La formación de la Tierra - National Geographic

Name: La formación de la Tierra - National Geographic
Uploaded: 2021-05-21T00:10:36.000Z
Duration: 3 h 8 min 2 s

The Birth of Earth: A Journey Through Time

The Uniqueness of Earth

Earth is the only known habitat with life in the universe, prompting exploration into what makes it special.

To understand Earth's uniqueness, we must travel back in time to witness early humans and the planet's formation.

Formation of the Planet

Our journey begins nearly 5 billion years ago when Earth was just a star-forming region with no recognizable planet.

Initially, there was only a young sun surrounded by dust; gravity began forming this dust into small rocks over millions of years.

Early Conditions on Earth

Approximately 4.54 billion years ago, Earth's surface was inhospitable, with temperatures exceeding 1,200 degrees Celsius and toxic gases present.

The newly formed planet resembled a molten rock ball with no solid surfaces—only an endless ocean of lava.

Catastrophic Collisions

A Mars-sized body named Theia collided with the young Earth at high speed, deforming its surface significantly.

This collision resulted in billions of tons of debris that eventually formed a ring around Earth.

Formation of the Moon

From this debris ring emerged our moon, which initially orbited much closer to Earth than it does today.

Following the impact, Earth's rotation sped up dramatically; one day lasted only six hours as it cooled down slowly over time.

Meteorite Bombardment and Water Accumulation

Millions of years later, meteorites bombarded Earth continuously for about 20 million years.

These meteorites contained water droplets within crystals resembling salt grains; their impacts contributed vital water to Earth's surface.

Emergence of Life-Sustaining Conditions

As meteorite bombardments continued, they created pools of water on solid ground while Earth's core remained molten.

The cooling surface allowed for crust formation; all current bodies of water have origins dating back billions of years.

Atmospheric Changes and Geological Activity

Rapid winds from mega storms shaped by fast planetary rotation created extreme weather conditions on early Earth.

Over time, as the moon drifted away and waters calmed down, conditions became more stable for potential life forms to emerge.

Volcanic Islands and Continental Formation

Volcanic activity led to islands rising from oceans as lava cooled; these would eventually merge into continents.

Despite emerging landmasses and water bodies forming familiar landscapes today, early atmospheric conditions were still hostile to life.

The Origins of Life on Earth

Formation of Chemical Conditions for Life

The underwater chimneys release a hot liquid, not smoke, as seawater seeps into the Earth's crust, heating up and collecting gases and minerals.

These chemical substances eventually combine to create life, although the exact process and timing remain unknown.

Emergence of Microscopic Life

Initially, only unicellular bacteria exist for hundreds of millions of years without any evolutionary progress.

Around 3.5 billion years ago, in shallow oceans, colonies known as stromatolites emerge from the seafloor, appearing like rocks or plants.

Photosynthesis and Oxygen Production

Stromatolites perform photosynthesis, converting sunlight into food by transforming carbon dioxide and water into glucose.

This process produces oxygen as a byproduct that gradually fills the ocean with oxygen.

Impact of Oxygen on Earth’s Environment

The increasing oxygen levels convert iron remnants in the water into iron oxide, forming deposits that will later be used for construction.

These ancient bacterial colonies are crucial for creating Earth's atmosphere; without them, complex life forms would not exist.

Geological Changes Over Time

For two billion years post-stromatolite emergence, oxygen levels rise while Earth experiences slow rotation leading to longer days (up to 16 hours).

Despite these changes over 1.5 billion years after Earth's formation, no complex life forms appear yet.

Geological Activity and Climate Change

Tectonic Movements and Continental Drift

The planet's surface is dynamic; tectonic plates shift due to heat from Earth's core causing geological activity.

Over millions of years, this movement leads to the formation of a new supercontinent called Rodinia.

Role of Stromatolites in Oxygen Production

In Rodinia's shallow waters, stromatolites continue their role in producing oxygen while conditions resemble those on Mars rather than modern Earth.

Catastrophic Climate Events

Approximately 750 million years ago, forces deep within the ocean begin tearing apart Earth's crust leading to significant geological upheaval.

