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I don't understand why we're not allowed to regrow limbs. What did that make room for in our DNA?

Some animals regenerate, some form scar tissue. It's thought that scar tissue is a cheaper and faster mechanism than regrowing limbs and has thus been selected in many cases.

If an iguana loses its tail, it doesn't just bleed until the new tail starts forming, right? Doesn't it seal up and then regrow?

Yeah it does form a clot and a thin skin layer, but it remains somewhat like a wound much longer and is easier to hurt again than scar tissue covers up a wound quite quickly.

The only animal that really does it properly is the salamander and I guess our family trees diverged before they figured that out?

Still scientists are working on it - they've done frogs https://www.nbcnews.com/science/science-news/can-humans-regr...

Can't just be the salamander. I saw an iguana regrowing its tale just last week. Geckos too. Pretty sure starfish as well.

> The only animal that really does it properly is the salamander

Vertebrates are animals, but not all animals are vertebrates.

A lot of invertebrates can regrow lost organs or even heads. Insects lose it for the luxury of having wings, but other arthropods can regrow lost limbs if they live for enough moults. Planarians can regenerate everything.

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