So just getting some of the fact sorted out. Slavery did exist post Roman Empire in Europe: Check.

Slavery in Europe was dieing out in the 15th Century in favour of serfdom (economic not iron clad slavery).
Some of the Nation States profited from slavery on and off right up to the mid 19th century. Check.

That's true for the menfolk but given Fragony's definition of slavery:
"If you want it to be, 19th century serfdom in Russia was basically the last of what is close to slavery in Europe. Poor working conditions, all times. But not real slavery, where someone is your property by law "

When did the women cease being the property of their fathers/brothers/husbands?

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As for the question can an economy thrive on having a hetrogenous population.
Demographics for Australia:
http://en.wikipedia.org/wiki/Australia_demographics

We manage, its a harsh environment so there is some give and take with the statistics, It's winter here and I'm in jeans, t-shirt and long sleeved top with the windows and doors opened. The beanie is probably extreme, but it helps protect my head when I headbutt the keyboard.