Genesis 1 describes God’s creation of all things, including the creation of every kind of animal. In Genesis 1:30 God says, “To every beast of the earth, to every bird of the air, and to everything that creeps on the earth, in which there is life, I have given every green herb for food.” God then declared the entire creation to be “very good.” Initially all animals were plant eaters.
Genesis 3 records the rebellion of humanity against God and the subsequent curse that fell on all the world. Many conservative Bible teachers believe animals began to eat meat as a result of the curse. The Bible does not say when certain animals began to be carnivorous. Passages like Isaiah 11 which speak of carnivores being restored to their original herbivorous condition and Romans 5 which says death came because man sinned. These passages lead to the conclusion that no animal ate the flesh of another until after man sinned. After man’s sin some animals became carnivorous. Whether the transition to carnivory was gradual or instant is unknown.
Those who study zoology (the science of animals) know the digestive system of a meat eater is quite different from that of a plant eater. To survive on a meat based diet the creature has to be able to eat and digest the meat. This requires unique features in the teeth, jaws, stomachs or intestines of carnivores. When God cursed the world did He renovate the innards of certain animals so they could begin to eat meat? The Bible does not say.
Most carnivores are able to live on a plant based diet. Relatively few obligate carnivores (meat eaters which can only survive on a predominantly meat based diet) exist. Cats, snakes and lizards are a few kinds of obligate carnivores. The majority of meat eating animals also have a diet containing a large percentage of plant based foods. Bears, dogs and apes are carnivores which also eat varying amounts of plant matter. A slow transition to carnivory can be imagined for those animals which are not obligate carnivores. Conditions in the cursed world may have required them to begin eating meat and the process of adaptation allowed those better able to process meat to survive and pass on their unique genetic features. Knowing man was going to sin God could have built into the genetic structure of many creatures the ability to process meat.
God could also have redesigned many animals at the same time He redesigned certain plants to bear thorns and thistles. A Divine re-plumbing of certain creatures to enable them to survive on meat is not an unreasonable assumption. The curse of Satan included a radical redesign of snake structure. The serpent was created with legs, but was cursed to crawl on its belly. For this to be a sustainable transformation something greater than mere amputation had to happen. The structures supporting the leg bones, muscles and tendons had to be removed and new structures put in place (assuming they were not already present) that allowed the snake’s muscles to push its scales backward, thus propelling the animal forward. This design change also required a change of the animals DNA or only the first generation of cursed snakes would have been legless. If God had not changed the serpent’s DNA its offspring would have been legged because the genetic code would have included the originally created instructions to form the the embryo according to the originally created, legged design. God’s curse of the serpent shows that the effects of the curse were much greater than might be thought. Thus, speculating Diving intervention to massively redesign other animals is not unreasonable.
Nothing can be said with certainty about how and when animals began to eat other animals. The Bible does not tell those details. The Bible does tell of a time when that process will be reversed. Isaiah 11 describes the conditions of the world after the return of Jesus to establish His kingdom on this earth. During that kingdom, “The cow and the bear will graze” and “the lion shall eat straw like the ox.” (Isaiah 11:7) When Jesus rules on the earth He will renovate the world to remove much of the curse. He will radically alter the behavior and internal physical structures of animals so even obligate carnivores will eat hay. Who is to say He did not perform similar alterations when He cursed the world because of sin?