IN A FAMOUS SPEECH at Oxford, Benjamin Disraeli addressed himself in 1864 to the unsettling evolutionary theories that had been recently advanced by Charles Darwin. "The question is this," Disraeli said. "Is man an ape or an angel? My lord, I am on the side of the angels. I repudiate with indignation and abhorrence the contrary view, which is, I believe, contrary to the conscience of mankind."

Disraeli was protesting as an alarmed conservative in an argument that was rightly seen as having ideological overtones. Those on the left, for their part, looked on Darwin as a hero - Karl Marx, for example, wished to dedicate Das Kapital to the reclusive scientist (who politely declined the honor). Of all scientific questions, none has been so intermingled with political attitudes as the debate over our animal origins.

In recent years, the debate has taken a fresh and surprising turn. It is the heirs of Disraeli who have looked to science for support, citing evidence which they say proves that man is innately aggressive, territorial and heirarchical. Wonderfully enough, the heirs of Marx today repudiate with abhorrence any unfalttering linkage between the human species and lower forms - man, they maintain, is unique, being solely the creature of his environment. Evolution, in effect, has brought about an achievement once ascribed to God: the appearance of a new species without any bestial taint.

There is no question where the authors of Origins stand. They are on the side of the angels. Richard Leakey is the son of a famous antropologist, the late Louis S. B. Leakey, and like his father he has found in East Africa fossilized bones which confirm that human ancestry is more ancient and complex than any had suspected. His collaborator is the science editor of the British weekly New Scientist and a biochemist.

As a scientific document, Origins is of obvious importance since it gives a connected, coherent account of all recent discoveries in Africa which have drastically extended the evolutionary timetable. We now know that more than two million years ago there were man-like creatures hunting in East Africa and most probably using tools. Our own direct line - Homo sapiens - is comparatively juvenile, not much more than 100,000 years old.

But as a layman who has followed the argument over man's animal nature, I was frankly more interested in the concluding chapters in which the authors staked out their own position in an increasingly bitter debate. Not only do Leakey and Lewin "emphatically reject" the view that man is incorrigibly belligerent but they affirm the contrary - that by instinct we are quite probably a "cooperative animal" with benign genes devoid of aggression, territoriality, sexism, and all other illiberal impulses. Evidence that early men were murderous predators ad cannibals is either denied, or smoothly explained away.

As debaters, however, Leakey and Lewin have picked their most vulnerable opponents: the popularizers Robert Ardey (African Genesis ) and Desmond Morris (The Naked Ape ), and Nobel Prize winner Konrad Lorenz (On Aggression ). Critics have attacked Andrey as a nonscientist, Morris as a sensationalist, and Lorenz because of his youthful involvement with the Nazis. Leakey and Lewis fail conspicuously to address the most considerable advocate of the contrary view - the Harvard biologist Edward O. Wilson, whose 1975 book, Sociobiology: The New Synthesis , caused un uproar among his Cambridge colleagues.

Wilson hypothesizes that as a species we carry with us a genetic bias rooted in our hunting ancestry, an ambiguous instinctive legacy with both positive and negative aspects. We have a nature both angelic and diabolic, and impulse to cooperate, and to destroy. Very cautiously, Wilson advanced this notion as a hypothesis, and was scrupulously cautious in drawing any political moral. In popular articles, he recognized the malleability of the human mind and urged that an awareness of our biological heritage did not imply a complacent acceptance of a conservative status quo.

In one of the more remarkable documents of modern science, Wilson was attacked as being virtually a cryptofascist in a better to the New York Review of Books (November 13, 1975) signed by Boston-area scholars and students who found his line of inquiry per se obnoxious. Stunned, Wilson quite properly protested "self-righteous vigilantism which not only produces falsehood but also injustly hurts individuals and . . . diminishes the spirit of free inquiry and discussion crucial to the health of the intellectual community."

Leaky and Lewin were all aware of this angry exchange, and indeed refer to it in an anodyne passage in their first chapter. But on the question of Wilson's freedom to pursue his inquiries they take no stand at all, and in their chapter on human nature they nowhere mention Sociobiology . The authors of Origins have every right to advance their own notions about human nature, but in their crucial concluding chapters they leave the Prince of Denmark out of Hamlet . Dare I suggest (as an interested spectator) that antropologists, too, are instinctively vulnerable to peer-group pressure?