Cenozoic Climate History and Human Evolution Practice Flashcards

Flashcards covering Cenozoic climate history, PETM, long-term cooling mechanisms, Milankovitch cycles, taxonomy, human evolutionary adaptations, and prehistoric cultural ages.

What do the terms Paleozoic, Mesozoic, and Cenozoic mean regarding the eras of animal life on Earth?

Paleozoic means old animal era, Mesozoic means middle animal era (when dinosaurs proliferated), and Cenozoic is the era following the Cretaceous-Paleogene mass extinction, characterized by the rise of birds, mammals, and flowering plants.

What does the acronym PETM stand for, and when did it occur?

PETM stands for Paleocene-Eocene Thermal Maximum. It occurred between the Paleocene and Eocene epochs, spanning from approximately $65$ million to $50$ million years ago.

What were the three key climatic conditions that characterized the PETM?

1. Peak temperature intensity of the entire Cenozoic era. 2. Ice-free poles resulting in low albedo and a positive feedback warming loop. 3. Atmospheric $\text{CO}_2$ levels estimated at roughly $1,600\,\text{ppm}$ (about $4\times$ modern levels of $400\,\text{ppm}$).

What is the rock weathering thermostat and how does it act as a negative feedback loop?

Increased atmospheric $\text{CO}_2$ raises temperatures and rainfall. The slightly acidic rainwater reacts with exposed surface rocks to form carbonic acid, weathering the rock and removing $\text{CO}_2$ from the atmosphere to cool the Earth.

How did plate tectonics drive long-term cooling following the PETM peak?

The collision of India into the Asian plate formed mountain ranges like the Himalayas and Tibetan Plateau, exposing vast rock surfaces to weathering. Additionally, the isolation of Antarctica formed a southern oceanic gyre that trapped cold water, growing ice sheets and increasing global albedo.

What are the three Milankovitch cycles and their approximate time scales?

1. Eccentricity: change in the shape of Earth's orbit around the sun ($\sim 100,000$-year cycle). 2. Obliquity: wobble/tilt of Earth's axis ($\sim 40,000$-year cycle). 3. Axial Precession: spinning of the axis around itself ($\sim 25,000$-year cycle).

What is the Holocene, and why is it important to human civilization?

The Holocene is the climatic period of the last $\sim 10,000$ years. It represents a period of unusual climatic stability following the last glacial cycle, which allowed complex human societies and agriculture to flourish.

What is the complete taxonomic classification hierarchy for modern humans from Kingdom to Species?

Kingdom: Animalia, Phylum: Chordata, Class: Mammalia, Order: Primates, Family: Hominidae, Genus: Homo, Species: sapiens.

According to the lecture, what are the approximate timelines for the hominin split from chimpanzees, the appearance of the earliest Homo genus, and the emergence of anatomically modern humans?

The split from chimpanzees occurred about $6$ million years ago, the earliest genus Homo appeared about $3$ million years ago, and anatomically modern humans emerged about $300,000$ years ago.

What physical adaptations developed in early hominins due to the expansion of East African grasslands?

Bipedalism (for efficient long-distance travel across open terrain), hairlessness (loss of thick body hair), and improved thermal regulation (such as efficient sweating under direct sun).

What social and cooperative behaviors resulted from human physical adaptations to open grassland habitats?

Persistence hunting (chasing prey over long distances until exhaustion), group defense against open-land predators, and increased group mobility across wide landscapes.

How did early humans adapt psychologically and physically to climate variability prior to the Holocene?

Through encephalization (expansion of brain capacity for cognitive flexibility and problem-solving) and dietary generalism (a flexible digestive system suited for consuming both meat and plant matter).

What does the term 'altricial infants' mean, and what cultural norms arose from it?

Altricial infants are born helpless and require extensive long-term parental care. This developmental trade-off required social practices such as obligate midwifery and alloparenting (group/village child-rearing).

What were the key characteristics and environmental impacts of the Paleolithic Age?

Lasting from $2,500,000$ to $12,000$ years ago ('Old Stone Age'), it featured nomadic hunter-gatherer societies, simple stone/wood tools, control of fire, hunting pressure on megafauna, and landscape modification through fire.

What major societal changes and environmental impacts defined the Neolithic Age?

Lasting from $12,000$ to $5,000$ years ago ('New Stone Age'), it brought agriculture, domestication of plants and animals, permanent River Valley settlements, complex stonework, and large-scale land clearing.

What advancements and early environmental issues marked the Bronze and Iron Ages?

Spanning $5,000$ to $2,000$ years ago, these ages introduced metallurgy (combining copper and tin for bronze, iron working for steel), pyrotechnics, and state-level societies, alongside early deforestation, soil erosion, and air pollution.

What is the Anthropocene?

A proposed geological epoch following the Holocene that refers to the modern era in which human activities significantly modify Earth's stable climate and ecological systems.