Amaranthus, Capsicum, Chenopodium, Cucurbita, Heli- 
anthus, Lycopersicon, Psidium, Salvia and Solanum. 
Many other plants, such as the cacti and fruit trees, must 
have been selectively encouraged before agriculture be- 
gan, just as they are at the present day. 
Anderson, in particular, has emphasized the role played 
by man in the dispersal of useful plants into new areas. 
This allows hybridization between varieties, and hybrid- 
ization and introgression between related species. Both 
of these processes serve at times to promote ‘‘weediness’’ 
and always to increase the variability of the populations 
involved, a very important factor in the origin and de- 
velopment of cultivated plants (7, 10, 126). This rela- 
tionship between man and useful plants doubtless began 
before agriculture, when man first carried a fruit with 
him for a while before eating it, thus discarding the seed 
in a new area. 
One cannot discuss the origins of New World agri- 
culture without mentioning the question of trans- Pacific 
cultural contact. Evidence has been presented concern- 
ing several cultivated plants, notably Gossypium, Ama- 
ranthus, Ipomoea, Lagenaria and Cocos, which has been 
interpreted as indicating early cultural contact between 
southeast Asia and tropical America (69, 105, 178). This 
evidence has been discussed at length and opinion is 
sharply divided (89, 40, 108, 128, 188, 189). This con- 
troversy has brought forth, on one extreme, vituperative 
and dogmatic insistence that no such contact has or could 
have occurred, and, on the other hand, the wildest flights 
of faney, in which all high cultures are derived directly 
and apparently recently from a single source. I have not 
cited the extremes on the more fanciful side as they are 
based largely on non-botanical arguments, if any. They 
are, however, often associated with other less imaginative 
views, much to the detriment of the latter. Though the 
[ 158 |] 
