Life’s cold start
Frigid cocoons may have incubated earliest replicating molecules
The hot spot for life on early Earth may have been a very cold place. Tiny pockets and channels that form inside ice can contain and protect replicating molecules, researchers report September 21 in Nature Communications.
The paper suggests that life could have sprung from icy slush covering a freshwater lake, rather than a broiling deep-sea hydrothermal vent or the “warm little pond” proposed by Charles Darwin. And perhaps the frigid, icy surfaces of other planets are not as barren as they appear, proposes the research team from the MRC Laboratory of Molecular Biology in Cambridge, England.
Scientists studying the origin of life have long been vexed by the problem of protecting and containing life’s starter molecules before the advent of the tidy compartments known as cells. In present-day organisms, cells concentrate molecules, keeping ingredients and machinery within each others’ reach. Cells also protect the molecules that encode genetic information: RNA, the molecule of heredity that presumably got the whole life thing going, is a very fragile affair.
Previous work had shown that nooks and tiny crevices within ice could provide a cozy, safe place for the construction of an RNA molecule. As ice forms, pure water becomes crystallized, while salts and other bits of debris accumulate in watery pockets. These impurities lower the water’s freezing point, and the little pockets may remain unfrozen within an otherwise solid chunk.