My Science School

It takes millions of years to make a fossil. An animal dies. Its body sinks to the bottom of a lake. Sand and silt cover its body. The flesh rots away. Minerals seep into the bones and turn them to stone. The animal is now a fossil. The fossil is found.

How do we know about life in the past?

We find out about life in the past by looking for evidence. Fossils are one kind of evidence. They are the remains of living things that have been preserved. Objects made by humans, such as stone tools, are another kind of evidence.

Is it true? Plants can’t be fossilized.

No. Plants can become fossils, in the same way that animals can. By studying them we learn about the plants that once grew on Earth.

Who looks for prehistoric life?

People who look for remains of prehistoric animals, such as dinosaurs, are called palaeontologists. People who look for ancient humans are archaeologists. They find great things, such as bones, tools, buildings, jeweller and weapons.

Amazing! A sticky resin that oozed from pine trees trapped insects that landed on it. It hardened into a substance called amber. Prehistoric insects are perfectly preserved inside it.

Just over 100,000 years ago Homo sapiens appeared. The name means ‘wise man’. They were modern humans. In Europe they lived during the freezing Ice Age, a time when glaciers covered the land. The Ice Age ended 12,000 years ago.

Is it true? Homo sapiens have all died out.

No. All people on Earth today are members of Homo sapiens. If they had died out, like other kinds of early human, none of us would be here today!

Where did they live?

Homo sapiens first appeared in Africa, and from there, they spread out across the world. They lived in cave entrances, and in places sheltered by overhanging rocks. In the open they made huts from branches, covered with skins.

Amazing! People who lived during the Ice Age played musical instruments. They made whistles from bones, and drums from shoulder-blades.

Were they artists?

The humans who lived in Europe during the Ice Age were among the first artists. They painted pictures of horses, bison and deer on the walls of their caves. Bone and ivory were carved into figures of animals and people.

The first people we think of as humans appeared in Africa. About two million years ago, Homo habilis (handy man) appeared. Then, more than one million years ago, Homo erectus (upright man) appeared, but they weren’t modern humans.

Did they have any tools?

Homo habilis was the first tool-user. This is why he is called ‘handy man’. He made simple tools, such as choppers, from pebbles. The tools made by Homo erectus were better. He shaped stones into hand axes, and he was the first to use fire.

What did they eat?

Homo habilis and Homo erectus ate meat and plants. Meat probably came from dead animals which they found. They may have hunted for some small animals. Plants gave them berries and leaves. They used stone tools to cut and scrape their food.

Amazing! Homo erectus had fire. Fire provided warmth, gave heat for cooking, and offered protection from predators.

Is it true? Homo erectus was a wanderer.

Yes. More than one million years ago, Homo erectus began to move out of Africa, travelling to Europe and Asia.

Mammals have backbones, their bodies are covered in hair or bristles, they make their own body heat, and they feed their young on milk. They have larger brains than most other animals.

When did the first mammals appear?

The first mammals appeared on Earth about 220 million years ago. They lived at the same time as the dinosaurs. Mammals survived after the dinosaurs died out, and then they became the ruling animals on Earth. There are about 4,200 different kinds of mammals alive today.

Amazing! Woolly mammoths were big elephants with extra-long tusks up to 3 metres long. Their bodies were covered in fur.

Did mammals only live on land?

Mammals came to live in all of Earth’s habitats. Many lived on land, but some, such as bats, were able to glide through the air on wings of skin. Other mammals swam in the sea, such as whales, dolphins and seals.

Is it true? The elephant is the largest land mammal ever to have lived.

No. Indricotherium was the largest land mammal. It was almost 8 metres tall and as heavy as four elephants.

Picture Credit : Google

Birds are animals with backbones; they lay eggs, can make their own body heat, and have wings. They are also the only animals with feathers. Not all birds can fly. The first birds lived at the same time as the dinosaurs.

Is it true? Ostrich eggs are the biggest eggs ever laid by a bird.

No. The extinct bird Aepyornis laid the biggest eggs of all time. Each one was about the size of 150 hen’s eggs.

Where do birds come from?

Birds evolved from small, meat-eating dinosaurs. Fossils show that some of these dinosaurs had feathers. They are called ‘dinobirds’. The first ‘dinobirds’ probably could not fly.

Amazing! Today’s hoatzin bird, which lives in South America, has claws on its wings when young - just like Archaeopteryx, its prehistoric ancestor did.

Which was the first true bird?

The first true bird - a bird that could fly - appeared about 150 million years ago. It is known as Archaeopteryx, which means ‘ancient wing’. It had claws on its wings.

