The outer dimension of protolanguage, on the other hand, that of ‘the world around us’, distinguishes 2 domains of material experience, the objective versus the intersubjective.
The intersubjective domain is that of ‘me-&-you’ — ie the 1st-&-2nd person domain
The objective domain is that of the rest — ie the 3rd person domain.
But how can the distinction of intersubjective versus objective arise before a socio-semiotic system is already established?
What distinguishes the intersubjective domain of ‘me-&-you’ in the material experience of an organism from the objective domain of everything else are perceivable behavioural (‘body-doing’) tokens of senser-sensings.
This is because (exterior) ‘body-doings’ identify (interior) ‘senser-sensings’ in the organism’s domain of material experience. That is, such behavioural tokens identify other fellow ‘subjects’.
Incidentally, this a semiotic explanation for what psychologists and philosophers term ‘theory of mind’.