This is an extremely entertaining YouTube clip from one of the many kook channels on that site, Universe Inside You.
Here, the narrator takes us into the outer fringes of crypto-zoology and summarizes the bizarre legend of the cynocephali or dog-men. The narrator clearly believes that cynocephali are real, although perhaps not canid. He ventures the guess that we are dealing with Neanderthals or some kind of apes or monkeys.
His main argument in favor of the cynocephali being real is that the stories are ”consistent”, but that doesn´t prove anything– ancient and medieval writers consistently borrowed from older sources since that´s how things were done back in them days. 16th century writer Olaus Magnus mentions a fight between Pygmies and cranes, placing it on Greenland. The story comes from the Iliad and was originally set in some unspecified southern land. By the logic of Universe Inside You, there are geographically distinct Pygmy populations actually fighting cranes in pretty much any distant land!
Many of the stories referenced are illogical, thus the ancient source always knows everything about the dog-men, down to details, including that they lived in far away caves very far away in the most far away hills…
*The* most bizarre legends are about Christian saints who were dog-men, most notably St Christopher. The problem? The saints themselves may be, for all we know, legendary.
The clip contains some factual errors. King Arthur isn´t a real historical person, and ”Beowulf” has nothing to do with Alexander the Great.
For the record, I don´t rule anything out on principle: all kinds of very, very strange creatures do exist, so why not cynocephali, werewolves or mermen (not to mention honest-to-god politicians or competent economists), but in contrast to Mr Inside You, I don´t think a bunch of ancient tall tales are proof enough.
A cynocephalid pelt, or a miracle by St Christopher, might perhaps do the trick.