Summary

The recurring key to regeneration seems to be that the developmental molecular machinery needs to be reactivated for regeneration to take place.

Many of the developmental molecules involved in regeneration are shared by animals as diverse as a hydra and a human. These molecules probably arose very early in evolution and did not change greatly.

It is interesting, but not too surprising, that even though there is great diversity in the ability to regenerate among different animals, the same molecules crop up over and over again, suggesting that the underlying molecular machinery is the same.

If the molecules of regeneration are so similar, why is the ability to regenerate so different between, for example, planaria and humans? This is an important question that researchers are trying to answer.

The similarity of the underlying mechanisms may allow us to learn medically relevant knowledge from simpler models.