I’ve come to a theory about Saru on Star Trek: Discovery. Obviously, spoilers ahead (at least, if you haven’t seen all of ST:DSC to this point, and if I’m correct).
Most of what we know about Kaminar and its inhabitants comes from Saru himself, who is probably not an impartial observer. What he’s told us is that Kaminar has two primary/sentient species: the Kelpians and the Ba’ul. The Kelpians are a prey species, somewhat analogous to sentient cattle; the Ba’ul are a predator species, occasionally “culling the herd” by gathering groups of Kelpians and taking them away.
We’ve seen that the Kelpians are a technologically primitive society, while the Ba’ul are technologically advanced, if not warp capable, then likely on their way there, as they appear to have developed some form of transporter technology (as evidenced by the “culling” seen in Saru’s Short Treks episode).
We’ve also seen that though a prey species, Kelpians can be rather formidable themselves, able to run quite fast and to defend themselves with strong kicks of their feet/hooves.
In the most recent episode of ST:DSC, “An Obol for Charon”, we learn that Kelpians aren’t chosen randomly to be culled by the Ba’ul, but are selected after a biological process begins, part of which involves the threat ganglia swelling. At this time, the usual Kelpian fear/threat response becomes heightened to the point of outright paranoia and what Saru describes as madness; this is the point at which the Ba’ul remove the affected Kelpians from their communities.
(In Saru’s Short Treks episode, this process was presented as a stylistically religious ceremony, with a group of Kelpians all proceeding to gather around a levitating Ba’ul device, after which they all disappeared simultaneously. Whether the biological process that starts this chain of events is triggered environmentally or remotely isn’t yet known, but given that Saru’s change was apparently triggered by the sphere artifact, and given that environmental triggers might make it difficult to get an entire group of Kelpians all ready to be gathered by the Ba’ul at the same time, I’m leaning towards the Ba’ul having some sort of control over the initiation of the process.
In Saru’s case, however, once the process was triggered, he wasn’t able to be gathered by the Ba’ul, and eventually his threat ganglia withered and fell away. Once this happened, he not only recovered from the flu-like symptoms he had been exhibiting, but described himself as not having the omnipresent sense of fear that he was used to, and even feeling a “sense of power” that he had not had before.
My current theory: There are no Ba’ul. Or, rather, the Kelpians and the Ba’ul are two stages of the Kaminarian primary species’ life cycle, similar to a caterpillar becoming a butterfly (only without the cocoon and drastic physiological shift). The Kelpians are the first, “child” stage, with an overdeveloped sense of self-protection to keep them safe as they develop; the Ba’ul are the second, “adult” stage, more able to protect themselves.
During this most recent episode, Saru went through the process that normally results in “culling” — only instead of being culled from the herd by the Ba’ul in the process, he completed the change himself. The culling process might not be the “death” that it has been assumed to be, but instead, is the Ba’ul taking those Kelpians who are ready for the next stage away from their still-developing peers.
(Just why Kaminarian life is set up this way, complete with two separate societies at vastly differing levels of technological development, and with the more primitive society having entire religious myths and traditions built up around the system, is still a big question, of course, if this theory is even true.)
This could also help to explain (in part) how Saru was able to understand and work with the Ba’ul tech he found and eventually adapted to send out the message that Starfleet received. While it seemed pretty far-fetched that he’d be able to gain that much understanding of an entirely alien advanced technology in an apparently short time, it could be easier if that technology was simply advanced, and not actually alien. Technology based on entirely alien viewpoints and approaches would likely be nearly impossible to understand, let alone adapt, but if the Kelpians and the Ba’ul are two stages of the same species, then they would share many of the same basic thought process and assumptions, which could help when trying to understand technology of a different level of development.
I might be entirely off base with this, of course. But I don’t think it’s a bad theory.