Extinction

Some animals go away forever.

This happens when the last one dies. If they cannot have babies, they will die out.

Animals might die out if their homes change. They might also lose a race for food.

Sometimes, people cause this to happen. Cutting down forests can take away their homes.

Some animals were thought to be gone. But then, people found them again!

It is important to help animals stay safe.

Extinction happens when the last member of a species dies. This means no more can be made. A species might become functionally extinct first. This means they cannot make new babies to grow their group.

Species die out for many reasons. They might not survive changing weather. They might also lose a race for food. Sometimes, a species is lost in just one area. This is called a local extinction. Other animals can move in to take that place.

Sometimes, people cause species to die out. We may cut down forests or change land for farms. This destroys their natural homes. This can cause a chain of extinctions. One group dying can hurt many other groups.

Some species are very rare. We call these endangered species. People try to help them in zoos. This is called conservation. Some species were thought to be gone. But then, people found them again! These are called Lazarus taxa.

A fish called the coelacanth was found again in 1938.

Extinction happens when the very last member of a species dies. When this happens, that group of living things can never return. Sometimes, a species becomes functionally extinct before the last one actually dies. This means the group is too small or too unhealthy to make new babies. Without new generations, the species cannot recover or grow.

Scientists often use a dagger symbol (†) to show a species is gone. It is hard to know exactly when this happens. Often, we only find out much later through fossils.

There are many ways a species can disappear. A species might fail to survive when the world changes around it. It might also lose a race for food to a stronger competitor. Sometimes, a species is lost only in one small area. This is called a local extinction. If the species still lives elsewhere, it is called extant.

Other species might face a mass extinction. This is a rare event where many different kinds of life die out at once. These events are a natural part of how life evolves on Earth.

Scientists have studied these changes for a long time. They know that most species that ever lived are now extinct. In fact, over 99.9% of all species are gone. Some species, called living fossils, stay almost the same for millions of years.

Other species, like the non-avian dinosaurs or woolly mammoths, are famous examples of extinction. We also see examples in the fossil record. Some species might even disappear and then reappear later. These are called Lazarus taxa, named after a person who came back to life.

Recent history shows that humans are changing things quickly.

Since the year 1500, at least 784 extinctions have been recorded. Many more likely happened without anyone noticing. Human activities like cutting down forests or overfishing cause much of this. A 2019 report said one million species are at risk right now.

This is a big problem for the planet. Some scientists worry that half of all species could be gone by the year 2100.

We can still work to help the living things that remain. Many animals are now called endangered because they are at risk.

Some species are extinct in the wild. This means they only live in zoos or special parks. Scientists use breeding programs to help these animals grow their numbers.

The goal is to eventually let them live in nature again. Protecting habitats is one of the best ways to stop the chain of extinctions. By saving one home, we can save many different lives.

Extinction is the permanent termination of a species. This occurs when the last living member of that group dies. Once a species is extinct, it cannot return to the world. A species may also become functionally extinct before the final individual dies. This happens when a population becomes too small or too unhealthy to reproduce. If they cannot create new generations, the species loses its ability to recover. Scientists often use a dagger symbol (†) next to a name to show a taxon is extinct.

Understanding extinction requires looking at how species change over time. Through evolution, new species arise through a process called speciation. Sometimes, a parent species transforms into a new one. This is called pseudoextinction or phyletic extinction. In this case, the original group vanishes because it has evolved into a successor.

This can be difficult to prove without a strong chain of fossil evidence. For example, it is debated if the early horse Hyracotherium is pseudoextinct or truly extinct. Because fossils rarely contain genetic material, we cannot always be certain.

Sometimes, a species that people thought was gone suddenly reappears. These are known as Lazarus taxa, named after a figure who returned to life.

This can happen because of large gaps in the fossil record. The coelacanth is a famous example. Scientists believed this fish had been extinct since the Cretaceous Period. However, a living specimen was discovered in 1938 near South Africa. Other examples include Attenborough's long-beaked echidna, which was recorded again in 2023 after being thought extinct since 1962.

Extinction can happen at different scales. Local extinction occurs when a species stops existing in one specific area. However, the species may still live in other parts of the world. These surviving species are called extant species.

If a species is at risk of disappearing everywhere, it is called endangered or threatened. When a key species dies out, it can cause a chain of extinction. This means the loss of one animal can lead to the loss of many others. This is especially common with keystone species that support an entire ecosystem.

There are many causes for these biological losses. A species might die out if it cannot adapt to changing environments. It might also lose a race for food to a better competitor.

Some extinctions happen suddenly due to disasters like toxic pollution. Others happen gradually over millions of years. Scientists also study genetic factors, such as a mutational meltdown. This happens when small populations accumulate harmful mutations, creating a loop that lowers their fitness. Over 99.9% of all species that ever lived are now extinct.

In recent history, human activity has become a primary driver of extinction. Humans can cause species to vanish through overharvesting, pollution, and habitat destruction.

Cutting down forests to create farms is a major cause. According to a 2019 IPBES report, the biomass of wild mammals has fallen by 82%. Natural ecosystems have also lost about half of their total area. Currently, one million species of plants and animals are at risk of extinction. This is often described as an ongoing mass extinction event.

Modern science works hard to prevent these losses through conservation. Some species are classified as extinct in the wild (EW).

These animals only exist in zoos or artificial environments. Zoos use carefully planned breeding programs to maintain viable populations. The goal is to eventually reintroduce these animals to their natural homes. However, the scale of the crisis is large. A 2018 study noted that restoring mammal diversity lost during the human era could take 5 to 7 million years.