By natural science we mean the knowledge of what exists in nature, may be material courses of events that are explainable or the principles and laws that can be established by logic and proof.

By natural science we mean the knowledge of what exists in nature, may be material courses of events that are explainable or the principles and laws that can be established by logic and proof. By Marxism we mean dialectical materialism which always finds contradiction and development under the principle `thesis-anti thesis-synthesis’.

    As science involves discoveries of laws, unveiling of mysteries in nature, and inventions depending on laws of nature, Marxian theory speaking of the formulations as to how changes are occurring in nature and how newer things are getting evolved by the process of ‘thesis, anti-thesis and synthesis’, is a part of science. If we now study the growth of science in the light of Marxian theory , we shall be able to see how nature is exposing its features and different aspects, day by day, following the theory of unity of two opposites, transformation and negation of negation. For explaining the unveiling of nature and discoveries of laws and properties of the ingredients of nature , there can be no surer method of understanding phenomena than that enshrined in dialectical materialism.

     Advancement of science illustrates that the thinking of a  parting age is surpassed by the thinking of the richer degrees of the incoming age along with a sort of  continuation of the former one.In the  amphibian animals originated from the aquatic ones and amphibians leading to reptiles, but not in the backward direction, some a sign of characteristics of the aquatic animals is carried over to the amphibian animals , so that they can well float in water and breathe as well in the shore. Along with the continuation of some qualities of aquatic animals, the amphibians develop some physical advantages to move on the shore and stay on. The advantages can be observed in the formation of legs, lungs, heart chambers, and the like. Before coming to the classes of vertebrates, let us examine the class invertebrata. There we find a huge variety of creatures, some dragging over the soil, some floating in water, some having wings to float along air and flying in air. Some aquatic animals exhibit parts of the body befitting reptiles or birds or even mammals to suit its environment and style of life. There are animals with multi-classed features , denoting incomplete signs of evolution . Some of such complex developments are given here under.

        If we examine the process of evolution from aquatic to amphibian level of development , we come across minute stages of developments in the attempt of animals to negate water . The fundamental truth in the nature is that all the entities are subject to negation , no structure is to exist without end and this truth is formulated by Karl Marx, with only exception that matter is ever existent with the quality of changing the forms according to contradicting virtue embodied in it. The theory of Marxism ,provides the principle of negation of negation, causing the truth that  development of some occurrences is always met with the negation of some aspects  and sometimes with absurdity, leaving remnants in the courses of evolution.

         It It has already been discussed that the first life appeared on the earth about 3.80  billion years ago. That form  of life  has undergone changes with the fact  that simple life form gradually turned into complex forms depending on the environmental and genetic courses of developments. During the long past since appearance of first life form , many  forms evolved and many went extinct. The first form was simple in organization . Subsequently , with the courses of changes in environment  of  the earth, the appearance of oxygen has had impacted to give forth various forms.  

  It is interesting to  take a stock of the changes that the Earth traversed through since its creation. As per geological study, the history of the earth  speaks of  the following phases that it has traversed through since its creation. The Earth was created 4.6 billion years ago(bya)ago. The pre-cambian period includes Hadean, Archean and Proterozoic periods. The break up of periods is as below: 

     Hadean period– 4.6 bya to 4.00 bya.      Archean period — 4.00 bya to 2.5 bya, Proterozoic period– 2.5 bya to 0.541  bya.  After that the era is named as Phanerozoic era continuing till now. The divisions of these periods clearly show how gradually the time moved forward carrying the earth along the courses of changes when, at some point of time, life evolved. Then life continually advanced to grow and take forms with the changes of levels, one after another, across the categories of  numerous patterns of invertebrates and then vertebrates. The Hadean era was given the name so,  according to the name of Hades , an underworld god of the ancient Greek to represent the then  hellish condition of the earth of the Earth. At that time the  Earth was very hot,  its surface appeared molten, the structure was massive, and reagent collision took place with other bodies in the solar system. The power of attraction of the gravity of the Earth was not strong enough to pull water vapour, hydrogen and such other substances towards itself.As the era covered as long as 60 crores of years, many a  change could have occurred  during this gap . The earth could cool down to a considerable extent , the phenomenon having been named as “ cool early earth”. This process of cooling paved the way to an  atmosphere congenial to emergence of life.

