Question

insert dashes where needed.
the cradle of humankind a unesco world heritage site that is home to an abundance of early hominid fossils lies in the gauteng province of south africa.

Explanation:

Dashes are used here to set off a non-restrictive appositive phrase ("a UNESCO World Heritage Site that is home to an abundance of early hominid fossils") which adds extra, non-essential information about "The Cradle of Humankind". Em dashes (represented by the given dash) frame this phrase to separate it from the main clause.

Answer:

The Cradle of Humankind — a UNESCO World Heritage Site that is home to an abundance of early hominid fossils — lies in the Gauteng province of South Africa.