is not tainted by even the slightest suggestion of generation times or advanced development." Thus, studying the mitochondrial DNA of cells in species that are suspected of being closely related can reveal whether in fact they are.

This is all very delightful. Yet, if present techniques are accurate, we have something of an intellectual time bomb on our hands that threatens to explode all previous theories about the origins of man. For this evidence suggests not only that man and chimpanzees are 99 percent identical, but that the line to man separated off from that of the chimpanzees only 4 1/2 million years ago, rather than the 20 million years ago accepted by paleo-anthropologists.

"The Monkey Puzzle" has two main aims: first, to present evidence for this claim and discuss its implications. In this, the authors succeed very well. The book is well-researched and -documented, taking us through the dimensions of geology, paleo-anthropology, linguistics and even behavior. It is also well-written, though the authors tend to hop around a lot, and this jack-in-the-box effect is intensified because they lose no opportunity to underscore their second aim: to popularize the work of two scientists, Vincent Sarich and Allan Wilson, whose empirical evidence is producing the time bomb.

The book had an unusual origin. Though both authors have a strong scientific background, and both have been practicing scientists, they were, at the time, journalists on the staff of the British weekly magazine The New Scientist. It was Gribbin, the anthropologist, who was first intrigued and then amazed. For as he pursued the work of the two scientists, he came to believe that there was "dramatic and important evidence of the origins of man." Yet every time a paper from these two appeared, it apparently sank without a ripple of interest stirring the calm waters of paleo-anthropology. The scientists were suffering the worst fate of all: indifference.

To an extent, then, the two authors have cast themselves in the role of T.H. Huxley in relation to the popularization of Darwin's ideas. They make no bones about this--pardon the pun. It is highly appropriate. They have made a scientific value judgment on this work: "It is based on a solid base . . . Together we establish to our own satisfaction that it is the new picture of human evolution based on the pioneering work of Sarich and Wilson, that stands up to the closest scrutiny. It is the old picture, founded on a few petrified bones and a great deal of imagination, that turns out to be a fraud."

This is a daring and courageous thing to do, but perhaps unwise. Certainly the authors have enough experience for their value judgments not to be dismissed as the ignorant enthusiasms of two people who know nothing of this particular professional field. But whether in fact they will succeed in their aim only time will tell. For actually, the authors now are addressing not the general public so much as professional paleontologists--the scientific peers of the people whose work they are supporting. As I read the book, I wondered whether the two scientists in question will have any feelings of gratitude for the two who have taken up the cudgels on their behalf--popularization often brings not only accusations of self-aggrandizement, but the work is then often subjected to the fiercest of scrutiny.

So we must ask ourselves: Will this book do anything to encourage paleontologists to go back and review this new evidence and its implications? I'm not sure, and my uncertainty is partly due to this fact: I do not think the authors have helped their case by the use of such words as "fraud." This was a terribly unfortunate choice, bringing with it the implications of deliberate deceitfulness. The interpretations of the paleo-anthropologists may be mistaken or misconceived, or incomplete, but, the Piltdown forgery apart, there is no evidence whatsoever that the work of such people as Leakey, Johannsen and a long line of hard-working paleontologists was conducted with anything but honesty. They have done their best with the evidence. Nor is the case made more convincing by such remarks as "Finally, we reserve our heartfelt thanks for the mass of experts in paleo-anthropology. Their unswerving devotion to the established picture, their ridicule of the molecular evidence, and their sneering dismissal of our questions about the work of Sarich and Wilson, convinced us that there must be a story worth telling." I do not think that this is the way to win friends for one's cause, and when directed straight at the very people whom one wishes to convince, it seems to me to be a major tactical blunder.

This is a great pity, for the case they make in this most interesting book is indeed a compelling one. I would add only one caveat. All scientific theories are mutable--not only those of paleo-anthropologists. The present evidence, which I do indeed find convincing, gives the branching-off point of man from the higher apes at 4 1/2 million years. But this evidence and this interpretation--just as all evidence and all interpretation in science--is a daughter of time and is in no way immutable.