About 300 million years ago, some amphibians changed into reptiles. They could live on land all the time. Reptiles have backbones and scaly skin, and most lay eggs. Many reptiles, such as crocodiles, spend lots of time in the water, but they can’t breathe underwater. They use the Sun to keep their bodies warm.

Is it true? Some early reptiles had sails, on their backs.

Yes. Dimetrodon had a skin ‘sail’ on its back. It soaked up the Sun’s heat, and controlled the animal’s body temperature.

Amazing! A small animal found in Scotland, in rocks that are 350 million years old, might be one of the first reptiles. But some scientists say it was an amphibian.

What did reptiles eat?

The first reptiles, such as Hylonomus, were small lizard-like animals that ate tiny creatures. Reptiles learned how to run quickly so they could catch fast-moving insects. As reptiles became larger, they caught and ate bigger prey, including other reptiles. Some reptiles only ate plants.

Which reptiles had fur?

Some prehistoric reptiles grew fur on their bodies to keep themselves warm. These were the cynodonts. They lived about 245 million years ago. Over time they changed into a completely new group of animals, called mammals.

Picture Credit : Google

Life on Earth began about 3.5 billion years ago. The first life appeared in the sea. It was born into a world that looked very different from today. The atmosphere was filled with poisonous gases. The sky was pink, and the sea was rusty-red.

Is it true? Earth is the only planet with life on it.

Maybe. This is one of the greatest unsolved mysteries. Life probably does exist on other planets besides Earth, but nothing has been found so far. The search continues.

How did life begin?

It is thought that life began when lightning hit the sea. Lightning sent energy into the water. Chemicals in the sea were mixed together by energy. New substances, called amino acids, were made, from which life was able to grow.

Amazing! The first living things on Earth were so small you could fit thousands of them on the head of a pin.

What were the first living things?

The first living things were bacteria. They lived in the sea. Some bacteria changed into algae, which were simple plants. Algae lived in the sea in masses, like huge blankets. They made oxygen, which helped to turn the sky and sea blue.

Picture Credit : Google

About 440 million years ago, the first life appeared on land. It was simple plant life, similar to today’s mosses. Then, about 400 million years ago, the first land animals -worms, spiders, scorpions and insects - evolved as they moved on to the land.

Is it true? There are no amphibians alive today.

No. There are many different amphibians in the world today. Frogs, toads and salamanders are all amphibians.

Why did some fish grow legs?

Some fish began to live in shallow water. It was difficult to swim in the shallows. To help these fish move around they grew short legs. Some of them also grew lungs, which meant they could breathe air. These animals could live in water and on land.

Amazing! The lungfish is one of today’s fish that can live out of water. It can breathe air.

Which animal lives in water and on land?

An animal that can live in water and on land is called an amphibian. It means ‘double life’. The first amphibians appeared by 350 million years ago. Gradually, they spent more and more time on land.

Picture Credit : Google

Earth is millions and millions of years old. In fact, our planet is four-thousand-six-hundred-million years old. When the Earth’s age (4.6 billion years) is written as a number, it looks like this: 4,600,000,000. It’s hard for us to imagine anything so old.

Has there always been life on the Earth?

Nothing at all lived on the Earth for the first billion (1,000 million) years of the planet’s existence. The conditions were not right for life. There were no plants or animals of any kind. Earth was a dangerous place where life could not survive.

Amazing! Some of Earth’s oldest known rocks are found in Scotland. They are about 3.5 billion years old.

Has the Earth always looked the same?

These maps show how Earth’s land and sea looked in the past. To fit everything on them, Earth has been drawn as an oval. For a long time, all land was joined together in one giant mass. Over millions of years it broke up into smaller pieces. They turned into today’s continents.

Is it true? The continents are still moving.

Yes. The continents move about 4 centimetres each year - the length of your little finger. Millions of years in the future, Earth will look very different from today.

Science fiction stories do come true all the time. Less than a hundred years ago, space travel was a fantasy invented by storytellers such as H G Wells and Jules Verne. When we consider the extraordinary advances made in the fields of travel and communications in the past century, it is tempting to believe that Star Trek may in the future be nearer to reality than at present seems possible!

Science fiction introduces us to elaborate, futuristic worlds that often sound like nothing more than a dream. But humanity has made incredible technological advancements over the past 100 years, and many of the ideas predicted in science fiction have now become reality.

Some predictions, like self-driving cars, are still in the early stages, but scientists and engineers have reached many other milestones first described in fiction, such as bringing people to the moon.

