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Evolution-not to be Equated with Progress

When we speak of evolution, it means man's exaltation and not just progress. Many things may be considered as progress for man and society without being evolution and exaltation for the human society. We say this to show that if some people have expressed doubts about such progress' worthiness to be called an evolution, their view is not without foundation. Although we do not confirm their view, yet what they have stated is not entirely pointless. Therefore, there is a difference between evolution on the one hand and progress and development on the other, for progress and development are almost similar in meaning.
Vestigial Structures
The human being has approximately one hundred structures in the body which do not seem to have any functional role. The same structures are represented in the lower vertebrates in which they have many useful functions to perform. Such structures are called vestigial structures.
The vestigial structures in the human include the following:
  1. The vermiform appendix which is a remnant of an organ that is useful in certain herbivorous animals and may have had a specific function in the human, generations ago.
  2. The third eyelid in the inner angle of the human eye corresponds to the nictitating membrane, or lid that moves laterally across the eye in such lower animals as the frog, bird and dog.
  3. Muscles of the external ear are useless for the human but are used by lower animals to turn the ear in the appropriate direction to receive the sound waves more accurately.
  4. The terminal vertebra (coccyx) is of no value to the human, but they are the foundation for the tail in lower animals. Early embryos of man also possess an external tail that is discarded before the later embryonic stages are reached. Occasionally the tail does persist in adult human beings as a developmental abnormality.
  5. The lobe of the ear is of no practical benefit to the human, although it may have had some function in the past.
  6. The point of the ear, known as Darwin's point, on the edge of the upper roll or margin of the human ear, corresponds to the tip of the ear of animals that hold their ears upright.
Comparative Structure of the Brain in Various Vertebrate Groups
Vestigial structures in other animals include:
  1. The splint bones of the legs of the horse which are remnants of original toes.
  2. The poison glands of certain snakes which are modified, specialised salivary glands from which they have evolved.
  3. The gill slits of embryos of higher vertebrates except one pair have disappeared and this pair which develops into the eustachian tubes connects the pharynx and the middle ear.
  4. The milk glands of mammals which are modified and specialised sweat glands of the skin.
  5. Hind limbs of certain snakes that structurally resemble those of other animals in which they are useful.
The existence of vestigial structures is strong evidences to point out that evolution has really taken place. Why such useless or harmless structures are present in certain animals, if they have not had their origin in some common ancestors?

Comparative Embryology

A comparative study of the embryonic stages through which animals pass reveals a widespread similarity and correspondence of developmental stages in higher forms with the existing adult stages of lower forms. The history of the embryonic development of an individual frequently corresponds, in a general and broad way, to the history of the development of the race as a whole (evolution).

A comparison of the developmental stages of vertebrate embryos such as fish, bird, pig and the human show close parallelism. Early stages of all vertebrate embryos are quite similar structurally and distinctive characteristics appear only later. A study of the embryonic development of heart in birds and mammals shows that various stages through which development occurs, succeed each other in the same general way from the two chambered to the four chambered condition. The same successive stages might have occurred when lower vertebrates, such as fishes evolved through amphibians, reptiles and birds to mammals.

A similar comparative study of the development of brain, reproductive, skeletal, and digestive systems of the vertebrates shows similar resemblances. The organs of higher animals, during their development, pass through the stages that correspond, in general, to the larvae or adult conditions of similar organs in the lower forms. These similarities of lower and higher types of organisms with respect to their embryological development, suggest that they might have evolved from a common ancestral group. Such similarities also show that the groups of animals are related to each other in an increasingly complex order.


Comparison of Vertebrate Embryos Showing Parallelism in Development

Human Evolution

Men of science assume two types of evolution for man: one of which is biological evolution, about which you may have read in biology and know that man is considered as the most perfect animal and the last in the natural evolution of animals. The meaning of biological evolution is clear: it is an evolution that the process of nature has produced without the intervention of man himself and without his asking for it. In this respect there is no difference between man and other animals, since every animal has reached a stage of evolution by a natural and coercive process. The same process has brought man to the stage where we call him a human being, and consider him a specific kind of species as distinct from other species.


There is no doubt that human society since its origin, that is, since civilization first began to appear, has continuously progressed and evolved. We all know that like the biological evolution, social evolution, too, has been gradual, with one difference, and that is, with the passage of time the rate of evolution has increased in speed.

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