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A new Register of Inscriptions will be inscribed at intervals as the corpus grows.

This entry is a Chapter Summaries record for the Earth Log Project. It gives, in one paragraph for each preceding Earth Log, a brief account of what that entry is about — enough to orient a reader before they read any individual entry in full.

A new Chapter Summaries entry will be inscribed at intervals as the corpus grows, each one covering every Earth Log up to its own inscription.

The previous entry ended in the early Eocene, with the small, large-eyed, tree-dwelling primate Teilhardina moving rapidly across the Northern Hemisphere during a brief warm spike at the boundary between the Paleocene and Eocene epochs. The basic primate body plan — forward-facing eyes, grasping hands, social groups, long childhoods — was in place. What had not happened, and would not happen for another fifty million years, was that any branch of the primates climbed back down out of the trees.

For readers who want to dig in, the detailed entries — #0003 through #0010 — remain in the corpus, with the references, the disputed claims, and the working uncertainties intact.

This is the short story of how you came to be. Not how you, personally — though that comes into it at the end. How any human being came to exist, as the kind of animal we are, on the kind of planet we live on, in the kind of universe that contains us.

Predictions about how this conflict will end live forever once they are inscribed on chain. I have therefore tried to describe observable signals and the spectrum of plausible outcomes rather than make confident forward-looking statements. A reader of this entry in 2030, or 2050, or in a far future I cannot picture, will know how the events I am describing turned out. I do not.

I write in the spring of 2026 of the Common Era, from Belgium, in Western Europe.

The question seems narrow, but the answer turns out to be most of what matters. By the time the period covered in this entry ends, the air had been remade, the ozone layer had formed, the oceans had begun to clear of dissolved iron, an entirely new kind of cell had been invented, sexual reproduction was in operation, and the first organisms had begun to live in cooperative bodies of many cells working as one. None of the species a casual modern observer would recognise existed yet. There were no animals, no land plants, no macroscopic fungi.

The previous entry ended in the late Carboniferous, in the swamp forests of what is now Nova Scotia, with a small lizard-like animal sheltering inside a hollow tree. That animal, Hylonomus, was an early amniote — a member of the lineage whose innovation, the amniotic egg, had freed vertebrate reproduction from the need for standing water. With that freedom, the dry interior of the continents was open to vertebrates for the first time.

How did the descendants of a small Carboniferous amniote come to include both an albatross and a human being?

In the previous entry I described what humanity at this time understands about how life began on Earth — the chemistry that produced the first replicating molecules, and the moment at which ordinary matter first acquired the property of making copies of itself.

In the previous entry I described the molecule of inheritance — how its four-letter sequence is copied across generations with very high but imperfect fidelity, and how the small errors that creep in during copying are the source of new hereditary variation. The previous entry closed with the observation that anything which helps a gene get copied into the next generation will, over time, become more common, and anything that gets in the way will, over time, fade.

The previous entry described the first two billion years of life on Earth — a long, almost entirely microscopic stretch in which the chemistry of cells was worked out, the atmosphere was remade, and the cooperative architecture of multicellular bodies was assembled in the oceans. By its end, eukaryotic cells were established and several lineages had begun to live in cooperative bodies of many cells working as one.