دانشگاه علوم پزشکی ایران
Iran University of Medical Sciences

Scientists Find Worms that Recently Evolved the Ability to Regrow a Complete Head

 | Post date: 2019/03/10 | 
Regeneration of amputated body parts is uncommon but does exist throughout the animal world–from salamanders, spiders and sea stars that can regrow appendages to a species of ribbon worm that can regenerate an entire individual from just a small sliver of tissue. But regenerative abilities were broadly assumed to be an ancient trait that some species managed to hold on to while most others lost through evolution.
All animals have some degree of regenerative ability. Even humans re-grow damaged skin over a wound. However, animal lineages that diverged very early in evolutionary history–such as sponges, hydroids and ctenophores–are often able to regrow entire individuals from even small amputated parts. As animals evolved greater complexity, regenerative abilities have become less dramatic and common.
Some of the non-head regenerating worms in the study survived months without heads. That could indicate a possible precursor to evolving the ability to regenerate a head, because surviving an amputation long enough for regeneration might be the first evolutionary step.


 



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