Evolutionary convergence: what it is, and examples

The animal kingdom is very varied, with all kinds of species with very different capacities. However, on more than one occasion we can see two animals that have limbs or organs that share the same function, despite not appearing to be related.

Evolution, although it is diverse in each animal species, can lead to the same result, causing two or more species to develop parts with similar functions. This is called evolutionary convergence., a process which we will see in depth below.

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What is evolutionary convergence, and when does it occur?

Evolutionary convergence is the evolutionary process from which two or more organisms that are phylogenetically separated give rise to similar structures, with a similar morphology. That is, it is about two species having an organ or limb that serves the same function, despite the fact that both species do not seem to be closely related in the evolutionary tree.

To give some examples, we have the case of bats and extinct pterosaurs, which both have wings, despite the fact that one does not descend from the other and their common ancestor lacked these extremities. The ancestor of bats and birds did not even have wings, so at some point these animals had to develop wings but separately.

Another example we have with sharks, dolphins and ichthyosaurs, animals that share a very similar morphology, but which turn out to be very different and phylogenetically distant. These marine animals have a spindle or torpedo shape, which makes them more hydrodynamic, making their movement in water much faster and more efficient. Despite their morphological similarity, they do not have an ancestor in common with that form..

Why happens?

Evolutionary convergence is a phenomenon that occurs because two or more species have the need to solve the same problem, although on their own. These species have the need to adapt to their ecological niches in order to survive And, for this, they have to develop the appropriate capacities to ensure their survival.

Nature endows convergent species with the same solution for the same problem, but in each of the evolutionary branches. Thus, if two species need to fly, they will have to develop limbs that allow them to goal, or if they need to swim, their body will have to acquire a more hydrodynamic shape and develop fins.

Example: the case of sea bream and humans

The sea bream fish (Archosargus probatocephalus) and humans are an example of how convergent evolution occurs.

The fish has teeth that can seem as comical as it is disturbing, since its teeth are very similar to those of human beings. It is clear that fish are not descended from monkeys, with which, What is the evolutionary explanation for such a striking trait?

One thing we share with the sea bream is that we too are omnivores, and our teeth show it. We have teeth to rip meat, like canines, and teeth to crush nuts and nibble roots, like molars.

The sea bream also has a diet that, broadly speaking, resembles that of humans and, for this reason, its teeth have evolved in a way that is so similar to ours.

The opposite situation: evolutionary divergence

As we have commented, there are species that, despite not being closely related, develop limbs and organs with similar functions. But, in addition, in nature the opposite situation can occur, that is, that two or more organisms with a common ancestor change some of their shared traits, adapting to environmental demands. This phenomenon, called evolutionary divergence, is one of the most studied cases in the limbs of mammals.

For example, if we compare the arm of human beings, the wings of bats, the hooves of horses and the claws of tigers, we will see that they are very different. Our hands are used to grasp things, the wings of bats to fly, the hooves of horses to walk, and the claws of tigers to attack and tear flesh.

These species have a common ancestor, from which we have inherited the same limb bones, although with some differences in their shape. Evolutionary divergence has been the phenomenon that has caused each species to have a different function.

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Evolutionary convergence and animal intelligence

In the animal world there are many species. The funny thing is that, and thanks to studies in primatology and anthropology, it has been seen that human beings, despite the fact that we can assure that we are the most intelligent species so far, we are not the only ones with striking intellectual aptitudes. Primatology has been in charge of showing that other primates, with which we are related, show quite sophisticated intelligence. This makes sense, since they are species that are close to us on the evolutionary tree.

However, it is also surprising that species very far from ours, such as octopuses, parrots and crows, present a fairly outstanding intelligence in the animal world. We do not descend from, for example, crows, nor do octopuses descend from us, with which our intelligence and yours are not directly related. Their intellectual aptitudes are due to processes of evolutionary convergence, to be able to efficiently solve different environmental demands.

The study of animal intelligence is quite old, dating back to Charles Darwin and the time when he published his most famous work, The origin of species (1859). Since then, Scientists have tried to understand how the thinking of animals works, and their similarities or differences with the intellectual capacity of the human being.

We understand animal intelligence as the set of skills and capacities that allow animals to survive environmental demands, adapting to their ecological niches.

Among the most intelligent animals, apart from the human species, we have the following.

1. The octopuses

Octopuses are cephalopod mollusks, invertebrate animals that demonstrate a very striking intelligence. Much has been done with them and it has been seen that they can perform complex tasks such as opening a boat to get what is inside. They have a great short and long term memory and great learning ability.

One of the most prominent octopuses is the mimic octopus (Thaumoctopus mimicus) which has the ability to imitate other species of animals, to camouflage or pose as a more dangerous animal and thus protect themselves from predators.

