A few of the world's religions have a simple answer to mankind's origin: clay. Now science might actually back this up.
New research from Cornell University suggests that life could have started in wet, wet clay. The study suggests that clay might have provided the perfect protective environment for life to materialize.
Mystery surrounds how biological molecules ever reacted with each other before they joined forces within Earth's first cell.
Nowadays, cell membranes provide the protective barrier to DNA and RNA as the two molecules work together to churn out proteins. But the Cornell team wanted to know how they first came together in a protective environment in the first place, before cells even existed.
The scientists created a gel with clay and ocean water – both elements that were plentiful on early Earth. When they added DNA and RNA to the mix, they found that the nucleic acids were protected from the enzymes that could destroy them.
They also found that the nucleic acids performed transcription and translation – the processes that generate proteins – remarkably well when confined within the clay.
"We surprisingly found that the coupled transcription/translation reaction...was not only preserved but was also consistently enhanced in the clay hydrogel environment," the researchers wrote.
The study finds that clay provided the protective encasing needed for the biochemical concoctions that could have led to early life.
Where DNA itself came from is another mystery altogether. NASA has found that nucleotides – the components of DNA – could have been made in space, supporting the theory that a crashing meteor might have delivered the ingredients for life.
It's the latest step in the study of life's origins, first stirred by the famous Miller-Urey experiment of 1953. That experiment, conducted at the University of Chicago, created organic material from the inorganic gases that were believed to have occupied Earth's early atmosphere.
The Cornell team also found that the gel also inhibited the activity of nuclease enzymes, which can "digest" RNA and DNA. The researchers thus suggest that the clay "selectively protected" the self-copying molecules.
"While the exact mechanisms remain to be delineated, we speculate that evolution might have already selected certain enzymes to be much more functional in the clay hydrogel environment than others," they write.