That's the third paper, talking about continuous transmission attested by archeological evidence during a period of time.

If you're restraining your though to transmission through a media like writing, recording and so on, then what about human oral cultures or pre-historical ones?

I feel the limit is much more tenuous and that it may be impossible to find something other than a difference in degree (of intelligence, communication, culture...) between species that are akin to ours.