Title: SETI in vivo: testing the we-are-them hypothesis,
Abstract: After it was proposed that life on Earth might descend from seeding by an
earlier civilization, some authors noted that this alternative offers a
testable aspect: the seeds could be supplied with a signature that might be
found in extant organisms. In particular, it was suggested that the optimal
location for such an artifact is the genetic code, as the least evolving part
of cells. However, as the mainstream view goes, this scenario is too
speculative and cannot be meaningfully tested because encoding/decoding a
signature within the genetic code is ill-defined, so any retrieval attempt is
doomed to guesswork. Here we refresh the seeded-Earth hypothesis and discuss
the motivation for inserting a signature. We then show that "biological SETI"
involves even weaker assumptions than traditional SETI and admits a
well-defined methodological framework. After assessing the possibility in terms
of molecular and evolutionary biology, we formalize the approach and, adopting
the guideline of SETI that encoding/decoding should follow from first
principles and be convention-free, develop a retrieval strategy. Applied to the
canonical code, it reveals a nontrivial precision structure of interlocked
systematic attributes. To assess this result in view of the initial assumption,
we perform statistical, comparison, interdependence, and semiotic analyses.
Statistical analysis reveals no causal connection to evolutionary models of the
code, interdependence analysis precludes overinterpretation, and comparison
analysis shows that known code variations lack any precision-logic structures,
in agreement with these variations being post-seeding deviations from the
canonical code. Finally, semiotic analysis shows that not only the found
attributes are consistent with the initial assumption, but that they make
perfect sense from SETI perspective, as they maintain some of the most
universal codes of culture.