Genesis 1:29

Every herb bearing seed... every tree. — Of the three classes of plants enumerated in Genesis 1:11, the two most perfect kinds are given to man for his food; while in Genesis 1:30 the birds and animals have not merely the cryptogamous plants of the first class, but every green herb granted to them for their sustenance. We are not to suppose that they did not eat seeds and fruits, but that the fundamental supply for the maintenance of animal life was the blade and leaf, and that of human life the perfected seed and ripe fruit. Man is thus from the first pointed out as of a higher organisation than the animal; and the fact that his food is such as requires preparation and cooking has been the basis, not merely of most of the refinements of life, but even of the close union of the family. For what would become of it without the common meal?

But undoubtedly the food originally assigned to man was vegetable; nor was express leave given to eat flesh until after the flood. Nevertheless the dominion given to man, in Genesis 1:28, over fish, bird, and animal, made it lawful for him to use them for his food; and the skins with which Adam and Eve were clothed on their expulsion from Paradise prove that animals had been already killed. After the fall, Abel’s sacrifice of the firstlings of his flock, and of the fat thereof, leads irresistibly to the conclusion that the flesh was eaten by the offerer and his family. In ancient times this was the rule. Flesh was not the staple of man’s diet, but the eating of it was a religious ceremony, at which certain portions were offered to God and burnt on His altar, and the rest consumed by man as the Deity’s guests. So we may well believe that until the flood the descendants of Seth partook of flesh rarely, and only at a sacrifice, but that after the flood a more free use of it was permitted.