To expand on my remarks, in order to suggest that early humans 40,000 years ago engaged in "free trade" you would have to establish that they regarded the products supplied by foreign tribes the same as identical products of their own making, and facilitated direct competition between the two. In the first place, there is no way I can think of to interpret such a thing; and second, there is very little reason to believe that they would trade for anything they could procure on their own.
We know more or less how basic subsistence cultures operate from experience with those that have entered the historical record, and "free trade" as commonly understood is hardly an accurate characterization. There are all kinds of direct and indirect barriers to trade with neighboring groups (even more so with distant, alien peoples). What reason is there to think that rudimentary cultures 40,000 years ago behaved any differently?
I question this. "Free trade" (or any other trade) is not based on groups going toe-to-toe over the merchandising of "identical products of their own making". Rather, trading hinges on Group A supplying the needs (real or created) of Group B, and visa versa.
IOW, it's not trading your length of rope for my length of rope; it's to trade your length of rope for my length of cloth, or my netting (made from your rope,perhaps?), or 1/2 dozen of my chickens, or whatever.
The question then becomes: What would Neanderthals have that the Cro-Mag. want? Esp. if, as one Freeper pointed out, the Neanderthals were highly territorial -- and contentedly so. Frankly, the only thing I can think of is human chattel, whether slaves/field hands/mates(wives).
I may have been unclear my post 11. Where Neanderthal and Cro-Magnon sites coexisted, a big difference between the two was that modern man had goods ( i.e. "crafted stone and bone tools, shell and ivory jewelry, and polychrome paintings") that had come from many hundreds of miles away. That we know. We can imagine that every single item was picked up by hand and carried by each individual user, or we can imagine an advanced "linguistic competence and cultural sophistication" --modern man traded things for the imports and Neanderthals preferred trade barriers,