One of the big questions we ask ourselves when we try to define what life is or what living beings are is: What are the characteristics of living beings
? If we were able to label the different characteristics that define living beings, we could differentiate them. of the rest of the elements of the universe. But this is not an easy task, since there are certain organisms that are on a fine line between some characteristics and others.

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Characteristics of living beings
As it could not be otherwise, when talking about characteristics of living beings we enter into the dilemma of having to choose the approach we adopt. You can find as many features as you want, if we change the focus, whether from a biological, philosophical, evolutionary, physical, chemical, etc. perspective.
For this article we have selected the main biological characteristics of living beings, leaving aside others , which despite not being less important, are more debatable and there is less consensus.
We must also remember that we always talk about the organisms on Earth that are the ones we know. We do not know what may be beyond, anywhere in the universe. Perhaps there are other organisms that do not have these characteristics of living beings to which we are accustomed.

1. Homeostasis
We begin our list of characteristics of living beings with one of the most essential elements that have allowed the survival of any living organism on Earth.
Homeostasis is a process that automatically regulates and balances the basic and vital functions of any living organism. If this regulation did not take place, I would not be able to live and would end up getting sick.

2. Relationship with other living beings
Unlike the rest of the elements that we can find in nature, living beings relate to each other , sharing information and regulating their activities to allow optimal coexistence and survival.

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3. Phylogenetic adaptation
Next we are going to comment on two characteristics of biological living beings that are related but take different degrees.
In this first case, the phylogenetic adaptation is that which a specific species of living being undergoes, normally to the environment and with respect to the rest of the living beings that inhabit it. The greatest intellectual exponent who explained this was Darwin.

4. Ontogenetic adaptation
On the other hand, another characteristic of living beings is the ability they have (or we have) to adapt individually to the environment. That is to say, now we are not talking about an evolutionary process , but about a learning process.
The animal (for example) that has learned that human beings try to hunt it because they have tried before, will be much more careful the next time it sees another person.

5. Metabolism
Metabolism is one of the characteristics of living beings that is always present since, without it, we could not process the nutrients we obtain to use them for our growth and benefit. Metabolism in turn consists of two synergistic parts: anabolism and catabolism.

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6. Growth
As we have mentioned, metabolism allows growth (among many other things). Undoubtedly, this characteristic of living beings is usually one of the best known, since it is one of the first that we were taught in school with the famous quartet: to be born, to grow, to reproduce and to die .

7. Consumption of nutrients
Closely linked to the two previous characteristics, living beings consume nutrients that they obtain from the environment to transform them into energy and other more complex nutrients through synthesis.
In fact, a large part of the adaptations that human beings undergo, whether at ontogenetic or phylogenetic levels, are to maximize the obtaining of nutrients in order to, in turn, increase their consumption.
This characteristic of living beings will give rise to the following.

8. Generation and expulsion of waste
Metabolic processes result in the living organism of a series of products that it does not need and which must be disposed of.

9. Reproduction
Along with nutrition, these two are the most basic and evolutionary functions. A large part (or almost all) of the adaptations that species experience are to enhance these two characteristics of living beings.
There are two types, called sexual and asexual reproduction.

Asexual reproduction
It is the most basic method of reproduction, in which the individual makes an exact copy, genetically speaking, of himself.

sexual reproduction
It is the type of reproduction that predominates among the most complex multicellular organisms . It requires two individuals of different sexes in order to create a new one.
It is a more expensive type of reproduction but it has a series of advantages that at an evolutionary level marked a substantial difference, allowing the birth of offspring that are more varied and adaptable to the environment.

10. DNA
Deoxyribonucleic acid is a type of acid that contains the genetic information of living beings and allows their development, birth and functioning.
This polymer is present in each and every one of the living beings and makes it one of the star characteristics at a biological level.

11. Death
How could it be otherwise, the moment we label an organism as a living being, we are admitting that it also dies. Something that is eternal by definition cannot be a living being .
In the same way, if it is alive, it has the potential to stop being alive at some point.