The fittest – those that make humans the sickest or that are tough enough to survive antibiotics, antiseptics and insurance-verification procedures survive long enough to produce new generations of even tougher bugs.
How disgusting is your keyboard? Not as bad as your skin.
According to lab studies funded by Irish office-supply company Viking, two thirds of the desks in an average office are infected with varieties of staphylococcus bacteria, a common bug that can cause anything from food poisoning to skin rashes to toxic shock.
An October study published in the African Journal of Microbiology Research showed 96 percent of common objects such as keyboards, computer mice and elevator buttons are commonly infected with a variety of pathogens, including staph and bacillus.
That all sounds horrible, of course. And it may be; about 82 percent of people coming down with communicable diseases get them from common objects like keyboards and mice.
On the other hand, staph, bacillus and many of the other species of pathogen found in high concentrations on your office equipment live so closely with humans we'd probably miss them when they're gone.
Between 20 and 30 species of staph live in the nose or on the skin of most people all the time, rarely causing infections themselves. Particularly virulent species like S. Aureus can cause skin infections, blood toxicity, and flesh-eating infections.
MRSA – an antibiotic-resistant strain of particularly nasty staph – is common in the U.S. and most common in hospitals.