Archaeological research in the Gulf Coast of Tabasco reveals the earliest r
ecord of maize cultivation in Mexico. The first farmers settled along beach
ridges and lagoons of the Grijalva River delta. Pollen from cultivated Zea
appears with evidence of forest clearing about 5100 calendar years B.C. (y
r B.C.) [6200 C-14 years before the present (yr B.P.)]. Large Zea sp. polle
n, typical of domesticated maize (Zea mays), appears about 5000 calendar yr
B.C. (6000 yr B.P.). A Manihot sp. pollen grain dated to 4600 calendar yr
B.C. (5800 yr B.P.) may be from domesticated manioc. About 2500 calendar yr
B.C. (4000 yr B.P.), domesticated sunflower seeds and cotton pollen appear
as farming expanded.