Winter often means more soup for dinner. Although the seasonal temperatures of Southern California seem moderate compared to places like the Midwest, the chill in the air still makes a good bowl of soup taste delicious. Keys to preparing a tasty soup include quality ingredients and cooking time. The primordial soup (mixture of organic molecules) evolutionary scientists propose to bring about the origin of life on Earth fails on both counts.
In order to make a good primordial soup, the early Earth needed to meet a few specifications. Most importantly, the atmosphere should have contained ammonia, methane, hydrogen, and other reducing gases. (Such gases, or reducing agents, donate electrons to compounds that then become “reduced” while the agents become oxidized.) Otherwise, the oxygen and oxygen-containing components of the atmosphere would break down any biologically necessary compounds (soup ingredients). And this reducing atmosphere needed to last long enough to drive life’s chemistry (cooking time).
Recent studies of the most ancient remains found on Earth make it unlikely that the original atmosphere was a reducing one. The amount of cerium (Ce) discovered in zircons that formed over four billion years ago provides information about the oxidation state of the magmas that produced the early Earth’s atmosphere. In these magmas where zircons form, Ce can exist in two different oxidation states, and the amount of Ce incorporated into the zircons depends on the ratio of these two states in the melt.
A team of scientists determined how to calibrate the ratio of the oxidation states based on the measured abundance of Ce in the zircons.1 Applying their calibration method to zircons dating 4.35 billion years old indicates the early Earth magmas would produce an atmosphere filled with water, carbon dioxide, sulfur dioxide, and nitrogen. Such an atmosphere (similar to today’s except for the lack of free oxygen) would be destructive to the biochemistry that origin-of-life scenarios require.
These results strongly argue against the existence of a primordial soup anytime within the last 4.35 billion years. Assuming conditions before that time permitted a reducing soup, it could remain (on the naturalistic stove) for no more than 200 million years. But, during this period Earth would have experienced numerous collisions resulting in the liquefaction of the upper miles of Earth’s crust. In other words, collisions would have wiped out––like a family pet spilling the pot onto the floor––any prebiotic chemistry that might have happened in this early epoch.
Naturalistic origin-of-life scenarios depend on the existence of a reducing primordial soup to produce the prebiotics for life to form. As this study shows, early Earth did not contain the right ingredients to produce a good soup, nor could the soup have cooked long enough to start life’s biochemistry. Instead, the rapid introduction of complex life into the hostile conditions of the early Earth points to the work of a Master Chef.