In 1865, author Jules Verne released From Earth to the Moon, which described three Americans' mission to launch a spacecraft and land on the moon. Parts of the novel were similar to the first real moon landing, which occurred 104 years later.

Both the NASA astronauts and Verne's characters launched from Florida. NASA's command module was named Columbia in another similarity to Verne's fictional spacecraft, the Columbia. NASA astronauts Neil Armstrong and Edwin "Buzz" Aldrin succeeded in walking on the lunar surface in 1969 while Michael Collins remained in the spacecraft. The three men in Verne's novel, however, never stepped foot on the moon.

NASA has acknowledged other similarities between Apollo 11 and Verne's novel as well. For example, the space agency said the Columbiad's shape and size closely resembled the Apollo spacecraft. The novel also claimed a telescope would be able to see the Columbiad mission's progress. When an explosion caused a malfunction during the Apollo 13 mission in 1970, a telescope at Johnson Space Center was able to see the accident, which took place more than 200,000 miles away (300,000 kilometres).

3D holograms have been featured in sci-fi for decades. In 2017, an Australian company claimed it has managed to produce a hologram table that resembles the futuristic holograms from the original "Star Wars" movie. Princess Leia called for Luke Skywalker's help using a holographic message in the 1977 "Star Wars" movie. Since then, scientists have worked on turning this technology into reality.

Euclideon, an Australian company, says it has made the first multi-user hologram table in the world. As many as four people can interact with the hologram at once using motion-tracking glasses. Though Euclideon's invention has been met with some scepticism, but New Atlas reported in November 2018 that the company is moving forward with bringing the hologram technology to market.

"Star Trek" featured replicators that could 3D print food and everyday objects in a few seconds. Scientists are now using 3D printing technology to make objects out of plastic, metal, and glass, though the process is not nearly as fast.

The New York-based nonprofit Mattershift says it has developed carbon nanotube membranes that could separate and put together individual molecules.

Forbes reported that Mattershift CEO Rob McGinnis says the membranes could help scientists make anything out of a set of basic molecular building blocks. "We're talking about printing matter from the air," McGinnis said, according to Forbes. "Imagine having one of these devices with you on Mars. You could print food, fuels, building materials, and medicines from the atmosphere and soil or recycled parts without having to transport them from Earth." In addition, startups like Natural Machines are working on making 3D food printers commercially available.

The Iron Man suit has become legendary since first appearing in Marvel Comics. People won't be flying around in suits anytime soon, but the US military is developing high-tech suits that will mirror some of Iron Man's capabilities. The military's TALOS program – short for Tactical Assault Light Operator Suit – aims to enhance human combat.

TALOS will take in huge amounts of data from drones, naval sensors, and reconnaissance aircraft to better inform soldiers, Military Times reported. The suit is expected to be light and include life support systems that will track soldiers' vitals. 3D sound pickups built into the suit will also help soldiers figure out where incoming fire and vehicles are coming from.

The biggest problems of space travel all have to do with the enormous distances that are involved. Using today’s technology, it would take years to reach even the nearest planets, and generations of space travellers would live and die on a journey to more distant ones. For this to happen, spacecraft will need to be self-supporting or able to travel faster than the speed of light.

The first hazard of a human mission to Mars is also the most difficult to visualize because, well, space radiation is invisible to the human eye. Radiation is not only stealthy, but considered one of the most menacing of hazards.

Above Earth’s natural protection, radiation exposure increases cancer risk, damages the central nervous system, can alter cognitive function, reduce motor function and prompt behavioral changes. To learn what can happen above low-Earth orbit, NASA studies how radiation affects biological samples using a ground-based research laboratory.

Mars is, on average, 140 million miles from Earth. Rather than a three-day lunar trip, astronauts would be leaving our planet for roughly three years. While International Space Station expeditions serve as a rough foundation for the expected impact on planning logistics for such a trip, the data isn’t always comparable. If a medical event or emergency happens on the station, the crew can return home within hours. Additionally, cargo vehicles continual resupply the crews with fresh food, medical equipment, and other resources. Once you burn your engines for Mars, there is no turning back and no resupply.

Planning and self-sufficiency are essential keys to a successful Martian mission. Facing a communication delay of up to 20 minutes one way and the possibility of equipment failures or a medical emergency, astronauts must be capable of confronting an array of situations without support from their fellow team on Earth.

The variance of gravity that astronauts will encounter is the hazard of a human mission. On Mars, astronauts would need to live and work in three-eighths of Earth’s gravitational pull for up to two years. Additionally, on the six-month trek between the planets, explorers will experience total weightlessness. 

