听力文摘：穴居人怎样抵抗疾病（在线收听）

How Neanderthals Fought Disease

穴居人怎样抵抗疾病

Every year people are encouraged to get their annual flu shots. Signs are posted at drug stores and clinics. Get your shots here. Modern preventive medicine has saved millions of lives. But you may be surprised to hear that Neanderthals may have helped ancient humans prevent disease. Not with medicine but with immunity genes.

每年人们都会被鼓励去打流感疫苗。告示会被贴在诊所和药店里：在这儿打疫苗。现代预防医学挽救了数百万人的生命。但是当你听到穴居人可以帮助过去的人预防疾病时，你可能会感到很吃惊，不是利用药物而是通过免疫基因。

Humans have a group of about two hundred genes that keep our immune system running smoothly. These genes allow our bodies to respond to a large number of disease causing agents and adapt to new disease. One of those genes has an allele, HLA C0702, that can be found in many European and Asian people, but not in Africans. Another allele, HLA A11, is found mostly in Asians.

人类有一组基因，大约200个，它们让我们的免疫系统正常地运转。这些基因使我们的身体对大量的病源物质做出反应，并且适应新的疾病。这些基因中的一个有 等位基因，HLAC0702，这种基因可以在许多欧洲或者亚洲人身上找到，但无法在非洲人身上找到。另一种等位基因HLA A11则在亚洲人身上最为常见。

Both alleles were found in Neanderthal DNA. Scientists studying ancient Neanderthals believe they may know why some modern people have the immunity alleles while others do not. When humans moved out of Africa one hundred thousand years ago, their immune systems were adapted to fight African diseases. Neanderthals on the other hand had already been living in Europe and Asia for thousands of years. They had been exposed to different diseases, and different alleles had evolved to combat them.

这两种等位基因在穴居人的DNA中却都可以找到。研究古穴居人的科学家们相信他们可能知道为什么一些现代人有免疫等位基因，而其他人没有。十万年前，当人 们搬离非洲时，他们的免疫系统就已经适应了同非洲疾病对抗。然而，穴居人在欧洲和亚洲已经生活了数千年。他们被暴露在不同的疾病之下，并且进化出不同的等 位基因同疾病对抗。

Scientists already know that the modern human genome is somewhere between one and four percent Neanderthal in origin. It is not a far leap to speculate that inbreeding may have resulted in shared immunity genes, too. More research is needed to determine if the gene alleles came from a common ancestor, or directly from Neanderthals. In either case, the story of inheriting disease resistance is important in understanding modern man’s survival and migration around the world.

科学家们已经知道现代人类基因组在某种程度上1%到4%是起源于穴居人。不难推测，近亲繁殖也许是造成免疫基因共享的原因。但我们还需要更多的研究来确定 是否等位基因来自于人类共同的祖先，还是直接来自于穴居人。在任何一个情况下，遗传抗病性在理解现代人生存和在全世界范围内迁徙都是十分重要的。