It’s not necessarily a physiological change. Many Fathers believed that we were always naturally mortal, like all physical things, and that Original Grace preserved us from that mortality (St. Athanasius, and I personally find this view to be the best). Others believed that it was the Fruit of Life that would have preserved us (St. Augustine).
That being said, whatever the nature of our mortality, the Fall caused us to have a limited lifespan. That view is the same in both East and West.
Peace and God bless!
*God made humans in His own image and likeness and showered them with all kinds of bounties. Adam and Eve apparently lacked nothing and even enjoyed a father- child relationship with God; how then did they fall into sin? A careful reading of Genesis 3 reveals complete absence of this one thing — gratitude. For all the love and loving bounties received from God, had there been any sense of gratitude in Adam and Eve, then they would have got Grace and held fast to God’s command and would have rejected Satan’s apparently attractive offer. The saving Grace would have enabled seeing through Satan’s deception; but sadly that was not to be.
**Gratitude is not only the greatest of virtues, but the parent of all the others. ***(Marcus Tullius Cicero—106-43BC).
*They ungratefully failed to provide any place for God in their hearts, rendering themselves vulnerable and paving the way for Satan to inject pride. They became spiritually blind because of their pride and stooped so low to do these detestable deeds:
• Eve took Satan’s advice to become like God.
• Adam followed suit and later went on to literally blame God by responding: "The woman You put here with me ….”.
Had Eve truly been in awe of God she would have rather told Him plainly: “Lord I am in awe of You; teach me Your ways”. It is quite obvious, that she had become filled with pride and envy after listening to Satan and blindly rejected her maker’s warning to readily believe the deceiver’s lie. Adam’s behaviour is the height of pride; Eve blamed the serpent but Adam blamed God.
In the words of St. Augustine of Hippo: **They would not have fallen into pride and lack of wisdom, if Satan hadn’t sown into their senses “the root of evil”. ***(Contra Julianum, I, 9.42; PL 44, 670)
*Pride is an ugly variety of self-love and better described as self-worship. It is Satan’s DNA that produces in us an exaggerated illusion of self, making us appear great in our own eyes and worse than that, like authors of our own greatness. Pride is our enemy no.1 that puts us in constant conflict with God, neighbour and self.
We may deduce that disobedience is the original sin and the cause is pride which entered humans because of ingratitude. When we fail to respond with gratitude for all of God’s bounties, we are only inviting Satan to afflict us with pride which will render us spiritually blind and slaves to all kind of sinful natures.
Never suffer pride to reign in your mind or in your words, for from it all perdition took its beginning. (Tobit 4:14)
Remember the Israelites in the Desert of Sin, who were ungrateful for the innumerable bounties received — freedom from cruel slavery, water-manna-quails in the wilderness. It is because of their ingratitude that they had no abiding Grace to fulfil God’s Law and stumbled.
“For although they knew God, they neither glorified Him as God nor gave thanks to Him, but their thinking became futile and their foolish hearts were darkened.”* (Rom 1:21)
*This is the process of falling into sin – as we are interiorly defiled we suffer from sinful urge and are helpless against temptations despite desiring good and end up sinning against our own will.
**“For we know that the law is spiritual, but I am carnal, sold under sin. For what I am doing, I do not understand. For what I desire to do, that I do not practice; but what I hate, that I do. If, then, I do what I desire not to do, I agree with the law that it is good. But now, it is no longer I who do it, but sin that dwells in me. For I have the desire to do what is good, but I cannot carry it out.” ***(Rom 7:14-18)
*Just as it takes two hands to produce a clap it takes two forces to commit a sin – an external temptation pulls us while an internal sinful urge pushes us and we fall into the quagmire called sin. There is very little we can do about external snares and our sole defence therefore is in cleansing ourselves of all interior defilement.
“For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, slander. These are what make a man ‘unclean’.” *(Matt 15:19-20a)