The citric acid cycle, not DNA, may be biology's oldest and most fundamental invention

Lane argues that the loop of reactions found in nearly every living cell today, long taught mainly as a step in energy production, is actually a far more versatile piece of chemistry than its textbook reputation suggests. Depending on conditions, this cycle can run in reverse, pulling in simple molecules like carbon dioxide and hydrogen and using them to build the amino acids, sugars, and other components life depends on, rather than only breaking fuel down for energy.

Because this reversible loop can plausibly run without enzymes under the right geochemical conditions, Lane treats it as a strong candidate for one of the earliest chemical processes on the path to life, predating anything resembling genes or cells. This reframes an ordinary metabolic pathway most people have never heard of as something closer to a founding document of biology.

Takeaway: the chemistry of energy and matter flow may be older and more foundational than the genetic code built on top of it.