18/07/2022
The study of the genomes of our closest relatives, the Neanderthals and Denisovans, has opened up new research paths that can broaden our understanding of the evolutionary history of Homo sapiens.
有關咱們親緣關係最接近之尼安德塔人及丹尼索瓦人的基因體研究已經開啟了，能擴大咱們對智人演化史之理解的諸多新研究途徑。
A study led by the UB has made an estimation of the time when some of the genetic variants that characterise our species emerged. It does so by analysing mutations that are very frequent in modern human populations, but not in these other species of archaic humans.
一項由西班牙巴塞隆納大學(UB ：Universitat de Barcelona)領導的研究已經估算了，一些表徵咱們物種遺傳變異出現的時間。該項研究藉由分析，在現代人類種群中，非常頻繁的突變，做到了這一點。不過，在這些原始人類的其他物種中，卻沒做到。
The results, published in the journal Scientific Reports, show two moments in which mutations accumulated: one around 40,000 years ago, associated with the growth of the Homo sapiens population and its departure from Africa, and an older one, more than 100,000 years ago, related to the time of the greatest diversity of types of Homo sapiens in Africa.
此些發表於《科學報告》雜誌的研究結果，顯示了兩個突變積累的時刻：一個是大約4萬年前，與智人種群的成長及其離開非洲有關。另一個是 10萬多年前，與在非洲之智人類型最多樣化的時期有關。
"The understanding of the deep history of our species is expanding rapidly. However, it is difficult to determine when the genetic variants that distinguish us from other human species emerged. In this study, we have placed species-specific variants on a timeline. We have discovered how these variants accumulate over time, reflecting events such as the point of divergence between Homo sapiens and other human species around 100,000 years ago ", says Alejandro Andirkó, first author of this article, which was part of his doctoral thesis at the UB.
本文首要撰文人，Alejandro Andirkó宣稱：「有關咱們物種之難解歷史的瞭解，正迅速擴大中。不過，很難確定，使咱們與其他人類物種區分開的遺傳變異，何時出現。在該項研究中，我們已經將特定物種的變異置於一個年表上。我們業已發現，隨著時間推移，這些變異如何積累。這反映了，諸如大約10萬年前，智人與其他人類物種之間分歧點等的進程。」本文是他，在巴塞隆納大學之博士論文的一部分。
The study, led by Cedric Boeckx, ICREA research professor in the section of General Linguistics and member of the Institute of Complex Systems of the UB (UBICS), included the participation of Juan Moriano, UB researcher, Alessandro Vitriolo and Giuseppe Testa, experts from the University of Milan and the European Institute of Oncology, and Martin Kuhlwilm, researcher at the University of Vienna.
該項由西班牙巴塞隆納市普通語言學部門所屬加泰羅尼亞研究高級研究所(ICREA：Institució Catalana de Reserca I Estudis Avançats)研究教授，及巴塞隆納大學複雜系統研究所(UBICS)成員，Cedric Boeckx領導之研究的參與者，包括巴塞隆納大學研究員Juan Moriano、來自意大利米蘭大學及歐洲腫瘤學研究所的專家Alessandro Vitriolo與Giuseppe Testa，及奧地利維也納大學研究員Martin Kuhlwilm。
The results of the research study also show differences between evolutionary periods. Specifically, they highlight the predominance of genetic variants related to behaviour and facial structure —key characteristics in the differentiation of our species from other human species— more than 300,000 years ago, a date that coincides with the available fossil and archaeological evidence.
該項研究的諸多結果也顯示了，演化時期之間的諸多差異。具體來說，他們強調了，與行為及面部結構相關之遺傳變異的顯著處(也就是，咱們物種與其他人類物種，在分化上的關鍵特徵)，超過30萬年前。這是一個與現有化石及考古證據相一致的時間。
"We have discovered sets of genetic variants which affect the evolution of the face and which we have dated between 300,000 and 500,000 years ago, the period just prior to the dating of the earliest fossils of our species, such as the ones discovered at the Jebel Irhoud archaeological site in Morocco", notes Andirkó.
Andirkó特別提及：「我們已經發現一組，影響面部演化的遺傳變異。且我們已經確定其年代，介於30萬到50萬年前之間的遺傳變異。此期間就在咱們物種最早的化石年代判定之前，諸如在摩洛哥傑貝爾依魯德考古遺址發現的化石。」
The researchers also analysed variants related to the brain, the organ that can best help explain key features of the rich repertoire of behaviours associated with Homo sapiens. Specifically, they dated variants which medical studies conducted in present-day humans have linked to the volume of the cerebellum, corpus callosum and other structures.
此些研究人員也分析了，與大腦相關的變體。此器官能最有助於解釋，與智人相關之豐富行為功能的諸多關鍵特徵。具體來說，他們確定了，在當今人類中進行之醫學研究，已經與小腦、胼胝體及其他結構體積聯繫在一起的變體日期。
"We found that brain tissues have a particular genomic expression profile at different times in our history; that is, certain genes related to neural development were more highly expressed at certain times," says the researcher.
此些研究人員宣稱：「我們發現，在我們歷史中的不同時期，腦組織具有一種，特定基因體表現的量變曲線；也就是說，某些與神經發育相關的基因，在某些時候較高度地作出表現。」
These results complement an idea that is dominant in evolutionary anthropology: that there is no linear history of human species, but that different branches of our evolutionary tree coexisted and often intersected.
