'You're Not Natural'

The biology team took a length of grass and put it under the microscope. Something in the leaf veins was pulsing. The sample label read: non-woody, non-cellulose, contains neurotransmitter protein.

The cross-section of the petiole had a vascular bundle structure, and that part was like an Earth plant; but at the centre of the bundle ran a further duct about 0.4 millimetres across, filled with an electrolyte solution whose ionic composition was almost identical to the fluid inside a vertebrate neuron's axon.

Plants should not have neurotransmitter protein. That is a structure belonging to animals, to things that can feel. Yet every blade of grass and every leaf in this forest came back the same.

There was no shortcut in the sampling procedure. A sample came off the surface into P1, went through P2 and P3, and was finally pushed into P4 containment at the innermost point of the Biology Section; the operator stripped off the EVA suit and changed into a P4 protective suit, the workbench cut off from the outside by a pane of airtight glass, the UV sterilization cycle running a pass at intervals. The first batch of 7 sample cases stood in a row on the bench, and the last of them held a single leaf and nothing else.

Mass spectrometry ran for 12 minutes. Earth biology uses 22 standard amino acids; this sample matched none of them — 19 non-standard amino acids, plus 2 organic molecules resembling amino-acid analogues, every peak falling where no known Earth organism has ever put one.

There was another set of figures harder to explain: the internal diameter of the leaf-vein duct varied by less than 0.02 millimetres, and the combination of those 19 non-standard amino acids had been optimized for metabolic efficiency. Natural evolution does not easily grow ducting to that tolerance.

In the annotation field of the report, a line was written against that length of grass that did not read like a scientific record:

You are not natural.

The person who wrote it gave no explanation. In the formal sections she kept the conclusion tight, writing only that it inclined toward having been designed, and marking that as a hypothesis. The opinion from the medical team was that artificial signatures and natural evolution can run in parallel. The 2 readings went up side by side, and neither was allowed to cover the other.

That annotation was not deleted. It went into the P4 archive together with the file for sample 005, under the field label "Unclassified Observation".