Evolutionary convergence: what it is, and examples

A summary of the characteristics of evolutionary convergence, with examples.

The animal kingdom is very varied, with all kinds of species with very different capabilities. However, on more than one occasion we may see two animals that have limbs or organs that share the same function, even though they do not appear to be related.

Evolution, although 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.which we will see in depth below.

What is evolutionary convergence, and when does it occur?

The 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, two species have an organ or limb that serves the same function, even though both species do not appear to be closely related in the evolutionary tree.

To give some examples, we have the case of bats and the extinct pterosaurs, which both have wings, although one is not descended from the other and their common ancestor lacked these limbs. 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 is 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 a common ancestor with this shape..

Why does it happen?

Evolutionary convergence is a phenomenon that occurs because two or more species have the need to solve the same problem, albeit on their own. These species have the need to adapt to their ecological niches in order to survive. and, in order to do so, they have to develop the necessary capabilities to ensure their survival.

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

Example: the case of the sheepshead bream and humans

The sheepshead bream (Archosargus probatocephalus) and humans are an example of convergent evolution.

The fish has teeth that we may find both comical and disturbing, since its teeth are very similar to those of humans. It is clear that fish are not descended from monkeys, so what is the evolutionary explanation for a fish? what is the evolutionary explanation for such a striking trait?

One thing we share with the chopa bream is that we too are omnivores, and our teeth show it. We have teeth for tearing flesh, such as canines, and teeth for crushing nuts and nibbling roots, such as molars.

The sheepshead bream also has a diet that broadly 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 already mentioned, there are species that, despite not being closely related, have developed limbs and organs with similar functions. But, in nature, the opposite situation can also occur, i.e., that two or more organisms with a similar ancestry can diverge, that is, two or more organisms with a common ancestor change some of their shared traits, adapting to environmental demands.to adapt to environmental demands. This phenomenon, called evolutionary divergence, is one of the most studied cases in mammalian limbs.

For example, if we compare the arm of humans, the wings of bats, the hooves of horses and the claws of tigers, we will see that they are very different. Our hands are for grasping things, bats' wings for flying, horses' hooves for walking, and tigers' claws for attacking and tearing flesh.

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

Evolutionary convergence and animal intelligence

In the animal world there are many species. The curious thing is that, thanks to studies in primatology and anthropology, it has been seen that human beings, although we can be sure that we are the most intelligent species so far, are not the only ones to show aptitude for intelligence, we are not the only ones with striking intellectual aptitudes.. Primatology has shown that other primates, with which we are related, show a fairly sophisticated intelligence. This makes sense, given that they are species that are close to us in the evolutionary tree.

However, it is also surprising that species very distant from ours, such as octopuses, parrots and crows, show a quite outstanding intelligence in the animal world. We are not descended from, for example, crows, nor are octopuses descended from us, so our intelligence and theirs is not directly related. Their intellectual aptitudes are due to processes of evolutionary convergence, in order to be able to efficiently solve different environmental demands.

The study of animal intelligence is quite old, going 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 animal thinking works, and its similarities or differences with the intellectual capacity of human beings..

We understand animal intelligence as the set of skills and abilities 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. Octopuses

Octopuses are cephalopod mollusks, invertebrate animals that demonstrate a very striking intelligence. They have been experimented with a lot 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 a great learning capacity..

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

2. Dolphins

It is well known in popular culture that dolphins are highly intelligent and sociable cetacean mammals. They have developed amazing adaptive capabilitiesThey are able to transmit information to each other, help each other if they are injured or sick, and can even emit sounds unique to 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 dolphins Akeamakai and Phoenix.

Akeamakai was trained in a language based on gestures with the arms and legs of her keeper. Phoenix was trained in an artificial click language that could be heard through underwater speakers.. Each language contained between 35 and 40 words, which referred 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 octopuses.

3. Chimpanzees

As we have already mentioned, it is not surprising that chimpanzees and apes in general manifest advanced intellectual aptitudes, considering their closeness to us.

Their social abilities, together with their ability to use toolsThe fact that they have a long memory, such as sticks to extract termites from trunks or stones to open fruits, makes them the most intelligent non-human animal species to date.

4. Pigs

Surprising as it may seem, pigs are very intelligent animals. In fact, research suggests that an adult pig has about the intelligence of a three year old childThis is well above the intelligence of other domestic animals.

5. Parrots

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

Even so, and given that 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 succeeded in teaching him 80 words and to understand their meaning, which included names of objects, shapes, numbers and some verbal phrases, as well as the functional use of "yes" and "no".

6. Elephants

Elephants are widely known as highly intelligent animals, and their brains are, in fact, the largest on earth. While in the animal world larger size does not necessarily mean greater intelligence, it is worth noting that in the case of elephants there does seem to be some relationship.

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

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

7. Crows

These birds are known in general culture for being intelligent, Machiavellianly 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 clever when it comes to 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 he or she is dangerous to them.

8. Rats

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

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

Conclusions

From both evolutionary convergence and divergence we can analyze that the traits of organisms do not always allow us to easily know what their common ancestor was. It may be the case that two species are phylogenetically very distant, but use the same limb for the same purpose, i.e., that they have lived for the same period of time.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 yet, due to environmental demands, one has chosen to use an organ or limb for one function while the other has chosen to use it for something else.

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 intelligence.

This is not because we are phylogenetically close to each other, which is not the case, but because these species, faced with a given environmental demand, have been forced to show advanced intellectual capacities in order to survive.

Bibliographical references:

• Cortès-Colomé, M. (2016). Psicología de la comunicación lingüística. Madrid: Síntesis.
• Fontdevila, Antonio and Andrés Moya. (2003). Evolución: Origen, adaptación y divergencia de las especies. 591 págs. Editorial Síntesis. ISBN 849756121X
• Arendt, Jeff y 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