Scientists Discover New Clues To Regeneration: How Flatworms Regrow Heads

An anonymous reader writes "Regeneration is one of the most useful skills that an organism can possess. Lizards can regrow their tails and starfish can regrow and entire part of themselves if they're cut to pieces. Yet scientists have long wondered why some creatures possess this ability while others don't. That's why they decided to examine the process of regeneration, looking at the masters of this particular adaptation: flatworms."

which is the "real" starfish

[callmebill]

Suppose you could cut a starfish into 5 segments, and they could each regenerate the missing 4. Which is the real one? How much of a body can one replace before it's a different body?

Evolution & scarring

[Valdrax]

Actually, it's more like the skill was lost in favor of one that was considered far more useful for survival -- inflammation and scarring.

Scarring stops bleeding and infection far faster than regeneration can and is a vital advantage in quick and dirty wound recovery. Scarring comes about because of a mutation that allows collagen to cross-link and build quicker scaffolding to seal the wound, but it comes at the cost of not being able to regrow tissues in the now "paved over" area. In the wild, this gave our distant mammalian ancestors the valuable ability to just kind of "write-off" the area and get up and going as fast as possible and avoid being preyed upon in a moment of weakness.

We may dismiss scarring today as ugly and wasteful of an opportunity to be made whole again, but without it, we probably wouldn't exist today.