Superman & Lois: How did a human heart make Superman mortal?

A plausible explanation could lie in the idea that Superman’s powers are intrinsically tied to his biology as a Kryptonian, which includes his unique cellular structure and energy absorption mechanisms.

Here’s how it could work:

1. Energy Absorption Dependency: Superman’s cells are designed to absorb and metabolize solar radiation from Earth’s yellow sun, which powers his superhuman abilities. A human heart, however, would lack the Kryptonian cellular structure required to facilitate this energy absorption. Over time, if the human heart becomes the central organ regulating blood flow and energy distribution, it might limit the effectiveness of Superman’s cells in storing and utilizing solar energy.
2. Immune Response and Adaptation: Superman’s Kryptonian biology might gradually adapt to the human heart. His immune system could adjust to avoid rejecting the transplant, which might inadvertently cause his body to shift toward functioning more like a human’s. This could include a reduction in the hyper-efficient energy metabolism that fuels his powers.
3. Systemic Dependency: The human heart could act as a bottleneck for oxygen and nutrient delivery. Kryptonian muscles, which are optimized for superhuman strength, may require significantly more resources than a human heart can provide. Over time, Superman’s physiology might downregulate its “super” capabilities to match the heart’s limited output.
4. Central Role of the…