Nature on the Earth has mind boggling diversity. Evolution has enabled species to diversify themselves and morph into altogether different species which are better equipped to adapt themselves to changing scenarios of weather and other variables like food availability and predator defence. Living beings are morphed into some of the strange shapes and sizes. Centipedes are the prime example.
Everyone must have seen Centipedes. Those crawling fear inspiring creatures. Although there are so many species of them, but all are called centipedes. How the name came about? Centipede means the one with 100 feet. But this is not true. The number of legs depend upon the segments present in the body of the centipede.
Centipedes have many species which have different sizes and number of legs. A full adult centipede can have 15 to 177 pairs of legs. This means the number of feet varies from 30 to 354. Typically a centipede has two legs per segment.
For example, Lithobiomorpha and Scutigeromorpha species have 15 pairs of legs. Scutigera have long, multi-articulate, hairy legs. It helps them to establish a solid grip on the ground and move very quickly but they are incapable of pushing themselves through soil or into detritus. The colorful Scolopendromorphs have from 21 to 23 pairs of legs.
The two legs in the first segment behind the head has been morphed into venomous fangs for hunting the prey. Legs of Centipedes become progressively larger as one moves from head to tail. This is evolutionary modified to provide better balance while moving. The tail legs are modified into sensory antennae to help the centipede move back when it encounters a dead end.
Birds evolved from aquatic animals when some of these animals ventured on land to escape the competition for resources and perils from the mightier ones. Reptiles came into existence but even here some of them lost two limbs and grew feathers and became a airborne again to be at safety from marauders. They became tree living and gained the advantage of having larger area under their surveillance for food and move to safer places.
But there are some birds which are fowls like hens and roosters and peacock which have limited capacity to fly. They live mostly on the lower branches of trees which are in the vicinity of crops where they can come down for foraging. One such bird is peafowl. They are beautiful birds with long feathers of brilliant colors. Mostly the feathers are blue in color. In the vicinity of our home are fields and woods and lot of these live there. They come to open fields in groups for foraging.
The male which we call as peacocks are more beautiful than female. They have very dense and long plume of feathers and are very heavy. During the mating season which is particularly during cloud laden days, peacocks open their feathers in the shape of a fan and dance to attract the female counterparts. Here are some pictures.
Human eye is a very complex structure. It can distinguish about 10 million colors. There are rod and cone cells in the retina which allow conscious light perception and vision including color differentiation and the perception of depth.
According to the evolution theory of Darwin, the living things evolved from simple to the the complex through gradations. So evolution of the eye poses a challenge to the Darwin’s theory because eye consists of many parts intricately connected to each other.
The critics argue how could something so complex, they argue, have developed through random mutations and natural selection, even over millions of years?
If evolution occurs through gradations, the critics say, how could it have created the separate parts of the eye — the lens, the retina, the pupil, and so forth — since none of these structures by themselves would make vision possible?
Darwin acknowledged from the start that the eye would be a difficult case for his new theory to explain. Difficult, but not impossible.
Scientists have come up with scenarios through which the first eye-like structure, a light-sensitive pigmented spot on the skin, could have gone through changes and complexities to form the human eye, with its many parts and astounding abilities.
Through natural selection, different types of eyes have emerged in evolutionary history — and the human eye isn’t even the best one, from some standpoints.
Because blood vessels run across the surface of the retina instead of beneath it, it’s easy for the vessels to proliferate or leak and impair vision. So, the evolution theorists say, the anti-evolution argument that life was created by an “intelligent designer” doesn’t hold water: If God or some other omnipotent force was responsible for the human eye, it was something of a botched design.
Biologists use the range of less complex light sensitive structures that exist in living species today to hypothesize the various evolutionary stages eyes may have gone through.
Here’s how some scientists think some eyes may have evolved: The simple light-sensitive spot on the skin of some ancestral creature gave it some tiny survival advantage, perhaps allowing it to evade a predator.
Random changes then created a depression in the light-sensitive patch, a deepening pit that made “vision” a little sharper. At the same time, the pit’s opening gradually narrowed, so light entered through a small aperture, like a pinhole camera.
Every change had to confer a survival advantage, no matter how slight. Eventually, the light-sensitive spot evolved into a retina, the layer of cells and pigment at the back of the human eye.
