In Depth

How life on Earth began

New discovery sheds light on beginnings of our planet - and could help in search for aliens

The conditions for life on Earth were created when the planet crashed into another body the size of Mars about 4.4 billion years ago, a new study claims.

For life to emerge on an otherwise dead planet, “an assortment of chemical compounds, or volatile elements, are required, including carbon, nitrogen and sulfur”, says science news site Gizmodo. Conventional scientific thinking has always been that Earth’s volatile elements arrived through a steady bombardment of ancient meteorites.

But according to the “giant impact hypothesis”, outlined in a newly published paper in journal Science Advances, a single catastrophic cosmic crash delivered most of the volatile elements essential for life to the Earth.

Lab experiments and computer simulations by scientists at Rice University, in Texas, “suggested that debris from the destroyed planet deposited the life elements on Earth”, included most of the nitrogen and carbon found in all living things, reports The Independent.

The scientists believe the debris from the collision also created the Moon, while the so-called “donor planet” is thought to have been an embryonic world with a sulphur-rich core.

Lead scientist Rajdeep Dasgupta said: “From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted.

“But the timing and mechanism of volatile delivery has been hotly debated. Ours is the first scenario that can explain the timing and delivery in a way that is consistent with all the geochemical evidence.”

He added that the study could boost scientists’ understanding of how the ingredients for life might form on other similarly rocky planets like our own.

“This study suggests that a rocky, Earth-like planet gets more chances to acquire life-essential elements if it forms and grows from giant impacts with planets that have sampled different building blocks, perhaps from different parts of a protoplanetary disk,” he said.

However, Dasgupta admitted to Gizmodo that the study was “based entirely on the geochemical behavior of elements” and didn’t look at the “dynamics or physical processes involved in planetary accretion and growth”.

The team now hope to integrate their new theoretical model with physical models.

“In other words, this ain’t over yet,” says the site.

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