Typical though process for adding new nodes to the historical tech tree (historicaltechtree.com):

Go to an airport for work → “Hmm I don’t have security scanner tech in the tree yet” → Research scanners and add X-ray backscatter and Millimeter wave scanners → Realize metal detectors are another security thing I don’t have → “When were metal detectors invented?” → Learn that they were invented for finding unexploded shells and/or land mines → Enter rabbit hole about explosive weapons → Add mortars, fuses, the 1823 Paixhans shell gun that led to ironclad ships because wooden ships became too vulnerable, caltrops as the predecessor to land mines, etc. etc. → “What were the predecessors of the 1831 safety fuse?” → Apparently ropes made of jute, covered in tar → Add jute (2200 BC in Harappa) → “Hmm jute sounds a bit like jukebox” → Research jukeboxes → “Hmm it’s just an Edison phonograph with a coin slot” → Decline to add the jukebox to the tree