Study: Empathy May Have Ancient Roots

A new study suggests that our ability to share other's feelings, also called empathy, may have very ancient beginnings.

The study, published recently in Science, says our ability to share experiences might have existed in animals that lived millions of years ago. It would be before fish and mammals took different evolutionary¹ paths.

Scientists generally resist assigning humanlike feelings to animals. But it is generally accepted that many animals have emotions, including fish.

The new study shows that fish can sense fear in other fish, and then become afraid themselves. This ability, the study says, is controlled by oxytocin, the same brain chemical that plays a part in human's ability to experience empathy.

The researchers investigated by deleting genes² linked to the production and absorption of oxytocin in the brains of zebrafish. The small tropical fish is often used in research.

The fish became antisocial after the treatment. They failed to sense or react when other fish showed worry.

After some of the changed zebrafish received oxytocin injections, their ability to sense and react to others' feelings returned. Scientists call the brain process "emotional contagion³."

Ibukun Akinrinade of the University of Calgary was a co-writer of the study. Akinrinade said about the fish, "They respond to other individuals being frightened."

In that way, "they behave just like us," she said.

Past research has shown that oxytocin plays a similar part in transmitting fear in mice.

The new research shows the " ancestral role" of oxytocin in transmitting emotion, said study co-writer Rui Oliveira of Portugal's Gulbenkian Institute of Science.

This brain processing "may have already been in place around 450 million years ago, when you and me and these little fish last had a common ancestor," explained Hans Hofmann of the University of Texas at Austin. Hofman was not involved in the research.

Oxytocin is sometimes thought of as a "love" hormone⁴, but Hofmann said it is actually more like "a thermostat⁵ that determines what is socially" important in a situation – activating⁶ parts of the brain "that may make you run from danger" or take part in mating or reproduction.

Such a thermostat could be important for the survival of many animals, especially those who live in groups, said Carl Safina of Stony⁷ Brook⁸ University. Safina was not involved in the study.

"The most basic form of empathy," he said, "is contagious⁹ fear – that's a very valuable thing to have to stay alive...."

Words in This Story

mammal -- n. a type of animal that feeds milk to its young and that usually has hair or fur covering most of its skin

evolutionary -- adj. describes the process by which changes in plants and animals happen over time

absorb – v. to take in (something, such as a liquid) in a natural or gradual way

respond -- v. to do something as a reaction to something that has happened or been done

transmit -- v. to give or pass (information, values, etc.) from one person to another

thermostat – n. a device that automatically adjusts the temperature in a room to a desired level

1 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

2 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

3 contagion   

n.(通过接触的疾病)传染；蔓延

参考例句：

• A contagion of fear swept through the crowd.一种恐惧感在人群中迅速蔓延开。
• The product contagion effect has numerous implications for marketing managers and retailers.产品传染效应对市场营销管理者和零售商都有很多的启示。

4 hormone   

n.荷尔蒙，激素，内分泌

参考例句：

• Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
• This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。

5 thermostat   

n.恒温器

参考例句：

• The thermostat is connected by a link to the carburetor.恒温控制器是由一根连杆与汽化器相连的。
• The temperature is controlled by electronic thermostat with high accuracy.电子恒温器，准确性高。

6 activating   

活动的，活性的

参考例句：

• "I didn't say we'd got to stop activating the masses! “我并没说就此不发动！ 来自子夜部分
• Presumably both the very small size and activating influence of fluorine atoms contribute to this exception. 这大概是由于氟原子半径小和活性高这两个原因的影响，氟原子对这种例外做出了贡献。

7 stony   

adj.石头的，多石头的，冷酷的，无情的

参考例句：

• The ground is too dry and stony.这块地太干，而且布满了石头。
• He listened to her story with a stony expression.他带着冷漠的表情听她讲经历。

8 brook   

n.小河，溪；v.忍受，容让

参考例句：

• In our room we could hear the murmur of a distant brook.在我们房间能听到远处小溪汩汩的流水声。
• The brook trickled through the valley.小溪涓涓流过峡谷。

9 contagious   

adj.传染性的，有感染力的

参考例句：

• It's a highly contagious infection.这种病极易传染。
• He's got a contagious laugh.他的笑富有感染力。