Question

During which geologic period did modern humans evolve? A. Quaternary B. Triassic C. Ordovician D. Tertiary

Short answer

Modern humans evolved in the Quaternary period.

Step-by-step solution

Understanding Geologic Time

First, we need to understand that the geological time scale is divided into several periods. The major segments are eons, eras, and periods, with periods being the shortest unit among these.

Identify the Time of Evolution

Modern humans, Homo sapiens, are known to have evolved during a specific time on the geological time scale. Homo sapiens appeared in the Pleistocene epoch, which is part of the Quaternary period.

Analyze the Options

Now, we need to analyze the given options. The Quaternary period includes the present and the recent past, which matches the timeline of the evolution of modern humans.

Conclusion

Upon examining all the periods provided: Quaternary, Triassic, Ordovician, and Tertiary, we find that modern humans evolved in the Quaternary period.

Key concepts

Human Evolution

The journey of human evolution is an intriguing story that spans millions of years. It traces the development of Homo sapiens from early ape-like ancestors, who lived in Africa. Our evolutionary path involves a series of adaptations and changes that led to the modern human form.

These changes were driven by environmental pressures and the need for survival. Consider some key aspects:

• Adaptive changes, such as walking upright on two feet, which freed up hands for tool use.
• The development of complex brain functions, leading to advanced problem-solving and communication skills.
• Changes in diet, including the mastery of tools to hunt and cook a variety of foods.

Over millions of years, natural selection favored traits that improved survival, slowly giving rise to Homo sapiens approximately 300,000 years ago. Understanding human evolution helps us comprehend the biological and cultural inheritance that shapes our identity today.

Quaternary Period

The Quaternary Period is the most recent period in the geological time scale. It spans from about 2.58 million years ago to the present. This period is crucial in understanding earth's history as it encompasses significant climatic and biological changes.

Key features of the Quaternary Period include:

• Glacial and interglacial cycles, with ice ages playing a pivotal role in shaping landscapes.
• Mass extinction events that impacted large mammals and reshaped ecosystems.
• The expansion and evolution of humans, including the spread of Homo sapiens across the globe.

The Quaternary is divided into two epochs, the Pleistocene and the Holocene, each characterized by distinct climatic patterns and biological developments. This period is essential for understanding the environments that humans have adapted to and modified during their evolution.

Pleistocene Epoch

The Pleistocene Epoch is known for its dramatic climatic changes and its role in human evolution. Spanning approximately 2.58 million to 11,700 years ago, it witnessed repeated glacial cycles. These cycles caused glaciers to advance and retreat across the continents.

Important aspects of the Pleistocene Epoch include:

• Alterations in habitats: Drastic climate changes influenced the availability and distribution of ecosystems and resources, posing challenges for life forms including hominins.
• Evolutionary developments: The epoch saw the emergence of Homo sapiens and their eventual dominance in the animal kingdom.
• Megafaunal extinction: Many large animals went extinct towards the end of the Pleistocene, possibly due to climate changes and human activities.

Understanding the Pleistocene Epoch provides insight into how ancient climate shifts influenced the survival and evolution of species, including humans, highlighting it as a pivotal time in natural history.