Consequences of Volcanic Activity

Intense volcanic activity releases large amounts of carbon dioxide into the atmosphere which combines with water to create acid rain.

Decline in Atmospheric Carbon Dioxide

Excessive absorption by newly exposed rocks results in insufficient atmospheric CO2 needed to retain solar heat.

The Snowball Earth Hypothesis

Onset of Extreme Cooling

Within a few million years following reduced CO2 levels, global temperatures plummet dramatically down to -50 degrees Celsius.

Evidence from Australia

Geological evidence indicates that around 650 million years ago marked the beginning of what scientists call "Snowball Earth," an extensive ice age characterized by massive ice sheets covering much of the planet.

Feedback Loop Effect

The Awakening of Earth: From Ice to Life

The Frozen State of the Earth

The majority of solar light and heat is reflected back into space, creating a frozen environment on Earth.

Volcanic activity has been ongoing since the onset of global freezing, yet it has not impacted the ice until now.

Before the great glaciation, volcanoes emitted billions of tons of CO2; however, with rocks covered in ice, there’s no absorption of this gas, leading to a greenhouse effect.

Melting Ice and Rising Temperatures

After 15 million years, temperatures rise enough for the ice to begin melting.

It is believed that during the Snowball Earth period, melting ice caused crustal uplift, creating fissures and more volcanic activity.

Increased volcanic eruptions release more CO2 into the atmosphere, further raising temperatures.

Chemical Reactions Under Ice

While frozen, ultraviolet rays from the sun reacted with water molecules in ice to produce hydrogen peroxide (H2O2), which is rich in oxygen.

As ice melts, hydrogen peroxide decomposes and releases significant amounts of oxygen into the atmosphere.

Emergence of Life

Around 600 million years ago, as conditions warmed and water levels rose, life began to flourish again after a long freeze.

Primitive bacteria likely survived beneath the ice; by 540 million years ago in an oxygen-rich ocean environment, they evolved significantly.

Evolutionary Developments

New complex multicellular organisms emerged alongside primitive bacteria; one notable example is Huaxia.

Increasing oxygen levels allowed creatures like trilobites—ancestors to insects—to thrive in oceans filled with diverse life forms.

Oceanic Biodiversity Flourishes

Anomalocaris emerges as a prominent predator in this vibrant ecosystem; it measures about 60 cm long with sharp teeth and large eyes for hunting.

Trilobites exhibit early signs of skeletal development while thriving amidst abundant marine life.

Transitioning to Land Life

The ocean teems with thousands of species as life progresses rapidly; however, land remains largely barren due to harsh conditions.

Approximately 460 million years ago saw tectonic shifts forming new continents like Gondwana but little terrestrial life due to intense solar radiation.

Formation of Ozone Layer

Complex life forms struggle on land due to lethal solar radiation until ozone begins forming from oxygen interacting with sunlight.

This ozone layer protects emerging terrestrial ecosystems from harmful radiation over time.

First Terrestrial Plants

With increased protection from radiation thanks to ozone formation, early plants such as mosses start appearing on land.

Evolutionary Milestones

Evolution of Life on Earth

The Transition from Water to Land

Over 15 million years, creatures evolved their limbs and adapted to spend more time out of water, eventually making land their home around 360 million years ago.

This evolutionary journey led to the emergence of all quadruped vertebrates, including dinosaurs, birds, mammals, and ultimately humans.

The Rise of Seed Plants

Early plants reproduced via spores that required significant water; however, seeds emerged as a revolutionary adaptation allowing survival far from water sources.

Seeds can endure months or even years without water, enabling them to propagate life across diverse environments and contribute significantly to oxygen production.

Emergence of Insects and Arthropods

Dragonflies like the meganura evolved large wings for extensive hunting territories; these insects were among the first arthropods on land.

Arthropods have existed for hundreds of millions of years and are similar in appearance to modern pests but were much larger during this era.

Evolutionary Advances in Reptiles

Creatures like the hilo gnomos laid eggs containing all necessary nutrients for offspring development outside aquatic environments.

