Summary

Introduction to Human Evolution

In 2000, a team of British, French, and Kenyan scientists made a groundbreaking discovery in Kenya, unearthing what could be the oldest human ancestor, potentially shedding light on the mysterious early beginnings of the human race and the transition from tree-dwelling to walking on two legs. This discovery, dubbed the “Millennium man,” was later scientifically named Orrorin, meaning “original man” in the local language.

The Discovery of Orrorin

The discovery of Orrorin was made in the Latino formation, an ancient lake basin created by a giant lava flow in Eastern Africa. The sediments between these lava flows, dated to around 6 million years old, contain important fossils, including hominids, providing a unique snapshot of prehistoric time and allowing for the understanding of the evolutionary process. Martin Pickford and Brigitte Senut made significant discoveries at a dig site, including a femur and humerus that appeared human-like, suggesting a possible hominid, and ultimately uncovered 13 fossil fragments from five different individuals of a previously unknown creature.

Understanding Human Ancestors

Australopithecus afarensis, known as Lucy, is a 3-4 million-year-old skeleton that was a significant discovery in understanding human ancestors. However, the new find, Orrorin, potentially 6 million years old, could provide a glimpse into an even more distant past, a period with very few fossils, making any discovery from this time crucial and highly important. Finding an ancestor of modern humans is extremely difficult due to the complex process of evolution, but one key characteristic that distinguishes humans from other primates is bipedalism, or walking on two feet, which may be a clue to identifying early human ancestors.

Bipedalism and Human Evolution

Evidence of upright walking is key to defining the human family tree, and finding proof of bipedalism in early fossils is crucial. The 6 million-year-old Orrorin could be the earliest ancestor, but the lack of a knee joint in the remains makes it difficult to confirm upright walking, as the knee joint is a vital indicator of bipedalism due to its unique adaptation in humans. A groove on the surface of the thigh bone may provide evidence of muscle attachment and usage, potentially indicating bipedalism. CT scans and 3D models of fossilized bones reveal the animal’s behavior and adaptations while alive, showing thicker bone on the underside of the neck to support weight, indicating it was adapted for walking, running, and standing on two feet.

Characteristics of Orrorin

Scientists have discovered that Orrorin has a mix of human and chimpanzee-like features, including teeth that resemble both species, with back teeth similar to modern humans and front teeth similar to chimpanzees. The shape of an animal’s teeth indicates its diet, with sharp teeth suited for leaves and flat teeth for crushing nuts and seeds. Orrorin’s teeth suggest an omnivorous diet of nuts, fruits, and insects, possibly including meat. It is likely that Orrorin lived in multi-male, multi-female groups, similar to modern primates, indicating a social behavior.

Early Human Environment and Behavior

Early human ancestors existed before the creation of stone tools, around 2.5 million years ago, and lived in a forest environment with abundant water and trees. Fossil evidence, including animal remains and the structure of the human arm and hand bones, suggests they were skilled climbers and likely spent time in trees, possibly even making nests and sleeping there. Lauren would have been cautious of predators, such as ancient big cats, which left behind evidence like tooth marks and finger bones.

The Emergence of Bipedalism

Bipedalism is a rare trait in mammals, and its emergence in humans is still not fully understood, with research suggesting it is almost twice as ancient as previously thought, prompting scientists to explore its advantages, including insights from robotics and biomechanics. Researchers at MIT developed various robots, including bipedal and quadrupedal ones, to study evolution and movement. They found that building a bipedal robot was easier due to reduced mechanical complexity. Bipedalism has advantages, such as increased maneuverability and agility, and the ability to use hands freely.

Challenging the Conventional Theory

The conventional explanation for human ancestors learning to balance and stand upright centers on a huge environmental change in Africa 10 million years ago, where thick forests gave way to open savannas due to tectonic activity. However, the discovery of Orrorin challenges this theory, as it shows that upright-walking may have appeared before the savannas were formed, and that early humans may have still lived amongst trees, contradicting the classic image of gradual evolution from quadrupedal to upright creatures.

Studying Orangutans to Understand Bipedalism

Researchers are studying orangutans to understand how bipedalism evolved in humans, as they believe it originated in a forested environment as a pre-adaptation before humans moved to savannas. Scientist Robin Crompton is analyzing the orangutan’s unique walking pattern, which is similar to humans, to explain how a tree-dwelling creature developed upright walking. Certain animals spend most of their time in the forest canopy, using their bodies to reach for branches and food, and have developed an acute sense of balance.

Conclusion

The discovery of Orrorin has provided significant insights into human evolution and the emergence of bipedalism. The characteristics of Orrorin, including its mix of human and chimpanzee-like features, suggest that it is a prototype for the human form that would eventually evolve into modern man. Further research into the evolution of bipedalism, including the study of orangutans and the use of robotics and biomechanics, will continue to shed light on the mysterious early beginnings of the human race.