      Then started the Archean period during which the earth’s crust gradually got cooled, rocks and continental plots began to form. The cooling activities turned towards formation of water.The parts of rocks got settled to form a layer  of sediments, mud stones, volcanic rocks and an iron layer accumulated to give the earth a magnetic field to attract and pull the atmosphere towards it. The temperature of the atmosphere came down to facilitate the formation of life.  If we start from the inception of life, 3.80 billion years ago, the life forms were alike bacteria and algae. About two thousand million years ago , invertebrates , shelled protozoans evolved. Other creatures gradually  evolved with the increasingly developed situation. It  has to be understood that  the lower animals got modified with the passage of time and developed  to  the new varieties of higher animal.  Some variety of fish had evolved into amphibian animal . There are  anomalies also, where fish variety got upgraded to reptiles, breaking normalcy,  having a composite structure.  The fish variety Crossopterygians developed lungs unlike fish. The following characteristics are found to develop in the animal :

• A more improved skeleton , * Enhanced nostril development, *Leg-like bone features in the fins.

 

The repeated attempts to breathe air acted in the development of lungs in crossopterygians . It had impacted the development of nostril. While attempting  to use fins to rise above water , generations after generation, these had gone to modify fins to turn into bony structure. So it is an animal of composite character. Towards the  end of the Palaeozoic  era, there were abundance of  primitive reptiles  with the decline of amphibians and   extinction of marine invertebrates .  The primitive reptiles appeared  at about 275 million years. The figures of reptiles are given below.

     This is a type  of animals which have short legs and moves with the body almost dragging along the soil. Their tails slide down the soil. They could not cope with the gravitational pulls. So they got involved in the struggle against gravitation. This struggle enabled the animals to develop strength and  acquire techniques, generations after generations,  and thus many changes in the varieties took place. This enabled animals to rise to the status of  stronger reptiles. This way came  the era of warm-blooded reptiles called dinosaurs  at the entry of the  era Mesozoic at 225 million years ago. This is a victory of animals’in fight against gravitation.

The image of dinosaur and the toothed bird(Archaeopteryx in the image) can be judged side by side. If you try to find analogy of teeth of the two, it appears that  the toothed birds evolved from a type of  reptiles before going to extinct. The period of dinosaurs   started at 225 million years BCE  and that of toothed bird at 180 million years BCE . All these have developed their reproductive system to the stage of laying eggs. At the period of 65 million years BCE, the rise of primary mammals came into being  along with the evolution of modern birds. This a sign of negation in an attempt to rise against gravitation and to reconcile evolutionary development in the  body structure, heart chambers, respiratory systems in relation to the evolution of animals from lower to higher stages. The sign of negation from the stage of flying in the sky to the stage of coming down to soil,   was due to the fact that the soil was safer in respect of food and shelt@er.  A remarkable development  has figured in the shape of legs with hoofs in some four footed animals to give well support to the body-weight of the animals and also to adopt the technique to run along the hard and stony soil with comfort. This will be evident from the study of evolution of the running animal horse.

Archaeopteryx

Archaeopteryx is an evolutionary missing link bird.  It is a fossilized animal. Its first fossil was discovered in Germany in 1861.This animal is identical with birds in many respects. It  has some characteristics of the Therapsid  group of Dinosaur also. So it can be selected to stand as a testimony for link between birds and reptiles. As such , the process of the evolution of the animals from reptiles to birds carries strong belief and make us confident to assert the material continuation  in the rise of the newer species  to be established scientifically.      

  

Here in above, there are charted the stages of five species in the evolution of the horse starting from Eohippus to modern stature. It is to be remembered that the evolution  carries with it the changes of forms in limbs, legs, teeth, size , etc, in proportion to the stages in particular. The developments are described as under:

# The length of the limbs has gradually increased.

# The number of digits has gradually decreased.

# Hoofs have developed in the lower end of the leg to provide an advantage to run on hard surface  of the ground .

# In order to browse on soft vegetables , the jaws and teeth have grown likewise in proportion to the stages of evolution. There are thick crown on the molars and premolars.

#  There is stout formation of the muscles in body. 

Now let us discus the aspects of evolution of man . Man is the last and most valuable of the creatures that have evolved in nature. It has not jumped down from heaven to the earth. Man has  evolved through the process of evolution termed as `ape to man’.

