How did scientist know prehistoric Indians existed if they didn't have a way to write things

One common educational practice is to chart students' progress over time so that students can see their own improvement. these progress charts often lead to higher student achievement in the absence of other observable forms of reinforcement. the effectiveness of such charts in changing behavior illustrates the role of reinforcement as:

What city was divided between communism and democracy/capitalism after world war 2

The platt amendment of 1901 forbade cuba from entering into any treaties that would allow undue foreign involvement in cuban affairs. this law was passed after the spanish-american war to make sure that european nations weren’t going to get involved with cuba. 1, why might the platt amendment be considered ironic? 2, what reasons would the united states have for not wanting european influence in cuba?