雅思阅读 86: The First Human to Walk Out of Africa（走出非洲的第一人）

改编自 Smithsonian Human Origins Program / Nature（2024年11月）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus

Reading Passage

A. For most of the twentieth century, the story of human origins ran in two acts. First, a small, brainy ape-like creature evolved in Africa; then, once its brain had grown large enough, it marched out into the wider world. The ordering made intuitive sense — intelligence, after all, is what allows a species to cross deserts, build rafts and survive unfamiliar climates. The discovery of Homo erectus, and in particular the fossils from a medieval hilltop at Dmanisi in the Republic of Georgia, overturned that order. The individuals buried at Dmanisi, dated to roughly 1.8 million years ago, are the oldest hominins known outside Africa. Their brains, measured in cubic centimetres, were smaller than those of many modern chimpanzees. Their bodies were shorter than ours. Yet they had left the continent. Whatever propelled humanity's first global dispersal, it was not a large brain. It was something else — posture, persistence, the ability to walk long distances on two legs — and that something else arrived long before intelligence did. The implication reverses a familiar prejudice. We like to think of our species as the brain that escaped from Africa. The fossils suggest instead that the body escaped first, and that the brain, given a few hundred thousand years of walking and talking and cooperating in groups, grew into the room the body had already booked.

B. Homo erectus was, by any measure, a successful species. It emerged in Africa around 1.9 million years ago, perhaps descended from the smaller, tree-climbing Homo habilis, and within a few hundred thousand years its bones turn up in Java, in China, and in the Georgian Caucasus. It persisted, in one form or another, for almost two million years — far longer than our own species has so far existed. The body plan that made this possible is recognisable in the earliest fossils and barely changes thereafter. A long, low, teardrop-shaped skull perched above a pelvis built for striding. Legs longer than arms, feet arched, fingers no longer curved for grasping branches. The famous Turkana Boy skeleton from Kenya, almost complete, shows a teenager who already walked like a modern human and ran like one, too. By the time Homo sapiens appears on the scene, Homo erectus had been an upright, long-distance walker for as long as Tyrannosaurus rex has been extinct.

C. The Dmanisi finds are peculiar because of their variation. Excavations beneath a ruined fortress over three decades have produced five crania, several lower jaws and scattered limb bones from a single ancient layer. Found at different sites, those five skulls would, by conventional classification, almost certainly have been assigned to several different species. One is tiny, with a brain close to 600 cubic centimetres; another is larger and more robust. The skulls include the famous "Skull 5", a heavily built male with a large face and small braincase, and the edentulous "Skull 4", an elderly individual who had lost every tooth years before death and must have been cared for by others. The most parsimonious reading is that this was a single population whose natural range — in skull size, face shape and body mass — was simply wider than textbooks assumed. The implication is unsettling for taxonomy: many of the "different species" of early Homo named from isolated fossils may instead be males and females, young and old, of the same highly variable creature.

D. In 2024, researchers added a quieter but deeper clue. They examined the microscopic growth lines preserved in the teeth of an eleven-year-old individual from Dmanisi, buried alongside the other fossils. Teeth, like trees, record their own age in daily increments, and the pattern revealed that this child's dental development was delayed relative to that of apes, resembling the slower, extended growth of modern human children. In apes, the first molar erupts at about three years; in modern humans, it arrives closer to six. The Dmanisi youngster followed something closer to the human schedule. That is significant because a long childhood is expensive: it demands many years of feeding, protection and teaching by adults. Homo erectus, it seems, had already adopted the slow, social, cooperative life-history that we used to think was invented much later, by big-brained Homo sapiens. Walking upright and living in small, interdependent groups came first; the large brain filled in afterward.

E. The picture is still contested. Some paleoanthropologists argue that the African fossils conventionally labelled Homo erectus — including the 1.9-million-year-old cranium from Gona, Ethiopia, which mixes primitive and modern features — show that the species did not appear fully formed but emerged gradually from a messy, interconnected network of early Homo populations across the continent. Others point to the newly described cranium from South Africa, DNH 134, whose long, low shape places it firmly with Homo erectus despite its age. Whatever the finer classification, two conclusions now look secure. The first is that the exodus from Africa was early, cheap and physically modest: small-brained bipeds, not geniuses, crossed the Sinai land bridge under their own power. The second is that the traits we consider uniquely human — prolonged childhood, cooperation, the shared care of the infirm — were already part of the package when they did. The long walk out of Africa was not the triumph of a genius. It was the first journey of a creature that had learned, almost against its nature, to take care of one another. That combination — an upright body, a cooperative group, and a slow childhood in which each new generation was taught rather than programmed — is the package that every later human species, including our own, inherited. Whatever else distinguishes us from the fossils at Dmanisi, the walk itself, and the company on it, were already in place 1.8 million years ago.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. The species that conquered two million years ii. Why Homo erectus went extinct iii. Wide variation in a single population at Dmanisi iv. New evidence for a long, slow childhood v. Remaining disputes and what is now secure vi. The discovery of fire by Homo sapiens vii. How tools were made from bronze

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. Why did Dmanisi overturn the traditional story of human dispersal? A. It showed that humans left Africa after their brains had reached modern size. B. It showed small-brained bipeds left Africa 1.8 million years ago. C. It proved that Homo erectus never left Africa. D. It suggested that chimpanzees can walk upright.

6. Why is the variation among the five Dmanisi skulls important? A. It proves that Dmanisi was invaded by five different species at once. B. It suggests many "separate species" may instead be one variable population. C. It shows that Homo erectus had a much smaller brain than expected. D. It indicates that the site was flooded five times.

7. What did the 2024 tooth study conclude about the Dmanisi child? A. Its dental development matched that of modern apes. B. Its growth was slow and extended, like modern human children. C. It died before reaching its first birthday. D. Its teeth showed no detectable growth lines.

8. According to the writer, what came first in human evolution? A. A large brain and then upright walking. B. Upright walking and cooperative care, then a larger brain. C. Complex language, then long-distance travel. D. Fire-making, then long childhood.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. The Dmanisi fossils are the oldest known hominin remains outside Africa.
10. Homo erectus survived for roughly the same length of time as Homo sapiens has so far.
11. The edentulous Skull 4 individual had lost all its teeth before death.
12. In modern apes, the first molar erupts at about six years of age.
13. All paleoanthropologists now agree on a single, neat classification of early Homo.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

The Dmanisi skulls show a wide range of variation in brain size and face shape, suggesting that many so-called separate (14) __________ may in fact belong to one highly (15) __________ population.

答案与解析

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