Over time a lens formed at the front of the eye. It could have arisen as a double-layered transparent tissue containing increasing amounts of liquid that gave it the convex curvature of the human eye.
In fact, eyes corresponding to every stage in this sequence have been found in existing living species. The existence of this range of less complex light-sensitive structures supports scientists’ hypotheses about how complex eyes like ours could evolve.
The first animals with anything resembling an eye lived about 550 million years ago. And, according to one scientist’s calculations, only 364,000 years would have been needed for a camera-like eye to evolve from a light-sensitive patch.
Charles Darwin’s work on the evolution theory is akin to the Laws of Motion by Newton. They stood like indestructible rocks for several decades. Yet as the new evidence gathers, chinks or limitations in these laws have been becoming visible. Einstein came and with his theory of relativity, made the laws of motion into approximation of the true laws at lower speeds. These laws breakdown and cannot explain phenomena at the extremities at both ends, at the sub atomic level as well as the parsec levels. Not only that, it is now doubted that Einstein’s theories which are based on the premise that speed of light is the ultimate barrier are correct or can explain all the observation.
Similarly, the Darwin’s theory has been found to have chinks. Its main postulate is that in nature evolution is taking place gradually. Dr. Stephen Gould amassed the available data and announced that things did not happen in gradual manner but in bursts with periods of lull or nonconformities in between. There were periods of intense activity in which many new species appeared and others got decimated. Now with the passage of every day, this theory seems to gaining strength.
Most obvious is the case of weather. Areas which were deserts are experiencing lots of rainfall, the areas which were previously most rainy are becoming devoid of the rain. Rains fall in torrents of such intensity that it seems that the land will submerge into the sea and it will like the olden times when all of Indian subcontinent was under the sea.
Then there will be periods of complete dry spells. So we have the perfect recipe for the disaster. First face the floods, then diseases in the aftermath, destruction of crops and increase in hunger. Oh God, was it the fate of the Earth when I was born?
There have been so many attempts to understand the human behavior, yet it refuses to come into the grasp or to follow some universal formula. Wise men started to understand it with animals (we being one of them) and the father of Evolution , Charles Darwin, came up with the formula “The species always compete for the resources and those who the fittest among them survive and ready themselves for another competition”. He called it survival of the fittest. It is the nature’s way of weeding out the weaker among the species. This is the way all living beings have evolved over millions of years. Humans are endowed with most complex brains and sit at the top echelon of the evolution ladder. Charles Darwin assumed that improvement or the evolution is gradual process taking place continuously over millions of years.
There are flaws in this line of approach to explain the observations. Some scientists, most notably Stephan Jay Gould, have come to conclusion that evolution had not taken place at a continual regular pace but in the bursts of intense activity followed by hiatuses of considerably long periods.
Then there were people like Peter Alekseevich Kropotkin, the Russian prince who renounced his aristocracy and settled in England in a fishing village, who held the diagrammatically opposite view. He argued that human beings tend to live in cooperation and help each other. Not only human beings, he observed so many animals living in groups in the Siberian forests where the food is scarce due to extreme cold. He said that human beings are good at heart.
According to the latest theory the human behavior towards each other is guided by self aggrandization. It says that behind every human action there is a selfish motive which may be tangible or intangible. It is argued that why a person tries to save a child from fire or a person from drowning even if a stranger, is that if he or she does not do it, afterwards his or her conscience will torment and the person will get tension. So to avoid the mental stress, one tries to help the others. May sound funny. I think I am not able to put the argument across properly.
I had a long cherished wish to watch the evolution in the making. But lifespan of us humans is infinitely short to witness the events taking place during the evolution which span over thousands or sometimes million years. But my desire grew with time. So I many a times felt anguished and helpless. We are living in a time when it is quite easy to access information. On the scientific front, there are wonderful instrument which are available making the life of a scientist comparatively easy. Think of the times, when Darwin, Newton, Kekule did their research. They were the really creative and genius people.
For a time assume I have been granted the power to travel back in time without affecting my present form. I remain the same. I have also been enabled to reach where ever I wish to in this universe. So I am flying on the wings of thoughts. I hover over some islands of Hawaii. The time is 5 millions years ago. What do I see?
The island is reeling under a very powerful hurricane. The trees are uprooted and being flung like light toys. The birds, especially those dwelling in the trees are swept away. As the fury of hurricane is spent, there are ruins everywhere. Devastation is all around. But there are birds called “Pollenpeepers” which have successfully weather the storm. One reason for their survival is that they live in the bushes nearer the ground.