Besides Mars and deep space there is a third gravity field that must be considered. When astronauts finally return home they will need to readapt many of the systems in their bodies to Earth’s gravity. Bones, muscles, cardiovascular system have all been impacted by years without standard gravity. To further complicate the problem, when astronauts transition from one gravity field to another, it’s usually quite an intense experience. Blasting off from the surface of a planet or a hurdling descent through an atmosphere is many times the force of gravity.

As there are billions of planets in our universe, it is likely that some of them could support life, but the vast distances that would have to be travelled to reach them are at present an immense problem. More possible is the idea that humans could build self-supporting communities on nearby planets. Ideally, these would need to be enclosed, containing their own atmosphere and able to support a variety of plant and animal life just as our planet does. Experiments are being made t9 see if it is possible to build artificial ecosystems like this here on Earth.

We know of only one living planet: our own. But we know it very well. As we move to the next stage in the search for alien life, the effort will require the expertise of planetary scientists, heliophysicists and astrophysicists. However, the knowledge and tools NASA has developed to study life on Earth will also be one of the greatest assets to the quest.

There are two main questions in the search for life: With so many places to look, how can we focus in on the places most likely to harbor life? What are the unmistakable signs of life -- even if it comes in a form we don't fully understand?

"Before we go looking for life, we're trying to figure out what kinds of planets could have a climate that's conducive to life," del Genio said. "We're using the same climate models that we use to project 21st century climate change on Earth to do simulations of specific exoplanets that have been discovered, and hypothetical ones."

Del Genio recognizes that life may well exist in forms and places so bizarre that it might be substantially different from Earth. But in this early phase of the search, "We have to go with the kind of life we know," he said.

Further, we should make sure we use the detailed knowledge of Earth. In particular, we should make sure of our discoveries on life in various environments on Earth, our knowledge of how our planet and its life have affected each other over Earth history, and our satellite observations of Earth’s climate.

Above all else, that means liquid water. Every cell we know of -- even bacteria around deep-sea vents that exist without sunlight -- requires water.

The saying that there is nothing new under the Sun is strangely true. The stuff that makes up everything on Earth —animals, plants, rocks, water — cannot be destroyed, although it can be changed from one form to another. Living things are almost entirely made up of six elements: carbon, oxygen, hydrogen, nitrogen, phosphorous and sulphur. When a plant or animal dies, it decomposes. Gradually, its body breaks down, and the elements it was made of go back into the soil or water. These elements in time are taken up by new plants, which in turn are eaten by animals. This cycle of elements being released and re-used can take millions of years, but it is quite likely that within your body there are chemicals that were once part of a prehistoric plant — or even a dinosaur!

Eventually, all living things die. And except in very rare cases, all of those dead things will rot. But that’s not the end of it. What rots will wind up becoming part of something else. This is how nature recycles. Just as death marks the end of an old life, the decay and decomposition that soon follow provide material for new life. “Decomposition breaks apart dead bodies,” explains Anne Pringle. She’s a biologist at Harvard University in Cambridge, Mass.

When any organism dies, fungi and bacteria get to work breaking it down. Put another way, they decompose things. (It’s the mirror image of composing, where something is created.) Some decomposers live in leaves or hang out in the guts of dead animals. These fungi and bacteria act like built-in destructors.

Soon, more decomposers will join them. Soil contains thousands of types of single-celled fungi and bacteria that take things apart. Mushrooms and other multi-celled fungi also can get into the act. So can insects, worms and other invertebrates. Yes, rotting can be yucky and disgusting. Still, it is vitally important. Decomposition aids farmers, preserves forest health and even helps make biofuels. That is why so many scientists are interested in decay, including how climate change and pollution may affect it.

Decomposition isn’t just the end of everything. It’s also the start. Without decay, none of us would exist. “Life would end without rot,” observes Knute Nadelhoffer. He’s an ecologist at the University of Michigan in Ann Arbor. “Decomposition releases the chemicals that are critical for life.” Decomposers mine them from the dead so that these recycled materials can feed the living.

The most important thing recycled by rot is the element carbon. This chemical element is the physical basis of all life on Earth. After death, decomposition releases carbon into the air, soil and water. Living things capture this liberated carbon to build new life. It’s all part of what scientists call the carbon cycle. The carbon cycle starts with plants. In the presence of sunlight, green plants combine carbon dioxide from the air with water. This process, called photosynthesis, creates the simple sugar glucose. It’s made of nothing more than the carbon, oxygen and hydrogen in those starting materials.

