The granular knowledge provided by gene sequencing has transformed the understanding of prehistory.
In this above line I speculate that granular knowledge means detail knowledge and gene sequencing means placing gene in correct order. If I am right then the meaning of the whole sentence is
The detail knowledge provided by gene order has changed the understanding of prehistory.
. I am not sure If I am right or wrong. It would be nice if anyone correct me.
The more granular something is, the more fine-grained it is, hence, in a figurative sense, the simpler it is, "simple" in the sense of "uncompounded".
For example, transactions with a DateTime column are temporally more granular than transactions with a simple Date column. From the DateTime transactions we could isolate transactions occurring within a particular hour of the day, say, or even a particular minute or second of the day, whereas with a Date column the greatest possible temporal refinement is the day.
While you may be right about granular knowledge, your interpretation of gene sequencing is incorrect. Gene sequencing is a laboratory process.
