Can anyone explain why the answer to 16 dn. - 1 down of bicentenarian given gab with his large heart? (3,5) - is LOG CABIN. 1 down is ORIGIN and bicentarian relates to Darwin but from other answers bicentaria also relates to Lincoln and the Gettysburg address.
LOG CABIN is an anagram of GAB and [L]INCOL[N], i.e. Lincoln's "large heart" is INCOL.
So "large heart" is being used to distinguish it from just C or NCO which might be clued by just "heart".
And Lincoln was famous for being born in a Log cabin (on 12-FEB-1809)
I was fooled by the double bicentennary being used as a theme, and I was intrigued that neither Darwin nor Lincoln explicitly appeared in the answers.