Genesis 7:1 - 24
ESV - 1 Then the Lord said to Noah, "Go into the ark, you and all your household, for I have seen that you are righteous before me in this generation. 2 Take with you seven pairs of all clean animals, the male and his mate, and a pair of the animals that are not clean, the male and his mate.
Leviticus chapter 11 and Deuteronomy chapter 14 are key passages in outlining to the people of God which animals are permitted for food and which are not. A good way to interpret the Leviticus and Deuteronomy texts is to affirm that God created certain animals intrinsically “tamei” (unclean) and others intrinsically “tahor” (clean). This is not a defect in the animals themselves. This speaks of the superior intellect of a Creator that is in control over the ecosystem that he created. Some animals ingest helpful items and consequently produce toxins. Other creatures ingest toxins and consequently produce helpful waste in its place. Obviously I am describing biological symbiosis. Even if we argue against this logic, based on our lack of understanding, we cannot argue that God told Noach (Noah) to gather two of each kind of every unclean animal into the ark while also commanding him to collect seven couples of the clean animals: "1. ADONAI said to Noach, "Come into the ark, you and all your household; for I have seen that you alone in this generation are righteous before me. 2. Of every clean animal you are to take seven couples, and of the animals that are not clean, one couple; 3. also of the birds in the air take seven couples - in order to preserve their species throughout the earth (Genesis 7:1-3). Clean and unclean, then, do not seem to be limited to the Torah (Law) that Moshe (Moses) handed down. After all Noach lived thousands of years prior to any written Torah that we know of. God knew which animals were clean and which were unclean because he made them that way and he obviously endowed Noach with a way to tell, and all of this was long before he told Moshe to pen Leviticus and Deuteronomy.