研究显示25万年来爸爸总比妈妈大

近日，来自美国印第安纳大学的一项新研究表明，在过去25万年中，人类生育孩子的平均年龄是26.9岁，父亲的平均生育年龄为30.7岁，母亲的平均生育年龄则为23.2岁。

但在过去5000年里，这一年龄差距有所缩小，该研究最新估计的母亲平均生育年龄为26.4岁。

🤔️小作业：

无注释原文：

Study reveals average age at conception for men versus women over past 250,000 years

From: Science Daily

The length of a specific generation can tell us a lot about the biology and social organization of humans. Now, researchers at Indiana University can determine the average age that women and men had children throughout human evolutionary history with a new method they developed using DNA mutations.

The researchers said this work can help us understand the environmental challenges experienced by our ancestors and may also help us in predicting the effects of future environmental change on human societies.

"Through our research on modern humans, we noticed that we could predict the age at which people had children from the types of DNA mutations they left to their children," said study co-author Matthew Hahn, Distinguished Professor of biology in the College of Arts and Sciences and of computer science in the Luddy School of Informatics, Computing and Engineering at IU Bloomington. "We then applied this model to our human ancestors to determine what age our ancestors procreated."

According to the study, published today in Science Advances and co-authored by IU post-doctoral researcher Richard Wang, the average age that humans had children throughout the past 250,000 years is 26.9. Furthermore, fathers were consistently older, at 30.7 years on average, than mothers, at 23.2 years on average, but the age gap has shrunk in the past 5,000 years, with the study's most recent estimates of maternal age averaging 26.4 years. The shrinking gap seems to largely be due to mothers having children at older ages.

Other than the recent uptick in maternal age at childbirth, the researchers found that parental age has not increased steadily from the past and may have dipped around 10,000 years ago because of population growth coinciding with the rise of civilization.

"These mutations from the past accumulate with every generation and exist in humans today," Wang said. "We can now identify these mutations, see how they differ between male and female parents, and how they change as a function of parental age."

Children's DNA inherited from their parents contains roughly 25 to 75 new mutations, which allows scientists to compare the parents and offspring, and then to classify the kind of mutation that occurred. When looking at mutations in thousands of children, IU researchers noticed a pattern: The kinds of mutations that children get depend on the ages of the mother and the father.

Previous genetic approaches to determining historical generation times relied on the compounding effects of either recombination or mutation of modern human DNA sequence divergence from ancient samples. But the results were averaged across both males and females and across the past 40,000 to 45,000 years.

Hahn, Wang and their co-authors built a model that uses de novo mutations -- a genetic alteration that is present for the first time in one family member as a result of a variant or mutation in a germ cell of one of the parents or that arises in the fertilized egg during early embryogenesis -- to separately estimate the male and female generation times at many different points throughout the past 250,000 years.

The researchers were not originally seeking to understand the relationship of gender and age at conception over time; they were conducting a broader investigation about the number of mutations passed from parents to children. They only noticed the age-based mutation patterns while seeking to understand differences and similarities between these pattens in humans versus other mammals, such as cats, bears and macaques.

"The story of human history is pieced together from a diverse set of sources: written records, archaeological findings, fossils, etc.," Wang said. "Our genomes, the DNA found in every one of our cells, offer a kind of manuscript of human evolutionary history. The findings from our genetic analysis confirm some things we knew from other sources (such as the recent rise in parental age), but also offer a richer understanding of the demography of ancient humans. These findings contribute to a better understanding of our shared history."

注：中文文本为机器翻译并非一一对应，仅供参考

含注释全文：

Study reveals average age at conception for men versus women over past 250,000 years

From: Science Daily

The length of a specific generation can tell us a lot about the biology and social organization of humans. Now, researchers at Indiana University can determine the average age that women and men had children throughout human evolutionary history with a new method they developed using DNA mutations.

特定世代时间（繁殖一代所需时间）可以告诉我们很多关于人类生物学和社会组织的信息。现在，印第安纳大学（Indiana University）的研究人员可以通过他们利用DNA突变开发的新方法来确定人类进化史上女性和男性的平均生育年龄。

表示“（生物物种的）变异，突变”，英文解释为“a process in which the genetic material of a person, a plant or an animal changes in structure when it is passed on to children, etc., causing different physical characteristics to develop; a change of this kind”如：cells affected by mutation 受到突变影响的细胞。

The researchers said this work can help us understand the environmental challenges experienced by our ancestors and may also help us in predicting the effects of future environmental change on human societies.

