He was a pioneer in his time with his multi-language comparative linguistics that led him to very fundamental assertions, such as all languages originated in Black Africa and from there moved to the whole world, explaining that all Black Africans who never left Africa and had had no procreative contact among their ancestors with people from the other continents do not have any Neanderthal or Denisovan DNA. They never met them. But at the same time he defended an absolutely binary method to reflect on the universality of language. He reduced it to an "either-or" approach, which is naturally false since languages are fundamentally ternary, and communication too. Walking on two feet is maybe human and good, though it requires quite a good set of muscles to keep the perfect running equilibrium and momentum based on falling from one foot to the next, though each leg has a ternary tempo: raise-land-push.
Jacques COULARDEAU (2026) studied this question.