Question

what does the line those dark and brutal curses of the countless centuries mean?

Answer 1

I think..
It means the curses of the generation is deep and is still continuing

Answer 2

The line 'those dark and brutal curses of countless centuries' suggests that the colonialism in the narattor's country which had been there for more than four centuries. The people who struggled to fulfil their  needs were not showing their love on others because the burden is still on their shoulders.