Origin and evolution of animals

The diversity and evolution of animals is directly related to the characteristics of ecosystems. As Darwin explained in his famous “Theory of Evolution” , diversity entails greater speciation, that is, the appearance of new subspecies (which differ in physical appearance and habitat) during the biological evolution of a given species and, consequently, to a greater capacity for evolution.

Based on this theory, it is currently possible to observe in the timeline of the evolution of animals how exactly the evolution of mammals has been, for example, as well as to know when the first mammals appeared, which would date back to the Jurassic Superior, about 160 million years ago. Likewise, we can know the evolution of reptiles and discover what groups of current animals come from reptiles, surprising us when we know how the evolution “from dinosaurs to birds” was.

What is biological evolution and its origin

To give a summary of the origin and evolution of animals , we begin by talking about what biological evolution is. The study of the origin and biological evolution of living beings is undoubtedly one of the most surprising discoveries revealed by scientific studies. Thanks to molecular techniques, paleontological studies and phylogenetic analysis, it is now possible to know how living beings have evolved throughout the biological history of their life on planet Earth.

If you wonder exactly what the evolution of animals is and what factors are considered to analyze said evolution, in the famous literary work “The Origin of Species”, Charles Darwin, revealed in his well-known “Theory of the Evolution of Species” , how animals have been modifying their anatomy and behavior with the ultimate aim of adapting to the conditions of the environment in which they live, as well as to be strong and competitive species and thus achieve their survival complying with “the laws of natural selection and of the survival of the best fit “.

To better understand these concepts that can be somewhat incomprehensible but at the same time fascinating, in the next sections we will see concrete examples of the origin and biological evolution of various groups of animals.

To talk about the history of the evolution of species , you have to start by talking about the origin of life on Earth , which took place in the oceans . Marine creatures adapted to aquatic ecosystems filled with life the oceans and seas of the primitive planet, very different from the one we know today divided into 5 continents.

Thus, as the planet underwent geological modifications, animals were also forced to develop new adaptations to become species capable of surviving in as many environments as possible. That is why the surprising process of evolution from aquatic animals to terrestrial animals occurred, which, little by little, were modifying their anatomy to adapt to the oxygenic atmosphere, as well as to move on land, first crawling and more. afternoon flying and walking on all fours and later on two legs too.

The evolution of vertebrate animals

The vertebrate animals ( fish , reptiles , birds , amphibians and mammals ) share many anatomical characteristics because of their common evolutionary origin . If we look at images of the first stages of embryonic development of animals from these five groups, we can see how they are very similar.

In addition, some vertebrates have vestigial organs (without apparent function), such as the pelvis and lower limb bones with no function that whales present, which show that the origin of their species was terrestrial quadruped mammals. Furthermore, the existence of analogous limbs (different structure and evolutionary origin but the same function, such as the wings of birds and insects ), as well as homologous limbs (same structure and evolutionary origin but different function, such as the forelimbs of humans and bats. ), are strong evidence of the surprising evolution of vertebrates.

The invertebrate animals appeared on the face of the earth over 500 million years ago . Scientific studies related to the evolution of invertebrates have revealed how the largest group of invertebrates, the arthropods , evolved from worms similar to current marine annelids, thus maintaining their curious anatomy with differentiated segments.

However, given the astonishing diversity of anatomical and functional characters that the numerous groups of invertebrates present, it would be necessary to study each group or lineage separately to better understand what their evolutionary origin was like, why they present or lack body tissues and symmetry, or how they developed shells and shells.

Examples of animal evolution

Did you know that the African elephant appeared on the planet 1.5 million years ago? The evolution of the elephant is undoubtedly one of the most surprising examples of biological evolution of animals , since it is difficult to imagine how, from the first mammal the size of a mouse, animals as heavy and gigantic as elephants and their ancestors (such as Mastodons). Next we will see a list with more striking examples of the evolution of animals:

  • Evolution of giraffes through changes in the structure of their necks in response to natural selection, since individuals with longer necks reached a greater number of leaves from the treetops, thus transmitting information from generation to generation. the 70 genes responsible for the surprising elongation.
  • Evolution of Darwin’s finches through changes in body size and beak morphology as an adaptive response to the different foods that exist in the Galapagos Islands.
  • Evolution of human beings from a common ancestor with the chimpanzee, where bipedalism was the key to the evolutionary success of our species Homo sapiens sapiens .
  • Evolution of dogs from a common past with wild wolves, through processes of adaptation to different territories and domestication (as with other domestic animals, such as cats and horses).

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