Urbanization seems the key, with better nutrition and schools, more exposure to TV and print media, and improved flow of information overall. You say NO, she's thinking of fraternals. Somehow the twins wind up with differing sex chromosomes, though chromosomally identical otherwise, says Bry. Possibly the original egg had a genetic defect such as extra chromosomes, or fragments of sex chromosomes stuck to non-sex chromosomes. This abnormality may occur either very early or even after the twinning division takes place.
Communications satellites do just that.
Now its centrifugal force offsets the colossal growing weight below. Unlike Star Trek's holodecks or warp drive, at least the ladder may be feasible. Subscribe to Cincinnati's Entertainment Newsletter . The Cincinnati Enquirer , a Gannett Co. Inc. newspaper.