Answer: their dependency on slave trade and domination of slave trade (caused by waging war)
Explanation: trust me
There are quite a few birds famous for doing ritualized mating dances, so I would only list 5:
The Red Capped Manakin,
The Black-footed albatross,
The Western and Clark's grebe,
The Superb bird of Paradise,
& The Victoria's riflebird.
I would have to say technology is using fewer resources to manufacture goods more efficiently.
The highest civic virtue in Rome was to put the well-being of the state and the republic above your own. The founding fathers believed that the US would prosper if people behaved in the same manner and fought together for a higher cause.