How do different animals have similar features independently of each other? Providence? Accident? Parallelism of evolution?
"One of the central statements of the synthetic theory of evolution (STE) is that all evolutionary changes are based on the selection of random, undirected mutations. However, evolution is not at all like a random, chaotic process," is written in the book" The birth of complexity. Evolutionary biology today: unexpected discoveries and new questions. But is evolution similar to some kind of random, non-linear development? Not at all. The simpler forms of life on Earth have become more complicated all the time. The fact is that, despite the presence of random mutations, the process of evolution over time discards unnecessary, "unprofitable" living entity mutations, and "remembers" the beneficial and necessary.
This regularity is most noticeable in such a phenomenon as parallelism. We are talking about those situations where in no way related groups of beings completely independently of each other appear similar features. Examples of this can be found very often. For example, fish, dolphins and ichthyosaurs at one time independently of each other took a fish-like shape for the convenience of swimming in the water. Even more surprising are examples of similar forms that appeared independently on different continents, isolated from each other. So, before South America separated from the rest of the continents, "ancient ungulates", the so-called primitive placental mammals, conditioned themselves on its territory. What happened to them as a result of millions of years of evolution? Many of them (forms that originated from notongululata, lithopters, astroporterias and pyrogenids) became strikingly similar to those ungulates that we know today on other continents: horses, rhinoceroses, camels, hares and even elephants. An interesting example with the South American extinct saber-toothed tiger? tilakosmilusom, which was remarkably similar to the "real" saber-toothed tigers inhabiting Asia, Africa and North America. In addition to external similarity, tilakosmilus also fed on the same hoofed (only South American), which saber-toothed tigers ate on the "Great Earth", and even their prey (about it already mentioned above) had an amazing external similarity.
Tilakosmil / ©Depositphotos
There are, however, wonderful examples of the dissimilarity of different animals. The same "glowing continent" once inhabited, and many inhabit today, such animals, "analogues" that scientists can not find in Asia, or in Africa, or in North America. Among them: armadilloes, anteaters, sloths, extinct giant sloths? megacities.
Noteworthy is the fact that the animals living in South America were generally less adapted and less perfect than similar animals living on the "Big Land". The same tilakosmiluses could not compete in dexterity and ingenuity with saber-toms, inhabiting other continents. Therefore, with the tilakosmiluses, giant predatory birds, fororakos, very successfully competed, which also inhabited South America. In addition, most of the fauna of the continent quickly disappeared from the face of the Earth after the two Americans joined in the Pliocene, and North American animals in large numbers began to move to the southern continent. This manifested one of the "rules" of evolution, which so far has no unambiguous explanation. The fact is that in large areas evolutionary progress and growth of competitiveness go faster than in small areas or on islands. On islands and small continents new unusual forms are formed quickly. Science has known this fact for a long time.
Fororakos / ©Depositphotos
In the last few decades, biology has learned a lot about how in the process of evolution, the most serious progressive changes of living beings occurred (they are called aromorphoses). It was possible to find out that in almost all carefully studied cases the transition from the simpler to the more complex (progressive) form did not take place for a single given evolutionary trajectory, but for several, developing in parallel. In this case, some of the signs from which the aromorphosis develops, sometimes appear in different lines almost simultaneously, and sometimes at different times and even in different orders. "Progressive" traits accumulate over time, until they finally appear in one or a few evolutionary lines, gathering together. This moment is called in paleontologists "the birth of a new group."
In this process, we can observe the entire pattern of evolutionary processes. At some point, a new "idea", for example, the idea of mammals starts to float in the air. And many different groups, without speculation, begin to develop in the same direction, although in slightly different ways.