研究人员说，这项工作可以帮助我们了解我们祖先所经历的环境挑战，也可能有助于我们预测未来环境变化对人类社会的影响。

"Through our research on modern humans, we noticed that we could predict the age at which people had children from the types of DNA mutations they left to their children," said study co-author Matthew Hahn, Distinguished Professor of biology in the College of Arts and Sciences and of computer science in the Luddy School of Informatics, Computing and Engineering at IU Bloomington. "We then applied this model to our human ancestors to determine what age our ancestors procreated."

“通过我们对现代人类的研究，我们注意到，可以根据人类遗传给子代的DNA突变类型预测生育年龄。”该研究的共同作者、印第安纳大学伯明顿分校（Indiana University Bloomington）艺术与科学学院生物学以及卢迪信息学、计算与工程学院计算机科学特聘教授马修·哈恩（Matthew Hahn）说。“然后，我们将这个模型应用于人类祖先，以确定我们祖先的生育年龄。”

procreate /ˈprəʊ.kri.eɪt/ 表示“生殖，生育”，英文解释为“to produce young”举个🌰：

Early marriage and procreation are no longer discouraged there. 早婚早育在那里不再遭到反对了。

According to the study, published today in Science Advances and co-authored by IU post-doctoral researcher Richard Wang, the average age that humans had children throughout the past 250,000 years is 26.9. Furthermore, fathers were consistently older, at 30.7 years on average, than mothers, at 23.2 years on average, but the age gap has shrunk in the past 5,000 years, with the study's most recent estimates of maternal age averaging 26.4 years. The shrinking gap seems to largely be due to mothers having children at older ages.

这项研究今天发表在《科学进展》（Science Advances）上，由印第安纳大学博士后研究员理查德·王（Richard Wang）共同撰写。研究表明，在过去25万年里，人类生育孩子的平均年龄是26.9岁。此外，父亲的平均生育年龄（30.7岁）一直比母亲的平均生育年龄（23.2岁）大，但在过去5000年里，这一年龄差距有所缩小，该研究最新估计的母亲平均生育年龄为26.4岁。这种差距缩小似乎主要是由于母亲的生育年龄更大。

作动词，表示“（使）缩小，（使）变小”，英文解释为“to become smaller, or to make something smaller”举个🌰：

The market for their products is shrinking. 市场对他们产品的需求在减少。

maternal /məˈtɜː.nəl/ 表示“母亲的；母亲般的”，英文解释为“behaving or feeling in the way that a mother does towards her child, especially in a kind, loving way”如：maternal instincts 母亲的天性。

Other than the recent uptick in maternal age at childbirth, the researchers found that parental age has not increased steadily from the past and may have dipped around 10,000 years ago because of population growth coinciding with the rise of civilization.

除了最近产妇生育年龄的上升之外，研究人员发现，父母年龄并没有稳步上升，而是可能在大约1万年前因人口增长与文明崛起反而下降了。

表示“增长；发展；上升”，英文解释为“an increase in something”举个🌰：

An uptick in once-struggling areas could make a significant difference to voters' perceptions of the economy. 贫困地区的经济发展会让选民对经济的看法产生显著的改变。

作名词，表示“（通常指暂时的）减少，下降，衰退”，英文解释为“a decrease in the amount or success of sth, usually for only a short period”，如：a sharp dip in profits 利润急剧下降。

表示降低，减少的词经常出现，比如：

📍fall表示“（水平、数量、价格等，尤指较大幅度地）下跌，下降，降低”（to go down to a lower level, amount, price etc, especially a much lower one）

📍slide表示“（价格等）下滑，下跌”（if prices, amounts, rates etc slide, they become lower）

📍diminish表示“（使）减少，（使）减小”（to become or make something become smaller or less）

📍dwindle /ˈdwɪndəl/表示“逐渐减少，缩小，变小”（to gradually become less and less or smaller and smaller）举个🌰：The factory's workforce has dwindled from over 1,000 to a few hundred. 该厂的工人总数已从1000多减少到了几百人。

