[thinden]

what tool did they use to drill the holes in the ivory?

[SunkenCiv]

Necessity, the mother of invention.

https://www.instructables.com/Fire-without-matches-or-metal/

https://www.loc.gov/item/2003652888/

https://vilda.alaska.edu/digital/collection/cdmg21/id/952/

[piasa]

Probably a drill made of wood with a chert tip. Could have been spun with bare hands, a pump drill or a bow drill.