Robert was born or died about 1712.
Per Mr. F. Pittman has a Y-DNA 37-Marker Match at FamilyTreeDNA with 3 Step Removed from Donovan Brown. I-M253/I-FTD56372 Haplogroup. Abbotsbury, Weymouth, Dorset, UK.
Based on a Genetic Distance of 3 at the Y-37 test level, Donovan Brown and F. Pittman are estimated to share a common paternal line ancestor who was, with a 95% probability, born between 1000 and 1800 CE. The most likely year is rounded to 1500 CE.
Donovan's 2nd GGF: https://www.wikitree.com/wiki/Brown-168375
Donovan and Mr. F Pittman do not appear to be currently in the Pittman DNA Project, please join. Jef Treece