This reproductive strategy marked a significant evolutionary step allowing reptiles to thrive on land.

Catastrophic Events Leading to Extinction

A massive accumulation of dead plant matter transformed into coal over millions of years due to heat and pressure from Earth's core.

The burning of coal today is linked back to ancient plant life that existed 300 million years ago.

Mass Extinction Events

The Impact of Volcanic Activity

Large herbivorous reptiles known as escuho saurians thrived before facing predation from aggressive carnivores like gorgonopsids.

A sudden volcanic eruption caused widespread destruction, marking the beginning of one of Earth's largest mass extinctions.

Global Consequences

Eruptions released vast amounts of ash and gases into the atmosphere, leading to global climate changes detrimental to many species.

Ashfall affected distant regions while sulfur dioxide emissions created acid rain that devastated ecosystems worldwide.

Oceanic Changes Post-Eruption

Despite initial signs suggesting life persisted in oceans, conditions worsened with rising temperatures causing oxygen depletion in marine environments.

The Catastrophic Effects of Mass Extinction

The Release of Carbon Dioxide

As ocean temperatures rise, previously frozen carbon dioxide is released into the atmosphere, significantly increasing global temperatures by nearly 40 degrees.

Aftermath of Siberian Eruptions

Following massive volcanic eruptions in Siberia, approximately 95% of life on Earth has been eradicated over a span of 500,000 years. The lava now covers an area equivalent to the size of the United States with a depth of 6 km.

Survival and Adaptation

Only a few creatures have survived this mass extinction by taking refuge underground and feeding on available resources.

Earth's Recovery Process

After 250 million years post-extinction, Earth becomes almost lifeless but begins to stabilize. A new supercontinent named Pangaea emerges as conditions improve for life to flourish again.

Emergence of New Species

With 95% of life gone, the planet is primed for new species to evolve. Dinosaurs emerge as dominant beings after adapting from surviving reptiles.

Geological Changes and Continental Drift

Evolution of Dinosaurs

Dinosaurs known as "amo saurians" evolve from surviving reptiles; they are large yet slow due to their size.

Volatile Planetary Conditions

Despite repopulation by dinosaurs, no species can dominate the unstable environment characterized by thinning crust and frequent earthquakes.

Formation of New Oceans

Around 190 million years ago, Pangaea breaks apart creating a new ocean called Tethys that fills gaps between landmasses.

Nutrient-Rich Waters and Fossil Fuels

Nutrient Flow into Oceans

Ocean currents transport nutrients to coastal waters in present-day Iraq and Saudi Arabia, attracting millions of fish which eventually die off.

Transformation into Fossil Fuels

Over millions of years, dead fish and plankton become buried under layers of rock and heat, transforming into petroleum—essential for modern fuels and plastics.

Continental Separation and Ocean Formation

Slow Drift Continues

By 180 million years ago, North America's western platform continues drifting away from Eurasia at a rate comparable to human fingernail growth.

Creation of the Atlantic Ocean

The separation between continents leads to the formation of the Atlantic Ocean while volcanic activity reshapes underwater landscapes.

Evolution in Response to Geological Activity

Undersea Mountain Ranges

A mid-ocean ridge forms due to tectonic activity where hot lava cools underwater creating new mountain ranges taller than existing ones like the Himalayas.

Adaptation Among Survivors

As geological changes occur continuously on Earth, surviving species must adapt or face extinction; some reptiles develop fins for aquatic living in newly formed oceans.

Dominance in Marine Ecosystems

Rise of Fast Predators

Newly evolved marine creatures like sound saurians thrive in oceans; they grow up to six meters long and become apex predators due to their speed (40 km/h).

Emergence of Pliosaurus

The pliosaurus evolves as a formidable predator with immense jaws capable of overpowering other marine life; it represents significant evolutionary advancements post-extinction events.

Mammals' Coexistence with Dinosaurs

Mammalian Evolution Post-Mass Extinction

Impact of an Asteroid: A Catastrophic Event

The Asteroid's Approach and Impact

Nothing on Earth can challenge the asteroid's power, emphasizing its immense destructive capability.