So now it is the aftermath of the hurricane. Life again sprouts. Due to the sweeping away of so many birds, the pressure on the pollen peepers is relieved. They find plenty to eat and begin to spread across the whole island. 1 million years go by.
Still the pressure is low. But the climate in the North and South of the island is becoming disparate. While North is wetter, the south is dry. In the North, the tall trees are flourishing while in the South it is bushes all around. The birds in the North eat insects in the Northern part and seeds in the South as the availability is such. The birds are assuming different features. For example, the beaks of the birds in the Northern part are becoming narrower suitable to catch insects whereas the Southern cousins have wider beaks to hold the seeds. Another million years go by.
The weather in the South takes a turn. It is becoming wetter like Northern part. hovering above, I see more and more clouds and rains in the South now. The bushes are being replaced by the taller trees. Availability of seeds is decreasing causing problems for the birds in the South. As the weather is becoming like the North, I can see the birds in the from North migrating to south also. The situation for southern birds is becoming very testing.
Now they are being outnumbered and decimated. The birds with narrow beaks are climbing another echelon of the evolutionary ladder. In the present times, I can see only the birds with narrow beaks dominating the whole island. I salute the Darwin who once carried out his work in these islands although those were very tough times and it was not easy to express such revolutionary evolutionary ideas.
It is all magical. I have seen a glimpse of the evolution in the making. I am again back to original self. but I feel how minuscule is our entity in the scheme of nature’s grand play.
Corn along with rice and maize are the basic grains used all over the world. They evolved in different parts of the world in different climates and conditions. Wheat for example is said to have been originated in Middle East. Rice requires plenty of water for cultivation and thus grown in the areas where rains are heavy or other sources of water are easily available. Here we are talking about the evolution of corn.
Evolution of the parent wild varieties have taken place through man’s method of selective breeding over the centuries. The history of modern-day maize begins at the dawn of human agriculture, about 10,000 years ago. Ancient farmers in what is now Mexico took the first steps in domesticating maize when they simply chose which kernels (seeds) to plant.
These farmers noticed that not all plants were the same. Some plants grew larger than others, or maybe some kernels tasted better or were easier to grind. The farmers saved kernels from plants with desirable characteristics and planted them for the next season’s harvest. This process is known as selective breeding or artificial selection. Maize cobs became larger over time, with more rows of kernels, eventually taking on the form of modern maize.
Evolution is said to be gradual and slow. But in the case of corn, it evolution occurred in a burst of fairly small time. After a long search, the scientists became sure about the ancestor of maize. Its name is Teosinte. Plants are totally dissimilar in physical appearance but their DNA is very similar and two can be easily crossed to produce modified intermediate varieties. Samples bear an unmistakable resemblance to modern maize.
Following shows a collection of sizes and shapes of cobs beginning from the earliest.
Second picture shows the comparison of Maize and Teosinte plant and cobs from which Corn has evolved over thousands of year. The hybrid corn resulting from crossing the two is also shown at bottom.
The author is thankful to the following link for the two diagrams and ideas
Equality between members of a species is against the nature’s law of evolution because it is the survival of the fittest. Nature continuously weeds out and eliminate the unfit.
Despite the saints or preachers in every faith and all over the globe trying their best to persuade the human beings to be like brothers (equal), disparity is always there. Humans have divided themselves along the lines of region, religions and caste systems. That is why human beings cannot become equal.
In fact the desire for superiority over others propels the human progress because to be superior one must strive harder or be more creative. It is another matter that some of the people who become more powerful than others try to be good to others and also some powerful try to torment the hapless ones to become more powerful. The difference between animals and humans in this regard is that the weaker ones get eliminated in the physical struggle whereas in humans it is the mind games that kill the weaker mentally if not physically.
It is a scientific fact that all living things evolved from the simplest single cell bacteria. These are called cyano-bacteria or green algae. They were the first harvesters of sun energy using photosynthesis and making food for themselves. Thus the food comes from the Sun.
Slowly, the life diversified, especially after the introduction of oxygen into the atmosphere thanks to these green algae. Living beings evolved which cannot make their own food like plants but use the food prepared by the plants and burn it with oxygen.
