Q: When naming the occupants of your household, you might start with yourself, then your spouse, your two kids and the family dog, for a total of five. What well-documented group have you not included in your list?

A: They are creepy-crawlies, averaging about 100 different species in each house, according to the first comprehensive census of house-dwelling arthropods, reports "New Scientist" magazine. Some are accidental visitors, others are part of "an intricate ecosystem" relying on food crumbs and nail clippings. Including 50 detached houses in Raleigh, N.C., the survey found 579 species of spiders, beetles, mites, flies, ants, etc. Residents of the houses were shocked and even horrified, "so we had to calm them down by saying it was normal," said survey leader Matt Bertone.

Thus do modern homes teem with unseen life, a far cry from the sterile deserts imagined by some observers. "The biggest surprise was finding at least one species in almost every room, with only five of the 554 rooms drawing a blank," says Bertone. Some like cobweb spiders and booklice have adapted to live in human homes permanently.

Q: One week each year for the past 14 years, German astrophysicist and science historian Mathieu Ossendrijver trekked to London's British Museum to study ancient Babylonian cuneiform tablets (dating from 350 to 50 B.C.E.) describing the motion of the planet Jupiter. Why, he wondered, is a trapezoid — a rectangle with a slanted top — referenced among the arithmetical calculations?


A: When the answer dawned on him, it rewrote a chapter of the history of mathematics, reports Ron Cowen in "Science" magazine. The trapezoid proved to represent a plot of Jupiter's speed versus time, showing that the Babylonians understood that the area was the distance Jupiter traveled. This concept of the area beneath a speed-time curve equaling distance is part of the branch of mathematics called calculus, which historians had long thought was invented in 14th-century Europe. As New York University historian Alexander Jones puts it, the new findings "testify to the revolutionary brilliance of the unknown Mesopotamian scholars who constructed Babylonian mathematical astronomy."

Q: "Backward," "backsliding," "backtracking," "having some backbone," "backcracking," "watch your back," "get off our backs" Let's get back to basics here on this central body part. Can you cite a few of them?

A: The human back is a marvel of load-bearing support and flexibility, though it is given to much pain, as you may know all too well from first-hand experience. Back problems have been "the scourge of our species," says Gemma Tarlach of "Discover" magazine. From top to tail, the standard 33 vertebrae include seven cervical, 12 thoracic, five lumbar, five sacral and four coccygeal, though this number can vary between 32 and 35, with the pelvic area accounting for the biggest range of difference.

"Back-cracking was widespread throughout the ancient world — for better or worse. Hippocrates, for example, advocated strapping someone with an abnormally curved spine to a ladder, and then dropping the ladder (and patient) from a height. Don't try this at home, kids."

And though the saying "watch your back" is commonly believed to derive from military tactics, according to the Oxford English Dictionary, it first appeared in Lee Floren's 1949 Western novel "Milk River Range." Disagree? Tarlach's answer: "Hey, we're just telling you what's in the OED so, you know, get off our backs (a saying with roots in the 17th century)."

Send STRANGE questions to brothers Bill and Rich at sbtcolumn@gmail.com