The world of invertebrates exists in a web of relationships with plants and other animals. Unique footage of the world's smallest insect (a fairy wasp only quarter of a millimetre long) shows it flying underwater to find the eggs of water beetles in which to lay its own brood. Some ants 'farm' the trees that give them shelter, creating areas known as 'Devil's gardens'. To make sure these grow without competition, they kill off other seedlings in the surrounding vegetation. The blister beetle's larvae huddle together on the end of a piece of grass and mimic a female bee. When a male bee tries to mate with the 'female', the larvae grab on to his belly. Confused, he flies away and searches for a real female. When he eventually finds her and mates with her, the beetle larvae hurriedly swap from his front on to her back, and hence get carried back to her nest where they eat her pollen supplies.

Invertebrates don't always operate alone. True society was the last feature to evolve in invertebrates, as recently as the time of Tyrannosaurus. In the last programme see the tensions below the surface in some of the great social structures built by insects, and witness the carnage when an ant colony and a termite colony wage war.

The episode begins with Tyson describing how pattern recognition manifested in early civilization as using astronomy and astrology to predict the passing of the seasons, including how the passage of a comet was often taken as an omen. Tyson continues to explain that the origin of comets only became known in the 20th century due to the work of Jan Oort and his hypothesis of the Oort cloud. Tyson then continues to relate the collaboration between Edmond Halley and Isaac Newton in the last part of the 17th century in Cambridge. The collaboration would result in the publication of Philosophiæ Naturalis Principia Mathematica, the first major work to describe the laws of physics in mathematical terms, despite objections and claims of plagiarism from Robert Hooke and financial difficulties of the Royal Society of London. Tyson explains how this work challenged the prevailing notion that God had planned out the heavens, but would end up influencing many factors of modern life, including space flight. Tyson further describes Halley's contributions including determining Earth's distance to the sun, the motion of stars and predicting the orbit of then-unnamed Halley's Comet using Newton's laws. Tyson contrasts these scientific approaches to understanding the galaxy compared to what earlier civilizations had done, and considers this advancement as mankind's first steps into exploring the universe. The episode ends with an animation of the Milky Way and Andromeda galaxies' merging based on the principles of Newton's laws.

We will nvestigate the first skeleton that really looks like us –Turkana Boy– an astonishingly complete specimen of Homo erectus found by the famous Leakey team in Kenya. These early humans are thought to have developed key innovations that helped them thrive, including hunting large prey, the use of fire, and extensive social bonds. The program examines an intriguing theory that long-distance running –our ability to jog– was crucial for the survival of these early hominids. Not only did running help them escape from vicious predators roaming the grasslands, but it also gave them a unique hunting strategy: chasing down prey animals such as deer and antelope to the point of exhaustion. Birth of Humanity also probes how, why, and when humans' uniquely long period of childhood and parenting began.

Widespread immigration to the U.S. from Latin countries begins – first with a small group from Cuba, then a larger one from Mexico. Both flee chaos and violence in their home country and are attracted by opportunities in the United States. In 1898, the U.S. helps liberate Cuba and Puerto Rico from Spain but then seizes Puerto Rico as its colony. The first Puerto Rican arrivals (now U.S. citizens) establish a network in New York.

In the 80s the nature of the Latino Diaspora changes again. From Cuba a second wave of refugees to United States – the Mariel exodus – floods Miami . The same decade sees the sudden arrival of hundreds of thousands of Central Americans (Salvadorans, Guatemalans, and Nicaraguans) fleeing death squads and mass murders at home like activist, Carlos Vaquerano. By the early 1990s, a political debate over illegal immigration – has begun. Globalization, empowered by NAFTA, means that as U.S. manufacturers move south, Mexican workers head north in record numbers. A backlash ensues: tightened borders, anti-bilingualism, state laws to declare all illegal immigrants felons. But a sea change is underway: the coalescence of a new phenomenon called Latino American culture-as Latinos spread geographically and make their mark in music, sports, politics, business, and education.