UndercoverWerewolf drew this for me, and we got into a discussion about the evolution of werewolves and cave-werewolves. So I whipped up this treatise on their evolution and natural history as a value-added bonus to accompany her detailed scientific diagram, which she graciously allowed me to post here. Go and favorite and comment on her diagram before reading the academic study which accompanies it!

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Lupine (or "werewolf")
Homo sapiens lupus

Their ancestors were the first anatomically modern humans to migrate to Europe, but given the cooler climate, the vast number of predators, and their small numbers, competition was fierce. The native population of homo neanderthalensis, the neanderthals, was fiercely competitive with the newcomers; isolated, they were under intense pressure. With a small population to begin with, and further migrations from the south blocked by the harsh geology of the Pleistocene ice age, the lupines' ancestral humans were highly susceptible to spontaneous mutation due to low genetic diversity (a phenomenon often called the "founder effect").

With the neanderthals filling the same hunter-gatherer niche as the anatomically modern humans, and lacking the numbers to push their competitors out, the humans evolved to take advantage of other food sources and hunting strategies. Nails evolved into claws, teeth evolved into fangs suitable for rending and tearing and crushing jugulars, and the body hair covering long since shed by their savannah ancestors reemerged. These features, which emerged at puberty, allowed the proto-lupines to use the feeding strategies of the other apex predators in Europe, namely wolves and lions. The adaptation worked in much the same way that caterpillars and butterflies or tadpoles and frogs increase feeding options with different diets and body forms for juveniles and adults.

Over time, convergent evolution let to the lupine adult body form taking on traits of wolves, even though the DNA remained free of any canine genes. Just like the Tasmanian Tiger was molded by natural selection and environmental pressures into a form almost indistinguishable from a dog, the same pressures resulted in the lupines becoming more wolflike as they evolved to compete for the same niche as actual wolves. But there was an evolutionary pressure in the other direction as well; it was difficult for the adult lupines to function without the benefits of more flexible fingers and other human traits which were lost at puberty. They did, after all, come from a lineage that had evolved to the modern human body form.

As a result, an unprecedented evolutionary compromise arose: like the caterpillar/butterfly and the tadpole/frog, the lupines had two different body plans and diets. But unlike them--or any other species on the planet--they had both body plans and diets simultaneously, and were able to shift between them. The ability arose at puberty, and throughout the Pleistocene epoch the lupines spent roughly 60% of their time in one form and 40% of their time in the other (60/40 human/"wolf" for males, 40/60 human/"wolf" for females). This allowed the benefits of an extraordinarily flexible diet and hunting strategy while retaining all the toolmaking, hearth-tending, and shelter-building advantages of the human form.

But as the climate changed and more anatomically modern humans began entering Europe and displacing the remaining neanderthals, the lupines once more found themselves maladapted. Ordinary humans were now a species apart (though interbreeding was possible) and would kill any lupines in their "wolf" form on sight as a predator. The lupine population crashed, and the few survivors had much shorter and more irregular periods in "wolf" form. As homo sapiens prevailed over the continent and the neanderthals became extinct, the lupines were forced to the periphery and eventually had to adopt the culture and appearance of their neighbors in order to survive. To this day, the culture of homo sapiens lupus emphasizes concealment and assimilation into modern human culture while retaining a sense of identity and retaining the ancestral ability to assume the form of a "wolf."

The change is hormonal and therefore unavoidable and unpredictable. Stories of the full moon and a "curse" spread by bites are of course nonsense and superstition, but all lupines have times when their hormones force them to change forms and ancient practices to control them, largely with societal pressure, organized periods of hunting, and herbs. Stress plays and important role as well, which is why most surviving lupines practice farming or husbandry far from major population centers. The few that do live in cities take extraordinary precautions, though the enduring tales of "werewolves" show that these are not always sufficient.

A real danger is for young lupines to become orphaned or lost and raised by modern humans; they will still undergo their first metamorphosis during puberty (typically anywhere from age 13 to age 18) and will still change forms occasionally after that. But without the underground lupine culture to prepare them for this, the results are often tragic. Many prominent disappearances over the ages can be traced back to lupine ancestry; approximately 50% of human-lupine hybrids will inherit the transformation ability, though it usually disappears quickly with further generations of breeding.

Thanks to mythology, cultural mores, and the like, open discussion of lupines in scientific and government circles is taboo. Estimates as to their number and range vary, but there are probably less than 100,000 full-blooded lupines worldwide, and possibly less than 10,000--enough to classify them as an endangered or critically endangered species if not for the cultural prohibition against acknowledging them.