The reference to the 400 kya spear discovery from Germany tells us it is important to remember that the peoples around at that time, such as the Qesem individuals from the Levant, were incredibly advanced even by this time. Read my article on the subject published in the past couple of days [www.ancient-origins.net] It argues that the Qesem people might well have been hybrids of proto modern humans and early Denisovans, and gave rise to the Siberian Denisovans. This would make sense of why swan ancestry, which unquestionably dates back to the Upper Paleolithic age, was so widespread in the very areas earlier occupied by the Denisovans - i.e. Siberia, Mongolia, northern China and China. It is simply speculation, of course, some somehow I sense we are on the right track with this one.
Clearly, it would not only have been swans that the Qesem people were interested in. They also took an interest in corvids, although how much we cannot say at this time.