Rumaisa and Hiba are the world's smallest surviving twins (at least as of 2012). Born September 19, 2004 in Maywood, Illinois, Rumaisa set a Guinness world record for the all-time lowest birth weight of 9.2 ounces; her sister weighed in at a slightly heftier one pound, five ounces. Today, according to the physicians who wrote the girls' case report in an article in Pediatrics, the official journal of the American Academy of Pediatrics (Dec. 12, 2011), both have normal motor and language development. Rumaisa and Hiba are also the two smallest surviving babies born in the U.S.

The present splendid functioning of the twins affirms the fact that, tiny as they were, these two little girls are human beings. They were demonstrably viable at an exceedingly low birth weight. Can an unborn child be too small to be considered human? Would humans lose their humanity if they got smaller? An example from a children's book makes a great point.

In Dr. Seuss's children's book Horton Hears a Who! (1954), Horton the Elephant hears a small speck of dust talking to him. The speck of dust is actually a minuscule planet populated by microscopic creatures known as "Whos." Horton, thanks to his large elephant ears, is able to hear the "Mayor of the Whos" quite well and agrees to protect the Whos from harm. "After all," Horton proclaims throughout the book, "a person's a person, no matter how small." The point here is more philosophical than biological. Size is relative, and it is prejudicial to assume that being too small is a disqualification for being a person.