Why are successive layers of periderm formed in mature woody dicot roots?

Many archeologists and anthropologists disagree with dr. thorne's view.  thorne strongly believes that what many calls "homo erectus"  was in fact  homo sapiens,  and that they migrated out of africa almost 2 million years ago and dispersed throughout europe and asia. that's way different  from what scientists have always believed about the evolution of the species.

25 ) where the jellyfish were counted at

Iwould assume they all have the sun in the center.

The answer is proteins