[ti:Scientists Use Ancient Genes to Estimate Contact Between Humans, Neanderthals]
[by:www.21voa.com]
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[00:00.04]Scientists have used ancient genes
[00:04.20]to learn more details about contact
[00:08.16]between Neanderthals and humans
[00:11.64]tens of thousands of years ago.
[00:16.08]Results of two recent studies
[00:19.44]estimate the two groups likely met
[00:23.32]and began mating about 45,000 years ago.
[00:28.96]Modern humans – also known as Homo sapiens
[00:35.00]– began in Africa hundreds of thousands of years ago
[00:40.00]and later started spreading
[00:42.92]to Europe, Asia and other places.
[00:47.48]Scientists believe that at some point,
[00:51.80]they met and mated with Neanderthals.
[00:56.84]The mixing of these groups
[00:59.60]had a major influence on humans' genetic code.
[01:04.84]However, scientists do not know exactly
[01:10.16]when or how the two groups interacted.
[01:15.00]But the two new studies
[01:18.00]provide some additional details
[01:21.24]about the timing of this contact.
[01:25.76]One group of scientists examined genetic material
[01:30.68]from three female and three male Homo sapien individuals
[01:36.64]who lived around 45,000 years ago.
[01:42.24]Reuters news agency reported that research
[01:46.72]involved the oldest genes from Homo sapiens
[01:51.12]ever examined, or sequenced.
[01:56.04]Some of the genes came from bones found in a cave
[02:01.16]in the central German village of Ranis.
[02:04.80]Other material came from a woman
[02:08.52]believed to have lived at around the same time
[02:12.80]in a cave in a mountainous area
[02:16.08]of what is now the Czech Republic.
[02:19.64]Researchers estimated the period of mixing
[02:23.48]between Neanderthals and humans
[02:27.12]at about 49,000 to 45,000 years ago.
[02:34.00]The findings were recently published
[02:36.96]in a study in Nature.
[02:39.84]A second group of researchers
[02:42.48]examined genetic material
[02:44.96]from 300 present-day and ancient Homo sapiens.
[02:50.96]This included 59 individuals
[02:55.72]who lived between 2,000 and 45,000 years ago.
[03:02.80]That study, published in the journal Science,
[03:06.56]estimated the period of mixing
[03:09.72]at about 50,500 to 43,500 years ago.
[03:19.08]The scientists said their new findings
[03:22.68]on the mixing and mating of the groups
[03:26.20]suggested the activities happened
[03:29.48]a little more recently than thought in the past.
[03:33.88]They believe the contact continued
[03:36.88]over many generations.
[03:40.56]Priya Moorjani was co-writer
[03:43.56]of the study appearing in Science.
[03:46.48]She is an assistant professor of molecular
[03:51.08]and cell biology
[03:53.20]at the University of California, Berkeley.
[03:57.80]She told Reuters,
[04:00.00]"Genetic data from these samples
[04:03.72]really helps us paint a picture
[04:06.80]in more and more detail."
[04:09.92]The team noted that it is difficult
[04:13.00]to know the exact nature of the interactions
[04:16.92]between Homo sapiens and Neanderthals
[04:20.92]based on the examined data.
[04:23.72]The researchers also could not confirm
[04:28.12]exactly where the mixing and mating happened.
[04:33.24]However, they believe it was most likely
[04:37.36]somewhere in the Middle East.
[04:40.92]The researchers noted most modern humans
[04:44.80]still have genetic material from Neanderthals
[04:49.04]that accounts for an estimated
[04:52.52]one to two percent of their DNA.
[04:56.08]They said modern-day genetic traits
[04:59.92]linked to skin color, hair color
[05:03.16]and even nose shape
[05:05.24]can relate back to the Neanderthals.
[05:09.76]Our genetic makeup also includes links
[05:13.68]to another group of human ancestors called Denisovans.
[05:19.68]Moorjani noted that the history of Neanderthals
[05:24.48]living outside Africa for thousands of years
[05:29.48]likely gave them a greater ability
[05:32.72]to deal with climate and diseases in new environments.
[05:38.96]"Some of their genes may have been beneficial
[05:42.72]to modern humans," she added.
[05:45.68]Rick Potts is director of the Smithsonian
[05:49.84]Institution's Human Origins program.
[05:53.80]He was not involved in the new research.
[05:57.88]Potts told The Associated Press
[06:01.24]he hopes future genetic studies
[06:04.48]can help scientists learn even more details
[06:08.76]about the interactions
[06:10.72]of Neanderthals and modern humans.
[06:14.80]He said, "Out of many really compelling areas
[06:19.52]of scientific investigation,
[06:22.32]one of them is: well, who are we?"
[06:27.04]I'm Caty Weaver. 更多听力请访问21VOA.COM
END OF TRACK. "END OF TRACK." The two men bowed. "Whoever was that person you were talking to?" she enquired, as soon as they stood together. The took of triumph faded from her eyes, she had grown worn and weary. The roses were wilting on the walls, the lights were mostly down now. Hetty, looking in to see if anything was wanted, found herself driven away almost fiercely. I only saw Master Jervie once when he called at tea time, The year 1747 was opened by measures of restriction. The House of Lords, offended at the publication of the proceedings of the trial of Lord Lovat, summoned the parties to their bar, committed them to prison, and refused to liberate them till they had pledged themselves not to repeat the offence, and had paid very heavy fees. The consequence of this was that the transactions of the Peers were almost entirely suppressed for nearly thirty years from this time, and we draw our knowledge of them chiefly from notes taken by Horace Walpole and Lord Chancellor Hardwicke. What is still more remarkable, the reports of the House of Commons, being taken by stealth, and on the merest sufferance, are of the most meagre kind, sometimes altogether wanting, and the speeches are given uniformly under fictitious names; for to have attributed to Pitt or Pelham their[112] speeches by name would have brought down on the printers the summary vengeance of the House. Many of the members complained bitterly of this breach of the privileges of Parliament, and of "being put into print by low fellows"; but Pelham had the sense to tolerate them, saying, "Let them alone; they make better speeches for us than we can make for ourselves." Altogether, the House of Commons exhibited the most deplorable aspect that can be conceived. The Ministry had pursued Walpole's system of buying up opponents by place, or pension, or secret service money, till there was no life left in the House. Ministers passed their measures without troubling themselves to say much in their behalf; and the opposition dwindled to Sir John Hinde Cotton, now dismissed from office, and a feeble remnant of Jacobites raised but miserable resistance. In vain the Prince of Wales and the secret instigations of Bolingbroke and Doddington stimulated the spirit of discontent; both Houses had degenerated into most silent and insignificant arenas of very commonplace business. "It certainly will be. Miss Widgeon," answered Maria, with strictly "company manners." "One who has never had a brother exposed to the constant dangers of army life can hardly understand how glad we all feel to have Si snatched from the very jaws of death and brung back to us." "Just plug at 'em as you would at a crow, and then go on your way whistlin'?" persisted Harry. "Hurroo!" echoed Hennessey; "that's the ticket." "Come forward, keeper," continued the baron, "and state how these arrows came into your hands!" "Yes." HoMEJULIA京香2018下载
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