VOA科学技术2024--Who Were the Denisovans, Ancestors of Modern Humans?

Pieces of bones in a cave in the Tibetan highlands have given researchers new evidence of the mysterious human ancestors known as Denisovans.

International researchers examined more than 2,500 bones found inside Baishiya Karst Cave. Most of the bones were from animals hunted by the Denisovans. The scientists studied proteins found in the bones to learn more about the Denisovans and the animals they depended on for food.

Baishiya Karst Cave is at a high altitude, or height above sea level, of 3,280 meters in the Tibetan Plateau.

The researchers discovered that the Denisovans hunted many different kinds of animals for food including sheep and a large, hairy animal called a woolly rhinoceros¹. The scientists published their findings this month in Nature.

Animal resources

Most of the bones were identified as belonging to blue sheep that still live in the Himalayan Mountains. Other animals included the woolly rhinos², yaks³, small mammals such as marmots, birds and the spotted⁴ hyena⁵, a dog-like creature that lived in an area called the Ganjia Basin.

In the cave containing animal bones, the researchers also discovered a rib⁶ bone from a Denisovan individual believed to be from 48,000 to 32,000 years old. That would make it the most recent Denisovan remains⁷ yet discovered.

The researchers believe the Denisovans killed the animals for their meat. There was evidence found on the bones suggesting the cutting, or butchering, of meat and processing of animal skins. There was also evidence of animal bone tools.

Frido Welker, a molecular⁸ anthropologist⁹ with the University of Copenhagen in Denmark, was one of the leaders of the research. He said, "It is the first time we have gotten an understanding of the subsistence behaviors of Denisovans." Welker added that these human ancestors were able to use "a wide range of animal resources."

Dongju Zhang, an archeologist with Lanzhou University in China was another study leader. He said, "I think the diverse animal remains found in Baishiya Karst Cave suggest that this location offered relatively¹⁰ better resources compared with the neighboring higher Tibetan Plateau to the west and the Chinese Loess Plateau to the north..."

The Denisovans

Scientists did not publish evidence of Denisovans until 2010, when research identified a bone that came from Denisova Cave in Russia's Siberia area. Genetic¹¹ examination showed that Denisovans were closely related to Neanderthals, other human ancestors who lived in Eurasia. Both groups are believed to have interacted a lot with Homo sapiens, or modern man, and are believed to have interbred with modern humans.

Welker said, "From genetics, we know they diverged¹² from Neanderthals around 400,000 years ago."

Denisovans are known only from remains found in three places. They are Denisova Cave, Cobra Cave in Laos and Baishiya Karst Cave in Tibet. The wide separation suggests they lived in many different areas.

Zhang said their presence in such a wide area "implies that Denisovans had high flexibility¹³ to adapt to different environments."

Another bone found in Baishiya Karst Cave is a lower jaw¹⁴ bone of a young Denisovan. It is believed to be 160,000 years old. The researchers said they thought the human ancestors lived there as early as 200,000 years ago. But the piece of rib suggests their presence was more recent.

"We don't know if the rib was from an adult or a child, nor its genetic sex," said Welker. He added it was the first time a Denisovan rib has ever been discovered.

Scientists say Homo sapiens did not populate the Tibetan Plateau until about 40,000 years ago and first appeared in Africa a little more than 300,000 years ago.

But what happened to the Denisovans seems to be a mystery.

"We know so little," Welker noted¹⁵, adding, "We know that Denisovans interbred with modern humans. We know that based on some Denisovan DNA¹⁶ that is present in the genomes of some modern humans living today."

He then said, "But when, where and why Denisovans ultimately went extinct, that we don't know anything about."

Words in This Story

anthropologist -n. a scientist who studies human race, society and behavior

subsistence -adj. related to the most basic needs for life such as food, shelter, protection and social structure

diverse -adj. involving many different kinds of related or similar things

interbreed -v. when two different species have mate and have babies

imply -v. to suggest

adapt -v. to change behavior to better meet the demands of new conditions

genome -n. to whole group of genetic information of a living thing

1 rhinoceros   

n.犀牛

参考例句：

• The rhinoceros has one horn on its nose.犀牛鼻子上有一个角。
• The body of the rhinoceros likes a cattle and the head likes a triangle.犀牛的形体像牛，头呈三角形。

2 rhinos   

n.犀牛（rhino的复数形式）

参考例句：

• There are many reports of people taming and even training Indian rhinos. 有许多关于人们驯养甚至训练印度犀牛的记载。 来自辞典例句
• The rhinos had fed during the night in the rice fields of these villagers. 犀牛夜里在这些村民的庄稼地里也已吃饱了。 来自辞典例句

3 yaks   

牦牛( yak的名词复数 )； 笑话

参考例句：

• The jokes get yaks. 那笑话引人发笑。
• Social species including birds, fish and yaks must have companionship. 习惯群居的生物，包括鸟类、鱼类和（牛毛）牛必须有伙伴。

4 spotted   

adj.有斑点的，斑纹的，弄污了的

参考例句：

• The milkman selected the spotted cows,from among a herd of two hundred.牛奶商从一群200头牛中选出有斑点的牛。
• Sam's shop stocks short spotted socks.山姆的商店屯积了有斑点的短袜。

5 hyena   

n.土狼，鬣狗

参考例句：

• African hyena noted for its distinctive howl.非洲鬣狗，以其特别的嚎叫而闻名。
• The hyena's public image is not aided by its ridiculous appearance.鬣狗滑稽的外表无助于改善它在公众心中的形象。

6 rib   

n.肋骨，肋状物

参考例句：

• He broke a rib when he fell off his horse.他从马上摔下来折断了一根肋骨。
• He has broken a rib and the doctor has strapped it up.他断了一根肋骨，医生已包扎好了。

7 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

8 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

9 anthropologist   

n.人类学家，人类学者

参考例句：

• The lecturer is an anthropologist.这位讲师是人类学家。
• The anthropologist unearthed the skull of an ancient human at the site.人类学家在这个遗址挖掘出那块古人类的颅骨。

10 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

11 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

12 diverged   

分开( diverge的过去式和过去分词 )； 偏离； 分歧； 分道扬镳

参考例句：

• Who knows when we'll meet again? 不知几时咱们能再见面！
• At what time do you get up? 你几时起床？

13 flexibility   

n.柔韧性，弹性，（光的）折射性，灵活性

参考例句：

• Her great strength lies in her flexibility.她的优势在于她灵活变通。
• The flexibility of a man's muscles will lessen as he becomes old.人老了肌肉的柔韧性将降低。

14 jaw   

n.颚，颌，说教，流言蜚语；v.喋喋不休，教训

参考例句：

• He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。
• A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。

15 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

16 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。