There’s a reason why dogs are called man’s best friend. Dogs and cats make wonderful companions and provide many emotional and physical benefits.

The most obvious benefits of pet ownership are love and companionship. We feel especially secure with dogs and cats because of the unconditional love they provide. 【小题1】 Taking care of a dog or a cat can provide a sense of purpose and a feeling of being accepted.

【小题2】 When you feel securely attached to this living being, there are biological brain effects that reduce stress response, so it may affect your breathing rate or blood pressure or anxiety level.

It’s not always easy caring for pets, however. Sometimes having them in the home poses safety threats for older adults. If you have problems with walking and stability and your pet can get under your feet or jump up and knock you over, then falls and broken bones are a real danger. 【小题3】 Animals carry all kinds of bacteria that can be transferred to humans. Dogs and cats can also cause allergic (过敏的) reactions in some pet owners.

Before getting a pet, consider if you’re physically and mentally able to care for it. 【小题4】 Do you have the energy and strength to feed it, play with it, and in the case of dogs, take it for daily walks? Do you have the financial means to pay for pet food and visits to the veterinarian (兽医)?

If you feel you have the mental, physical, and financial means to care for a pet, take the pet’s size into consideration — not too big and not too small. And consider the animal’s personality. 【小题5】

The latest in cat research reveals that the lovely animal seems to have a basic grasp on both the laws of physics and the ins and outs of cause and effect.

According to a newly published study, cats seem to be able to predict the location of hiding prey (猎物) using both their ears and an inborn (天生的) understanding of how the physical world works.

In a recent experiment, Japanese researchers taped 30 domestic cats reacting to a container that a team member shook. Some containers rattled (发出响声); others did not. When the container was tipped over, sometimes an object fell out and sometimes it didn’t.

It turns out that the cats were remarkably smart about what would happen when a container was tipped over. When an object did not drop out of the bottom of a rattling container, they looked at it for a longer time than they did when the container behaved as expected.

“Cats use a causal-logical understanding of noise or sounds to predict the appearance of invisible objects,” lead researcher Saho Takagi says in a press release. The researchers conclude that cats’ hunting style may have developed based on their common-sense abilities to infer where prey is, using their hearing.

Scientists have explored this idea with other lovely creatures: babies. Like cats, babies appear to engage in what’s called “preferential looking”—looking longer at things that are interesting or unusual than things they perceive as normal.

When babies’ expectations are not met in experiments like the ones performed with the cats, they react much like their animal friends. Psychologists have shown that babies apparently expect their world to obey the laws of physics and cause and effect as early as two months of age.

Does the study mean that cats will soon grasp the ins and outs of cause and effect? Maybe, Okay, so cats may not be the next physics faculty members at America’s most important research universities. But by demonstrating their common sense, they’ve shown that the divide between cats and humans may not be that great after all.

Imagine an albatross (信天翁) with a hacksaw for a mouth. Set that strange creature about 50 million years in the past and you’ve got the image of a pelagornithid, a group of ancient birds that included some of the largest flying birds of all time.

Now paleontologists have uncovered in that group what may be the largest known flying birds ever, with wingspans of roughly six meters. By comparing a pair of polar fossils to the remains of related birds, paleontologists have been able to identify the early history of huge fliers that were some of the first birds capable of flying across seas.

During the 1980s, University of California Berkeley paleontologist Peter Kloess says, scientists searching for Antarctic fossils found some delicate bird bones — a jaw and part of a foot from an ancient bird.

The bird jaw, which came from a rock formation laid down over 37 million years ago, looks almost like a woodcutting tool rather than a bone. The jaw has a series of large and small spikes, outgrowth s of the beak that are similar to teeth. Because of that feature, the paleontologists immediately identified the jaw as belonging to a pelagornithid, also known as bony-toothed birds that have a very long fossil record. The oldest pelagornithids evolved about 56 million years ago, and the most recent flew through the skies about two million years ago.

The foot bone came from another large Antarctic pelagornithid, but its real importance was in its age. The fossil was found in a rock layer in the La Meseta Formation, about 50 million years old. This falls within a time called the Eocene, when life had recovered from the asteroid-induced mass extinction and was thriving again. Together, the foot bone and the jaw indicate that large bony-toothed birds thrived in the Antarctic for millions of years.

Paleontologists have found bony-toothed birds from places all over the world, from New Zealand to South Carolina. The newly-described Antarctic fossils, though, are the oldest known and hint that these birds quickly diversified into a range of sizes within six million years of their origin. Previous studies have calculated that the largest of the bony-toothed birds could be near the limit of how big a bird could get and still fly, meaning these birds are the strongest competitors for the largest flying birds to ever fly.

Those impressive wings would have allowed the pelagornithids to range far and wide, flying long distances on outstretched wings. That helps explain why fossils from various species of pelagornithids have been found all over the world during their extended evolutionary period.