Marcus: Whistles go back a way.
Jerome: I guess they signal something?
Marcus: Sure. You know what long-long-short-long means?
Marcus: Approaching a public crossing. Rule 14L.
Jerome: Hmm. Hoot. Hoot. Hoooooot. Hoot?
Marcus: You got it. But the system can do emotions too.
Jerome: Sad whistles as in Woody Guthrie?
Marcus: Can be a whole railroad folk song in one steam train whistle hoot. Like this. Listen.
Signaling systems have a limited lexicon. “Watch out! Coming through.”
Language systems have big refined lexicons and complicated syntactic systems. “See you downtown in the King George for a pint after I hand over 454 to maintenance?“
And yet the mechanistic signaling system early on was adapted to include emotional expression. Unsurprising really since emotions probably preceded lexis.