【英语时差8,16】DNA

（单词翻译）

You may already know that DNA¹ is a long molecule² found in almost every cell in your body that contains your genetic³ blueprints⁴. Encoded in the particular sequence of your DNA is a description of what kind of organism you are, how you work, and how to make more of you. DNA can be extracted from living things–run your fingernail along the inside of your cheek to harvest a DNA sample right now–or from dead remains⁵. Now, it turns out DNA can also be extracted from the soil, even without a body anywhere near. Researchers from the University of Copenhagen took a sediment⁶ core from a permafrost plain in Siberia. A “sediment core” is just a long, strait tube of earth. Imagine pushing a straw slowly into ice cream and then removing the straw: inside it would be a long thin ice cream sample. Since the surface of the earth is constantly covering itself over. With a sediment core, the lowest parts of the tube correspond to the oldest time period, while the highest parts are more recent.