Why do atlatls bend upward?

A little off-the-cuff discussion video. Lots of archeologic atlatls have an upward curvature. The distal end of the ventral surface is often elevated relative to the proximal end. (The spur end is higher than the handle end). Why? Pretty simple, really, and (spoiler) it's not to make the atlatl work as a spring. Apologies if this info is way too basic for everyone, but it is a question that comes up kind of a lot, so I thought it worth discussing.

[@KeefsCattys]

Excellent video, clearly explained. Many thanks

[@OKBushcraft]

Thanks for the info. Makes perfect sense.

[@Lukos0036]

Few questions. How do you impart a curve to a flat board? Where do you source your wood from? What wood do you use? Thinking of making my own.

[@BasketmakerII]

Lukos0036 Thanks for the questions-I'm uploading a video answering them. Hope it helps!

[@Lukos0036]

BasketmakerII Thanks I look forward to seeing it =D