Given that literally nobody has ever needed, nor will they ever need, to talk about file sizes in millibits, there is no ambiguity involved.
Even though it’s unlikely anyone will think it’s referring to millibits, there’s still a decent chance some will assume Mb (Megabits) due to the lowercase 'b' instead of the intended MB (Megabytes).
game cartridges used to be specced in megabits
I wonder what the transmission rate of information through genetic evolution is.
Kilo base pairs among other things.
Over time, yes, but I suspect the per-second bitrate is extremely small.
Do not forget parallelism. Neural networks, electronic circuits, and a lot of other processes in nature occur simultaneously at an enormous scale.