Is there something like evolution?

Synthetic theory of evolution:

Let us observe and evaluate how the synthetic theory of evolution (the currently known theory of evolution). Darwin's theory of evolution combined with Gregor Mendel's genetics is known as the synthetic theory of evolution. This is the most accepted theory today.

When we refer to Darwinism nowadays, we refer to the synthetic theory of evolution. Click here to see what Darwin actually said. All that it says is that complex organisms like modern humans evolved from simpler organisms, which in turn evolved from even simpler ones. There is no progress as such. The simple creatures changed into more complex forms as time passed owing to processes like:

1) Natural selection

2) Random genetic drift

3) Mutation etc

Organisms evolve as they try to adapt to new changing environments of the earth and this is known as adaptation. This is a brief introduction to the theory of evolution. All this is fine, but is there enough evidence to clearly point out that such changes did happen and that species evolved from a single ancestor? Let us view some of the evidence-

1) Order of the rise of different creatures -

Fossils have been found and dated and they show us at which point of time, the different species of creatures began to appear. Due to this, scientists have been able to ascertain that first invertebrates came, then the amphibians, then the reptiles, then came the mammals and man evolved only quite recently. If evolution is true, the different groups should be successively more complex and this can clearly be seen by comparing a fish and a man. This geological evidence clearly points in the direction of evolution

2) Homologous organs

We know that the forelimbs of the dog and the horse bear weight and are used for running. Bats and birds useforelimbs for flying. Whales use them as paddles. Human arms however are free, and are used for not locomotion but for holding things with the exception being while swimming etc. Note that these animals use their forelimbs for different purposes, yet they have the nearly same structure, location and also develop in the same way. These are known as homologous organs and such traits are known as homologous traits. The minor differences are due to the variation in habitat. Homologies like body size cannot be compared as there are chances for variation and this misleads scientists. For example, the African elephant is the largest land animal, but this does not mean that the elephant is the most highly evolved creature. By comparing organ sizes such as the heart and brain, we can get to know about their complexity.

In the structures of the hearts of the vertebrate groups - fish, amphibians, reptiles and mammals, we can observe the following features:

a) They consist of the same basic structure- auricle, and ventricle.

b) The number of chambers in the amphibians increases to 3 from 2 in the fish.

c) In reptiles, the ventricle is partly divided.

d) In humans, there are 4 chambers, two auricles and two ventricles. This is definitely an improvement, because the pure and impure blood of the human never mixes and this means that there will be an increased supply of pure blood to all parts of the body.

Similarly the concentration of nerve cells (neurons) in the brain means higher intellectual power of the organism.

3) The fossil record:

Although the fossil record is by no means complete, there are evidences which show that there have been transitionary species (or intermediate species) having characteristics of both groups though not fully developed. For example, the archaeopteryx which had features of both reptiles and birds, and the lungfish which was the intermediate between fish and amphibians.

4) The different species of one organism spread throughout the world:

Take into account, the different kinds of deer - spotted, Sambar, musk etc. All of them fall under the category of deer, but yet there are some differences, which have led to their naming. Does this similar structure not suggest that there must have been a common ancestor from which this branched out? But because we cannot actually find such a fossil, there has been constant criticism. What about hybridization of plants and cross breeding of dogs? We can clearly monitor the growth and rise of the new species and establish the fact that many hybrids can develop from a single species. This applies not only to plants but also to every species.