Purdue University chemists found the first building blocks of life tilted to the left. That suggests why, on a molecular level, all living things have a southpaw bias.
In a series of experiment, the Purdue scientists looked for the reasons why all 20 of the amino acids that comprise living things exhibit what is called "left-handed chirality." That refers to the basic direction that amino acids -- basic biological molecules -- twist.
Amino acids -- which possess the same chemical properties regardless of their chirality -- can be oriented either to the left or right. But, for some reason, living things evolved using only amino acids with left-handed chirality. The reason for this has puzzled scientists for years. But the Purdue team says it's found the answer.
A single amino acid called serine set the standard eons ago and all other biological molecules were forced to behave the same way. "We believe that serine was the first biological molecule to make a chiral choice, possibly one of the root steps in chemical evolution itself," researcher R. Graham Cooks says in a news release.
"Left-handed serine was able to form clusters with strong bonds, and left-handed serine clusters are able to link to other left-handed amino acids. So once serine took the left fork in the road, only the lefties in the primordial soup got to partner up for the dance of life," Cooks explains.