“Americans are so cheerful because of historic immigration levels. There is a direct correlation between immigration levels and happiness. In both the USA and Canada, the citizens come from a huge number of source countries – Canada has 63 and the USA has 83. If you have to cross over language boundaries, you have a greater reliance on facial expressions and gestures, which builds trust and cooperation.”
Possibly flying in the face of the statement above, my girlfriend tells me that in Sardinia there is such a range of hand signs that quite lengthy exchanges are sometimes conducted non-verbally.
It is possible that human language first developed through the use of signs, gestures, postures, mimicry and pantomime.
Verbal sounds may have started as noises to draw attention to the “speaker” or to add emphasis.
Having spent many a night in noisy rock clubs, some means to be understood when you cannot be heard would have been useful.
Perhaps the conlang that is really needed is a system of standardised hand signs.
In a large area of North American Plains Indian Sign Language (PISL) was supposedly used as a lingua franca.
In actuality, a number of languages and multiple dialects have been recorded. Standardization was not really practical at that time, but the system seemed to work.
Unlike many sign language systems, PISL also had a “written” equivalent in the form of pictograms.
A modern sign language conlang would also need a written form.
This might be based on Bliss, LoCas, Semiotic Standard and/or Spacer Runic.