Q. Aren't we humans all one big family - and not just metaphorically speaking?

A. If you trace your family tree back just 30 generations, and assume 25 years for a generation, your ancestry over this 750 years encompasses first 2 parents, then 4 grandparents, 8 great-grandparents, 16 great-greatgrandparents, 32 great-great-great-grandparents, 64, 128, 256, 512, 1024, 2048. . . finally, 1,073,741,824 people!

But 750 years ago it was the 13th century and there were fewer than a billion people in the world. Which means that more recently than a scant 30 generations ago your mother's and father's gene lines were merged, with ancestors common to both.

Follow your lineage back 50 generations and the number of common parental ancestors grows enormous. In fact, estimates Guy Murchie in "The Seven Mysteries of Life," the entire human species can be encompassed "within the scope of fiftieth cousinhood."

If this estimate is correct, it would mean that "your own ancestors, whoever you are, include not only some blacks, some Chinese and some Arabs, but all the blacks, Chinese, Arabs, Malays, Latins, Eskimos and every other possible ancestor who lived on Earth around A.D. 700. It is virtually certain therefore that you are a direct descendant of Muhammad and every fertile predecessor of his, including Krishna, Confucius, Abraham, Buddha, Caesar, Ishmael and Judas Iscariot."

Q. You're going in for surgery that requires general anesthesia. Any chance you'll be able to overhear what the operating team says while you're unconscious?

A. Don't rule it out. A woman named Karen had an oral cyst removed, then was told in the recovery room that everything was just fine, report Philip Zimbardo and Ann Weber in "Psychology." But for days afterward she felt depressed and at night had bad dreams.

Hypnotized by a therapist who asked her what was wrong, she blurted out: "The cyst may be cancerous!" This, it turned out, was exactly what the surgeon had said minutes into the operation, before a biopsy proved him wrong.

Karen's depression lifted after she received assurances the cyst was indeed benign.

Karen's case is not unusual. "Our hearing sensitivity appears to remain on alert even under adequate anesthesia. . . . Because of this sensitivity, even casual remarks in the operating room can be dangerous." On the positive side, "therapeutic suggestions during anesthesia may improve patients' postoperative recovery, as shown by reduced use of morphine and earlier discharge."

Q. The Earth is an estimated 4 1/2 billion years old. If geologic time were somehow compressed into a single calendar year, on what date would human beings appear?

A. On January 1, Earth formed out of matter surrounding the sun, then in mid-March the oldest known rocks formed, sea life sprang up in May, plants and animals emerged in late November, dinosaurs ruled in mid-December but bowed out by December 26, say Paul Hewitt et al. in "Conceptual Physical Science."

Our species Homo sapiens wouldn't make its debut until December 31 at around 11:00 p.m. All of recorded history would take place in the last few seconds of New Year's Eve!