While there are certainly varying beliefs on how life on how life emerged on our planet, the scientific consensus has long been the most humbling one: Around 4 billion years ago, our ancestors were simple molecules swishing around in a primordial soup.
That broth had just the right ingredients — methane, ammonia water, a dash of energizing lightning — to nurture the earliest organic compounds. At one point, the soup overflowed from shallow ponds and the chemistry of life, in its simplest form, spilled forth and multiplied.
At least, that's been the narrative for the last century or so — a theory first suggested by famed naturalist Charles Darwin and refined decades later by scientists A.I. Oparin and J.B.S. Haldane.
We've been debating and frequently disagreeing over that hypothesis ever since.
Even Darwin acknowledged the theory's fallibility back in 1871, when he penned this to a friend:
But if (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts,— light, heat, electricity & c. present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present day such matter wd be instantly devoured, or absorbed, which would not have been the case before living creatures were formed.
With details from 4 billion years ago being a bit sketchy, it's understandable that Darwin — and the scientists who came after him — dangle such a resounding "if" in front of the theory.
And scientists from University College London made the origin of life in those shallows an even iffier proposition.
According to their study, published this month in the journal Nature Ecology & Evolution, life may have sprung from a perfectly cooked soup, but the pot wasn't a "warm pond" after all.
Rather, life may have sprung from the deepest trenches of the ocean, specifically heated fissures on the seafloor in volcanically active regions.
Those hydrothermal vents may have been the real cradle of life.
"There are multiple competing theories as to where and how life started. Underwater hydrothermal vents are among most promising locations for life's beginnings — our findings now add weight to that theory with solid experimental evidence," the study's lead author, Nick Lane, noted in a statement.
The key to their findings was the humble protocell, considered the most basic building block for all life on Earth. The scientists were able to replicate the formation of protocells in an environment very similar to that found in a hydrothermal vent. Typically protocells form naturally in freshwater bodies. The ocean, on the other hand, with its salt and high alkalinity levels, wouldn't seem like the ideal nursemaids for these infant cells — particularly the heated regions near undersea volcanoes.
In past experiments, as IFLScience reports, protocells successfully spawned in the cool freshwater of labs, quickly became undone when exposed to briny seawater.
But the presence of a hydrothermal vent may change everything. These vents could only be explored relatively recently thanks to modern technology. They're constantly heaving out minerals in a gush of brine warmed by volcanoes below. And when those minerals circulate with seawater, a unique marine environment is formed.
That's where the marriage of hydrogen and carbon dioxide, the researchers claim, begets a variety of organic compounds — our most ancient and distant relative, the protocell.
Considering the vast timeframe involved it may seem like a niggling detail: what does it matter that life may have sprung from the depths of the ocean, rather than from shallow freshwater pools?
Ultimately, it may not be about tracing life here on Earth — but its existence in other parts of the cosmos.
Consider Jupiter's fourth largest moon, Europa. Scientists suspect the vast ocean beneath its frozen enamel may be packed with sodium chloride, also known as table salt. Add potential volcanic activity below the seafloor — and someone may be cooking with gas.
Indeed, the new research suggests primordial soup may not be such a uniquely homemade creation at all.