此些研究結果補足了，那是在演化人類學中，一種具有影響力的見解：因為，人類物種沒有線性歷史。至少，咱們演化樹的不同分支共存且經常交叉。
"The breadth of the range of human diversity in the past has surprised anthropologists. Even within Homo sapiens there are fossils, such as the ones I mentioned earlier from Jebel Irhoud, which, because of their features, were thought to belong to another species. That's why we say that human beings have lived a mosaic evolution," he notes.
他特別提及：「於過去，人類多樣性的廣度，一直令人類學家們感到驚訝。即使在智人體內也有，諸如我稍早提到之來自傑貝爾依魯德的化石。由於其特徵，它們被認為屬於另一個物種。那是為何我們宣稱，人類業已經歷一種鑲嵌性演化(即演的化變化發生在某些身體部位或系統中，而其他部位沒有同時發生變化。另一個定義是“物種內部與物種之間以不同速率演化的特徵)。」
“Our results,” the researcher continues, “offer a picture of how our genetics changed, which fits this idea, as we found no evidence of evolutionary changes that depended on one or a several key mutations," he says.
該名研究員繼續說，他宣稱：「我們的諸多研究結果提供了一種，咱們遺傳現象如何改變的概念，這符合上述見解。因為，我們沒有發現，依賴一個或幾個關鍵突變之演化改變的證據。」
The methodology used in the study was based on a Genealogical Estimation of Variant Age method, developed by researchers at the University of Oxford. Once they had this estimation, they applied a machine learning tool to predict which genes have changed the most in certain time windows and which tissues these genes may have impacted.
在該項研究中使用的方法是以，由英國牛津大學研究人員們所開發之變異時期法的系譜估算為基礎。一旦有了此估算，他們就應用機器學習工具來預測，於特定時框中，哪些基因曾變化最大，及此些基因可能曾影響哪些組織。
Specifically, they used ExPecto, a deep learning tool that uses a convolutional network — a type of computational model — to predict gene expression levels and function from a DNA sequence.
具體來說，他們使用了ExPecto。這是一種，使用卷積網絡(一種計算模型)來從一個DNA序列，預測基因表現水平及功能的深度學習工具。
"Since there are no data on the genomic expression of variants in the past, this tool is an approach to a problem that has not been addressed until now. Although the use of machine learning prediction is increasingly common in the clinical world, as far as we know, nobody has tried to predict the consequences of genomic changes over time,” notes Andirkó.
Andirkó特別提及：「因為於過去中，沒有攸關變體基因體的表現數據。此工具是一種，對迄今一直未被解決之問題的方法。雖然機器學習預測的使用，在臨床領域越來越普遍。不過，據我們所知，無人曾試圖預測基因體之變化，隨時間推移的後果。」
In a previous study, the same UB team, together with the researcher Raül Gómez Buisán, used genomic information from archaic humans. In that study they analysed genomic deserts, regions of the genome of our species where there are no genetic fragments of Neanderthals or Denisovans, and which, moreover, have been subjected to positive pressure in our species:
在先前的一項研究中，該相同的巴塞隆納大學團隊，連同研究員Raül Gómez Buisán，使用了來自古代人類的基因體訊息。在那項研究中，他們分析了基因體沙漠(缺乏蛋白質編碼基因的基因體區域)。這是咱們物種的基因體，沒有尼安德塔人或丹尼索瓦人之遺傳片段，而且在咱們物種中，一直遭到正壓力的區域：
that is, they have accumulated more mutations than would have been expected by neutral evolution. The researchers studied the expression of genes — i.e., which proteins code for different functions — found in desert regions throughout brain development, from prenatal to adult stages, covering sixteen brain structures. The results showed differences in gene expression in the cerebellum, striatum and thalamus.
也就是說，它們已經積累了多於，中性演化能被預期的突變。此些研究人員研究了，從產前到成年階段，涵蓋十六個大腦結構之整個大腦發育過程中，在沙漠區域被發現的基因(即哪些為不同功能編碼的蛋白質)表現。此些研究結果顯示了，在小腦、紋狀體及丘腦中，基因表現上的差異。
"These results bring into focus the relevance of brain structures beyond the neocortex, which has traditionally dominated research on the evolution of the human brain," says Juan Moriano.
Juan Moriano宣稱：「這些研究結果將焦點集中於，新皮質之外的大腦結構關聯性上。傳統上，新皮質一直左右有關人類大腦演化的研究。」
Moreover, the most striking differences between brain structures were found at prenatal stages.
此外，在產前階段，發現了大腦結構之間最顯著的差異。
"These findings add new evidence to the hypothesis of a species-specific trajectory of brain development taking place at perinatal stages — the period from 22 weeks to the end of the first four weeks of neonatal life — that would result in a more globular head shape in modern humans, in contrast to the more elongated shape seen in Neanderthals," concludes Moriano.
Moriano下結論：「此些研究發現，將新證據添加到，大腦發育發生於生產前後諸階段(從22周到新生兒誕生後前4周結束的時期)之物種特異性軌蹟的假設中。那或許導致了，在現代人中，與在尼安德塔人身上，看到之較細長形狀成對比的較球狀頭形。」
網址：https://www.ub.edu/web/ub/en/menu_eines/noticies/2022/07/032.html
翻譯：許東榮
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