A team of scientists working in Georgia, in the former Soviet Union, has unearthed the remains of four human-like creatures dating to 1.8 million years ago, which they say sheds new light on a key stage in human evolution. The specimens are the oldest hominids to ever be found outside of Africa.
The Dmanisi site where the bones were discovered, was once near a lava flow where these primitive humans are believed to have scavenged carcasses for meat. But it appears these early humans ancestors became the unfortunate victims of a large carnivore, as their collective bones were marked by animal teeth and found in a lair-like deposit.
In the journal Nature, the researchers outline details of the partial skeletons uncovered. The bones are a mixture of primitive and advanced features, team leader David Lordkipanidze explains. These early hominids were likely “ancient pioneers”, as they appear to be among the first to leave Africa to colonize other parts of the world.
"Dmanisi is a real gift, because nothing in the world exists like this for this time," says lead author David Lordkipanidze.
Discovered in the early 1990s, the Dmanisi site has been a rich source of remains and artefacts from the early Pleistocene Epoch. Studying the various skulls and jaws has given scientists important information about the early species that lived here. But until recently they had little information about the rest of the skeleton. The remains uncovered at the town of Dmanisi consist of the partial skeleton of an adolescent individual associated with a skull, and the "post-cranial" remains of three adults.
The well-preserved fossils resemble Homo erectus, a species from the genus Homo that first appeared in Africa some two million years ago and quickly spread throughout Europe and much of Asia.
Lordkipanidze and his colleagues note that the skeletal fossils of shoulder, arm, spine and leg show that the individuals were small (about 50 kilograms on a frame of some 150 centimetres tall), had modern-human body-limb proportions. They have remarkably human-like spines and lower limbs that would have been well suited for long distance travel. Their feet had well-developed arches. The small difference in the size of males and females would put them in the same company as Homo erectus and Homo sapiens.
However, they also have relatively small brains and primitive upper limbs, traits which they share with the earlier Homo habilis, and even with the more primitive Australopithecus, such as the famous “Lucy”, specimen which lived in Africa some four million years ago.
"The really important point is you have multiple individuals from the same time and location," notes Tim White, a palaeoanthropologist at the University of California, Berkeley. With just one individual specimen it is quite difficult to determine whether a specific feature such as head size is typical of the entire species or just characteristic of that one individual. However, finding the remains of three adults and an adolescent all in the same place, presents a much clearer picture of what the species was like as a whole.
译文:
四种类人生物的遗骸揭示了新的发现
一组科学家们在前苏联的格鲁吉亚地区工作，在那里出土了4个距今有180万年历史的类人生物的遗骸，科学家们认为这在人类进化史中是一个关键的时期。这些标本是非洲以外发现的最古老的原始人。
这些骨头是在德马尼西遗址发现的，是一个靠近熔岩流的地方,原始人在这里清理尸肉。但现在看来，这些人类的早期祖先成为了一个巨大的肉食兽底下的受害者，因为他们的骨头和动物的牙齿是在一个洞穴里一起发现的。
在自然周刊中，研究者可以从中查阅到人类局部骨骼的轮廓。队伍的领导人大卫解释道，这些骨头同时具备原始人和现代人的特征。这些早期的原始人可能是“古老的开荒者”，他们似乎是第一批离开非洲去世界其他地方开拓殖民地的人。
“德马尼西真是个上天的礼物，因为在这个时候世上没有这样的遗迹存在，”主要发起人大卫说道。
20世纪90年代初发现，德马尼西遗址已经成为早更新世时期以来具有丰富遗骸和文物的源泉。研究各种不同的头骨和下颚骨能给科学家们带来许多有关早期生物在此生存的重要信息。但是直到前不久他们才获得一点点有关其余骸骨的信息。于是在德马尼西遗址发现了一个青少年的个体骨架和一个头骨，还有三个成年人后颅的骨骼。
这些保存完好的化石类似于直立人，从这个属系的人类来说，最早是在二百万年前出现在非洲的一些地方，并迅速蔓延至整个欧洲和亚洲大部分地区。
大卫和他的同事注意到这种骨骼的化石如肩膀、手臂，脊柱和腿部都显示出这种个体是很小的（大约50公斤重，150厘米左右高），具有现代人体肢体比例。他们有明显的类似人的脊椎和较短的腿，这些很适合长途的旅行。他们的脚具有很发达的足弓。男性和女性尺寸上的细微差别是可以将他们从同一堆人中区分出直立人和智人。
然而，他们还有相对较小的大脑和原始的上肢，具有同早期原始人相同的特征，甚至具有更原始的南方古猿的特征，如著名的标本“露西”，是四百万年前生活在非洲的其中之一。
“真正重要的一点是，你发现有许多不同的个体都来自于同一个时期和地点，”加州大学伯克利分校的古猿学家帝姆怀特说道。仅有一个个别标本是很难决定其特征的，典型的如头部大小或一个人的特点都是很难决定整个物种特征的。然而，在同一个地方发现的三个成年人和一个青少年的遗骸，能更清楚的去了解这整个物种。