Wind, moving water and sunshine are always to be found somewhere on the Earth. All of these can be harnessed to provide energy. Wind farms, consisting of fields of enormous windmills, have been set up in many parts of the world to capture the wind's energy. Hydroelectric power uses the force of water hurtling over dams. Solar panels are warmed by the Sun and can be used to heat water and homes. At the moment, these methods are not able to produce all the energy that the world needs, but they hold out hope for the future.

A renewable resource is one that can be used repeatedly and does not run out because it is naturally replaced. A renewable resource, essentially, has an endless supply such as solar energy, wind energy, and geothermal pressure. Other resources are considered renewable even though some time or effort must go into their renewal (e.g., wood, oxygen, leather, and fish). Most precious metals are renewable also. Although precious metals are not naturally replaced, they can be recycled because they are not destroyed during their extraction and use.

A renewable resource is different from a nonrenewable resource; a nonrenewable resource is depleted and cannot be recovered once it is used. As the human population continues to grow and demand for renewable resources increases. Types of biofuel include biodiesel, an alternative to oil, and green diesel, which is made from algae and other plants. Other renewable resources include oxygen and solar energy. Wind and water are also used to create renewable energy. For example, windmills harness the wind's natural power and turn it into energy.

The United States currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels are non-renewable, that is, they draw on finite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. In contrast, the many types of renewable energy resources-such as wind and solar energy-are constantly replenished and will never run out.

Most renewable energy comes either directly or indirectly from the sun. Sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses.

The sun’s heat also drives the winds, whose energy, is captured with wind turbines. Then, the winds and the sun’s heat cause water to evaporate. When this water vapor turns into rain or snow and flows downhill into rivers or streams, its energy can be captured using hydroelectric power.

Living things can grow and reproduce themselves. Given the right conditions, they can continue to do this for millions of years. But some of the Earth’s resources cannot renew themselves. When they have been used up, there will be no more. Perhaps the most important of these non-renewable resources are what are known as fossil fuels. Both oil and coal were made millions of years ago when the bodies of prehistoric plants and animals were crushed under enormous pressure beneath moving rock. There is a limited supply of these fuels, making it necessary for us to develop energy sources that cannot run out.

Renewable and nonrenewable resources are energy sources that human society uses to function on a daily basis. The difference between these two types of resources is that renewable resources can naturally replenish themselves while nonrenewable resources cannot. This means that nonrenewable resources are limited in supply and cannot be used sustainably.

There are four major types of nonrenewable resources: oil, natural gas, coal, and nuclear energy. Oil, natural gas, and coal are collectively called fossil fuels. Fossil fuels were formed within the Earth from dead plants and animals over millions of years—hence the name “fossil” fuels. They are found in underground layers of rock and sediment. Pressure and heat worked together to transform the plant and animal remains into crude oil (also known as petroleum), coal, and natural gas.  

The plants and animals that became fossil fuels lived in a time called Carboniferous Period, around 300 to 360 million years ago. The energy in the plant and animal remains originally came from the sun; through the process of photosynthesis, solar energy is stored in plant tissues, which animals then consume, adding the energy to their own bodies. When fossil fuels are burned, this trapped energy is released.

Crude oil is a liquid fuel fossil fuel that is used mostly to produce gasoline and diesel fuel for vehicles, and for the manufacturing of plastics. It is found in rocks below Earth’s surface and is pumped out through wells. 

Natural gas is widely used for cooking and for heating homes. It consists mostly of methane and is found near oil deposits below Earth’s surface. Natural gas can be pumped out through the same wells used for extracting crude oil.  Coal is a solid fossil fuel that is used for heating homes and generating power plants. It is found in fossilized swamps that have been buried beneath layers of sediment. Since coal is solid, it cannot be extracted in the same manner as crude oil or natural gas; it must be dug up from the ground. Nuclear energy comes from radioactive elements, mainly uranium, which is extracted from mined ore and then refined into fuel. 

Unfortunately, human society is—for the time being—dependent on nonrenewable resources as its primary source of energy. Approximately 80 percent of the total amount of energy used globally each year comes from fossil fuels. We depend on fossil fuels because they are energy-rich and relatively cheap to process. But a major problem with fossil fuels, aside from their being in limited supply, is that burning them releases carbon dioxide into the atmosphere. Rising levels of heat-trapping carbon dioxide in the atmosphere is the main cause of global warming. 

Alternative energy sources, such as wind and solar energy, are a possible solution to the depletion of nonrenewable sources. Both of these clean energy sources are available in unlimited supply.