科学美国人60秒:Allergies May Have Been Bequeathed by Neandertals

古人遗留的过敏反应

Homo sapiens may dominate Europe and Asia today. But hundreds of thousands of years ago—long before we got there—the land was ruled by our now-extinct cousins, the Neandertals and Denisovans. "One important thing to realize is that, given that Neandertals and Denisovans had lived in Europe and Asia for such an extended time they were probably quite well adapted to the local conditions." Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology. "So they were well adapted to the pathogens, to the foods that were available, to the climate."

今天，现代人可以主宰欧洲和亚洲。但是，几十万年前——在我们还没有到达这片土地之前——这片土地是由我们的表亲安德特人和丹妮索瓦人所统治。而现在他们已经灭绝。“我们需要知道的重点就是，由于安德特人和丹妮索瓦人已经生活在欧洲和亚洲很长一段时间，他们已经能很好的适应当地的环境了。”珍妮特·凯利斯，是普朗克研究所进化人类学研究方面的一名计算机生物学家。她还说到，“因此，他们也适应了疾病、现存的食物以及气候。”

The invading newcomers probably found themselves less well adapted to the local conditions. So when H. sapiens shacked up with their close evolutionary relatives, it gave them a shot at picking up some advantageous genes.

入侵的人员可能发现自己并不太适应当地的环境。因此当现代人和两种人类进化的近亲同居时，现代人试着挑选一些有利基因。

Kelso and her colleagues hunted modern human genomes for strings of DNA that closely resembled those known to be from Neandertals and Denisovans. And indeed, on human chromosome number four they found a stretch of archaic DNA, 140,000 bases long.

凯利斯和她的同事们从现代人类基因中寻找与安德特人和丹妮索瓦人相似的DNA字符串。事实上，在人类的四号染色体上，他们发现了一段古老的脱氧核苷酸，约14万个碱基。

The genomes of many non-African humans today have this sequence, which includes a cluster of genes that code for Toll-like receptors, or TLRs—a type of immune protein that sniffs out pathogens. And it turns out that archaic variants of that gene are associated with lower microbial loads in present-day humans — a trait that may have been quite valuable to our ancestors as they settled new lands. The study appears in the American Journal of Human Genetics.

现代，非洲之外的人口也有这段序列，这段DNA序列包括和谐以编码样受体的基因簇。样受体是一种可以检测病原体的免疫蛋白。结果表明，这段基因的变异和现代人类微生物负载量较低有关——而此项特征对我们的祖先非常的重要，因为他们定居在新的大陆。此项研究结果发表在《美国人类遗传学》杂志上。

Problem is, that increased immune vigilance has a side effect: allergies. “Our speculation is that this is some kind of trade-off, right? In the past you needed to resist some kind of pathogen, and the trade-off or sacrifice you have to make for that is some increased responsiveness to nonpathogenic allergens." So next time some of you get the springtime sniffles, blame your distant ancestor—the one with the heavy brow ridge.

但问题是，免疫力增强也有副作用：过敏。“我们猜测，这是两者之间的一种平衡。以前，人类需要抵抗某种病原体，但是我们所做的牺牲增加了无致病能力过敏原的反应能力。所以，下次春天感冒时，责怪遥远的祖先吧——谁让他们有着大大的眉骨呢。