Margret RoadKnight, as I'm not a musician, even to partially answer your question I'm going to have to largely rely on quotes.

"Alan Lomax {1975}.. found that across black Africa there exist
an extraordinary homogenity of African song style ..When most Africans sing they are non-tense, vocally; quite repetitious, texually; rather slurred in enunciation;,lacking in embellishment and free rhythm; low on exclusive leadership; high on antiphony; chorally; especially high in overlappping antiphony; high on one-phrase melodies; on litany form;very cohesive, toanlly and rhythmically in chorus; high on choral integration or part-singin; high on relaxed vocalizing; and highest on polyrthymic [or hot]accompaniments....

Lomax's survey shows that prominent in African culture is
the use of bodily polyrhythm, in which the trunk and the pelvis of teh dancer and teh hands and sticks of the drummer steadily maintain two seperate and conflicting meters. The non-complex structure of text and tune and the mult-leveled structure of Pygmy-Negro performance style afford added incentives for group participation, opening the door for anyone to make a contrastive and complementary personal contribution to the whole sound..
[Alan Lomax, Africanisms in New World music : in The Haitain Potential, New York; Teachers College Press]quoted in Samuel A. Floyd, Jr's "The Power of Black Music", 27

end of quote

It is this 'steadily maintaining of two seperate and conflicting meters' and the'contrastive and complementary' handclapping on the off-beat while some are clapping on beat that Jerry and I are referring to.

Also, Olly Wilson has observed in African music what he calls a 'heterogeneous sound idea' that results from 'the timbral mosaic created by the interaction between lead voice, chorus, rattle, metallic gong, hand clapping, various wind or string instruments, and drums, which exist in greater and lesser degree in almos all ensemble music. He goes on to say that the hetergeneous sound ideal is reflected in vocal music as well."
[quoted in Samuel A. Floyd, Jr's "The Power of Black Music", 28,29]

end of quote..

I've read that there is a preference in African and African descent vocal and isntrumental music for 'dirty' sounds [as opposed to 'pure'/'clean' sounds]..as reflected vocally in gritty, gravelly, hoarse voices and the addition of groans; moans,interjetions, beads added to the iron tong on finger pianos to added a buzz like sound, metal shanka shankas on djembe drums etc.

In addition see this quote from Kebede, 1982 that is cited in Floyd's "The Power of Black Music" [p.31-32}..traditional Afrian music made use, variously, of a musical vocabulary that included melodic monophony, heterophony, and polyphony; parallel thirds, 'tongue clicks, suction stops, explosive endings, throaty gurgles; ovrlaping call-and-response events; and "hand-clapping with off-beat syncopation".

end of quote

Hopefully, some musicians can 'break this down' for you..
'I know that I know' but I'm not sure that I have adequately explained off beat clapping.

Best wishes,
Azizi