There are millions of different types of plants and animals in our planet. The basic underlying genetic plan or structure of all those animals are similar. Of all the million types of possible molecules that we have on earth, strangely all the living animals and plants have genes that are made up of the similar molecule, the DNA. That can’t possibly be just a coincidence. Most people brush off the idea of evolutionary theories being wrong even while struggling to understand the basic principle under work here. Why does Evolution makes sense?
The simplest of way to understand the trends in evolution comes from taxonomy. Taxonomy refers to the science of systematics and classification of organism. Most people, even the students of Zoology and Botany, fail to realize that, what classification shows is a gradual change from a primitive animal to more advanced forms of organisms climbing up the ladder of classification system. It shows that in the series of animals starting from Protozoa to Mammals, the invertebrates to vertebrates of highest forms, there is a gradual change in forms in the animals that follow up the ladder. If there was no gradual change from a primitive animals to the advanced forms, why is it that we don’t see an advanced form of animals in the middle of the ladder of classification? Why is there a distinct pattern of Evolution seen there? Let’s say, if it was a random origin, or if someone created all the animals in the world, why do we not see animals such as birds, which are advanced form of life, between Platyhelminthes and say Arthropoda? Or why do we not see Mammals, the most advanced forms of animals before Protozoa? If not for Evolutionary concept, religious, mammals or especially humans are the most important animals or most talked about, why were the Protozoans created first and only few billions years later mammals were created? That surely doesn’t make sense, does it? Let’s not talk about the advanced mammals or humans. Let’s just talk about the fishes, as soon as the hot mass of earth cooled, there was water eventually, but still the fishes first appeared in the Silurian period of Paleozoic era.(Silurian period is when diversification of bony fishes took place, though the earliest fishes were prevelant in during Ordovician period) Why? They could have easily come in between Poriferans and Coelenterates who fully enjoyed living in the water? Why they had to wait for millions of years to exist? That too with characters accumulated gradually with time with all the preceding animals? It would take a whole book to give examples of such events! I have just outlined the evolutionary events within the Animals, there are plenty of such examples within plants and even microorganisms.
Apart from that there’s a chain of Genetic similarity, the match in genetic make-up different organism. There’s anatomically evidence, Embryological evidence! Why does the bones underlying the wings of birds corresponds with highly evolved mammals such as humans? Or less developed amphibians? Why does the embryo of developed mammals such as humans are similar to fishes or amphibians?
The thing is most people confuse themselves with evolution and origin of life, the origin of first life form. Evolution doesn’t deal with the origin of life, evolution only refers to how a pre-existing life form got better with time, slowly and gradually. The theory of evolution doesn’t describe how life originated on earth, it only describes how life changed once it was formed. How it got better and better with time and how so many variations exists in present day Earth. There are about 8.7 million different species, different life forms in the Earth today! Why do they share a common genetic makeup and most characteristics? Why not a single one is made up of different content? That’s too absurd to be a coincidence.
- Charles Darwin and Theory of Natural Selection
Charles Robert Darwin, in 1859 published his book “Origin of Species” whereby explaining the process of evolution by natural selection yet failing to explain how it actually worked. He knew that animals evolved from a preexisting animal but he had no way to explicate the phenomenon. It was only much later that biologist understood the mechanism, after the discovery of DNA it became more clear. The base to genetics was undoubtedly laid down by Gregor Mendel with his Laws of Inheritance but with recent advancement in molecular biology and genetics has finally casted the light upon the mechanism underlying the process of Evolution. Darwin explained that variation among the animals are brought about by the pressure that nature exerts upon the living organisms. The animals that are best adapted to changing environmental condition survive and the animals that fail to survive die. In simplest of terms, an animal which can cope up with the changing environment lives on and reproduce, and the one which can’t die hence, cannot reproduce, leaving a better species in the Gene pool. Darwin at his time, had no idea that the variation actually resulted from genetic mutations. He just knew that all the animals shared a common ancestors. The concept of evolution by natural selection doesn’t mean that an animal can bring about changes that it desires to, it is a process where the nature selects the better adapted animals. Mutation brings about various changes in animals, it can be both positive or negative. To clarify it, I have an example of Natural Selection that actually happened during our time.
- Natural Selection at work
There is a moth called the Peppered moth widespread in Britain and Ireland. Morphologically the Peppered moths are white with black spots, which provides a perfect camouflage on lichen covered tree trunks. With the onset of Industrial revolution in the Great Britain, the Peppered moth, was replaced by a black peppered moth. Before that event, a white form of moth dominated the area but after the onset of industrial revolution, with smokes from the industries polluting the environment and blackening the tree trunks, a mutated form of black moth appeared and dominated the area. Here’s what happened :
The white bodied moth was perfectly adapted to living in tree trunks with lichens in it, perfectly camouflaged, but when the tree trunks were darkened, the white most became susceptible to the predators, easily seen and couldn’t survive, but a mutated form of moth, with dark pattern, was now completely camouflaged within the dark branches of the trees flourished. The weaker ones, the white moths couldn’t adapt to the environment and couldn’t reproduce, but the mutated form, the dark moth was adapted to the environment and hence could easily survive and it reproduced on and on until it replaced the white moths. But after the air pollutions in Britain were reduced and the lichens started growing again, the white moths replaced the area again!
Two different Peppered moths
- Darwin’s Finches
This event gave a firm idea on what Darwin had actually said about Natural selection. What Darwin saw at his time was just that variations exists and with those variation different animals evolve into a better species. During his visit to the Galapagos Island, he saw different varieties of Finches, which looked similar except in their beaks. All the finches from different island looked similar in appearance but had a different beaks. Natural selection is a process and the mechanism that work under it are, Genetic drifts, Isolation and Mutation, which can be interrelated from Darwin’s example too. Darwin saw that the species drifted from a central mainland after the island drifted, within the island, with different feeding habits or available food resources, the beak of different but evolved with respect to the vegetation on different island. It’s not that the birds evolved themselves with the changes that they needed. Let’s say that a group of bird ended in an area with plants with seeds, they’d need a beak like that off a parrot, and only those birds with mutated forms of beaks that can adapt in such environment would survive and reproduce and those which couldn’t die, and in the long run the island was overruled by the birds with similar beak, and on another island, different finches evolved in similar manners.
- Fast evolving lizards
There are plenty of other such examples, countless examples of natural selection working at present day scenario as well. There are lizards which have adapted to a fossorial mode of life and started to lose their limbs, because they’d need a slender body for that mode of life. Just like snakes who lost their limbs in similar process, some of the lizards are gradually losing their limbs, lizards such as Lerista punctovittata have very reduced limbs compared to other lizards. The origin of snakes from lizards happened in similar manners some millions of years ago.
- Other evidences
It would take a whole book to give examples of such events! This is just an outline of the evolutionary events within the animals, there are plenty of such examples within plants and even microorganisms.
Apart from that there’s a chain of Genetic similarity, the match in genetic make-up different organism. There’s anatomically evidence and embryological evidence! Why does the bones underlying the wings of birds corresponds with highly evolved mammals such as humans? Or less developed amphibians? Why does the embryo of developed mammals such as humans are similar to fishes or amphibians?
Anatomical Similarities among Human, Seal and Whale
There are still too many things that are left to describe, the article will be too long, so I will do sections of it, will deal with the anatomical and embryological evidences in next article. But even these few points is good enough to establish a fact that Evolution makes sense!
“Nothing in Biology Makes Sense Except in the Light of Evolution” – Theodosius Dobzhansky
(P.S. All the photos used in the article was taken from Google Images, couldn’t pinpoint the owner of the photo but all the photos are are credited to the owner)