Here's a familiar story.You're sitting at the dinner table with a furry, four-

legged friend scratching at your feet.When you look down, those cute eyes are almost impossible to resist.

What is it about a dog's gaze that makes it so charming？ A new study by Japanese scientist Miho Nagasawa seems to have found the answer, and it has to do with something called the cuddle(爱抚)chemical.

The cuddle chemical has another, more scientific name: oxytocin.Oxytocin is a substance in the blood that encourages bonding.Levels of oxytocin increase, for example, when a mother feeds her newborn baby.According to Nagasawa's study, the same is true when we look deeply into the eyes of a dog.

The results of this study can tell us a lot about the history of the bond between humans and dogs.It all started somewhere tens of thousands of years ago.Scientists believe that wolves used to follow humans who were hunting large animals.The wolves would eat the food left behind by the humans.

Humans realized that they could use the wolves to help with the hunt, and eventually both species began to work together toward survival.

Over time, the wolves that interacted with the humans began to change.They became more loyal to their human partners.The wolves and humans started to depend on each other and bond with each other.These changes are what caused some of the wolves to turn into what we now know as dogs, a new specie evolved to better survive in their environment.

This process depended a great deal on the bond humans formed with them.And according to Nagasawa's study, this bond was formed with the help of oxytocin, the cuddle chemical.

11.What do we know about oxytocin？()

A.It regulates blood flow

B.It promotes bonding

C.It is in the human gene

D.It is good for health

12.When we look deeply into a dog's eyes, the levels of our oxytocin ____.

A.reduce over time

B.go either up or down

C.are on the rise

D.remain unchanged

13.At the beginning wolves followed humans to ____.

A.eat the food left by humans

B.guard against large animals

C.take humans for food

D.hunt large animals together

14.Over time some wolves turned into dogs ____.

A.due to their loyalty

B.due to the changing environment

C.for better survival

D.for better cooperation

15.What does Nagasawa9s study aim to do？()

A.Explore the role of human-wolf partnership

B.Show the characteristics of the cuddle chemical

C.Explain the bond between humans and dogs

D.Understand the evolution of species