According to the Talmud, some animals are so innately dangerous that they are always considered to have been forewarned, meaning they are publicly known to cause damage. This classification matters, because if a person owns one of these and they do cause damage, their owner is liable for the full price of what they broke, and additional penalties if they kill a person. And the Talmud lists some of them:
The wolf, the lion, the bear, the leopard, the bardelas, and the snake.
Now we might ask why someone would choose to own such a dangerous animal to begin with, but the existence of zoos, exotic animal ranches and the Netflix hit docuseries Tiger King all remind us that lots of people do in fact claim ownership over these kinds of animals.
But the Talmud on today’s daf asks a different question: What is a bardelas?
Rav Yehuda said: It is a nafreza. What is a nafreza? Rav Yosef said: It is an appa.
A bardelas is a nafreza is an appa. Well that clears things up. But before we unpack what all these terms mean, the Talmud offers another complication — an alternative tradition in which Rav Yosef states that:
A hyena (tzavoa) is an appa.
Whatever these various terms mean, how could Rav Yosef say that an appa is both a bardelas and a tzavoa?
It is not difficult: A tzavoa is a male hyena, and a bardelas is a female hyena.
The Gemara reads the word appa as a term for all hyenas, and the terms tzavoa and bardelas as sex-specific (for an English example, think of deer, which are either bucks or does). And what is their proof that there are different terms for male and female hyenas? An earlier rabbinic tradition:
After seven years the male hyena becomes a female (hyena), and after another seven years becomes a bat. After seven years the bat becomes a vampire bat. After ten years the vampire bat becomes a nettle. After seven years the nettle becomes a thorn. The thorn after seven years becomes a demon.
In this fascinating tradition, found only in Babylonian rabbinic sources, the rabbis describe an animal metamorphosing over 55 years from a male hyena to a female hyena then to other animals and plants until finally becoming a demon — evolving along the way into many different kinds of environmental dangers. This tradition effectively clears up the confusion over the bardelas, pointing out that male and female hyenas are referred to with different terms, while insisting that both are profoundly dangerous. But it also raises a new set of questions, especially about how the rabbis draw boundaries between one kind of animal and another, and between animals, the plant world and the invisible world of demons. And, pushing things further, this tradition includes human beings in that interconnected world:
A person’s spine, seven years after his death, metamorphoses into a snake. And this matter applies where he did not bow during the blessing of thanksgiving (in the Amidah).
Leaving aside the question of whether this kind of evolution is scientifically possible, this discussion does two things: It demarcates certain animals as always and innately dangerous, and it undoes the strict boundaries between the different parts of creation. Sources of danger, perhaps like animals themselves, are always evolving.
Read all of Bava Kamma 16 on Sefaria.