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2. The Dolphins

It is known in popular culture that dolphins are highly intelligent and sociable cetacean mammals. They have developed amazing adaptive capacities, and they are capable of transmitting information between them, helping each other if they are injured or sick and, even, they can emit their own sounds for each individual, as if they were names.

Although it has not been possible to teach them language in a complete way, they have been taught some concepts, being remarkable the experiments of Louis Herman in the eighties with the Akeamakai dolphins and Phoenix.

Akeamakai was trained in a language made of gestures with the arms and legs of her caregiver. Phoenix was trained in an artificial click-type language that could be heard through underwater speakers. Each language contained between 35 and 40 words, referring to objects in the pool, actions, location, and direction.

Although 40 words are very few, knowing what they mean and getting to make syntactic structures with them is something really amazing, making dolphins in the group of the most intelligent animals in the sea, along with the octopuses.

3. Chimpanzees

As we have discussed, it is not surprising that chimpanzees and apes generally display advanced intellectual abilities, considering their closeness to us.

Your social skills, along with your ability to use tools, like sticks to extract termites from logs or stones to open fruits and their great memory, make them the most intelligent non-human animal species to date.

4. Pigs

As surprising as it may sound, pigs are highly intelligent animals. In fact, research suggests that an adult pig has about the intelligence of a three-year-old, far above the intelligence of other domestic animals.

5. The parrots

Parrots are intelligent birds, and not because they can repeat words from human language. These animals have the ability to differentiate and recognize different human faces, and, although their ability to "Speaks" is rather by imitation, they do have a great memory that allows them to remember how to make such sounds.

Even so, and since they are capable of repeating human sounds, science did not miss the opportunity to try to teach them to speak, being very famous the case of Irene Pepperberg and her gray parrot Alex (Psittacus erithacus).

After 13 years of experimenting with Alex, Pepperberg managed to teach him 80 words and that she understood the meaning of it, which included names of objects, shapes, numbers and some verbal phrases, in addition to the functional use of "yes" and "no".

6. The elephants

Elephants are widely known as highly intelligent animals, and their brains are, in fact, the largest on earth. Although in the animal world a larger size does not necessarily mean greater intelligence, it should be noted that in the case of elephants there does seem to be a certain relationship.

They have an amazing capacity for socialization, in addition to feeling empathy and feelings that until relatively recently were considered purely human, such as compassion, mourning or altruism.

They are capable of, when they see the bones of an elephant, stand up and pay homage to it, recognize that those bones had life and was a fellow of theirs. Also, they are self-aware.

7. The crows

These birds are known in the general culture to be intelligent, Machiavellian intelligent. They are able to build tools, use them and keep them for other occasions.

In addition, they can solve problems and reason, which makes them especially smart when trying to steal things. They are aware of themselves and others and can remember other individuals of their species. They are also capable of remembering a specific human being if it is dangerous to them.

8. The rats

Finally we have the animal most used in experimentation: rats. These rodents have quite developed intellectual capacities, which is why they are so widely used in psychology laboratories. They have quite remarkable empathic abilities, using them with their fellows, they are even capable of sacrificing themselves for the common good.

It has been seen that they dream in a very similar way to people, in addition to being able to get out of the most complicated labyrinths thanks to their ability to analyze situations with the various sensory stimuli that receive.

Conclusions

Both of evolutionary convergence and divergence we can analyze that the traits of organisms do not always help us to easily know what their common ancestor was. It may be the case that two species are phylogenetically far apart, but use the same limb for the same, that is to say, that they have undergone a process of evolutionary convergence.

On the other hand, it may be the case that two species are closely related in the evolutionary tree and, nevertheless, by demands some have chosen to use an organ or limb for one function while others have chosen to use it for another thing.

Finally, we have that intelligence in the animal world, specifically that of species such as rats, crows, dolphins, parrots, pigs and octopuses can be related to human.

This is not due to the fact that we are phylogenetically close to each other, which is not the case, but to the fact that these species, faced with a certain environmental demand, they have been forced to show advanced intellectual capacities in order to be able to survive.

Bibliographic references:

• Cortès-Colomé, M. (2016). Psychology of linguistic communication. Madrid: Synthesis.
• Fontdevila, Antonio and Andrés Moya. (2003). Evolution: Origin, adaptation and divergence of species. 591 pp. Editorial Synthesis. ISBN 849756121X
• Arendt, Jeff, and David Reznick. (2008). Convergence and parallelism reconsidered: what have we learned about the genetics of adaptation?. Trends in Ecology and Evolution 23: 26-32. ISSN 0169-5347