During which period did humans first appear on Earth?
Quaternary
Neogene
Paleogene
Cenozoic
Humans first appeared on Earth during the Quaternary period.
Where do scientists find pollen grains to study ancient climate change?
What attribute of the pollen grains helps scientists identify the types of plants they belonged to?
Scientists find pollen grains to study ancient climate change in sediment cores obtained from lakes, bogs, and other bodies of water. These sediment cores contain layers of accumulated pollen, providing a record of plant species present in the past.
The attribute of the pollen grains that helps scientists identify the types of plants they belonged to is their morphology or shape. Each plant species produces pollen with distinct morphological characteristics, such as size, shape, and surface features. These features can be observed under a microscope and compared to existing reference collections of known plant species to determine which plants the pollen grains originated from.
Which of these are causes of long-term climate change? Check all that apply.
Earth's orbit around the Sun
fossils
movement of continents
solar energy
volcanic activity
The causes of long-term climate change include:
- Earth's orbit around the Sun
- Movement of continents
- Solar energy
- Volcanic activity
Humans first appeared on Earth during the Quaternary period.
The correct answer is the Paleogene period. Humans first appeared on Earth during the Paleogene period, which is part of the Cenozoic era. To arrive at this answer, you need to have a basic understanding of geologic time scales and the history of human evolution.
The Cenozoic era is divided into three major periods: Paleogene, Neogene, and Quaternary. The Paleogene period lasted from about 66 to 23 million years ago. During this period, the early ancestors of mammals, including primates, began to diversify. However, it was not until the later part of the Paleogene period that humans (specifically, the genus ) first appeared.
The Neogene period followed the Paleogene and extended from about 23 million years ago to 2.6 million years ago. During this time, the progress of primate evolution continued, with the development of more advanced primates. However, modern humans did not emerge until the final period of the Cenozoic era.
The Quaternary period is the most recent period, starting around 2.6 million years ago and continuing to the present day. This period encompasses the emergence and evolution of modern humans, as well as the subsequent development of human civilizations.
Therefore, the correct answer to the question "During which period did humans first appear on Earth?" is the Paleogene period, which is part of the larger Cenozoic era.