Finding an answer to the question «what is evolution »
Biological evolution is one of the most intriguing and absorbing mysteries of the world. These days, it’s hard to meet a person who wouldn’t want to learn exactly «what is evolution ». We’ll try to answer here below.
To cut a long story short, evolution in terms of biology is an ongoing genetic change from one generation to another. The direction and speed of change is variable, including different species lines at different times. Ongoing revolution across numerous generations can result in the development of new species and varieties. When any organism fails to evolve, sooner or later it will come to complete extinction.
Various aspects of evolution
Perhaps, you’d like to know how all of this has occurred. Well the evidence for biological evolution has come from four major sources:
- The recorded genetic changes in living creatures in many generations.
- The geographic distribution of related species.
- The fossil record of change in earlier species.
- The anatomical and chemical similarities of related life forms.
Now let’s have a closer look at each of them.
When talking about the fossil record, we mean exactly remains of plants and animals normally discovered in sedimentary rock deposits. They give us an impressive record of changes of the past. The given evidence actually attests to the obvious fact that there has been an enormous variety of living organisms.
Some extinct species boasted traits, which were transitional between key groups of living organisms. Their existence proves that species can’t be fixed. On the contrary, they’re capable of evolving into other species over time.
The evidence also reveals that gaps in the fossil record can be explained by incomplete or wrong data collection. The more we learn about biological evolution of specific species lines, the more gaps we’ll fill.
One of the naughtiest gaps is between birds and bipedal dinosaurs. Two years after the publication of Darwin’s work «On the Origin of Species» in southern Germany archaeologists discovered an old fossil Archaeopteryx aged approximately 150 million years. The discovered creature featured a long bony tail, typical to dinosaurs, broad wings with feathers, jaws with teeth, not to mention birds’ skeletal features. The given discovery proved the assumption that birds had reptilian ancestors.
Apart from that, the fossil record proved that today’s complex plants and animals were preceded by earlier simple ones. Additionally, it clearly shows that multicellular organisms evolved right after the first single-celled ones. That definitely fits all the predictions of the evolutionary theory.
The vast majority of living things are fundamentally similar in terms of the chemical composition and anatomical structure. In fact, it doesn’t matter whether they’re highly complex organisms or single cells, all of them start their existence as single cells, gradually reproducing by means of division processes. They both have a limited life span, respectively they get old and finally die.
All animals and plants, receive specific properties from their parents by simply inheriting certain combinations of genes. Molecular biologists have found out that genes are segments of DNA molecules in cells. Segments of DNA feature chemically coded recipes for building proteins by linking certain amino acids in quite definite sequences.
Evidently, all of the tends of thousands of protein types in living creatures, are mainly composed of twenty kinds of amino acids. Notwithstanding this enormous diversity of life on our planet, the simple language of the DNA code is a must-have component of any living thing. That’s the true evidence of the fundamental molecular unity of the planet’s life.
Apart from molecular similarities, the vast majority of living things share one vital thing. All of them need energy and they get it in a variety of ways. Some living beings get energy for repair, growth and reproduction via sunlight or in other words by means of photosynthesis. They can also get this stuff indirectly by simply consuming plants as well as other living organisms.
Many groups of species boast the same types of body structures. It’s because they simply inherited them from a common ancestor. When we stumble on any anatomical or chemical similarities between living organisms, we can assume that they might have shared a common ancestry.
Another valuable clue to patterns of biological evolution is rooted in the natural geographic distribution of related species. That’s absolutely clear that main isolated land areas as well as island groups often were used to evolving their own distinct plant as well as animal communities. For example, before human beings came 60000 years ago, there were more than 100 species of koalas, kangaroos as well as marsupials in Australia, though more advanced terrestrial placental mammals, including cats, dogs, horses or bears were absent there.
Furthermore, land mammals were absolutely absent in the isolated islands making up New Zealand and Hawaii. Each of these places boasted a great number of insect, plant, as well as bird species, which had been met nowhere else throughout the world. Perhaps, the most suitable explanation for the existence of those unique biotic environments is that for millions of years the life forms there had been evolving in complete isolation from the rest of the world.
