Smithsonian magazine reports:

Among biologists, few questions have been debated as fiercely as the origin of life. How did self-sustaining organisms, capable of transforming molecules to capture energy, arise on the primitive Earth?

Before any cells existed, scientists suspect chemical reactions occurred around deep-sea hydrothermal vents, where heat and high pressures led to spontaneous chemistry that was sped up, or catalyzed, by metals in Earth’s crust. One possibility for the origin of life is that, over time, these relatively simple geochemical reactions evolved into the reactions that create the building blocks of life.

Living creatures rely on a core network of about 400 metabolic reactions that are catalyzed by proteins known as enzymes. This “core metabolism” creates energy and makes key materials for cells, like nucleic acids, amino acids and vitamins.

Now, a team of researchers has retraced the steps for how this essential metabolic network was assembled, in a paper published today in Science Advances. One of their most striking findings: Life on Earth likely evolved not once, but twice. [Continue reading…]