纽约时报 为何美军内部性侵频发(5)（在线收听）

Yet the way nature alters things is also profoundly haphazard. Sometimes a plant will acquire one trait at the expense of another. Sometimes it actually becomes worse. The same is true for agricultural crossbreeding. Not only is there no way to control which genes are kept and which are lost; the process also tends to introduce unwanted changes. The technical term for this is "linkage drag": all the unintended, and unknown, genes that get pulled along during cross-pollination, like fish in a net. Commercial berry growers spent decades trying to create a domesticated version of the black raspberry through crossbreeding but never succeeded: the thornless berries either tasted worse or produced almost no fruit, or they developed other problems. It's also why meeting the needs of modern agriculture — growing produce that can be shipped long distances and hold up in the store and at home for more than a few days — can result in tomatoes that taste like cardboard or strawberries that aren't as sweet as they used to be.

然而，大自然改变事物的方式也是极其随意的。有时一种植物会以牺牲另一种植物为代价获得一种特性。有时情况会变得更糟。农业杂交也是如此。不仅没有办法控制哪些基因被保留和丢失；这一过程也往往还会带来意外的变化。这一现象的专业术语是“连锁累赘”：在交叉授粉过程中，所有意想不到的、未知的基因会被拖着走，就像网中的鱼一样。商业浆果种植者花了几十年的时间试图通过杂交培育出一种家养黑覆盆子，但从未成功：无刺浆果要么味道更差，要么几乎不结果实，要么会产生其他问题。因此，满足现代农业的需求——种植可以长距离运输并在商店和家里存放几天以上的农产品——会导致番茄尝起来像硬纸板，或草莓不再像过去那样甜。

In recent years genetic-engineering tools like CRISPR have offered a way around this imprecision, making it possible to identify which genes control which traits — things like color, hardiness, sweetness — and to change only those.

近年来，CRISPR等基因工程工具提供了一种绕过这种不精确性的方法，使识别哪些基因控制哪些特性——比如颜色、耐寒性、甜度——并只改变这些特性成为可能。

Last year, the U.S.D.A. ruled that plants that had undergone simple cisgenic edits — changes to the plant's own DNA, of the kind that could theoretically be created by years of traditional crossbreeding — would not be subject to the same regulation as other G.M.O.s.

去年，美国农业部规定，经过简单顺基因编辑的植物——即改变植物自身DNA，理论上可以通过多年的传统杂交产生——将不再受到与其他转基因生物相同的监管。

The policy is partly a holdover from the early days of genetic engineering, when less was known about the process and its effects. But it has persisted, in part because of powerful anti-G.M.O. campaigning.

这项政策在一定程度上是基因工程早期的遗留问题，当时人们对这一过程及其影响知之甚少。但它一直存在，部分原因是强大的反转基因运动。