**9. Summary**

In the complex interplay between organization of the living matter, natural selection and adaptation, mammals have evolved with limited or no re-generative capabilities of the heart after birth.

The reasons for this apparent flaw is far from being understood, however, they are closely related to the concept of organization and allocation of resources in a hierarchically struc‐ tured multi-cellular organism with an evolved system of transport and communication, such as the circulation of blood. In humans this flaw may not have been a problem for thou‐ sands of years until, in the twentieth century, the increase in life expectancy has given rise to diseases generally less frequent in the first three or four decades of life. Therefore, the signif‐ icant increase in morbidity and mortality related to cardiovascular disease, seen mainly in Western countries in the last years, has brought to the foreground the problem of cardiac damage and of its repair. In order to develop new therapies for cardiovascular damage aimed at reawakening and, possibly, expanding the limited re-generative capabilities of the heart is necessary to reconsider the basic concept on adaptation and functional reserve allo‐ cation in complex organisms.

In this regard, the demonstration of a temporary re-generative window in the post-natal heart of higher vertebrates may provide an opportunity to investigate when, why and how the re-generative capabilities are self-limited in some organs by the genetic program.

Therefore in this chapter we will consider this window that appears to be the last post-natal re-generative "chance" of the heart and try to place it in the general context of the adaptation by assuming that its meaning is, at least in part, related to the cardiovascular adjustment in a gravitational environment.
