It depends if you wish to assign magical powers to being sentient.
sen·tient, adjective, able to perceive or feel things.
synonyms ; capable of feeling, living, live;
Being sentient is not necessarily equivalent to being conscious. IMO, sentience just means ability to experience external influences and react to these influences. Paramecium, when encountering an obstacle, will back up, and adjust course until it is able to avoid the obstacle in its path. It "perceives" the presence of the obstacle and takes corrective action.
I agree, this is an unconscious response mechanism, however it is subjectively sensitive to external conditions and displays reactive behavior. Even if it is purely physical, Paramecia are made of the same stuff as humans, and there is no known reason why simple organisms should not be able to display sensitivity to their environment.
The acquisition of consciousness in humans is a result of evolved complex fermionic and bosonic fields and chemical memory via microtubules, which Paramecium have in abundance and which allows for cognition and processing of information from external stimuli.
Paramecia have no cognition of specific stuff, but they recognize obstacles as obstacles and take corrective action. To me that is the very essence of "proto-sentience", a rudimentary ability to react to stimulus.
This only means the presence of required physical assets (building blocks) for evolving conscious sentience,
proto-type patterns and cellular constructs.
A Cuttlefish, the descendant of a mollusk, is sentient, conscious, and highly intelligent.
This would suggest that mollusks have certain specific physical features which make it possible for a cuttlefish to evolve into the sophisticated creature it is today. Thus mollusks have cellular equipment that makes them
proto-sentient to touch. I bet this identifies the presence of microtubules, the processors of physical information.
Tap a mussel and it will snap shut. How does it do that? Sentience? Proto-sentience? Micro-tubules?
How does a Venus fly-trap know there is an insect within its trap. Actually we do know that when the insect trips two microtubules in the plant's "flower", this triggers a hydraulic action which forces the leaves (petals) to close rapidly, trapping the insect.
The same as a patch of light sensitive cells may evolve into an eye. The patch is a proto-eye.
The development of the eye is considered by most experts to be monophyletic; that is, all modern eyes, varied as they are, have their origins in a proto-eye ...
https://www.sciencedaily.com/terms/evolution_of_the_eye.htm
The eye has many micro-tubules!
In summation; all organisms which share (the genetic formation of) microtubules at birth, possess rudimentary cell structures or proto-types of all sensory abilities.
A "common denominator" in all sentient or conscious or intelligent organisms are
microtubules (biological proto-computers)
.
When did action/reaction become sentient? I submit that, if action/reaction is always governed by a mathematical form or function, then one could argue that the universe itself is a proto sentience. An active and reactive medium possessing all qualities and quantities necessary in the formation and expression of biological organisms.
Some cosmic dust clouds are proto-stars and will create all the elements necessary for human life. It's all chronologically and mathematically connected. Bohm's potential "Implicate".
