say hi to your daddy LUCA, the last common universal ancestor.

ONCE upon a time, 3 ga BP, there lived a single organism called LUCA. It was enormous, a mega-organism like none seen since, it filled the planet’s oceans before splitting into 3 and giving birth to the ancestors of all living things on Earth today.

by comparing their sequence of DNA letters, genes can be arranged in evolutionary family trees, a property that enabled Dr. Martin and his colleagues to assign the 6m genes to a much smaller number of gene families. Of these, only 355 met their criteria for having probably originated in Luca, the joint ancestor of bacteria and archaea. The 355 genes pointed quite precisely to an organism that lived in the conditions found in deep sea vents, the gassy, metal-laden, intensely hot plumes caused by seawater interacting with magma erupting through the ocean floor. Dr. Sutherland too gave little credence to the argument that Luca might lie in some gray transition zone between nonlife and life just because it depended on its environment for some essential components. “It’s like saying I’m 50% alive because I depend on my local supermarket.”

2024-07-23: Molecular Adam and Eve

These 2 proteins, emerging as mirror images from the same gene, form the foundation of all subsequent encoded proteins. Given their central role in the inception of the genetic code—perhaps the most critical moment in the origin of life—Carter named them Αδάμ and Εωε (Adam and Eve, in Greek characters). Their existence underscores a fundamental principle: a code can only arise when there are at least two options to choose from.

Through the pioneering biochemical experiments conducted by the Carter laboratory, it was revealed that molecular Adam and Eve exhibited distinct specificities towards different groups of amino acids. This specialization allowed them to carry out an initial, albeit rudimentary, production of proteins (themselves), marking a significant advance over random synthesis. Over millions of years of evolution, these 2 proteins each diversified into 10 distinct forms. The fact that the symmetry was maintained between the two classes suggests that they were still part of bidirectional genes as they coevolved. The diversification process mirrored the complexity of the genetic code itself: the incorporation of new amino acids led to the addition of new codons, and at the same time allowed the synthetases to become more accurate at decoding genetic information. This cycle of coevolution between the code and its interpreters elegantly exemplifies how a code can be refined by the very entities it generates.