1）表示“（两件或更多的事情）同时发生”，英文解释为“(of two or more events) to take place at the same time”举个🌰：

It's a pity our trips to Hangzhou don't coincide. 真遗憾我们不能同一时间去杭州旅行。

I timed my holiday to coincide with the children's. 我把我的假期安排在孩子们学校放假的时候。

2）表示“（想法、意见等）相同；相符；极为类似”，英文解释为“(of ideas, opinions, etc.) to be the same or very similar”举个🌰：

The interests of employers and employees do not always coincide. 雇主和雇员的利益并不总是一致的。

"These mutations from the past accumulate with every generation and exist in humans today," Wang said. "We can now identify these mutations, see how they differ between male and female parents, and how they change as a function of parental age."

“这些过去的突变会在每一代人中积累，并存在于今天的人类中，”理查德·王说。“我们现在可以识别这些突变，看看它们在父母之间的差异，以及是如何随着父母年龄的变化而变化的。”

表示“积累；积聚；积攒”，英文解释为“to collect a large number of things over a long period of time”举个🌰：

As people accumulate more wealth, they tend to spend a greater proportion of their incomes. 人们积累了更多财富后，他们的花费占收入的比重也往往会增加。

📍《经济学人》（The Economist）一篇讲述疫情期间房价上涨的文章中提到：Professionals who have carried on working from home but cut back on their spending have accumulated cash to splash. 那些改换成在家中继续工作但减少了开支的专业人士则积攒了可大笔支出的现金。

对比：

📍amass 表示“（尤指大量）积累，积聚”，英文解释为“to collect sth, especially in large quantities”举个🌰：

He amassed a fortune from delivering newspapers.他靠送报纸积累了一笔财富。

📍rack up表示“大量获得（利润）；严重遭受（损失）；（体育中）多次赢得（比赛）”，英文解释为“If a business racks up profits, losses, or sales, it makes a lot of them. If a sportsman, sportswoman, or team racks up wins, they win a lot of games or races.”

Children's DNA inherited from their parents contains roughly 25 to 75 new mutations, which allows scientists to compare the parents and offspring, and then to classify the kind of mutation that occurred. When looking at mutations in thousands of children, IU researchers noticed a pattern: The kinds of mutations that children get depend on the ages of the mother and the father.

孩子从父母那里遗传的DNA大约包含25到75个新突变，这使得科学家能够将父母和后代进行对比，并对发生的突变类型进行分类。观察了数千名儿童的突变后，印第安纳大学研究人员注意到一个模式：孩子获得的突变类型取决于母亲和父亲的生育年龄。

inherit /ɪnˈher.ɪt/ 1）表示“经遗传得到（父母的性格、外貌、品质、特征）”，英文解释为：to have the same character or appearance as your parents，举个🌰：

I inherited my mother's curly hair. 我遗传了母亲的鬈发。

2）表示“继承（财产）”，英文解释：If you inherit money or property, you receive it from someone who has died. 举个🌰：

He has no son to inherit his land. 他没有儿子来继承他的土地。

Previous genetic approaches to determining historical generation times relied on the compounding effects of either recombination or mutation of modern human DNA sequence divergence from ancient samples. But the results were averaged across both males and females and across the past 40,000 to 45,000 years.

以前确定历史世代的遗传学方法依赖于现代人类DNA序列与古代样本差异的重组或突变的复合效应。但结果是在过去4万到4.5万年间男性和女性的平均值。

2）表示“（围起来的）场地，楼群，院落”，英文解释为“an area surrounded by fences or walls that contains a group of buildings”举个🌰：

They marched into the compound. 他们进入大院。

作动词，表示“使加重，使加剧，使恶化”，英文解释为“to make a problem or difficult situation worse”举个🌰：

Her terror was compounded by the feeling that she was being watched. 她有种被人监视的感觉，这加剧了她的恐惧感。

表示“一连串；一系列；顺序，次序；序列”，英文解释为“a series of related things or events, or the order in which they follow each other”举个🌰：

