The study of ancient DNA is helping to solve modern crimes

reference: The Economist

Eske Willerslve, an expert in ancient DNA, was recently asked to convince a jury that he could contribute to another field entirely: crime scene investigation.

• convince (v.) 說服：作為動詞，表示說服他人接受某種觀點或立場。
• contribute to (v.) 貢獻於/促成：作為動詞短語，表示在某個活動或目標中扮演積極角色，提供幫助或支持。
• crime scene investigation (n.) 犯罪現場調查/刑事現場調查：作為名詞短語，表示對犯罪現場進行的調查，專注於收集和分析證據以幫助案件破案。

The crime was the murder of a girl named Emilie Meng, a 17-year-old Danish girl whose strangled body was found in a lake. The police had hoped to find valuable DNA evidence from her trousers, but the trousers had been exposed for six months, resulting in less useful material due to significant damage. Desperate for answers, the police turned to Dr Willerslev.

• murder (n./) 謀殺：指謀殺行為
• strangled (adj.) 勒死/窒息而死：表示用力勒住脖子使人窒息。
• valuable (adj.) 有價值的/珍貴的：形容詞，表示某物具有很高的價值或重要性。
• evidence (n.) 證據：名詞，指支持某個觀點或指控的證據或線索。
• due to (prep.) 由於/因為：介詞短語，表示原因或起因。

The forensics community is rightly conservative when it comes to using new technology that could help. That's why they start taking up some new inventions.

DNA is composed of four distinct molecules called bases, which are arranged in combinations to form long polymer chains. These chains are linked together in pairs through bonds between their bases, resulting in the well-known double-helix structure of DNA. At specific locations along the chains, short sequences of bases are repeated multiple times, forming what are known as short tandem repeats (STRs).The number of short tandem repeats (STRs) at each genetic locus varies among individuals, enabling DNA samples to be matched to their owner by measuring the number of repeats.

• forensics (n.) 法醫學/鑑識學：名詞，指用於犯罪調查的科學方法和技術。
• conservative (adj.) 保守的/傳統的：形容詞，表示傾向於維持傳統和避免改變。
• is composed of (v. phrase) 由…組成：動詞短語，表示某物由不同部分或元素組成。
• distinct (adj.) 明顯不同的/獨特的：形容詞，指具有獨特特徵或易於區分。
• molecules (n.) 分子：名詞，指由原子組成的化學物質的最小單位。
• bases (n.) 鹼基：名詞，指DNA或RNA中的基本構件，如腺嘌呤（A）、胸腺嘧啶（T）、鳥嘌呤（G）和胞嘧啶（C）。
• polymer chains (n.) 聚合物鏈：名詞短語，指由重複單元組成的長鏈狀分子結構。
• double-helix (n.) 雙螺旋：名詞，指DNA的特徵結構，由兩條螺旋鏈組成。
• short tandem repeats (STRs) (n.) 短串聯重複序列：名詞短語，指DNA中重複的簡短序列，常用於DNA分析。

Locations where individual pairs of nucleotides differ between people are called single nucleotide polymorphisms (SNPs). Scientists often identify tens of thousands of such sites. Dr Willersleve had obtained SNPs from Meng's trousers. Then he tried to identify whom they could have come from.

• nucleotides (n.) 核苷酸：名詞，指DNA或RNA的基本單位，由一個磷酸鹽、五碳糖和一個鹼基組成。
• single nucleotide polymorphisms (SNPs) (n.) 單核苷酸多態性：名詞短語，指DNA序列中單一核苷酸的變異，是基因組中最常見的遺傳變異形式。