The planet’s environments have constantly been changing in both subtle and complex ways. When radical changes occur, going beyond what the vast majority of the population’s members can tolerate, widespread death comes. However, even in this case not all individuals die. That’s so great that natural populations feature genetic diversity. There’s one solid law – those individuals, whose characteristics enable them to survive any environmental disaster will be the only ones capable to reproduce. It’s no wonder that their traits are going to be quite common in the next generation. That’s a typical example of successful evolution.
The history of evolution
The whole history of evolution definitely deserves tons of books, but we’ll try to make just a brief review of it.
All the major ancient civilizations, including Greek, Chinese, Roman, not to mention medieval Islam considered an idea of biological evolution. In Western countries, the real development of this discipline started only in the 18th century.
Lord Monboddo (1714-1799) appeared to be the first to point out to a connection between human beings and chimpanzees.
Erasmus Darwin (1731-1802). Sounds familiar, really? Yes, that was Charles Darwin’s grandfather. From his point of view, all warm-blooded animals arose from one living filament dubbed Zoönomia.
Jean-Baptiste Lamarck (1744-1829). He firstly proposed that life evolved from species to species. His name is firmly associated with Lamarckism. The very essence of this idea is that traits developed during a lifetime can passed to offspring.
Charles Darwin (1809-1882). Well, most people associate the whole theory of evolution exactly with this scientist. He came to the world history of science as «Father of Evolution». Indeed, his contribution to the discipline is enormous. For most people that’s the man who knew for sure what is evolution. He was convinced that all species have descended from common ancestors. In 1859, he published his number one work, which brought him glory and fame in the world of science – On the Origin of Species. The book suggested that the cornerstone of evolution is natural selection, where ongoing struggle for existence has much common with artificial selection, used in selective breeding.
However, even such a bright scientist as Charles Darwin appeared to be unable to understand the whole mechanism of descent with modification, though he certainly knew it happened.
Gregor Mendel (1822-1884) was the first scientist, who stuck to the ideal of genes. To prove his idea he conducted a series of successful experiments on pea plants. It’s so sad his work wasn’t popular in the world of science, when he was alive, and it was recognized after 50 years.
Finally, James Watson and Frances Crick discovered DNA in 1953. Considering that DNA gives instructions for the development of every living cell, it has become known how every living organism descends. Without DNA no one can answer what is evolution.
Modern Evolutionary synthesis
The theory of evolution has never stood still since Charles Darwin’s times, as people have always tried to figure out what is evolution. Of course, much more data has been collected and analyzed since those times. Needless to say, all of this greatly helped to sharpen and enhance the progressive idea that species change over time.
As for today’s synthesis of the theory of biological evolution, it combines several scientific disciplines as well as their overlapping findings.
One should stress that the original theory of evolution was mainly built around the work of old-school naturalists, while the modern synthesis has derived benefits from longstanding research in Paleontology and Genetics, to say nothing of other subjects closely connected with biology.
The actual up-to-date synthesis can be defined as a sort of collaboration of a large body of work from such reputable scientists as Ernst Mayr, J.B.S. Haldane and Theodosius Dobzhansky. Some today’s scientists consider Evo-Devo to be a component of up-to-date synthesis, though others are assured that it has never played a significant role in today’s evolution theory.
While many Darwin’s ideas are still present in the modern synthesis, there’re several fundamental differences. Well, modern followers of the evolution theory aren’t willing to understate the whole importance of Darwin’s great contribution to biology. On the contrary, they support most of his ideas, published in this most important work «On the Origin of Species.» However, we should draw attention to the three major differences between the authentic theory of evolution via natural selection developed by Darwin and today’s evolutionary synthesis.
- Today’s synthesis officially recognizes several different evolution mechanisms. Darwin’s theory can’t do without natural selection, while one of those alternative mechanisms is genetic drift.
- Secondly, the modern evolution theory states that inherited characteristics are transferred from parents to their offspring via parts of DNA genes. As for variation between various individuals, it can be explained by the presence of numerous alleles in a gene.
- Thirdly, today’s synthesis suggests that speciation is caused by the gradual accumulation of subtle mutations or changes at the gene level. So, in other words microevolution generates macroevolution.
Due to years of thorough research conducted by prominent scientists across many disciplines, we all enjoy a better understanding of how evolution actually works. We fully understand what changes these particular species undergo over time.
Though different aspects of evolutionary theory have undergone changes, the basic ideas firstly offered in the previous centuries, are still relevant today.
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