ScienceIQ.com

What Is The Periodic Table?

The periodic table of the elements is a representation of all known elements in an orderly array. The periodic law presented by Dmitri Mendeleev in 1869 stated that if the (known) elements are arranged by atomic weight, then certain trends in chemical properties can be observed. That is to say, when the elements are arranged by atomic weight, then ...

Continue reading...

WhatIsThePeriodicTable
Biology

New Ideas About An Old Puzzle

There's a familiar way of talking about language as a 'tool,' but of course that's just a metaphor. Literal tools made of rock can last for millennia as evidence of the skills of early humans. Not so ... Continue reading

NewIdeasAboutAnOldPuzzle
Medicine

When and Why is Blood Typing Done?

Fans of the popular television show ER know how important blood type is in an emergency. 'Start the O-neg,' shouts Doctor Green, and the team swings into action. Green calls for type O, Rh-negative ... Continue reading

BloodTypes
Medicine

Who was Typhoid Mary?

Mary Mallon lived in New York about 100 years ago, and worked as a cook. It seemed that every family she worked for suffered an outbreak of typhoid fever! The Dept. of Public Health found that she ... Continue reading

WhowasTyphoidMary
Engineering

Making Cars Out of Soup

There was an old TV show set on a spaceship some time in the future which included a machine about the size of a microwave oven. Whenever people wanted something like a meal or a component to repair ... Continue reading

MakingCarsOutofSoup

Marmaduke and the Taco Bell Chihuahua Are Cousins

MarmadukeYou would never think Marmaduke, the enormous great dane of the newspaper cartoons, and the tiny Taco Bell chihuahua are close relatives. But the fact is, ALL dogs are pretty close relatives. Scientists now believe that all dogs, including the semi-wild dingoes of Australia, Arctic huskies, Shetland sheepdogs, great danes and tiny chihuahuas, are descended from only two original domestic dogs. DNA evidence also suggests that dogs are all derived from wolves, not coyotes or jackals.

The DNA evidence further suggests that dogs were first domesticated about 100,000 years ago. However, the first dog fossils, found in Europe and Asia, date from only 14,000 years ago. The scientists who did the DNA study think that early dogs looked so much like wolves that they can't be distinguished from them in the fossil record until about 14,000 years ago. People later took their dogs with them as they spread out over the globe, to Australia, the New World, and the Pacific Islands. Wild dogs recently discovered in the southeastern United States may be descended from the dogs kept by the Native Americans.

Domestic dogs are smaller than their wild forebears, with smaller brains, less acute senses, and smaller teeth. In appearance and behavior, they are immature, puppy-like wolves.