Hundreds of thousands of people worldwide are killed every year by malaria 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 amber.
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 evolutionary 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 anatomy of the two mosquitoes was beautifully saved in the fossils. Both insects had sharp and triangle-shaped jaw 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 nutritious fluids.
Plant evolution may have affected 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 noted that molecular 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 annually from malaria - a parasitic infection - mostly children under age 5.
I’m John Russell.
Will Dunham reported on this story for Reuters. John Russell adapted it for VOA Learning English.
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