unknown

For reasons unknown, that's one historical divergence that Scott chose not to take.

Communications chief Carlos Denvers said: "Many unknown individuals tried to transfer the drugs to another container that would be shipped on a vessel to Belgium."

Police are still on the hunt for the suspected killer, whose motivation is unknown, but authorities have revealed messages written on shell casings found at the scene.

The other two have unknown origins, which is a foreboding indicator that human-to-human transmission could be occurring, a prerequisite for another pandemic.

It was unknown whether the ability to flexibly organize behaviours in this way is unique to humans, or also present in other primates.