Anatomically ,the modern human being is well formed . It has evolved through evolution from ape. Now first of all let us know about ape. Is it monkey? The fundamental differences are :

• Apes do not have tails. Most of the monkey species do have tails.
• Apes are larger, monkeys are smaller.
• Ape species include humans, gorillas, chimpanzees, orangutans, gibbons, and bonobos.

In evolutionary aspects, the ape species are much closer to humans than monkeys.

      The first species at the dawn of humans was the genus Homo. The traits that differentiate man from its predecessor species are the characteristics of bipedalism,  capture of language, size of brain etc. Genetic studies show that the primates of humans diverged from other mammals  about  in the cretaceous period ( a period between 140 mya and 65 mya characterized by the extinction of dinosaur and rise of Jurassic). The main feature that segregates humans from other species of mammals is bipedalism, that is , the ability earned through continuous efforts  to make two legs free from walking purpose and subsequently converting these two legs into two hands. This quality of bipedalism had been the adaptation which caused first separation between humans and  chimpanzees from the common ancestor. It entailed skeletal changes shared by all bipedal  hominids. This incidence of bipedalism arose some 6-7 million rears ago.  This historic phenomenon brought many sided  radical advantages. Now the hands became the tools to perform necessary activities at ease. He could reach food and  carry it with him comfortably. It requires less energy  to move ,  making it easy to view things at distance. As the back bone and  the position of the brain were on a straight line , the gravitational pull on the brain was checked . The head being heavy in comparison to the body, it was difficult to hold it high for the quadruped animal , because the head would be held horizontally. Now the head would be having a technique of prevention against gravitation. The eyes now could make focus at far straight way. These were some of the advantages for the humans being two-legged. Remarkable changes  had  occurred in the shape of legs and feet, shape of the palm and the feet-bases. A long-drawn  efforts were exerted for bringing about the evolutionary changes.

Evolution of horses

 

( the facts below taken from `10 missing link’ vide web site –ThoughtCo——– I am grateful  to the authority. )….. Matilal Sarkar .

Search Results

 We can observe and learn :

 

 

Here under we  see  that aquatic animals are of varied types that have originated from its predecessors. The bare necessities, the exercises of the limbs in the efforts of earning livelihood and for maintaining existence in the teeth of oppositions of so many kinds , the body formation have resulted in the attainment of  some structures . The patterns of structures so attained remain almost static for a period, generation after generation, but always  in struggle against the existing structure for a still better life ahead. Here the eco-system can be evaluated in respect of  the natural food and consumer relations established through centuries.

 

Further information: Marine mammal

An Amazon river dolphin (Inia geoffrensis), a member of the infraorder Cetacea of the order Cetartiodactyla

A Ladoga seal (Pusa hispida ladogensis), a member of the clade Pinnipedia of the order Carnivora

Aquatic and semi-aquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water. They include the various marine mammals who dwell in oceans, as well as various freshwater species, such as the European otter. They are not a taxon and are not unified by any distinct biological grouping, but rather their dependence on and integral relation to aquatic ecosystems be taken into account. The level of dependence on aquatic life are vastly different among species, with the Amazonian manatee and river dolphins being completely aquatic and fully dependent on aquatic ecosystems; whereas the Baikal seal feeds underwater but rests, molts, and breeds on land; and the capybara (south American mammal) and hippopotamus are able to venture in and out of water in search of food.

Mammal adaptation to an aquatic lifestyle vary considerably between species. River dolphins and manatees are both fully aquatic and therefore are completely tethered to a life in the water. Seals are semi-aquatic; they spend the majority of their time in the water, but need to return to land for important activities such as mating, breeding and molting. In contrast, many other aquatic mammals, such as rhinoceroses, capybara, and water shrews, are much less adapted to aquatic living. Likewise, their diet ranges considerably as well, anywhere from aquatic plants and leaves to small fish and crustaceans. They play major roles in maintaining aquatic ecosystems, beavers especially.

Aquatic mammals were the target for commercial industry, leading to a sharp decline in all populations of exploited species, such as beavers. Their pelts, suited for conserving heat, were taken during the fur trade and made into coats and hats. Other aquatic mammals, such as the Indian rhinoceros, were targets for sport hunting and had a sharp population decline in the 1900s. After it was made illegal, many aquatic mammals became subject to poaching. Other than hunting, aquatic mammals can be killed as bycatch from fisheries, where they become entangled in fixed netting and drown or starve. Increased river traffic, most notably in the Yangtze river, causes collisions between fast ocean vessels and aquatic mammals, and damming of rivers may land migratory aquatic mammals in unsuitable areas or destroy habitat upstream. 

