Other planets ruled by an advanced form of dinosaurs? It's a concept broached in a new scientific paper on the building blocks of amino acids.
"We would be better off not meeting them," author Ronald Breslow, a chemistry professor at Columbia University, concludes in the study , which appears in the Journal of the American Chemical Society.
In the paper, Breslow raises the possibility in response to the question of why amino acids (which make up proteins), genetic materials DNA and RNA, as well as sugars, exist mainly in one orientation or shape.
Like hands, the two orientations – left or right – mirror each other, which is called "chirality," the paper said.
Life arises because proteins, for instance, contain only one chiral form of amino acids, left or right. On Earth, all amino acids have the left-handed orientation, except for a few bacteria. Sugars, meanwhile, are oriented as right-handed.
In his paper, Breslow seeks to answer why amino acids are lefties on Earth. He notes evidence that the unusual amino acids could have been carried to a lifeless Earth by meteorites about 4 billion years ago. That concept could explain the pattern for normal amino acids with the L-geometry and how those could lead to D-sugars of the kind in DNA, according to the study.
"Of course, showing that it could have happened this way is not the same as showing that it did," he said in the release. "An implication from this work is that elsewhere in the universe there could be life forms based on D-amino acids and L-sugars. Such life forms could well be advanced versions of dinosaurs, if mammals did not have the good fortune to have the dinosaurs wiped out by an asteroidal collision, as on Earth. We would be better off not meeting them."
A Smithsonian blogger challenged the idea.
"To say that there are dinosaurs on alien worlds presupposes that there is an irresistible direction that all life follows, and that dinosaurs are an inevitable actors in the drawn-out drama," wrote Brian Switek. "There is no evidence that this is so."