and (conj.) Look up and at Dictionary.com
Old English and, ond, originally meaning "thereupon, next," from Proto-Germanic *unda (cognates: Old Saxon endi, Old Frisian anda, Middle Dutch ende, Old High German enti, German und, Old Norse enn), from PIE *en; cognate with Latin ante, Greek anti (see ante). Phrase and how as an exclamation of emphatic agreement dates from early 1900s.