VOA科学技术2024--Ants Can Perform Amputations to Save Lives

Human doctors perform amputations, or removal of an arm, leg, or finger, after a serious injury. The purpose of this action is to prevent infection or disease. But humans are not alone in doing them.

New research shows that some ants perform amputations on injured ants to help them survive an injury. The behavior was documented in Florida carpenter ants, also known by their scientific name Camponotus floridanus. The reddish-brown insect is about 1.5 cm long. They live in parts of the southeastern United States.

Lifesaving care

Scientists said they observed these ants treating injured ants in the colony in two ways. They either cleaned the wound using their mouthparts or amputated the limb, or leg, by biting it off. The choice of care depended on the injury's location. When it was further up the leg, they always amputated. When it was further down, they never amputated.

Erik Frank of the University of Würzburg in Germany is the lead writer of the research. It appeared recently in the publication Current Biology. Frank said the study describes "for the first time how a non-human animal uses amputations on another individual to save their life."

He believes "that the ants' 'medical system' to care for the injured is the most sophisticated in the animal kingdom," and compares well to human medicine.

Decision made after injury

The researchers studied injuries to the upper part of the leg, the femur, and the lower part, the tibia. Such injuries are commonly found in different kinds of ants while fighting and hunting among insects and animals.

However, they watched the ants in a laboratory.

Frank said that the ants "decide between amputating the leg or spending more time caring for the wound. How they decide this, we do not know. But we do know why the treatment differs."

It has to do with the flow of hemolymph, the bluish-green fluid equivalent to blood in most invertebrates³, or animals without a backbone⁴.

Timing⁵ is important

"Injuries further down the leg have an increased hemolymph flow," Frank said. So harmful bacteria can enter the body after only five minutes. An amputation¹ would not help infection after that time.

He continued, "Injuries further up the leg have a much slower hemolymph flow, giving enough time for timely and effective amputations."

In either case, the ants first cleaned the wound using fluids from their mouth. The amputation process itself takes at least 40 minutes and sometimes more than three hours. The ants keep biting the patient at the shoulder.

The study found that after an upper leg injury, an ant who experiences amputation has a survival rate of 90 to 95 percent. For lower leg injuries in which just cleaning was performed, the survival rate was about 75 percent, compared to about 15 percent for injuries that received no care.

Ants can function well without one of their six legs. And only female ants perform the treatment of wounds by cleaning or amputation.

"All worker ants are female. Males play only a minor⁶ role in ant colonies," Frank said.

Why do the ants do this?

So why do ants do these amputations?

Frank said, "There is a very simple evolutionary⁷ reason for caring for the injured. It saves resources." He noted⁸ that if an ant could be saved with little effort to remain productive, "there is a very high value of doing so."

"At the same time, if an individual is too heavily injured, the ants will not care for her, but rather leave her behind to die," Frank added.

Words in This Story

limb - n. a leg or arm

sophisticated - adj. highly developed and complex

invertebrate² - n. a type of animal that does not have a backbone

role - n. the part that someone has in a family, society, or other group

evolution - n. a theory that the differences between modern plants and animals are because of changes that happened by a natural process over a very long time

1 amputation   

n.截肢

参考例句：

• In ancient India,adultery was punished by amputation of the nose.在古代印度，通奸要受到剖鼻的处罚。
• He lived only hours after the amputation.截肢后，他只活了几个小时。

2 invertebrate   

n.无脊椎动物

参考例句：

• Half of all invertebrate species live in tropical rain forests.一半的无脊椎动物物种生活在热带雨林中。
• Worms are an example of invertebrate animals.蠕虫是无脊椎动物的一个例子。

3 invertebrates   

n.无脊椎动物( invertebrate的名词复数 )

参考例句：

• Insects and worms are all invertebrates. 昆虫和蠕虫都是无脊椎动物。 来自辞典例句
• In the earthworm and many other invertebrates, these excretory structures are called nephridia. 在蚯蚓和许多其它无脊椎动物中，这些排泄结构称为肾管。 来自辞典例句

4 backbone   

n.脊骨，脊柱，骨干；刚毅，骨气

参考例句：

• The Chinese people have backbone.中国人民有骨气。
• The backbone is an articulate structure.脊椎骨是一种关节相连的结构。

5 timing   

n.时间安排，时间选择

参考例句：

• The timing of the meeting is not convenient.会议的时间安排不合适。
• The timing of our statement is very opportune.我们发表声明选择的时机很恰当。

6 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

7 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。

8 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。