[Polybius]

Those Spartan babies were a significant proportion of their newborn.

Historical citation, please.

In regards to the 40 million Americans aborted in the past 26 years, even if not a single one reproduced, they would account for 13% of the entire current U.S. population.

That’s a “civilisation” that doesn’t exist anymore, and been dead for centuries, if not eons, remember? They must have messed up somewhere along the way.

Actually, that "civilization" is very much alive.

Civilizations that are "dead" are those civilizations whose deeds and examples have been forgotten or ignored and no longer inspire or affect the modern World in any way, shape or form.

The Nabataeans are now a "dead" civilization.

The example of Sparta, Athens and Rome, however, have inspired and culturally shaped our Western Civilization to this very day.

In regards to the city state of Sparta not surviving the Roman conquest, all that proves is that a cobra, no matter how agressive, will never defeat a determined elephant.

[CarrotAndStick]

What aspect of Spartan culture, has found its way into modern Western Civilisation, exactly?

I’d have said that strong Roman rule, with its nature of imposing Roman culture in those areas it conquered; all over Europe, one time or the other; before and after the formation of the Church, was what shaped Western Culture, with the Romans themselves borrowing from the Greeks.

But the Greeks and Spartans were at odds, most of the time.