The Bible specifically teaches that in the original "very good" (Genesis 1:31) Earth, all of the animals were to be plant eaters (v.30). It wasn't until after Adam sinned and the curse of death was pronounced on all creation (Genesis 3:14-19) that things began to die. How is it then, that so many animals seem fully designed to be meat-eaters? Some produce deadly poisons, others have armored plates as elaborate defense mechanisms. If animals were created to live in harmony, what was the purpose?
Unfortunately, God doesn't give us all the details. All we can do is begin with what we do know and make reasonable inferences. I can think of several possibilities which are Biblically acceptable, but it may be that a combination of these or some other best reflects the truth.
The first is that God, in His foreknowledge, knew that soon things would change, and so He created animals with features they would need in the new economy. Or it may be that these features had some other more benign function originally.
The second option is that a great deal more potential for variation was placed in the original genome. At first the animals were designed to live a herbivores lifestyle, but adopted new habits in the more harsh world following the curse. Today, following many generations of variation, adaptation, and selection, animal groups have speciated so much that extensive variation is impossible.
Or it may be that something more sinister was involved. Remember the overall scenario. Lucifer, the highest in God's angelic hierarchy, had been defeated and cast out of heaven. His arrogant pride had been wounded. In his rage he may have set out to ruin God's beautiful creation, first recruiting Adam and Eve to follow him, and then after the curse proceeded to so distort "the image of God" in man that the perfect "seed of the woman" could not follow. Is it possible that this highly intelligent being performed breeding experiments, or genetic engineering on both mankind (Genesis 6:2-4 perhaps) and the animals, in his attempt to mock the true Creator/God and usurp His authority? Perhaps even the ancient legends of composite mixtures of beasts and half men/half beast have some basis in fact.
My preferred speculation follows. The Genesis 3 account of the curse speaks of the great changes which would follow, and each one requires a genetic change. Plants would grow "thorns and thistles" (v.18). The serpent would slither on his "belly" (v.14), cursed along with the rest of the animals. Eve's body style would be changed, making childbirth a laborious experience (v.16). Each of these changes requires a DNA alteration, and now instead of being "very good," "the whole creation groaneth and travaileth in pain" (Romans 8:22) due to the presence of sin and its penalty - death.
I suspect that in His infinite wisdom, God completely changed creation, with all things dying and some animals quite vicious, from then on giving eloquent testimony to the awful consequences of sin. From then on, whenever Adam saw one of the animals kill another, he would have experienced remorse for what he had brought on creation.
And today, as we see the same thing, it should drive us back to our Creator's gracious provision for sin, and to expectantly look forward to the time when there "shall be no more death" (Revelation 21:4).
* Dr. John Morris is President of ICR.