Many people have this false notion that people are being abducted because the aliens just want to study human beings. This is incorrect. The purpose of abductions focuses on reproductive matters, i.e. the harvesting of sperm and ova, gynecological exams, the implantation of fetus, the removal of fetuses, the touring of a "nursery" in which fetuses are maturing in artificial wombs, and the presentation of strange-looking babies which look part alien and part human.
Other tests are indeed performed on abductees. Certain neurological procedures and physical tests do occur but these are secondary in importance. The emphasis is on reproduction.
From the very first case of a reported alien abduction this reproductive emphasis was apparent. It was still apparent in the first reported case of abduction in the U.S, i.e. the Betty & Barney Hill abduction. It is still apparent today.
The first abduction report was made by Antonio Villa Boas. His experience occurred in 1957 but didnt' receive wide-spread media attention in the U.S. until AFTER the Betty & Barney Hill case. Boas was forced to mate with a strange looking female and actually begged that this be kept from the report. During the Betty & Barney Hill experience, Barney had a sperm sample taken from him and he did not want this to appear in the book, so it was withheld. This is important because Barney did not know of Boas' experience, and later male abductees who reported sperm samples being taken from them were not aware of Barney Hill's experience. This is a form of corroboration. Additionally, Betty had a "pregnancy test" administered on her that involved a long needle that was inserted into her navel.
Alien abductions center around reproduction. That is the core reason for the abduction. The aliens are not picking up people to study them. They are picking up people for reproductive purposes.
Antonio Villas Boas