蚊子是如何进化到被人类吸引的，这对未来意味着什么

蚊子是如何进化到被人类吸引的，这对未来意味着什么

Not all mosquitoes are created equal, even if it feels that way when they bite you.

并非所有的蚊子都是生而平等的，即使它们叮咬你时的感觉是一样的。

There are about 3,500 species of mosquitoes around the world, but only a few are responsible for spreading infectious diseases to humans.

世界上大约有3500种蚊子，但只有少数几种会向人类传播传染病。

Among those mosquitoes that are thirsty for human blood is the Aedes aegypti, which is the primary spreader of yellow fever, Zika virus, dengue and Chikungunya virus.

在那些嗜血的蚊子中有埃及伊蚊，它是黄热病、寨卡病毒、登革热和基孔肯雅病毒的主要传播者。

But how did Aedes aegypti mosquitoes evolve to specialize in biting people? New research published today in the journal Current Biology has revealed that two factors play a major role: dry climate and city life.

但是埃及伊蚊是如何进化成专门叮咬人类的呢?今天发表在《当代生物学》杂志上的一项新研究显示，有两个因素在其中发挥了重要作用:干燥的气候和城市生活。

Scientists studied mosquitoes across sub-Saharan Africa and found that mosquitoes actually have wide-ranging palates.

科学家研究了撒哈拉以南非洲地区的蚊子，发现蚊子的味觉其实很广泛。

"There's a huge diversity in mosquito preferences. Some like to bite humans and others don't like to bite humans at all," said the paper's co-author Noah Rose, a postdoctoral researcher at Princeton University in New Jersey.

“蚊子的偏好有很大的差异。有些喜欢咬人，有些则根本不喜欢咬人，”论文的合著者、新泽西州普林斯顿大学的博士后研究员诺亚·罗斯说。

"At first we thought that mosquitoes who lived around people would simply like to bite people and that those who lived in the forests wouldn't like to bite humans," Rose said. "We were really surprised that that wasn't the case."

罗斯说:“一开始，我们认为生活在人类周围的蚊子只会叮咬人类，而生活在森林里的蚊子不会叮咬人类。”“我们真的很惊讶事实并非如此。”

While mosquitoes living near dense cities such as Kumasi, Ghana, or Ouagadougou, Burkina Faso, showed increased willingness to bite humans, researchers found that city life alone didn't explain the mosquitoes' evolution. In fact, any mosquitoes living in large cities still preferred to bite animals rather than human hosts.

尽管蚊子生活在加纳的库马西或布基纳法索的瓦加杜古等人口密集城市附近，但它们更愿意叮咬人类，研究人员发现，城市生活本身并不能解释蚊子的进化。事实上，任何生活在大城市的蚊子仍然更喜欢叮咬动物而不是人类。

That's where the second factor -- dry climate -- comes in. In areas with harsh dry seasons, such as Africa's Sahel region, extending from Senegal to Sudan and Eritrea, mosquitoes evolved to have a strong preference for humans.

这就是第二个因素出现的原因——干燥的气候。在干旱季节恶劣的地区，比如非洲的萨赫勒地区(从塞内加尔延伸到苏丹和厄立特里亚)，蚊子进化得对人类有强烈的偏好。

"Mosquitoes are dependent on containers of water for their larvae," Rose told CNN. "So in places with an intense long dry season, mosquitoes become very dependent on humans who store water."

“蚊子依赖装有水的容器来喂养它们的幼虫，”罗斯告诉CNN。“所以在干旱季节非常漫长的地方，蚊子变得非常依赖储存水的人类。”

The mosquitoes' evolution to bite humans is a by-product of their dependency on breeding in areas close to human city life. That means urbanization in the coming decades could lead to even more human-biting mosquitoes in the future.

蚊子进化成叮咬人类，是它们依赖于在靠近人类城市生活的地区繁殖的副产品。这意味着未来几十年的城市化可能会导致更多叮咬人类的蚊子。

Urbanization to spark further change in mosquitoes

城市化将进一步引发蚊子的变化

Sub-Saharan Africa is expected to see an increase in the total number of births over the next several decades, as well as increasing life expectancy, according to population projection datafrom the United Nations. That means a projected population increase of 1.05 billion in sub-Saharan African countries in the next three decades, for an estimated total population of more than 2.1 billion people.

根据联合国的人口预测数据，在未来几十年，撒哈拉以南非洲地区的出生人数将会增加，预期寿命也会延长。这意味着，预计撒哈拉以南非洲国家的人口在未来30年将增加10.5亿，估计总人口将超过21亿。

The new research predicts this rapid urbanization will drive further mosquito evolution, causing a shift toward biting humans in many large cities by 2050.

这项新的研究预测，这种快速的城市化将进一步推动蚊子的进化，导致到2050年许多大城市的蚊子转向叮咬人类。

"We should be watching these mosquitoes," said Rose, noting that the future of mosquito adaptations is still uncertain.

“我们应该观察这些蚊子，”罗斯说，并指出蚊子适应的未来仍然不确定。

"We don't really know what will happen when the urbanization of sub-Saharan Africa moves beyond what we see in the present day. But we know something will happen and we think that it will be a shift to biting more human hosts."

他说:“我们真的不知道当撒哈拉以南非洲地区的城市化超越我们目前所看到的水平时，会发生什么。但我们知道会发生一些事情，我们认为这将是一个转变，(蚊子会)咬更多的人类宿主。”

That means the way mosquitoes spread disease could also change.

这意味着蚊子传播疾病的方式也可能改变。