The tasks had to be performed in a particular sequence. 这些任务必须按一定次序去执行。

divergence /ˌdaɪˈvɜː.dʒəns/ 表示“差异；分歧”，英文解释为“the situation in which two things become different”举个🌰：

The divergence between the incomes of the rich and the poor countries seems to be increasing. 富国与穷国之间的收入差距似乎正在拉大。

Hahn, Wang and their co-authors built a model that uses de novo mutations -- a genetic alteration that is present for the first time in one family member as a result of a variant or mutation in a germ cell of one of the parents or that arises in the fertilized egg during early embryogenesis -- to separately estimate the male and female generation times at many different points throughout the past 250,000 years.

马修·哈恩、理查德·王以及他们的共同作者建立了一个模型，使用从头突变（de novo mutation）——一种由于父母一方生殖细胞的变异或突变而首次出现在家庭成员中的基因变化，或者在早期胚胎发育期间出现在受精卵中的基因变化——分别评估过去25万年中许多不同时间点的男性和女性世代时间。

alteration /ˌɒl.təˈreɪ.ʃən/ 表示“（通常指轻微地）改动，修改；改变，（使）变化；变化（过程）”，英文解释为“a change, usually a slight change, in the appearance, character, or structure of something”举个🌰：

The landscape has undergone considerable alteration. 这里的风景发生了很大改变。

The researchers were not originally seeking to understand the relationship of gender and age at conception over time; they were conducting a broader investigation about the number of mutations passed from parents to children. They only noticed the age-based mutation patterns while seeking to understand differences and similarities between these pattens in humans versus other mammals, such as cats, bears and macaques.

研究人员最初研究并不是为了了解受孕时性别和年龄的关系；而是对父母遗传给孩子的突变数量进行更广泛的调查。他们只是在寻找人类与其他哺乳动物，如猫，熊和猕猴之间这些模式的差异和相似之处时，注意到了基于年龄的突变模式。

1）表示“观念；概念；见解；构想”，英文解释为“an idea of what something or someone is like, or a basic understanding of a situation or a principle”

2）熟词僻义，表示“受孕，怀孕”，英文解释为“the process of a male and a female sex cell joining and causing a baby to start to form”如：at/from the moment of conception 在/从受孕的那一刻。

"The story of human history is pieced together from a diverse set of sources: written records, archaeological findings, fossils, etc.," Wang said. "Our genomes, the DNA found in every one of our cells, offer a kind of manuscript of human evolutionary history. The findings from our genetic analysis confirm some things we knew from other sources (such as the recent rise in parental age), but also offer a richer understanding of the demography of ancient humans. These findings contribute to a better understanding of our shared history."

“人类历史的故事是由各种各样的来源拼凑而成的：书面记录、考古发现、化石等。”理查德·王说。“我们的基因组，即在我们每个细胞中发现的DNA，提供了一种人类进化史的手稿。基因分析结果证实了我们从其他来源里了解到的一些事情（比如当前父母生育年龄的上升），也提供了对古人类人口结构更丰富的理解。这些发现有助于更好地理解人类共同的历史。”

piece /piːs/ 表示“拼合；凑集”，英文解释为“to create something by joining the separate parts of it together or by joining different things together”举个🌰：

The ancient skull has been pieced together from fragments. 这个古人类头骨是由头骨碎片拼合起来的。

archaeological /,ɑ:kiə'lɔdʒikəl / 表示“考古学的；和考古有关的”，英文解释为“involving or relating to archaeology”如：an archaeological dig/excavation 考古发掘。

demography /dɪˈmɒɡ.rə.fi/ 1）表示“人口统计学”，英文解释为“the study of changes in the number of births, marriages, deaths, etc. in a particular area during a period of time”如：historical demography 历史人口统计学。

2）表示“人口统计，人口状况”，英文解释为“The demography of an area is the number and characteristics of the people who live in an area, in relation to their age, sex, if they are married or not, etc.”

- 今日盘点 -

mutation、 procreate、 shrink、 maternal、 uptick、 dip、 coincide、 accumulate、 inherit、 offspring、 compound、 sequence、 divergence、 alteration、 arise、 conception、 piece sth together、 archaeological、 genome、 demography

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