I have removed the following as it's speculation and is very long:
T'Pol prefaced her statement about abductions on Earth with "If I'm not mistaken", and in fact may have been. In reality, alien abduction cases entered the popular consciousness in the 1960s, which when you add the minimum of two centuries implied would suggest that alien abduction beliefs were still alive in 2151, which seems inconsistent with the past tense of the statement. A possible solution would be that she viewed alien abductions as a continuation of earlier, supernatural abduction narratives, a common interpretation amongst mythologists.
Obviously a large number of aliens have engaged in abducting people on Star Trek, often even as a common practice, for example the Borg, Caretaker or Nyrians. One example that is particularly notable is Barash's species, which actually resembles the "Grey" aliens common in abduction lore.
In 4000 BC, Humans were abducted from Earth to the hidden Assigners' planet approximately 1,000 light years away, where they and their descendants were given knowledge of future events and trained to work as agents on Earth to prevent Human civilization from destroying itself before it had the chance to mature into a peaceful society. (TOS: "Assignment: Earth")
Adding refs even if the term isn't used is one thing, but in neither case was it explicitly said that these Humans were abducted. For all we know these (seemingly benevolent & humanitarian) civilizations just went to the guys, honestly explained the situation, and got them to agree to be taken away from Earth. -- Capricorn 11:28, August 30, 2011 (UTC)
Here's another recently added section I've removed. Crop circles are not associated with cornfields, and the line is in any case more likely to be a reference to Klaang. -- Capricorn (talk) 09:38, July 16, 2012 (UTC)
As a reference to the crop circle phenomenon, CaptainJonathan Archer jokingly stated, that this must be why aliens always land on corn fields.