[Fred Nerks]

We also point out that during Solutrean times lower sea levels greatly reduced the distance between the Celtic and the North American Continental Shelves...

they could have walked if the continents hadn't split apart...

[SunkenCiv]

Land exposed by the fallen sealevels (due to glaciation, whatever its cause) would be relatively warmer due to lower altitude, well-watered, full of food, etc, and ideal for maritime cultures. :’)