I have recently been more interested in a “theology of the Garden” so to speak. I live in an area that has a prominent religion that has some interesting concepts. I don’t want to hi-jack your thread into a discussion of them, but they are who piqued my interest in a real Garden. Until learning of their strange beliefs, I was fine with just saying the Garden was a story, a fairy tale, and ignoring it. But their beliefs are tied to exactly what you are asking. Their answers get people to join their religion. They are very, very moral people, but their theology is just full of holes.
So to your question, they believe that while in the Garden, Adam and Eve* couldn’t* procreate. They believe that the Fall was a *necessary *evil in order to "be fruitful and multiply. They believe that as long as death wasn’t in the world, then new life couldn’t be either. (Overpopulation myth maybe?) Read that again. They believe that *disobedience *was *necessary *to follow the command of God. Basically, they were going completely against Catholic theology that one cannot do evil so that good may come.
So then I had to start looking at the situation as “What if the Garden was real?” in order to have counter-arguments to that situation. So without going into my further musings on what the Garden might have been like I will answer your question similarly to how I answer it for people in this religious group.
The Garden is the perfect model of existence. Yes, animals would reproduce because that is their nature. Then, like now, they follow their instincts, but they do not make a choice. Whether Adam and Eve were “put here” as adults or they evolved as the first conscious humans doesn’t really matter. The point is there came a time when they could make the *choice *to become one flesh. It was not instinct alone. Marriage is a decision. Lots of animals are monogamous. So what makes humans unique? Two words. Free will.
We say, “Bad dog!” when he chews through a pillow. But do we say, “Sinful dog!” No. He is just being a dog. He didn’t say, “Look, they are ignoring me and I am really upset about it. I am going to do this because I know it will hurt them.” No. He is just being a dog. They are instinctual and conditioned. But they do not have free will. They don’t actually have an ability to love. They have an instinct to respond in a way that we find to be affectionate. They are *conditioned *to respond in a way that we identify as “love.”
The first sin was a sin of disobedience. If we were just animals, God would have said, “Bad humans! Drop the apple!” But he didn’t. He said our disobedience was sinful. We *can *know better.
So to make a long story short (oops too late.) It wasn’t that Adam and Eve *couldn’t *reproduce. It was that they hadn’t yet. Otherwise there would not have been the command to be fruitful and multiply. Maybe they were too young or whatever if you want to look at it as a literal Garden, but the point was, they had to make the *choice *to be fruitful and multiply. They had to make the *choice *of generosity. Animals don’t make that choice. They just do what they do by the nature that God designed.