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西伯利亚偏远山洞的DNA揭示了当地第一个尼安德特人家庭_我的网站

A |     Texas Governor Greg Abbott has authorized his state’s National Guard and the Department of Public Safety to detain migrants who illegally cross the border between ports of entry and return them to US-Mexican border entry points.,The federal government is normally responsible for enforcement of immigration; Governor Abbott stressed in an executive order announced on Thursday that while US President Joe Biden “refuses to do his job and enforce the immigration laws enacted by Congress, the State of Texas is once again stepping up and taking unprecedented action to protect Americans and secure” the US southern border.,The governor referred to the US Constitution, which he said stipulates that the country “shall protect each [State in this Union] against [a border] invasion.”,The announcement comes after former Trump administration official Ken Cuccinelli said he wanted Abbott to declare an invasion and enact a Title 42-style program, which envisages migrants being “repealed at the border” and automatically turned away.,Cuccinelli’s remarks followed US authorities saying in late June that at least 51 migrants had died after being trapped inside a sweltering tractor-trailer truck found abandoned in Texas. The deceased 39 men and 12 women were discovered on the outskirts of San Antonio, in what became one of the deadliest human trafficking tragedies in recent history.,At the time, Abbott pointed the finger at the “open border policy”, pursued by Biden, who in turn said that the incident “underscores the need to go after the multi-billion dollar criminal smuggling industry preying on migrants and leading to far too many innocent deaths.”,The Biden administration is grappling with increasing border arrivals as US Customs and Border Protection (CBP) data revealed in mid-June that that Border Patrol agents apprehended 239,416 illegal migrants on the US southern border in May, a new record high.,'Doing Nothing': Border Patrol Union Chief Rips Biden Migrant Policies for 'Benefiting Smugglers'2 April, 14:25 GMT,This year, the number of illegal migrants detained every month on the US’ southern border hit two record highs, in March and April, 222,339 and 235,478, respectively, according to CBP.,In a separate development in March, Biden told migrants not to come to US, insisting that there had been a surge in immigration "in the last two years", but that that the current rise "could be" worse.,Former US President Donald Trump, for his part, argued at the time that Biden had "eroded" the successful system that Trump had put in place, and that his policies "were working better than they have ever seen on the southern border.",The crisis on the US southern border began almost immediately after Biden took office in January 2021 and revoked Trump-era immigration policies, including the 45th president’s signature border wall and the “Remain in Mexico” program. Other measures, including promises to “restore and expand” the US asylum system, and to potentially provide a “path to citizenship” for more than 11 million undocumented immigrants already residing in the US, led to a further surge in entry attempts.。    十三个尼安德特人的古老基因组为他们的社区和社会组织提供了一个前所未有的快照。2010年，第一个尼安德特人基因组草案被公布。自那时起，马克斯-普朗克进化人类学研究所的研究人员已经对来自整个欧亚大陆14个不同考古遗址的另外18个基因组进行了测序。尽管这些基因组提供了对尼安德特人历史的总体轮廓的见解，但我们对个别尼安德特人社区仍然知之甚少。尼安德特人是一个已灭绝的古人类物种或亚种，他们在大约4万年前一直生活在欧亚大陆。

B | 目前还不清楚尼安德特人的血统何时从现代人的血统中分裂出来，以及他们为何消失。为了探索尼安德特人的社会结构，科学家们将注意力转向了西伯利亚南部。这是一个以前对古代DNA研究非常有价值的地区--包括在著名的丹尼索瓦洞发现丹尼索瓦人的遗骸。从该遗址的工作中，我们知道尼安德特人和丹尼索瓦人在这个地区存在了几十万年。我们还知道，尼安德特人和丹尼索瓦人曾相互影响--正如发现一个父亲为丹尼索瓦人、母亲为尼安德特人的孩子所表明的那样。第一个尼安德特人社区在他们的新研究中，由马克斯-普朗克进化人类学研究所的研究人员领导的国际团队专注于Chagyrskaya和Okladnikov洞穴的尼安德特人遗骸，这两个洞穴距离丹尼索瓦洞穴100公里（60英里）以内。尼安德特人在大约5.4万年前曾短暂地在这些地方生活过，并且考古学家从其沉积物中发现了多具可能是同时代的尼安德特人遗骸。科学家们成功地从17具尼安德特人遗骸中提取了DNA--这是迄今为止在一项研究中对尼安德特人遗骸进行测序的最大数量。俄罗斯科学院考古与民族学研究所的研究人员在过去14年里对Chagyrskaya洞穴进行了挖掘。除了几十万件石器和动物骨骼外，他们还发现了80多块尼安德特人的骨骼和牙齿碎片，这不仅是该地区也是世界上最大的这些人类化石的集合体之一。

C | Chagyrskaya洞穴，西伯利亚在Chagyrskaya和Okladnikov的尼安德特人狩猎山羊、马、野牛和其他在洞穴所俯瞰的河谷中迁移的动物。他们在几十公里外采集石器的原材料，在Chagyrskaya和Okladnikov洞穴出现相同的原材料也支持了遗传学数据，即居住在这些地方的群体是紧密联系的。以前对德尼索瓦洞的脚趾化石的研究表明，尼安德特人居住在阿尔泰山区的时间也相当早，大约在12万年前。

D | 但遗传数据显示，来自Chagyrskaya和Okladnikov洞穴的尼安德特人不是这些早期群体的后代，而是与欧洲尼安德特人关系更密切。这也得到了考古材料的支持：来自Chagyrskaya洞穴的石器与德国和东欧已知的所谓Micoquian文化最为相似。这17具遗骸来自13个尼安德特人--7个男人和6个女人，其中8个是成年人，5个是儿童和年轻的青少年。在他们的线粒体DNA中，研究人员发现了几个所谓的异质体，这些异质体在个体之间共享。异质体是一种特殊的遗传变异体，只在少数几代人中持续存在。最东边的尼安德特人在这些遗骸中，有一位尼安德特人的父亲和他十几岁的女儿。研究人员还发现了一对二级亲属：一个小男孩和一个成年女性，也许是表妹、姨妈或祖母。

E | 异质体和相关个体的结合强烈表明，Chagyrskaya洞的尼安德特人一定是在大约同一时间生活-和死亡。"他们在同一时间生活的事实是非常令人兴奋的。这意味着他们很可能来自同一个社会社区。

F | 因此，我们第一次可以用遗传学来研究尼安德特人社区的社会组织，"Laurits Skov说，他是这项研究的第一作者。

G | 另一个引人注目的发现是这个尼安德特人社区内的遗传多样性极低，与10至20人的群体规模一致。这比任何古代或现今人类群体的记录都要低得多，而且与濒临灭绝的濒危物种的群体规模更为相似。然而，尼安德特人并没有生活在完全孤立的社区中。通过比较父亲遗传给儿子的Y染色体上的遗传多样性和从母亲那里继承的线粒体DNA多样性，研究人员可以回答这个问题。在社区之间迁移的是男人还是女人？他们发现线粒体遗传多样性比Y染色体多样性高得多，这表明这些尼安德特人社区主要是由女性迁移联系起来的。尽管离Denisova洞很近，但这些迁徙似乎并不涉及丹尼索瓦人--研究人员在Chagyrskaya尼安德特人中没有发现在这些个体生活的最后2万年中丹尼索瓦人基因流动的证据。"我们的研究提供了一幅尼安德特人社区可能是什么样子的具体画面，"该研究的最后一位作者本杰明-彼得说。"在我看来，它使尼安德特人看起来更像人类"。

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Published on:02:10:58