From what I heard somewhere you can achieve less latency using a USB dongle than Bluetooth. Bluetooth also can interfere with WiFi. And that mouse could just not support Bluetooth.
From what I remember Our common ancestor lived 500 milion years ago. It was rather a realy simple creature. With not many neurons and I think this is some kind of estimation. Of course we can't be sure but we never can be sure.
I hope you can understand me my english isn't very good