Why did Abel "keep the flock" when the family was vegetarian?
God created Adam and Eve on the first Friday, and they were told to eat "of every tree whose fruit yields seed, to you it shall be for food" (Genesis 1:29-30). So they were vegetarians and ate the fruits from every tree except the tree of the knowledge of good and evil (Genesis 2:16-17). We can reasonably assume God had not given them permission to eat meat because He gave that permission 1,657 years later to Noah when he disembarked from the ark following the Flood. God said, "Every moving thing that lives shall be food for you … all things, even as the green herb … but you shall not eat the flesh with its life, that is, its blood" (Genesis 9:3-4).
The Genesis account is very brief but the details are only revealed as we progress through the rest of Scripture. Eve conceived and bore Cain, then bore again and conceived Abel (Genesis 4:1-2). Scripture does not provide dates or Eve's age for these events and we tend to collapse the time frame in our thinking to accommodate the brevity of the narrative. How old did Adam appear to be at his creation? Rather than in mid-life as seen in some imaginative medieval paintings, how about 12 years – the same as the last Adam when he began His ministry (Luke 2:42)? How 1ong were they in the Garden before the Fall? One day? One week? She was not pregnant as that would have involved an innocent party. However, we are given some clues. The life-span of Adam and each of the pre-flood patriarchs given in Genesis chapter 5 is almost a thousand years. Our life-span today is less than one tenth of that time. Reasonably, people matured much more slowly in that pre-Flood world. There is even a suggestion of this in Genesis 3:16 when God said to Eve: "I will multiply your [potential for] conception [Hebrew word HEBRON]" (i.e., will increase the frequency of ovulation meaning that in the beginning it was a lot less frequent than once every 28 days as it is today; just possibly it was once every seven years while the child-bearing years began at seventy.
The Book of Jubilees or The Little Genesis, written about 200 BC, gives us a little insight and cause for suggesting these figures although it is emphasized that the book is not inspired. Adam lived for 930 years (Genesis 5:5) and we can reasonably assume Eve lived to about the same age. According to The Little Genesis, they were in the Garden for 7 years before the Fall. Cain appears to have been Eve's first child and she was at that time 70. Seven years later she gave birth to Abel and so on every seven years having in total 33 sons and 23 daughters. The number of sons and daughters are given as a footnote to chapter 2 of The Works of Josephus. Her period of fecundity was therefore 392 years or proportional to what it is today. Again, from The Little Genesis, Cain was 35 when he murdered Abel at 28.
Abel was a keeper of the flock – some Bibles say sheep, but it could equally as well be goats since they are related. Recall that this murder took place after the Fall when they were required to wear clothes (Genesis 3:20), and sheep or goat hair was used to make clothes. That was one reason for "keeping the flock." The second reason is that goat's milk or even sheep's milk was always the drink of pastoral peoples; moreover, milk tends to go sour quickly in hot climates but when converted to cheese it becomes a staple food for desert travelers. The third reason for "keeping the flock" was for the atonement sacrifice. The reasons for this and the instructions do not appear until Leviticus chapters 16 and 17. However, the atonement sacrifice was undoubtedly introduced by God to Adam just after the Fall. There is a brief reference to the atonement sacrifice when Noah received from God seven of each clean animal and seven of each clean bird as part of the cargo for the ark (Genesis 7:2). Since only males were used for the sacrifice, there would have been six males and one female of the animals and similarly of the birds. The clean animals included the sheep or goats and, upon landing, Noah built an altar and sacrificed five males of the clean animals and five males of the clean birds (Genesis 8:20). Noah clearly knew what he was doing and why he was doing it. These, then, are the reasons Abel was a keeper of the flock.