There's an interesting article on organ regeneration at EurekAlert that has fascinating philosophical implications. Here's an excerpt:
When a portion of a zebrafish's heart is removed, the dynamic interplay between a mass of stem cells that forms in the wound and the protective cell layer that covers the wound spurs the regeneration of functional new heart tissue, Duke University Medical Center scientists have found.
The scientists further discovered that key growth factors facilitate the interaction between the cell mass and the protective covering, encouraging the formation of new heart muscle.
Many cell biologists believe the ability to regenerate damaged heart tissue may be present in all vertebrate species, but that for unknown reasons, mammals have "turned off" this ability over the course of evolution. Zebrafish could provide a model to help researchers find the key to unlocking this dormant regenerative capacity in mammals, and such an advance could lead to potential treatments for human hearts damaged by disease, the Duke scientists said.
"If you look in nature, there are many examples of different types of organisms, such as axolotls, newts and zebrafish, that have an elevated ability to regenerate lost or damaged tissue," said Kenneth Poss, Ph.D., senior researcher for the team, which published the findings on Nov. 3, 2006, in the journal Cell. First authors of the paper were Alexandra Lepilina, M.D., and Ashley Coon.
"Interestingly, some species have the ability to regenerate appendages, while even fairly closely related species do not," Poss added. "This leads us to believe that during the course of evolution, regeneration is something that has been lost by some species, rather than an ability that has been gained by other species. The key is to find a way to 'turn on' this regenerative ability."
This is strange given the Darwinian paradigm. One would think that regeneration would have tremendous adaptive value to an organism and thus be strongly conserved. Why would such a capacity, once developed, get turned off?
It's also strange that it's very hard to turn on a capacity that is believed to be already present and latent within us, but the development of that capacity by the blind, undirected forces of evolution isn't considered at all extraordinary. If turning the capacity on is proving devilishly difficult how much more astonishing is the erection of the entire biochemical apparatus from scratch?
Finally, does the latent power of regeneration in mammals suggest that our ancient ancestors were at least in some ways more highly evolved than we are today? In other words, the evidence from regeneration suggests that rather than evolving from more primitive states to more advanced, we may have started out as more highly advanced and subsequently devolved from that initial state over time to a state of lower complexity. This evidence, at least, seems to suggest that living things are not as complex as they originally were, which is precisely the opposite of what Darwinian evolution maintains.
Now wouldn't more evidence for that hypothesis just throw the Darwinians into a tizzy?