Then Darwin came and after a massive study and observations in the Canary Islands announced that higher forms of living things evolve slowly from the lower forms. This is a consequence of struggle for survival and survival rate of the fittest or the species which are capable of modifying themselves according to the environment are the best. Humans are a mere speck in this diversity majority of which is staked by the bacteria.
From water to land and from crawling to walking on four limbs, human freed their forelimbs to use them as tools and also stand upright which helps in running away from danger, following the prey and gain the greater ability to watch up to far away distances to locate the danger as well as food. But we have to pay the price for this in the form of backaches, diseases and difficult child birth.
Natural selection continuously sifts the best from the individuals of each generation. But this sometimes occurs clumsily, as old parts and genes are co-opted for new roles. As a result, all species inhabit bodies imperfect for the lives they live. Our own bodies are worse off than most simply because of the many differences between the wilderness in which we evolved and the modern world in which we live. We feel the consequences every day. Here is the first.
Our cells are weird chimeras
Multicellular life started when two cells merged and fused into one. The hunter cell swallowed the prey cell and encapsulated it. Then the prey became the mitochondrion. This is the machinery which provides the cell energy and makes possible its survival. Most of the time, this ancient symbiosis proceeds amicably.
But every so often, our mitochondria and their surrounding cells fight. The result is diseases, such as mitochondrial myopathies (a range of muscle diseases) or Leigh’s disease (which affects the central nervous system).
Other handicaps shall be discussed in subsequent posts.
Darwin, father of the theory of evolution, taught us the behavior of species. The main tenet of his theory was that when the resources for which the members of an species are competing are not sufficient, there is a fierce struggle amongst the members to outdo one another and in the end it is the strongest and fittest which emerges the winner.
This theory has many opponents not only in religious quarters but within science itself. And the issue is not satisfactorily settled.
For almost 100 years, no single person did more to promote the study of the Evolution of Cooperation than Peter Kropotkin.
His thesis is also based on thousands of observations he made while visiting through Siberian jungles and villages. Even though the resources are threadbare, but he did not find the brutal dog-eat-dog world of Darwinian competition.
He searched high and low—but nothing. “I failed to find, although I was eagerly looking for it,” Kropotkin wrote, “that bitter struggle for the means of existence, among animals belonging to the same species, which was considered by most Darwinists (though not always by Darwin himself) as the dominant characteristic of the struggle for life, and the main factor of evolution.”
Instead he saw mutual aid—everywhere. “In all these scenes of animal life which passed before my eyes,” Kropotkin wrote, “I saw Mutual Aid and Mutual Support carried on to an extent which made me suspect in it a feature of the greatest importance for the maintenance of life, the preservation of each species and its further evolution.”
And it wasn’t just in animals. The peasants in the villages he visited were constantly helping one another in their fight against the brutal environment of Siberia.
What’s more, he noted a correlation between the extent of mutual aid displayed in a peasant village and the distance of that village from the hand of government.
It was just as the anarchists had suggested. “I lost in Siberia,” he wrote, “whatever faith in state discipline I had cherished before. I was prepared to become an anarchist.”
And now another piece of research has thrown its weight with Kropotkin. Complex social behavior was considered to be unique in animals, especially humans. Now with recent findings, we may need to extend this ability to plants.
The old wives tale, “if you talk to your plants, they will grow better” may actually have a string of truth to it. Except they don’t have ears to hear, they have chemical sensors in their roots, like “tongues in the earth.”
Recent studies have shown that plants seem to respond to other neighboring plants, and will alter their growth patterns accordingly. At McMaster University, Ontario Canada, Susan Dudley and Amanda File have demonstrated that plants grown near their siblings are less competitive than when they are grown near unrelated “strangers” of the same plant.
The response of plants to competition in their environment has been well documented. They are known to sprout deeper roots for water and nutrients. However, recognition of their own genetic kin has never been seen before.
In their experiment, Dudley and File grew batches of Cakile edentula (the Great Lakes Sea Rocket) together in pots of four. Some were paired with members of the same maternal family and others were paired with unrelated families. Considering that the plants were of the same species, the growth of their root masses were expected to be the same.
Surprisingly, a greater mass of roots were grown when plant “strangers” were grown next to each other, while less root mass was associated with tandem plants of the same maternal line, thus indicating a sharing of resources as opposed to competing for them. The mechanism behind plant kin recognition is still a mystery.