The asteroid is described as a massive rock fragment, measuring 10 km in diameter, larger than Mount Everest.

Traveling at over 70,000 kilometers per hour, it heads towards the Gulf of Mexico near the Yucatán Peninsula; its speed means the impact will be nearly instantaneous.

Upon impact, the asteroid reaches a height comparable to that of passenger airplanes (almost 11,000 meters).

The force of the impact is so great that it destroys everything in its vicinity and causes the asteroid itself to disintegrate.

Aftermath of the Impact

The explosion creates debris that spreads like shrapnel from ground zero.

Minutes after impact, earthquakes and tsunamis occur thousands of kilometers away from where the asteroid struck.

A plume of lava and dust envelops the planet; temperatures soar to 275 degrees Celsius, igniting vegetation spontaneously.

Smoke and ash block sunlight leading to mass plant death and subsequent starvation for herbivores.

Extinction of Dinosaurs and Rise of Mammals

Approximately 65 million years ago, this catastrophic event led to the extinction of dinosaurs after their reign lasted 165 million years.

Mammals survive by living underground; their diverse diets allow them to thrive while more specialized species perish.

Evolutionary Developments Post-Dinosaur Era

Early Ancestors and Fossil Evidence

With dinosaurs extinct, mammals begin evolving in a peaceful environment; evidence suggests they could lead to primates.

Fossils indicate creatures like Ida (Darwinius massillae) may have evolved into monkeys or humans over millions of years.

Geological Changes Affecting Life

The lake where these fossils are found was once part of a volcanic crater that preserved life forms without oxygen.

Understanding our evolutionary path connects various life forms from ocean bacteria to terrestrial mammals.

Geological Transformations Leading to Human Evolution

Climate Change and Habitat Shifts

Around 47 million years ago, Earth's atmosphere closely resembled today's conditions with similar temperatures and day lengths.

Tectonic activity begins shifting continents; India moves northward toward Asia causing significant geological changes.

Formation of Major Landforms

As tectonic plates collide, mountains rise along a vast line creating features such as the Himalayas which includes Mount Everest at high altitudes suitable for air travel.

Rivers formed from melting snow will eventually provide water for nearly half of humanity’s population.

The Emergence of Humanity Amidst Environmental Changes

Climatic Shifts Impacting Species Survival

By around 20 million years ago all continents were positioned similarly as today but lacked human presence.

A significant rift opens along East Africa due to tectonic movements affecting climate patterns.

This rift leads to mountain formations which create barriers impacting local ecosystems.

The Evolution of Humanity

The Importance of Bipedalism

The act of walking on two feet is highlighted as a pivotal moment in human history, suggesting that geological movements may have influenced this evolution.

Early humans, specifically Homo erectus, are introduced through a scene depicting a man and child from 1.5 million years ago, showcasing the first footprints resembling modern human feet.

Migration Out of Africa

Climate changes around 70,000 years ago allowed early Homo sapiens to cross from Africa to Arabia due to lowered sea levels.

It is believed that all non-African populations descended from a small group of these early humans who migrated out of Africa.

Expansion Across Continents

As ancestors spread into India and then Asia and Europe, they faced challenges such as advancing ice sheets during their migration northward.

A significant cooling period led to unexpected environmental changes where summer conditions were replaced by frozen landscapes.

Ice Age Impact

The Earth entered an ice age with glaciers reshaping the northern hemisphere's landscape at a slow but steady pace.

Approximately 20,000 years ago, glaciation peaked with massive ice sheets covering much of the northern hemisphere.

Human Migration to the Americas

A land bridge emerged between Siberia and Alaska due to falling sea levels, facilitating human migration into the Americas around 14,000 years ago.

As glaciers retreated, new lakes formed in North America from glacial depressions left behind.

Reflection on Earth's History

After billions of years of geological changes and climatic shifts, humanity has reached a point where we can understand our planet's complex history.

This journey illustrates how life on Earth is shaped by both catastrophic events and serendipitous occurrences leading up to our current existence.

Future Prospects for Earth