What happened on earth before humans were created?

 

THE TIME OF DINOSAUR EXTINCTION

Introduction

The appearance of humans and the development of civilization are fairly new occurrences in the long history of Earth. Yet, billions of years before the appearance of human beings, Earth experienced radical transformation—creation, destruction, evolution, and regeneration. From the planet's creation to the appearance of human beings, the path involves the birth of life, mass extinctions, the evolution and extinction of dinosaurs, and the evolution of mammals. Let's embark on this grand timeline.

Earth Formation and Early Time (around 4.6 billion years ago)

The Earth formed around 4.6 billion years ago when the solar system was being formed. Earth, in its initial stage, was a molten, hot ball of rock without life, water, or atmosphere. Over time, it cooled to create a solid crust. Volcanic activity, impacts from asteroids, and chemical reactions formed oceans and the early atmosphere.

This period is referred to as the Hadean Era.

Origin of Life (approximately 3.8–4 billion years ago)

Life started about 3.8 billion years ago with simple, single-celled organisms such as bacteria and archaea. This occurred during the Archean Eon. These organisms lived in extreme environments, usually around underwater volcanic vents.

Some of them, particularly cyanobacteria, evolved photosynthesis—the capacity to transform sunlight into energy, yielding oxygen as a waste product. This process over time raised the level of oxygen in Earth's atmosphere, clearing the way for more advanced life.

The Great Oxidation Event (about 2.5 billion years ago)

This was a landmark moment in the history of Earth. Oxygen created by cyanobacteria started accumulating in the air, suffocating a vast number of anaerobic species that could not survive oxygen levels, and preparing the atmosphere for more intricate, oxygen-breathing life forms. 

Evolution of Advanced Cells (about 2 billion years ago)

The first eukaryotic cells emerged—cells with an internal structure and a nucleus. These gave rise to animals, plants, and fungi. Others of these cells even formed multicellular organisms, such as algae and sponges, paving the way for more complicated creatures.

The Cambrian Explosion (approximately 540 million years ago)

This time saw the emergence of suddenly and immensely high levels of biological diversity. The explosion, or the Cambrian Explosion, produced creatures with eyes, limbs, skeletons, and nervous systems. There were abundant amounts of marine life forms in the oceans in the form of early fish, mollusks, and arthropods.

Life Comes to Land (about 450–350 million years ago)

Plants and insects started to migrate from water to land. Some of the first land ecosystems developed, with primitive ferns and mosses thriving. Fish started to develop features like limbs, lungs, and skin, eventually growing into amphibians—animals that lived both in water and on land. This was an important milestone in the development of vertebrate life on land.

The Age of Dinosaurs (approximately 235–65 million years ago)

This period consists of three large divisions:

1. Triassic Period:  The earliest dinosaurs and mammals evolved.
2. Jurassic Period:  Dinosaurs emerged as the superior animals. Such famous creatures as Brachiosaurus and Stegosaurus dominated Earth.
3. Cretaceous Period:  Advanced dinosaurs like Tyrannosaurus rex and Triceratops appeared on Earth. Flowering plants developed at that time too.

Dinosaurs held a kingdom over Earth for more than 160 million years.

The End of Dinosaurs (65 million years ago)

About 65 million years ago, a huge asteroid hit the present-day Yucatán Peninsula in Mexico (Chicxulub impact). The impact ignited wildfires, created climate change, and obstructed sunlight with ash and debris. This impact caused the extinction of nearly 75% of all animals, including most of the dinosaurs.

A few small creatures—like early mammals and birds—managed to survive this mass extinction.

Rise of Mammals (65–2 million years ago)

With dinosaurs extinct, mammals flourished. They were warm-blooded, had superior brains, and took care of their young. Mammals diversified into different forms, such as primates, which are the precursors to monkeys, apes, and ultimately humans.

The Emergence of Early Humans (approximately 5–7 million years ago)

Certain primates started walking upright, utilizing tools, and having larger brains. These were called hominins, which comprise various species such as Homo habilis, Homo erectus, and eventually Homo sapiens—humans today.

Humans emerged around 200,000 to 300,000 years ago in Africa and eventually migrated to the rest of the globe.

Conclusion

Prior to the existence of human beings, our planet went through billions of years of transformation—from volcanic origins to oceans, from bacteria to giant dinosaurs, and lastly, to intelligent mammals. Humans are the product of a lengthy and intricate process of evolution.

This history informs us how fragile life is and how intimately linked we are with Earth's natural processes. Our present existence rests on the emergence and demise of millions of species over millions of years.