Key Vocabulary

Term	Definition	Example Usage
Orrorin	A 6 million-year-old human ancestor discovered in Kenya, potentially the oldest known human ancestor.	The discovery of Orrorin has provided significant insights into human evolution and the emergence of bipedalism.
Bipedalism	The ability to walk on two feet, a characteristic that distinguishes humans from other primates.	Bipedalism is a rare trait in mammals, and its emergence in humans is still not fully understood.
Australopithecus afarensis	A 3-4 million-year-old human ancestor, also known as Lucy, discovered in Ethiopia.	Australopithecus afarensis is a significant discovery in understanding human ancestors, but Orrorin may be an even more ancient relative.
Hominid	A member of the human family, including modern humans and their extinct relatives.	The discovery of Orrorin has provided important evidence of a previously unknown hominid.
CT scans	A medical imaging technique used to create detailed images of the inside of the body or, in this case, fossilized bones.	CT scans of Orrorin’s fossilized bones have revealed important information about its behavior and adaptations.
Biomechanics	The study of the mechanical properties of living organisms, including the movement and structure of the body.	Researchers are using biomechanics to understand the emergence of bipedalism in humans and its advantages.
Orangutan	A great ape species native to Indonesia and Malaysia, known for its intelligent and social behavior.	Researchers are studying orangutans to understand how bipedalism evolved in humans, as they believe it originated in a forested environment.
Savannas	Grasslands with scattered trees, often found in tropical and subtropical regions.	The conventional explanation for human ancestors learning to balance and stand upright centers on a huge environmental change in Africa, where thick forests gave way to open savannas.
Tectonic activity	The movement and interaction of the Earth’s lithosphere, including the formation of mountains and volcanoes.	Tectonic activity is believed to have played a role in the formation of the savannas in Africa, which may have influenced the evolution of human ancestors.
Pre-adaptation	A trait or characteristic that evolves in one environment but becomes advantageous in a different environment.	Researchers believe that bipedalism may have originated as a pre-adaptation in a forested environment before humans moved to savannas.

Watch The Video

The Discovery Of The Earliest Human Ancestor | First Human | Timeline

Vocabulary Quiz

1. Which term refers to walking on two feet, a key characteristic that distinguishes humans from other primates?

A) Quadrupedalism
B) Omnivorous diet
C) Bipedalism
D) Tree-dwelling

2. What does the shape of an animal’s teeth indicate about its behavior?

A) Its ability to climb trees
B) Its social behavior
C) Its diet
D) Its environment

3. According to the text, what is the name of the 3-4 million-year-old skeleton that was a significant discovery in understanding human ancestors?

A) Orrorin
B) Millennium man
C) Australopithecus afarensis, known as Lucy
D) Orangutan

4. What is the name of the scientist who is analyzing the orangutan’s unique walking pattern to explain how a tree-dwelling creature developed upright walking?

A) Martin Pickford
B) Brigitte Senut
C) Robin Crompton
D) Lauren

5. What is the estimated age of the Orrorin fossils, which could provide a glimpse into an even more distant past of human evolution?

A) 2.5 million years old
B) 3-4 million years old
C) 6 million years old
D) 10 million years old

Answer Key:

1. C
2. C
3. C
4. C
5. C

Grammar Focus

Grammar Focus: The Use of the Present Perfect Simple and Past Simple Tenses to Describe Discoveries and Events

The present perfect simple and past simple tenses are used to describe discoveries and events in the text. The present perfect simple tense, formed with “has/have” + past participle, is used to describe an action that started in the past and continues up to the present, or has a connection to the present. For example, “The discovery of Orrorin has provided significant insights into human evolution” shows that the discovery has had an impact that continues up to the present. On the other hand, the past simple tense is used to describe completed actions in the past, such as “A team of British, French, and Kenyan scientists made a groundbreaking discovery in Kenya” which describes a completed event. Understanding the difference between these two tenses is crucial for effective communication in English.

Grammar Quiz:

1. By the time the scientists arrived at the dig site, the local team ____________________ the fossils and was waiting for further instructions.

a) has uncovered
b) had uncovered
c) uncover
d) were uncovering

2. The discovery of Orrorin ____________________ significant insights into human evolution and the emergence of bipedalism.

a) has provided
b) provide
c) provides
d) was providing

3. Researchers ____________________ various robots, including bipedal and quadrupedal ones, to study evolution and movement.

a) have developed
b) develop
c) developed
d) are developing

4. By 2000, a team of scientists ____________________ a groundbreaking discovery in Kenya, unearthing what could be the oldest human ancestor.

a) has made
b) made
c) make
d) were making

5. The conventional explanation for human ancestors learning to balance and stand upright ____________________ on a huge environmental change in Africa 10 million years ago.

a) centers
b) centered
c) has centered
d) was centering

Answer Key:

1. b) had uncovered

2. a) has provided

3. c) developed

4. b) made

5. b) centered