Was it caused by competition with modern humans, by environmental changes, by the disruption of the long-established ecological balance of the regions they inhabited?

Did some Denisovan populations persist into the relatively recent past in remote areas of Southeast Asia?

The question of the other Denisovan population — the second, distinct Denisovan lineage that appears in the genetics of Tibetan and South Asian populations — is particularly intriguing.

This second population appears to be more closely related to the Altai Denisovans in some ways but genetically distinct from them.

How did the two Denisovan populations relate to each other?