Résultats Éditeur "Charles River Editors" dans Sciences biologiques

As the oft-repeated and invariably accurate pearl of wisdom goes, a dog truly is man's best friend. For a long time, people have almost universally loved dogs, and it seems to have been that way for at least tens of thousands of years. When affection is abundantly and consistently expressed, this pure, unspoken, wholesome love is one that is very much requited, and then some. This bond can be demonstrated by the mere existence of pet keepers who unironically refer to themselves as “dog parents,” not merely “dog owners”.

The early history of Earth covers such vast stretches of time that years, centuries, and even millennia become virtually meaningless. Instead, paleontologists and scientists who study geochronology divide time into periods and eras. The current view of science is that Earth is around 4.6 billion years old, and the first four billion years of its development are known as the Precambrian period.

The evolutionary path from the original primates to modern man is a long one and has taken many twists and turns, but naturally, as the fossil record grows, scientists gain a more complete understanding of our own mental and physical history in terms of genetics and anatomy. However, the correct order and relationships of the various specimen types are difficult to pin down.

The early history of our planet covers such vast stretches of time that years, centuries, and even millennia become virtually meaningless. Instead, paleontologists and scientists who study geochronology divide time into periods and eras. The current view of science is that planet Earth is around 4.6 billion years old. The first four billion years of its development are known as the Precambrian period.

It has long been a maxim that it is easy to forget when one is at war who the enemy really is, and that can certainly be said for the Ebola virus, which recently catapulted into headlines and instantly became the most feared disease in the world. In the case of the fight against Ebola, the enemy is not the person who has contracted the disease, nor is it the region where the virus has flourished. The enemy is a microscopic virus that, when seen under sufficient magnification, looks like a piece of loosely knotted rope.

The early history of Earth covers such vast stretches of time that years, centuries and even millennia become virtually meaningless. The first four billion years of its development are known as the Precambrian period. For the first billion years or so, there was no life in Earth. Then the first single-celled life-forms, early bacteria and algae, began to emerge. We don’t know where they came from or even if they originated on this planet at all.

Mankind's obsession with felines is an enigma in and of itself. Unlike dogs, famously known as man's most excitable, trustworthy, and loyal friend, cats are oftentimes indifferent, guarded, and yet finicky little furry creatures that only yearn for attention and affection when one is neck-deep in work or otherwise preoccupied. And still, people adore them all the same.

Imagine a feline with the spirit of a lion, the sneakiness of a puma, the terrifying walk of a black bear, and the strong arms of a gorilla. This amazing creature was best known as the saber-toothed tiger, an animal so fearless, it could beat beasts even twice their size! After dinosaurs, few vanished animals are as famous as the woolly mammoths, or in 18th-century scientist George Cuvier’s words, "some kind of extinct elephant".

Scientists have long attempted to understand Earth’s past, and in service to that effort, they have divided the world’s history into eons, eras, periods, epochs, and ages. For example, the current eon is called the Phanerozoic Eon, which means “visible life”. This is the eon in which multicellular life has evolved and thrived. Before this, life was microscopic (single cells).

It is difficult to ignore the effortless cool of a saber-toothed tiger. The fanged feline was equipped with the savage strength of a lion, the lethal stealth of a puma, the intimidating gait of a black bear, and the strapping, muscular arms of a gorilla. Amazingly, however, those traits did not stand out as much as the long, dagger-like fangs that earned the Smilodon its famous nickname. The saber-toothed tiger, legend has it, was as ferocious as it was fearless, often tackling beasts twice its size.

At one point or another, just about everyone has heard of the dodo bird, which is almost universally described as a cuddly, whimsical creature renowned for its alleged stupidity. This prehistoric avian had been known for hundreds of years, before it was made popular around the world in Lewis Carroll’s 1865 classic Alice's Adventures in Wonderland.

The acrid stench of asphalt and sulfur singes the hairs of people’s nostrils, and when the blustering winds subside, the potent miasma lingers in the air. To the untrained eye, the La Brea Tar Pits seem to be nothing more than simply pools of thick, viscous black sludge...The pit’s contents have spelled the doom for a countless number of creatures both large and small, from legions of insects to mighty mastodons, mammoths, and snarling saber-toothed cats from the Pleistocene Era. La Brea Tar Pits are considered by many scientists to be among the greatest finds in modern history.

The oceans of the world have always had an air of mystery. About 71% of the Earth's surface is covered by water, and until the 20th century no one had plumbed its depths. Even today the bigger seas and oceans remain a largely unexplored frontier, with new species being discovered every year. Thus it comes as no surprise that countless legends have arisen of strange creatures lurking in the depths.

The largest structure ever built was not made by humans, but by incredibly tiny organisms known as coral polyps. Over the course of tens of thousands of years, these small organisms have put together a collection of nearly 3,000 reefs, known as the Great Barrier Reef, which form a collective stretching across 130,000 square miles. Scientists have counted about 1,500 different fish species that use the reef, and it's estimated that 1.5 million birds use the site.

The Mesozoic Era, which lasted from about 252 to 66 million years ago, is divided into three periods, the Triassic, Jurassic, and Cretaceous. During this era, one type of life came to dominate the planet more completely and for a longer period than had been seen before or since; this was the Age of Reptiles. Beginning in the Triassic but especially in the Jurassic period, reptiles came to dominate the oceans, the land and even the skies.

The current view of science is that Earth is around 4.6 billion years old. The first four billion years of its development are known as the Precambrian period. For the first billion years or so, there was no life on Earth, and then the first single-celled life-forms, early bacteria and algae, began to emerge. It’s unknown where they came from or even if they originated on this planet at all, but this gradual development continued until suddenly (in relative geological terms), more complex forms of life began to emerge.