Is there evolution in a closed terrarium?

Will your closed terrarium show evolution in the animals and plants within? The short answer is yes. Will you be able to observe these changes and eventually see completely altered creatures? Unfortunately, no. What exactly evolution is and why you won't see it, I'll explain in this article.

What even is evolution?

Simply put, evolution describes the change of living things over several generations. As you surely know, half of your genetic code comes from your mother and the other half from your father. However, every day your cells are copied millions of times. This process is not perfect and errors can occur that alter your genetic code (your DNA). This is called a mutation.

Most of the time, these changes do not manifest themselves at all. Rarely do they bring negative aspects (such as color blindness) and even more rarely do positive aspects arise. For a single living being, these changes are so minimal that they are usually not even noticeable. Over many generations, however, the evolutionary innovations can become consolidated through further inheritance and thus create new characteristics in a species.

Hier kommt das Prinzip des Survival of the Fittest (deutsch: Überleben des am besten Angepassten) ins Spiel. Je besser ein Lebewesen an seine Umgebung angepasst ist, desto wahrscheinlich wird es sich fortpflanzen können und seinen genetischen Code weitervererben. Einfach ausgedrückt setzen sich gute Eigenschaften also durch, während schlechte Eigenschaften langsam aber sicher verschwinden.

Berühmte Beispiele für Evolution

Charles Darwin is famous for the theory of evolution
Charles Darwin is famous for the theory of evolution. Source:

The first idea of evolution was published by Charles Darwin in 1859 in his book The Origin of Species. Darwin's finches are often mentioned as the decisive species for the development of the theory of evolution. However, this is not true. They are mentioned only in passing in his book, but have nevertheless become a famous and, above all, illustrative example of evolution.

Darwin's finches

Darwin's finches are 18 very closely related bird species from the Galápagos Islands in the Pacific Ocean. They are therefore also called Galápagos finches. The Galápagos archipelago consists of 13 volcanic islands that have never been connected to the mainland, and thus to some extent represent a closed ecosystem for land animals. They are not entirely dissimilar to a closed terrarium as a result.

Darwin's finches evolution
All 18 Darwin's finches originate from a single ancestor species. Source: Wikimedia Commons

Originally, only a small group of tanagers came to the Galágapos Islands. Yes, you read correctly. Darwin's finches are not descended from the finches. It is even possible that only a single pregnant female arrived on one of the islands, from whose offspring a new population developed. Since there were different conditions on the 13 islands and the birds did not often fly between them, different characteristics of the birds evolved over a long period of time. So they split into different species that were better adapted to their islands.

They differ especially in the shape of their beaks and their feeding habits. Long, pointed beaks, for example, are better for picking insects out of flowers. Thick and wide beaks help to crack nuts.

The longest experiment of evolution ever

The longest-running experiment to date to prove the theory of evolution is being conducted by Prof. Dr. Richard Lenski at Michigan State University. For over 30 years, new E. coli bacteria have been grown there every day and their changes observed. So far, more than 50,000 generations have been observed and some mutations have already been detected. You can find all the information about the experiment here. Derek from Veritasium has summarized and visualized the experiment in the following YouTube video.

Does a closed terrarium have evolution?

Yes, of course an closed terrarium has evolution! As soon as you close your closed terrarium, completely new conditions will prevail for your animals and plants. On the one hand, the humidity and also the temperature will be higher than they were before. In addition, both will also remain much more constant than before. There will be no wind and it won't really rain anymore. Some plants and insects will also no longer have predators and can suddenly develop much more freely than they ever could.

In your closed terrarium there will inevitably be an evolution of all species. Unfortunately, you will not recognize this in your lifetime. Mutations are so incredibly small and rare that it can take hundreds until the smallest changes appear. It can even take up to a million years for truly long-lasting changes to show up. If you design your closed terrarium really perfectly, your descendants may see different animals than you do today. You yourself, however, will probably see little difference.


Evolution is a constantly ongoing process that will never stop. Random mutations always occur because the process of cell division is not perfect. This results in copying errors that can give a living being other characteristics. Even a closed terrarium shows evolution. But it can take centuries or even millions of years until noticeable differences appear. So, unfortunately, you won't live to see it. You will, however, see several life cycles of the plants and animals in it, which can be just as exciting!

You can read about the world's largest, closed terrarium next!

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