Hunger and tiredness both take a long time to cause a human baby to cry but hunger is often the longer of the 2. Now, yes, for us humans, a hunger cry is important, even though it attracts predators.
But that doesn't mean that my Kepler Bb humanoids, anatomically similar externally, but different internally, couldn't have evolved to not have a hunger cry.
I mean, that species originated on Kepler B#, a nearby planet that is also habitable. And on that planet, with their underground living, since they evolved into the species that they are, they have survived all mass extinctions, even ones that killed really huge animals.
This means that they must have encountered a variety of predators, each with a different affinity towards humanoids and baby cries. This would mean that a general strategy had to evolve when it came to baby cries or they wouldn't have gotten to the futuristic age and settled on Kepler Bb.
What I am proposing is this:
Since hunger cries are often the loudest of all baby cries when the baby is not in pain, this would have the highest potential of attracting predators, even ones that would ignore adult humanoids. This meant trouble in an evolutionary sense. The species could evolve to have less hunger or it could evolve to get rid of the hunger cry. Less hunger would probably mean eventual starvation through the whole species since the majority of this evolution occurred during a "stone age" type era(millions and millions of years). During the stone age, there is no way that you would know when food came. Even time of year is not all that accurate of a sign.
So I figured that instead of being less hungry and the whole species starving to extinction, that there be more time between first hunger cue and crying and quieter hunger cries. This would be less likely to lead to starvation and attract fewer predators.
So over time, as cries get quieter and there is more time in between cries, eventually the hunger cry is gotten rid of completely. Likewise, mothers pay more attention to hunger cues to compensate for this.
Now, here is the big question. Is this plausible? Could evolution favor no hunger cry over a loud hunger cry?