 If we examine reptiles, we come across species close  to amphibian , proving that the evolution  traced through  minutes of stages , appearances of creatures in the middle.  The period of reptiles covered the ages about 320 to 310 million years ago. Its  period originated the period of swamps of the late carboniferous period. The oldest amniote animal, a reptile evolved from amphibian stage, was  Casineria.  Dinosaur is also an animal in the way to completion of the evolution from reptiles to mammals. 

Reptiles first arose from amphibians in the swamps of the late Carboniferous era. Increasing evolutionary pressure and the vast untouched niches of the land powered the evolutionary changes in amphibians to gradually become more and more land-based. This reminds us of the fact that the changes in quantity gradually proceed to give vent to form a new quality and then to secede from the existing pattern and evolve  completely into a new quality. The processes  advance  like this:   environmental selection propel the development of certain traits, such as a stronger skeletal structure, muscles, and more protective coating (scales) become more favourable, the accumulation of changes create pressure for the basic foundation of reptiles . The evolution of  lungs and legs are the main transitional steps towards reptiles, but the development of hard-shelled external eggs, replacing the amphibious water bound eggs is the defining feature of the class Reptilia and is what allowed these amphibians to fully leave water. This tendency to get rid of water is a trend to negate water, the most fundamental phenomenon in the evolution. Another major departure  from amphibians is the increased brain size, more specifically, the enlarged cerebrum and cerebellum. Although their brain size is small when compared to birds and mammals, these enhancements prove vital in hunting strategies of reptiles. The increased size of these two regions of the brain have allowed for improved motor skills and an increase in sensory development. All these changes have  driven the conditional circumstances to a favourable direction of changes to ultimately change the amphibian animals to the immediate new structure of animal , negating water completely and becoming terrestrial fully. Then reptiles started improving .

Realities Learnt

The fore-going discussion brings forth the dialectical values prevalent in natural science as below:

• Present is the outcome of the past and the future will be born of the present.
• The past is reflected in the present. Likewise the lustre of the present will be carried over to the future. Proverb sounds: like father like son.
• The incoming quality surpasses the outgoing ones.
• Environment and allied causes pose barriers. In overcoming those barriers or difficulties, the quality gets enriched.
• Evolution upgrades properties as interaction within it and with the changing situation. newer edition.
• No stage of development is permanent. Negation is a must.
• The movement of the things is towards something new and the old entity gets extinct leaving some residues behind.                                                                                                                                                                                       
• The whole process of the evolution follows the theory of evolution enunciated by Charles Darwin. The study of evolution enriches one with knowledge in science and discards beliefs in arbitrary placement of unseen forces to be acting in dropping the creatures from heaven or any super natural space away from the natural world. Evolution theory is a testimony to lay the strength of reality quite opposite to the teleology in support of  ideology without the background of science.  
• The study of evolution and an analysis  over the process register in man’s views the idea of material way of changes in a gradually forward direction, where the conditions of an animal in some level interact with environmental disadvantages. This is termed by Karl Marx as contradiction. This is internal contradiction in the process. The  execution of efforts to overcome this contradiction is the application of external force. By the combination of the two forces the conditions of the animal’s body or parts of the body get changed, turning it to a new form , i.e. evolving to a higher animal.
• So the evolutionary process is a scientific process, caused by matter, what so ever, in order to respond to the contradictions. Matter in the physical body of the animal at the lower level provides energy According to Marx, matter changes and develops to energy.So energy is the developed matter. This energy takes part in changing the condition. The horse has hoof in the foot to run along hard soil or stone by withstanding gravitation. Man’s foot become flattened for withstanding the weight of his erected body. Here, containment of the straight body on the soil against gravitation is the contradiction. The weight owing to gravitation and efforts against it are two opposite forces and their effect is the flatness of the foot.

In this way , the changes that have taken place in the courses of evolution of the invertebrates to vertebrates and the enumerable changes occurring in evolution of lower to higher animals do all pertain to three principles of dialectical materialism. So matter  is the source of every thing.