VOA科学技术2023--Researchers Make Surprising Discovery about Ancient Mosquitoes

Researchers Make Surprising Discovery about Ancient Mosquitoes

Hundreds of thousands of people worldwide are killed every year by malaria¹ and other diseases that are spread through mosquito bites.

Female mosquitoes are responsible for these deadly bites because they have a special mouth design that male mosquitoes do not have.

But it has not always been that way. Researchers said they have discovered the oldest-known fossils of mosquitoes - two males located in pieces of an ancient orange-colored substance known as amber².

The male mosquitoes date to 130 million years ago. They were found near the modern town of Hammana in Lebanon. To researchers' surprise, the male mosquitoes had long mouthparts seen now only in females.

Dany Azar is a researcher at the Chinese Academy of Sciences' Nanjing Institute of Geology and Paleontology and Lebanese University. Azar said they were clearly blood-eaters. The lead writer of the study, recently published in Current Biology, added, "This discovery is a major one in the evolutionary³ history of mosquitoes."

The two fossilized mosquitoes, both representing the same species that has died off, are similar in size and appearance to modern mosquitoes. However, the mouthparts used for getting blood are shorter than in today's female mosquitoes.

Study co-writer André Nel of the National Museum of Natural History of Paris described the finding as "quite surprising."

The special anatomy⁴ of the two mosquitoes was beautifully saved in the fossils. Both insects had sharp and triangle-shaped jaw⁵ anatomy and a long structure with tooth-like elements.

The researchers said they suspect that mosquitoes evolved from insects that did not consume blood. They think that the mouthparts that were developed for getting blood meals were originally used to pierce plants to get nutritious⁶ fluids.

Plant evolution may have affected⁷ the differences in feeding between male and female mosquitoes. At the time when these two mosquitoes became stuck in tree sap that eventually became amber, flowering plants were beginning to spread for the first time.

From the findings, Azar said that all early mosquitoes, both male and female, were bloodsucking. And male mosquitoes lost the ability later.

The researchers said while these are the oldest mosquito fossils, mosquitoes probably appeared millions of years earlier. They noted⁸ that molecular⁹ evidence suggests mosquitoes developed from about 200 million to 145 million years ago.

There are more than 3,500 species of mosquitoes worldwide, found everywhere except Antarctica. Some species spread diseases such as malaria, yellow fever, Zika fever, dengue and others. The World Health Organization says more than 400,000 people die annually¹⁰ from malaria - a parasitic¹¹ infection - mostly children under age 5.

Words in This Story

fossil – n. something (such as a leaf, skeleton, or footprint) that is from a plant or animal which lived in ancient times

evolution – n. an idea that the differences between plants and animals are because of changes that happened by a natural process over a very long time

species – n. a group of animals or plants that are similar and can produce young animals or plants

anatomy -- n. the parts that form a living thing

pierce -- v. to make a hole in or through something

sap – n. a watery juice inside a plant that carries the plant's food

1 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

2 amber   

n.琥珀；琥珀色；adj.琥珀制的

参考例句：

• Would you like an amber necklace for your birthday?你过生日想要一条琥珀项链吗？
• This is a piece of little amber stones.这是一块小小的琥珀化石。

3 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。

4 anatomy   

n.解剖学，解剖；功能，结构，组织

参考例句：

• He found out a great deal about the anatomy of animals.在动物解剖学方面，他有过许多发现。
• The hurricane's anatomy was powerful and complex.对飓风的剖析是一项庞大而复杂的工作。

5 jaw   

n.颚，颌，说教，流言蜚语；v.喋喋不休，教训

参考例句：

• He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。
• A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。

6 nutritious   

adj.有营养的，营养价值高的

参考例句：

• Fresh vegetables are very nutritious.新鲜蔬菜富于营养。
• Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。

7 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

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。

9 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

10 annually   

adv.一年一次，每年

参考例句：

• Many migratory birds visit this lake annually.许多候鸟每年到这个湖上作短期逗留。
• They celebrate their wedding anniversary annually.他们每年庆祝一番结婚纪念日。

11 parasitic   

adj.寄生的

参考例句：

• Will global warming mean the spread of tropical parasitic diseases?全球变暖是否意味着热带寄生虫病会蔓延呢？
• By definition,this way of life is parasitic.从其含义来说，这是种寄生虫的生活方式。