I see few references to language as I skimmed.
The point I tried to make is that behavioral modernity and language development took place around the same time as the worldwide human migration that you described.
Now you're talkin'. I think it's specifically the development of
dead reckoning in language that precipitated homo sapien wanderlust. To this day a quarter of all languages confer
dead reckoning, the ability to always know exactly where N S E & W are, predominantly in the Pacific islands.
In Papa Negrini one of their languages has 96 directions, 8 by 12, which encompasses both of the most common directional divisions in human numerical systems. To say hello you have to say which of the 96 directions you are going in, which is an almost superhuman challenge.
A young graduate student who had studied the language so intensively as to speak reasonably well got no respect because she couldn't even say hello. After 2 weeks of overwhelming frustration from not being able to get past hello, she suddenly developed a video game-like compass in her mind where she could visually see her direction extremely precisely. Suddenly she could say hello and was immediately treated with much greater respect.
As soon as she was able to speak to gathered female elders she describes her new handy mental videogame-like radar window in her mind and asks if they know what she is talking about. They reply: "Doesn't everyone have this?"
As far as Genesis is concerned, it is clear to me that the creation of Adam in Gen 2 is different from the creation of the world (including hominins) in Gen 1. But at some stage, these 2 groups had to completely mix together, genetically.
I agree totally that adam (which is not a proper noun in Hebrew and actually means mankind or man in the generalized term) could easily refer to multiple similar events. For example,
linguistically the oldest languages are in the
farthest Southern Africa, despite the
greatest genetic diversity being in
East Africa.
You can tell how old a language is by the number of syllable consents it has.
Languages shift and
lose consonants, but they
never gain new consonants.
There are 5 South African languages that are a superset of all consonant combinations and
uniquely containing the "click consent" where you suck in hard and abruptly let your tongue free creating a quick "shnuk" sucking in sound. One of these 5 languages actually uses it as a consonant in words. The most well-known example is "g!nu" where the '!' represents the click consonant.
So it's assumed that there were survivors in the genetic bottleneck from both East Africa and Southern Africa because
East Africa may have the
most genetic diversity in the world but
South Africa has the
most linguistic diversity in the world.