For much of history, biologists and behaviorists assumed that intelligence of species could be neatly organized into a hierarchy. Modern man was placed at the top, followed by other mammals (哺乳动物). Then came the birds, reptiles (爬行动物) and insects.

However, research suggests that intelligence is actually distributed in different ways across the animal kingdom. In the 1960s, a new generation of researchers pushed the rest of the academic community to define animal intelligence in looser terms. They thought the conventional definition of intelligence — something made up of both consciousness and the ability for abstract thought — was too particular to our own species. Because every animal followed a completely different evolutionary journey, intelligence should be measured in relative terms instead of absolute terms.

In the following decades, a variety of technologies that allow us to observe animals for longer periods of time without disturbing their normal routines revealed that animal behaviors are far more complex than many previous thoughts. In Melbourne, some remote controlled machines are helping researchers to better understand the breeding patterns of southern right whales. Meanwhile, they use the computer to learn to understand, track and predict the movements of organisms.

Regardless of our rapidly changing conception of animal intelligence, it is best recognized when the behavior of an animal is similar to our own behavior. For example, elephants, which are said to remember and return to the tomb sites of dead members of their herd. They also exhibit an unusual interest in the dead bodies of other elephants, signaling their attention to death and perhaps even realizing their own death.

As time passes, we are continuously amazed at the level of cognitive (认知的) complexity exhibited by animals. At times, their madness can be difficult to spot. Modern technology finally allows us to look with some precision. Though the search only got underway a few decades ago, we have already discovered more similarities between animals and ourselves than we previously expected.

Researchers in Australia, who studied 1 , 500 people and their lifestyle, have found that having good friends can help you live longer. An American study of 1 0,000 students, over a period of 35 years, also found that if you make more friends than the average person at school, you’ll receive a higher salary（薪水） in later life. People need good social skills at work to manage people and work in a team successfully. These are the same skills we use to make friends at school.

On average(平均), teenagers aged between 1 5 and 1 7 have 500 “friends”on their favourite social networking site. Adults have 1 30. So if you believe this research, you might live for a long time and be very rich.

However, according to Professor Robin Dunbar from the University of Oxford, it probably won’t make any difference. Dunbar studied the number of messages between users of a popular social networking website, each of whom had between 200 and 2,000 friends. He found that they always communicate with a maximum (最大量) of 1 50 people.

Among these 1 50, Dunbar believes that around five people are close friends. You’ve mostly known them for a long time; they are probably old friends and you share all your good and bad experiences with them. Then there are ten more friends. Although they’re close to you, you may not keep in touch with them every week. Next there are 35 people who you might spend time with because of a shared interest. You aren’t close. And finally, there’s a large group of 1 00. You see or speak to these people at least once a year, but you don’t know them well. Beyond this number, Bunbar says, it’s impossible to make any relationship meaningful.

If you have a lot of online “friends”,try this experiment: First take away anyone you haven’t been in touch with for a year. Then remove people you can’t remember and, finally, take away friends who you wouldn’t mind losing touch with. How many do you have left? How many of these people are actually good friends? According to the research, these are the only people that really matter.