Bar-Ilan University's Parashat Hashavua Study Center

Parashat Shemini 5766/ April 22, 2006

Lectures on the weekly Torah reading by the faculty of Bar-Ilan University in Ramat Gan, Israel. A project of the Faculty of Jewish Studies, Paul and Helene Shulman Basic Jewish Studies Center, and the Office of the Campus Rabbi. Published on the Internet under the sponsorship of Bar-Ilan University's International Center for Jewish Identity. Prepared for Internet Publication by the Computer Center Staff at Bar-Ilan University. Inquiries and comments to: Dr. Isaac Gottlieb, Department of Bible,



“These You May Eat”


Prof. Mordechai Kislev


Faculty of Life Sciences


The system of kashruth laws pertaining to animals and birds, given us at Mount Sinai, corresponds to the modern taxonomy, systematization, and nomenclature and is based on giving a name to every species, distinguishing them by signs that are characteristic of each species and particular to it.  In Sifra we read (Shemini, Ch. 2.2):

“These are the creatures that you may eat” (Lev. 11:2) – this indicates that Moses would hold the creature up and show it to the Israelites, saying to them:   This you may eat, and this you may not eat.  “These you may eat of all that live in water” (Lev. 11:9) – these you may eat and these you may not eat.   “The following you shall abominate among the birds” (Lev. 11:13) – these you shall abominate and these you shall not abominate.   “The following shall be unclean for you” (Lev. 11:29) – this is unclean and this is not unclean.

Kosher Signs

In other words, Moses showed all the Israelites the prototype of each of the animals, these permissible to eat and these unclean.  The same is done today in science text books, both in botanics and zoology.   In addition to specifying the signs of kashruth in animals, the Torah gives a detailed list of the names of the kosher animals and beasts:  “These are the animals that you may eat:  the ox, the sheep, and the goat; the deer, the gazelle, the roebuck, the wild goat, the ibex, the antelope, the mountain sheep” (Deut. 14:4-5).   It also lists all the unclean birds (Lev. 11:13-19; Deut. 14:12-18).

The Sages used systematic principles to organize related species into genera, and related genera into families.   This classification was based on several principles:  1) the prototype, 2) the signs and characteristics by which other species were included in the same group, 3) the number of species included in the group belonging to this prototype.   For example, “It has been taught:   Issi b. Judah says:   there are one hundred unclean birds in the East, and all are a sort of vulture” (Hullin 63b).That is to say, all one hundred birds belong to the same class.   Similarly, Maimonides stated with respect to cloven-hoofed animals, which in theory should all be kosher:   “There are no beasts and animals in the world that are permissible for eating save for the ten species listed in the Torah, … they and their related species” (Hilkhot Ma’akhalot Asurot 1.8).  But in fact, even this limited list is not what we eat today. Why are we not permitted to eat all the kosher animals, all the kosher birds, and all the rest of the kosher animals?

The Tradition of Kashruth

An answer is given by the Sages:   “Rabbi Isaac said:   clean birds are eaten according to the tradition; a hunter may be trusted to say:  this bird is clean, as relayed to me by my rabbi” (Hullin 63b).  If there is no tradition, then the case is doubtful:  “Rav Assi [in Babylonia] said:   there are eight cases of doubt,” whereupon he listed the names of eight kinds of fowl (Hullin 62b).   The doubts arose when the Jews were exiled and lost the information which Moses had shown the people in the wilderness, which birds were clean and which unclean.   If we had museum exhibits of all the animals and birds from that time, then we could use methods that exist in biology today in order to go back to the prototype and establish anew which species belong to it.

The tradition of associating every clean animal with one of ten categories of clean species also began to become less well-defined in the time of the Sages.  They no longer knew, for example, whether the Lebanese goat (or forest goat) belongs to the species of goats or ibexes.  This distinction is significant in determining whether the animal is kosher for offering on the altar.  The Sages held a comprehensive discussion of the characteristics that distinguish between a beast and an animal with respect to what they called jamus, or koi in Hebrew.  This animal, similar to a cow, was apparently brought to the country from India in the beginning of the time of the Sages, and was somewhat more wild than it is today.   The characteristics of the koi helped the Sages arrive at a thorough clarification of the characteristics of a beast that had become wild; it helped them establish the law regarding cross-breeds of a beast and an animal; it helped determine whether a semi-domesticated animal is considered beast or animal, and whether these intermediate creatures have a special status or belong to one or the other of the groups – either animals or beasts. 

Today we know of kosher cloven-hoofed creatures which do not fit clearly into the category of animals or beasts, such as the muflon sheep – an animal of the Mediterranean region that became wild, or the northern deer – a semi-domesticated animal, and others.   Is it obligatory to cover their blood when they are slaughtered, and may one eat their fat parts (helev)?   Perhaps the case of the jamus needs to be re-investigated, since in the intervening years it has become more domesticated.  Incidentally, it is difficult for us to return to the former tradition and call the jamus a koi, since this word has come to symbolize an animal that is in doubt, even though we know what the jamuskoi is today.

Nature of Language

One of the answers for the lacunae in the tradition also has to do with the nature of the language.  Hebrew, like most spoken languages, is a living, breathing language and the meaning of words and names expands and contracts, and sometimes a word even disappears or appears in new garb in different contexts, from one era to another.   The Sages noted the dynamic quality of the language and accordingly defined several relevant terms.   For example:   “Rabbi Yashia said:   wherever it is written tzippor [bird], it refers to a clean bird.  Rabbi Isaac said:  a clean bird may be denoted by the words off and tzippor, but unclean birds are denoted only by the word off (Sifre Deuteronomy, Re’eh, pisqa 100).  In other words, according to the Sages, off and tzippor are two terms with partial overlap in meaning when it comes to kashruth.   However, in time the distinction between tzippor, which is clean, and off, which is unclean, became blurred because various cases of doubt arose and controversies emerged regarding the definition of the determining characteristics, especially which ones are necessary in order to establish that a given bird is not a bird of prey and may be declared kosher.  In contrast to spoken languages, Latin, which is used today as the language for taxonomical descriptions in science, is known to be a fossilized language, with fixed syntax, with a fixed and consistent interpretation for each and every word, and with a lexicon that hardly expands.

The cases of doubt regarding birds are more serious than those regarding cloven-hoofed animals because the Torah did not establish signs for them.   Indeed, the Sages supplied some guidelines for determining which birds belong to the category of the eagle, which is unclean, and which belong to the category of the turtledoves and pigeons, which are fit for offering on the altar (Sifra, Shemini, Chapter 5.4-6; parallel variants:  Sifre Deuteronomy, Re’eh, pisqa 103; Hullin 60b-61a).



Turkeys and Buffalos

The turkey is a strange bird which we eat even though it has no clear and well-proven continuous tradition passed down from Mount Sinai.   Turkeys came to the Old World from the continent of America in 1542.   In this regard, we cite the following interesting remark: “Turkeys, called Indian hens, which came from India to the British Isles and from there to Franco-Germany, we eat everywhere without the slightest hesitation, even though they are very strange in comparison with our hens…   Hence ‘the son asks’ [adopting the style of the Haggadah to say, ‘one wonders’] whence the permission to eat them” (Nahal Eshkol, letter yod, 1868).

A similar problem arises with regard to the bison or buffalo, both American species. It seems the bison was considered kosher because the traits of the jamus were transferred to it. Perhaps in the future, due to such things as the mad cow disease, or for other good reasons, we shall have need of additional ‘strange birds’ such as these.