Stone Tools Might Be Earliest Evidence of Human Ancestors in Europe

Stone Tools Might Be Earliest Evidence of Human Ancestors in Europe

　　Researchers say they have identified stone tools that might represent the oldest-known evidence of humans in Europe.

　　The recent research suggests that the human ancestors started settling Europe 1.4 million years ago. That is hundreds of thousands of years earlier than previously¹ thought.

　　The stone tools were first discovered in the 1970s near the town of Korolevo, close to Ukraine's borders with Hungary and Romania. But the tools' age had remained unclear.

　　The place of the find is important for understanding how humans first spread into Europe. They moved into the area during warm periods, called interglacial periods. Those were times, in between Ice Ages, when huge amounts of ice covered Europe.

　　The scientists used a method for estimating the age that identifies the effects of cosmic rays on some kinds of minerals. The new method placed the age of the sediment² layer containing the stone tools at around 1.4 million years.

　　The researchers believe that the maker³ of the tools was likely a human ancestor called Homo erectus. That early human species appeared around 2 million years ago and spread across Africa, Asia and Europe before disappearing perhaps 110,000 years ago.

　　"No bones were found at Korolevo, only stone tools. But the age suggests that Homo erectus was the only possible human species at the time. We know very little about our earliest ancestors. They used stone tools for butchery and probably used fire," said Roman Garba of the Czech Academy of Sciences. Garba was the lead writer of the research published in Nature.

　　Homo erectus was the first member of our evolutionary⁴ lineage. Homo erectus had body proportions like our species, Homo sapiens, though with a smaller brain.

　　The tools, made of volcanic⁵ rock, were made in a way that is called Oldowan. While simple, they represent the beginning of human technology.

　　Until now, the oldest-known evidence of humans in Europe was from about 1.2 million years ago from a place called Atapuerca in Spain.

　　The Korolevo findings suggest how the first humans might have moved into Europe. Homo erectus fossils from 1.8 million years ago are known from a place in the Caucasus Mountains in Georgia called Dmanisi. Garba said the evidence from Korolevo and Dmanisi suggests Homo erectus entered Europe from the east or southeast, moving along the Danube River.

　　It has been difficult to identify the age of places like Korolevo. The study dated the tools, left by their makers⁶ on a riverbed, by estimating when the layer holding the objects was buried under sediment.

　　Mads Knudsen of Aarhus University in Denmark described how scientists were able to date the prehistoric⁷ tools.

　　He said cosmic rays from outer space are always passing through the Earth's atmosphere. When they do, they create particles that are smaller than atoms, such as neutrons⁸ and muons. These particles are so small that they pass through all sorts of materials.

　　These particles react with minerals in rocks to produce radioactive nuclides, a class of atoms. The sediment was dated based on the ratio of two nuclides. This is possible because the two nuclides break down at different rates, through the process of radioactive decay.

　　Europe was later colonized⁹ by other human ancestor species including Homo heidelbergensis and Neanderthals. Scientists say Homo sapiens evolved in Africa about 300,000 years ago. They arrived in large numbers in Europe around 40,000 to 45,000 years ago.

　　The researchers suspect evidence of human occupation in Europe that is even older than Korolevo will be found.

　　"The question is not 'if' but 'when' we will find a site of similar or older age somewhere else in Ukraine, Romania, Bulgaria or Serbia," Garba said.

　　Words in This Story

　　cosmic rays – n. particles of atomic or smaller size that pass into the Earth's atmosphere from space at extremely high energy levels

　　sediment – n. material (such as stones and sand) that sinks to the bottom of a body of water forming a layer that solidifies¹⁰ into rock over long periods of time

　　species –n. a group of animals or plants that are similar and can produce young

　　butchery – n. the job or act of preparing meat for eating

　　lineage – n. the people who were in someone's family in past times

　　proportion – n. the relationship between the size, shape, and position of the different parts of something

　　fossil – n. something (such as a bone or footprint) that is from a plant or animal that lived in ancient times

　　ratio –n. a numerical relationship between two values

1 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

2 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

3 maker   

n.制造者，制造商

参考例句：

• He is a trouble maker，You must be distant with him.他是个捣蛋鬼，你不要跟他在一起。
• A cabinet maker must be a master craftsman.家具木工必须是技艺高超的手艺人。

4 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

5 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

6 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

7 prehistoric   

adj.（有记载的）历史以前的，史前的，古老的

参考例句：

• They have found prehistoric remains.他们发现了史前遗迹。
• It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。

8 neutrons   

n.中子( neutron的名词复数 )

参考例句：

• The neutrons and protons form the core of the atom. 中子和质子构成了原子核。 来自《简明英汉词典》
• When an atom of U235 is split,several neutrons are set free. 一个铀235原子分裂时，释放出几个中子。 来自《简明英汉词典》

9 colonized   

开拓殖民地，移民于殖民地( colonize的过去式和过去分词 )

参考例句：

• The area was colonized by the Vikings. 这一地区曾沦为维京人的殖民地。
• The British and French colonized the Americas. 英国人和法国人共同在美洲建立殖民地。

10 solidifies   

（使）成为固体，（使）变硬，（使）变得坚固( solidify的第三人称单数 )； 使团结一致； 充实，巩固； 具体化

参考例句：

• Jelly solidifies as it gets cold. 肉冻冷却就凝固。
• It is stirred with 10%sodium carbonate solution(50ml)and then with water (50ml), after which It'solidifies. 与10％碳酸钠溶液（50毫升）混合搅拌，然后再用50毫升水混合搅拌，从而析出固体。