Big History: The Big Bang, Life on Earth, and the Rise of Humanity

Is it possible to tell a story of everything, from the big bang up to the present day? This episode introduces the background and unique aspects of this broad, multidisciplinary perspective on history.

Most history series cover time spans of a few decades or a few centuries, but big history requires us to survey the past over scales that span billions of years. This episode explores ways to become more familiar with the immense scales needed to cover the modern creation story.

In this episode, we introduce one of the unifying themes of the series: the development of increasing complexity since the creation of the Universe. Here, we'll examine the definition of complexity and ask how our Universe builds more complex entities.

Why should we trust the claims of modern science about events in the distant past? This episode lays some ground rules about evidence for proving scientific claims and describes how new dating techniques have allowed scientists to peer further back into the past than previously thought possible.

We encounter the first threshold of complexity (the creation of the Universe at the moment of the big bang) and explore the scientific evidence that allows us to piece together this ever-evolving story of creation.

This episode surveys the history of different ideas about the creation of the Universe, from Ptolemaic theories of an Earth-centered cosmos to the modern notion of a constantly expanding Universe.

How did the Universe change from a cloud of dust to a constellation of stellar bodies? This episode describes how gravity was fundamental in crossing the second threshold of the series: the creation of stars and galaxies from huge clouds of hydrogen and helium atoms.

Stars created the preconditions for crossing a third threshold of complexity: the formation of chemical elements. As stars collapse and die, they fuse to create new atoms that are the building blocks of all the complex chemicals that make up our Earth.

With this episode, we shift from the scale of the Universe to that of our solar system. Here we examine the processes by which planets and solar systems are created and the evidence that helps us piece together this part of the story.

The tumultuous early history of the Earth is presented in this episode, including the development of our planet's internal layers, the generation of its magnetic field, the creation of the first seas, and the appearance of its early atmosphere.

In this episode, we examine the history of the Earth's surface and learn how the notion of our planet as fixed and unchanging was eventually overturned by a new vision of the Earth's crust as broken into plates that are constantly on the move.

With the consideration of the next threshold of complexity, life, we develop a definition of life itself, and begin to consider how life-forms adapt and change over time.

In "On the Origin of Species," Charles Darwin revealed a new story: an account of how all living species change and adapt. This lecture recounts how Darwin arrived at his revolutionary theory, and how he shared his ideas with contemporaries who were making similar breakthroughs.

In this episode, we examine the various kinds of evidence Darwin used to establish his theory of natural selection, including the fossil record, similarities among species, and the geographic distribution of species. We also review modern evidence of natural selection.

How was life first created from non-life? Modern biologists tell a complex story of the creation of life which involves the development of organic matter from simpler molecules such as amino acids, nucleic acids, sugars, and proteins.

Here, study the first four (out of eight) major evolutionary transitions, embracing the first 3 billion years of the Earth’s history, a period in which all living organisms consisted of single cells.

The fusion of single-celled organisms into larger, multi-celled organisms c. 600 million years ago marked a turning point in the development of life forms on this planet. In this lecture, we focus on the evolution of multi-cellular organisms, tracing four evolutionary steps leading to our own species, "Homo sapiens."

How did modern humans evolve from ape-like ancestors? This episode surveys the evolution of primates and great apes, and then traces the adaptive development of hominines, a group of bipedal primates that appeared in Africa 7 million years ago.

To construct the story of hominine evolution, scientists rely on three kinds of evidence: archaeological evidence, evidence based on the study of modern primates, and evidence based on genetic comparisons between modern species of primates, including ourselves.

Human beings represent a new threshold of complexity in the story of life on Earth. In this episode, we examine two things that make us unique: use of symbolic language and collective learning.

Does the archaeological record reveal when the first members of our species appeared? In this episode, we examine evidence from the Stone Age and consider several theories of the early history of the first humans.

Using remains left behind by our ancestors and studies of modern societies that still use stone technologies, modern researchers have constructed a portrait of the Paleolithic way of life. In this episode, we enter into this world and learn what life was like for our distant ancestors.

Change was gradual over the course of the long Paleolithic era, but there were some significant shifts that altered lifeways for human beings. These include climate changes during two ice ages, the rise of various technological innovations, and adaptive migration to nearly all parts of the globe.

The appearance of agriculture set human history off in entirely new directions by increasing human control of food, energy, and other resources. The development of agriculture brings about changes in the environment and lays the foundation for the development of more complex human societies.

Why, after 200,000 years of foraging, should human communities in quite different parts of the world take up agriculture almost simultaneously? In this episode, we explore the different factors leading to this innovation.