HERE'S AYLA again, the Wonder Woman of the Pleistocene, back with all new adventures in Jean M. Auel's The Mammoth Hunters,

"the third installment (of a proposed six) devoted to the saga of "Earth's Children." Like The Clan of the Cave Bear and The Valley of Horses, this new novel, already a best seller, deals with our Ukrainian forebears of 25,000 or so years ago, when the ice age was in a remission of several millennia.

Here we have the period of brief overlap of coexistence and conflict between Neanderthal and Cro-Magnon man and, in Auel's ice-age, they can and do interbreed, although the Neanderthals are widely regarded as little more than animals, called "flatheads," and by and large the offspring considered abominations. Only Ayla, by the way, has a pretty good idea of how babies are made. Both the Clan (Neanderthal) people and the "Others" (the Cro-Magnon of which Ayla is one) believe it is a man's intangible "spirit" that enters the woman and creates the babies.

But Ayla, raised with the Clan, as we discovered in the first book, The Clan of the Cave Bear, and forced out on her own in The Valley of Horses, having to abandon her half- Clan son, is remarkably advanced for her day.

In addition to figuring out the birds and the bees, she gives her friends, in this book the Mamutoi, such helpful healing accoutrements as buffered aspirin (willow bark and yarrow) and digitalis. She also invents the sewing needle.

We know from The Valley of Horses that she has a way with animals. She's already tamed and ridden not one, but two horses and raised a formidable lion from a cub Androcles.

In The Mammoth Hunters Ayla takes this one step forward and brings the puppy into the lives of men.

Her wolf, named Wolf, chews leather shoes (just like some Labradors we all know and love). But Wolf is eminently useful and as advanced for his day as Ayla is for hers -- no silly fetching of frisbee for this prototype pet. No indeed, he understands the signs of a half-Clan child -- Auel's Neanderthals don't speak, but have developed body language to a sophisticated degree -- and, when so ordered, Wolf takes off across the icy steppes to find Ayla and signal her by prearranged training that she is needed back at the camp. And when one or another of Ayla's swains isn't sharing her bed, Wolf is.

Oh yes, Ayla's sex life.

Very active. Very active indeed, and very clinical. Her sexual encounters are described in the most minute, painstaking detail. For someone as wise as Ayla, she is positively wimpy when it comes to her boyfriends.

The classic ugly duckling during her Clan childhood -- and she's only about 16 or so in this book -- Ayla grew up as the unwilling receptacle for a Clan-brother's repeated attempts to exert his (sexual) power over her, although she was clearly faster and smarter than he. Somebody must have told Auel to get a little spice into Ayla's life, so now Ayla stirs genuine passion in every Cro-Magnon male who catches sight of her, and once she is awakened (in the previous book) to the joys of sex, or as Auel calls them "the Pleasures," we are made privy -- on almost every other page -- to Ayla's erotic exploits. Sometimes these are with her own true love Jondalar and sometimes with her new playmate Ranec.

Nevertheless, these adventures are a bit too self-conscious to be erotic and are somehow more intrusive than titillating.

AUEL is a prodigious researcher, and the book is strongest when she is describing the lives and the believably complex tribal and cultural mores of these ancient peoples. When she first became involved with the late Pleistocene she spent some time in a survival camp in the American northwest where she learned how to knap flints and eat biscuit root. She often carried samples around with her as she flogged that first book. By the time she got to The Mammoth Hunters she had traipsed through Ukrainian, Czechoslovakian, French, and Austrian prehistoric sites, visited modern museums of anthropology and paleontology, and consulted with experts on such things as early carvings of mother-goddess figures and the domestication of the wolf.

Jondalar's spears and flints are as authentic as Ranec's skilled carvings. And who is to say that the racial memories of Auel's Neanderthals were not what gave the forward thrust to their heads? Moreover, after a slow start, and despite the interludes of Ayla's Pleasures, the ongoing narrative of this book, as with the others, is lively and interesting, enhanced greatly by the vividly colored backdrop of early humanity.