As this metagut gives birth to its offspring, this child passes very near the exit of that metagut and is thus 'christened' in the funk of a gut and gains its flora.
Have you ever seen a cladogram?
This is the tree of life, all branches of which lead to one common ancestor 3+ billion years ago. If one can imagine humanity, and the path it took along that tree, all the branches and subbranches its ancestry has passed through to where it is today we get a sense of the lifestyles and predation practices that could contribute to the metagut of humanity. Contained in all those predation patterns, those sustenance practices, all the ancestor organisms from which humanity came provide humans today with both a genomic artifact of this ancestry and an accompanying microbiome, which offers up a sort of unbroken continuity between 3+ billion years ago and now. From the virulent unicellular organism to the colony biofilm into the highly specialized cooperative cell community that is today's organismic life all that accumulated biomolecular programming is both a memory of its past forms and the very scaffolding upon which this current human lifeform is draped like the sheet of a ghost.
What's important to note is the importance of a gut to the branch of eukaryota to which we belong. Our ancestors didn't, like other lifeforms, form a house for the photosynthetic bacterial analogues, which became chloroplasts, but instead they formed a house for a molecule-to-energy transformer known as the mitochondrion, which, itself, is a vestige of the cooperative unicellular oceanic soup from which all our ancestry derived. This body, its homeostatic parameters, and the biomolecular landmarks provide the keen observer with a museum of some ancient oceanic location that it carries around within itself, specifically forming a within in a double sense. Our class of organisms are discrete locations of ambulatory cells apart from the environment. The gut serves as a sort of interface, a Love Canal if you will, where organism and world find a specific homeostatic environment that perhaps mimics those ancient oceanic conditions where all these biomolecules first learned to form their initial 'within' and interact at that level. This initial within would be the discrete cell, itself, that unit, which had learned how to communicate, cooperate, and coordinate within morphospace with its neighbors. It would find a seemingly higher goal-based unity together that it could coordinate in real-time through manipulation of the electromagnetic spectrum made manifestly available through voltage differences propagated and held within the selective cell membrane, that very thing that established a within, the thing which set the cellular material apart from its environment.
It's easy to veer off into nonsense land in this discussion. That isn't to say that my attempt here at being concise and somewhat clear in my understanding of life as an organizational pattern of physical phenomena and temporal continuity has failed. This continuity happens by virtue of life's programmatic replication of its basic unit, the cell, to grow itself out and continue against senescence to maintain itself for a length of time.
