  Spin measurement of the 6.5 billion solar mass black hole in M87 from the
Event Horizon Telescope image is the latest in a series that span a wide range
in values, but that tend to share the feature of co-rotation between the
accretion flow and black hole. The spin paradigm for black holes predicts very
high black hole spin which in that framework was produced in its last
significant merger. High black hole spin appears to be ruled out in the gap
paradigm, however, which predicts early formation with a mass already in excess
of 4 billion solar masses. In this picture, the black hole experienced slow
evolution as it departed from its original radio quasar phase and over billions
of years not only failed to double its mass but also fell short of regaining
its original high spin, such that it is now compatible with a co-rotating
accreting black hole whose dimensionless spin fits best in the range 0.2 < a <
0.5.
