Scientific American - Ask the Experts

Why haven't we evolved eyes in the backs of our heads?

Thu, 02 Jul 2009 11:00:00 EST

As much as we might appreciate the value of detecting predators that approach from behind--or of keeping an eye on the offspring who follow us--it is important to remember that selection is not directed toward the development or formation of anything, let alone “perfect” organs. In other words, just because some feature seems like a good idea, random mutation and selection will not necessarily fashion it.

Body parts that enable us to detect the sights, sounds, smells, tastes, temperature and tactile elements of our environment did not arise from some master plan or blueprint. Rather selection crafted body parts from available components of cells and tissues within existing forms of life, molding ancient and intermediate versions of sensory cells and organs--each elegant in its own right--like lumps of clay over aeons into the shape and form of our modern bodies. There have never been perfectly formed organs for sight or hearing--just versions that get the job done.

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How Do Stress Fractures Develop?

Thu, 02 Jul 2009 08:00:00 EST

Considering the forces involved in many sports, it's no surprise that professional athletes sustain serious injuries to their muscles, ligaments, tendons and bones. A spate of bone fracture–related injuries seems to be dogging professional teams this year. The Houston Rockets of the National Basketball Association lost seven-time all-star Tracy McGrady to season-ending microfracture surgery in February. And on Monday, Rocket’s team physician Tom Clanton announced in the Houston Chronicle that all-star center Yao Ming's fractured foot, which he sustained in a play-off game against the Los Angeles Lakers in May, has worsened over time and may end his career. The possibility that New York Mets centerfielder Carlos Beltran might have a microfractured knee turned fans and fantasy baseball owners into nervous wrecks. Such an injury ended the career of NBA star Jamal Mashburn.

So how do these fractures develop? And why can they have such impact on athletes' careers, in some cases forcing players into early retirement? To find out, we turned to Howard Palamarchuk, a former Olympic-class race walker who is the director of sports medicine at Temple University School of Podiatric Medicine.

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How Does Geothermal Drilling Trigger Earthquakes?

Mon, 29 Jun 2009 13:38:00 EST

Despite the promise of cheap, clean power, geothermal energy development may be on shaky ground. There have been rumblings from residents and scientists alike that drilling deep to tap naturally occurring heat could cause bigger earthquakes. [More]

What is a pitot tube?

Tue, 09 Jun 2009 20:55:00 EST

As Brazilian authorities retrieved 16 more bodies from the Air France Flight 447 crash this morning, investigators were focusing on airspeed indicators called pitot tubes as the cause of the disaster. [More]

Is there such a thing as "cell phone elbow"?

Thu, 04 Jun 2009 19:35:00 EST

As CNN and others are reporting, an increasing number of cell phone gabbers are complaining of an ailment called "cell phone elbow." Here are the symptoms: pain or numbness in the hand--especially the pinky and ring fingers. Not to be confused with tennis or golfer's elbow (forms of tendonitis), this new diagnosis stems from the nerves that run through the elbow. [More]

Why do whales beach themselves?

Mon, 01 Jun 2009 17:30:00 EST

On Sunday morning, scientists and volunteers struggled to get some of the 55 false killer whales that washed up on a beach near Cape Town, South Africa, back into the frigid water. [More]

What is Hemoglobin A1c?

Fri, 29 May 2009 17:50:00 EST

If she makes it through the nomination process, Judge Sonia Sotomayor would not only be the first Hispanic to sit on the U.S. Supreme Court, she would also be the first member with type 1 diabetes. [More]

Can You Lose Your Fingerprints?

Fri, 29 May 2009 16:38:00 EST

A 62-year-old man from Singapore was traveling to the U.S. to see relatives last December and was detained after a routine fingerprint scan showed that he actually had none. So how did this happen? [More]

Why do two great tastes sometimes not taste great together?

Fri, 22 May 2009 08:00:00 EST

Why do two things I like to eat sometimes taste so bad when eaten together? --R. Lange, Houston

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What is Morgellons Disease? Is it a physical or psychological condition?

Wed, 13 May 2009 16:15:00 EST

Last year, the U.S. Centers for Disease Control and Prevention (CDC) launched a study of a curious and controversial condition known as Morgellons disease, which is characterized by creeping, crawling and stinging sensations under the skin. [More]

How do marine mammals avoid freezing to death?

Wed, 13 May 2009 14:40:00 EST

Whales, dolphins, seals and other marine mammals can generate their own heat and maintain a stable body temperature despite fluctuating environmental conditions. Like people, they are endothermic homeotherms--or more colloquially, "warm-blooded." [More]

Why don't trees lean toward the equator?

Fri, 08 May 2009 09:00:00 EST

Indoor plants tend to grow toward the light, so why do trees outdoors grow straight instead of leaning toward the equator? --W. Anderson, Sacramento, Calif.

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Is Cellulite Forever?

Mon, 04 May 2009 15:25:00 EST

Editor's Note: This story is part of an In-Depth Report on the science of beauty. Read more about the series here. [More]

Why Should We Worry about Swine Flu?

Wed, 29 Apr 2009 14:09:00 EST

Swine flu is sweeping--if not the nation, then at least the nation's media. But what is special about this virus and what, if anything, should ordinary citizens do about it? [More]

What is a megamouth shark? Is it still a scientific mystery?

Thu, 09 Apr 2009 20:00:00 EST

On the morning of March 30, fishermen casting their nets in the Burias Pass, a centrally located channel in the Philippine archipelago, got the catch--not to mention surprise--of their lives: a megamouth shark so rare that some people still consider it a "cryptid", a creature that is seen so infrequently science can't confirm its existence. [More]

When air is the same temperature as our body, why do we feel hot?

Wed, 08 Apr 2009 09:00:00 EST

"If normal body temperature is about 98 degrees Fahrenheit, why do we feel hot at that air temperature?" --S. Meyer, Melbourne, Fla. [More]

Can someone live to be a supercentenarian?

Wed, 01 Apr 2009 20:15:00 EST

And you thought you felt old: Last week, in the village of Prishakhtinsk in central Kazakhstan, Sakhan Dosova celebrated what she, her family and Kazakh officials all agree was her 130th birthday. If true, her advanced age would shatter the old-timer record set by Jeanne Calment, who died in Arles, France, in 1997 at the age of 122. [More]

What is norovirus? How Contagious is it? Can it be fatal?

Mon, 30 Mar 2009 19:20:00 EST

An outbreak of stomach flu believed to be caused by norovirus has prompted a temporary shutdown of Babson College, a small business college and graduate school in Babson Park, Mass. School officials announced that classes, meetings, athletic events and all other activities would be canceled until Wednesday, when the school is expected to have the outbreak under control. [More]

Do dangerous spiders lurk in grocery store produce?

Tue, 24 Mar 2009 18:10:00 EST

Last week, a store manager at a Whole Foods in Tulsa, Okla., was surprised--to say the least--to find a large brown spider lurking in a bunch of bananas. The spider was initially identified as a Brazilian wandering spider, a menacing-looking creature with furry fangs and legs as long as five inches (12.5 centimeters) that is considered to be one of the world's most venomous spiders, and one of the few that can kill humans. (Luckily, an anti-venom to the Brazilian’s bite was developed in 1996.) [More]

What is "talk and die" syndrome?

Wed, 18 Mar 2009 15:55:00 EST

Last night, British-born actress Natasha Richardson, 45, was rushed from Montreal to New York City in critical condition after a seemingly minor fall on a Quebec ski slope apparently led to bleeding in her brain. [More]