God told Noah to take clean and unclean animals onto the ark. This was the first time animals were categorised this way in the scripture. In creation this category didn’t exist, but all animals were “good.” Some may claim that Moses wrote this category back into the text, from his own day’s perspective, so the animals from Noah’s perspective may have just been domesticated and non-domesticated. But I doubt Moses put words into God’s mouth.
It is clear that by the time of the Flood the categories of clean and unclean existed, though there is no explanation in scripture of when this began, the reason it began and who initiated it. The category is a ceremonial one, meaning that animals were used to sacrifice in worship. We see Noah making a burnt offering after the Flood, so the concept existed at that time. But there is no word from God on killing animals or eating them until after the Flood. I would assume then that this practice was adopted before the Flood, but that it was not commanded by God. This aligned with the prophets of the Old Testament, who repeatedly claimed that sacrifice of animals was not God’s will and that he didn’t command it (e.g. Psalm 40:6, Jeremiah 7:22, Hosea 6:6). This is similar to the temple David wanted to build, not commanded by God (Psalm 50:7-13, 2 Samuel 7:5-7). The scripture has many instances of God condescending to man’s ways (even to our liturgical language) and revealing himself through them and in time transforming what worship means from his view.
We don’t know when sacrifice began. I made a couple of comments on this back in chapter four. René Girard researched the anthropology of these early days and some of his reflections are very helpful. Sacrifice was invented to appease human wrath to limit wars and was likely brought into the worship of God from this human custom, as a way of appeasing. There is a concept in the human heart that substitutionary death makes a clean slate, for a new beginning. However, it doesn’t work because death just escalates. Jesus’ teaching in the Sermon on the Mount and in his parables overthrew all Israel’s assumptions about sacrifice and the temple made with hands, which was largely why Christ was rejected. Some see God bringing death in massive scale (like in the Flood) as an atonement. However, God’s judgment instead allows evil to run its own destructive course, to remove the wicked, to free the oppressed from their hand and to heal the earth.
We can see how powerful this concept of sacrifice is in the human psyche and our cultures. Today we may not offer blood sacrifices, but we “offer up others” by blaming them for our own choices. It is so easy to see how sacrifice developed naturally in our fallen cultures. It is our default reaction to deflect our own faults.
Noah was 600 years old at the time of the Flood and I have no reason to believe this wasn’t literal. Again, the scripture isn’t mere allegorical text. I have no solid idea about why people lived so long in those days. However, I think it does point to different conditions on earth in the pre-Flood and early post-Flood era. The scriptures say that God decreed to lower the age of humans after the Flood, and this took place gradually. It seems that divine decrees like this unfolded within the changed natural conditions. God said it was to stem the damage evil men could do, so lowering their age of mortality was an act of grace towards the oppressed. We might assume that animals initially lived longer also, and the animal-pairs Noah brought into the ark would later have repopulated the world and diversified very quickly. Early post-Flood conditions would have allowed intercontinental migration before some species were finally separated. It seems evident from the text that the deterioration of changed natural conditions on earth after the Flood lowered our general health and longevity. This again indicates the universality of the Flood.
I can’t even begin here to touch on the numerology and poetic significance of passages like Noah’s Flood. Seven pairs of clean animals speak of new creation. The rain falling for forty days speaks of the later Wilderness wanderings for forty years, in which the wicked likewise perished. There are some very valid commentaries available on the numerology and poetic structure of the Flood story, which highlight the extensive way in which this text speaks of the divine renewal and restoration of his world. Valid commentaries on this structure of the Noah story are very enlightening and encouraging to the church, called to the same mission of local and global renewal today.