Scientists trying to create artificial life generally work under the
assumption that life must be carbon-based, but what if a living thing
could be made from another element?
One British researcher may have proven that theory, potentially
rewriting the book of life. Lee Cronin of the University of Glasgow has
created lifelike cells from metal — a feat few believed feasible. The
discovery opens the door to the possibility that there may be life forms
in the universe not based on carbon, reports New Scientist.
Even more remarkable, Cronin has hinted that the metal-based cells may be replicating themselves and evolving.
"I am 100 percent positive that we can get evolution to work outside organic biology," he said.
The high-functioning "cells" that Cronin has built are constructed from
large polyoxometalates derived from a range of metal atoms, like
tungsten. He gets them to assemble in bubbly spheres by mixing them in a
specialized saline solution, and calls the resultant cell-like
structures "inorganic chemical cells," or iCHELLs.
The metallic bubbles are certainly cell-like, but are they actually alive?
Cronin has made a compelling case for the comparison by constructing
the iCHELLS with a number of features that make them function much as
real cells do. For instance, by modifying the outer oxide structure of
the bubbles so that they are porous, he has essentially built iCHELLs
with membranes capable of selectively allowing chemicals in and out
according to size, much as what happens with the walls of real cells.
Cronin's team has also created bubbles inside of bubbles, which opens
the door to the possibility of developing specialized "organelles." Even
more compelling, some of the iCHELLs are being equipped with the
ability to photosynthesize. The process is still rudimentary, but by
linking some oxide molecules to light sensitive dyes, the team has
constructed a membrane that splits water into hydrogen ions, electrons
and oxygen when illuminated — which is how photosynthesis begins in real
cells.
Of course, the most compelling lifelike quality of the iCHELLs so far
is their ability to evolve. Although they aren't equipped with anything
remotely resembling DNA, and therefore can't replicate themselves in the
same way that real cells do, Cronin has nevertheless managed to create
some polyoxometalates that can use each other as templates to
self-replicate. Furthermore, he is currently embarked on a seven-month
experiment to see if iCHELLs placed in different environments will
evolve.
The early results have been encouraging. "I think we have just shown the first droplets that can evolve," Cronin hinted.
Though the idea of a strange new metal-based form of life rapidly
evolving in a lab somewhere on Earth may sound ominous, the finding
could forever change how life is defined. It also greatly improves the
odds of life existing elsewhere in the universe, since life forms could
potentially be built from any number of different elements.
The possibilities are exciting to imagine, even if Cronin's iCHELLs
eventually fall short of full-blown living cells. His research may have
already blown the door off previous paradigms about the conditions
necessary for life to form.
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