We feel that natural selection would be a sufficiently valid explanation for the various relationships between the biodiversity of life on earth.
Firstly, fossil records provide direct evidence of evolution and detailed information on the ancestry of organisms. By looking at the fossil records, we would discover that organisms would tend to become more complex and the reason that is provided for this would be the continual change of the environment around them which results in their continual need for adaptation to the new conditions. This would serve to validate Darwin’s theory that organisms will have a struggle for existence due to the competition for the limited resources and would thus develop characteristics which would give them an edge over the rest and pass this on to future generations.
Also, homologous structures of organisms, for example the pentadactyl limb, are proof that they came from a common ancestor. To adapt to different environmental conditions unique to it, a gradual spreading of the homologous structure takes place in different organisms. Another example of homologous structures is the embryo. Species that look very different from each other in their adult form may have look similar in the embryonic stages, in the case of the human foetus. The gill-like structures and a “tail” which is present for a period of the time during its development, looks like those of a fish (in its embryonic development) and our primate relatives respectively. Hence, it can be said that humans and primates or humans and fish share homologous structures, even though they look different in their adult stages.
Next, there would be the example of the finches in support of Darwin’s theory. From his observations and study of the finches, he revealed that all the finches on the Galápagos Island descended from one original colonist species that adapted to a variety of feeding conditions went and that they eventually diverge into different species as they adapt to their different ecological niches. This would back Darwin’s theory that organisms will adapt to the environment due to the competition for resources and this advantage which they have gained would be passed down to their offspring which would in time result in the divergence of the finches into different species.
Aside from this, the example of the peppered moth (i.e. Biston betularia) where it shows how the dark-coloured moths would eventually dominate as compared to the light-coloured one as natural selection would favour them more.
Other prevailing theories were also rejected as they were proven untrue. For one, the theory of inheritance based on acquired traits by Lamarck was not supported by experiments. Even though this theory would provide an explanation for the biodiversity of life here on earth and his first statement s generally held to be true, experiments would serve to refute the second law he proposed — purely "acquired traits" do not appear to inherited by the offspring. (eg. a human child must learn how to catch a ball even though ancestors before him or her have learnt the same skill when they were children) However, there appears to be no substantial evidence refuting the theory of natural selection.
However, we feel that students should be exposed to the other current theories other than evolution, as they should understand that there is a variety of differing opinions and beliefs with regards to evolution. Also, they should understand that the theory of evolution, like science, is tentative and is subject to change with the development of science and research. Opposing theories such as Creationism, which focuses more on the religious aspect of human belief, should be briefly introduced in class so as to provide the students with the basic information of the prevailing theories in conflict with Darwin’s. Students should be encouraged to do their own research to better understand such other theories and their evidences. From there, students can be draw their own conclusions and form their own judgments and perspectives based on the newfound knowledge they have about evolution and its opposing theories.
Therefore, we feel that natural selection would be a sufficiently valid explanation for the various relationships between the biodiversity of life on earth and should hence be taught in science classes.
Sunday, April 22, 2007
Opposing Evolution: Creationism
Introduction
Creationism
Creationism is the belief that there exists a supernatural Creator who possesses the wisdom and knowledge to create living things on Earth, instead of them evolving from natural selection. Creationism is based on the Book of Genesis (the Bible), which states that The Creator, also known as God, created the universe and organisms in 6 days, making the Earth less than 10 000 years old. Creationism is one of the main current opposing theories of evolution.
Intelligent Design Theory
The Intelligent Design Theory, in support of Creationism, also claims that God creates and perfects His design of organisms so that they are purposefully given the abilities, characteristics, body parts etc. to carry out different processes necessary for their survival.
Such a theory is supported by English theolgian, William Paley made the famous watchmaker analogy:
"If we find a pocket watch in a field, we immediately infer that it was produced not by natural processes acting blindly but by a designing human intellect. Likewise, the natural world contains abundant evidence of a supernatural creator." (http://www.actionbioscience.org/evolution/nhmag.html, 9th April 07)
Evidence
A Creator
Creationism explains that everything is created by God for a purpose. As Paley said, there is much evidence that such a Creator exists, and such can be seen from the evidence provided:
Position of Earth from the Sun
The light and heat from the Sun is of paramount importance to organisms on Earth; processes such as photosynthesis depend greatly on the energy from the Sun. In fact, all life on Earth is linked very closely to the energy (light and heat) received by the Sun, without which would cease to exist.
Approximately 93 million miles away from the earth, the Sun is at exactly the right distance for Earth to bear life, which is not possible on any other planet in the solar system due to their positions from the Sun (either too near therefore making it too hot, or too far away, making it much too cold). The Earth is the only planet that is at a precise climatic distance such that the production and maintenance of life is possible. With reference to Genesis 1:1 “In the beginning God created the heavens and the earth”, the Earth’s positioning from the Sun is the creation of God, who purposefully placed the planet from the Sun, such that life could be supported by the energy received. This is evidence that a supernatural Creator exists, and proves the theory of Creationism.
Instinct
Instincts are evidence of God’s creation of organisms. For a plant to grow towards an area with a higher intensity of light due to the need for light energy for photosynthesis, explains how God created natural reactions in organisms to aid in their survival. Instincts are part of the Intelligent Design of organisms by God, which ultimately helps them to live on.
An example of instinct present in organisms can be seen in spiders. All web-weaving spiders are perfectly able to weave their own webs without being taught how. Such an instinct cannot be explained by evolution, but Creationism is able to explain this. As God created creatures and their complex reactions for a purpose, the spider’s ability to weave its web based on its instinct created by God for it to survive.
Proportion of roles of bees
There is diversity in the roles of bees in a hive. In an article by Jean George, which appeared in the Reader's Digest, 1966, it is explained that nurse bees, which feed the queen bee and the larvae, have special glands in their heads to form milk. Other bees with different roles have different abilities, for example to turn honey into beeswax. The proportion of the roles of bees in a hive has always been maintained at equilibrium, such that there are not too many queen bees or too few nurse bees.
Evolution by natural selection cannot explain how this correct proportion of the roles of bees is maintained. It is only through Creationism that such a phenomenon can be explained: God has created bees with the design and purpose, so that the maintenance of the equilibrium of the roles of bees is possible, hence the different productions can be carried out at suitable proportions, enabling the entire hive to survive.
A Young Earth
As from the Book of Genesis, it is said that God created the universe in 6 days, and the Earth is less than 10 000 years old, instead of the generally-believed 4.5 billion years old by evolutionists.
Cosmic dust on the Moon
It is believed by scientists that cosmic dust is like dust on Earth; it collects on the surface of heavenly bodies over time. As such, the measure of cosmic dust on the Moon has been used as a measure of the Earth’s age (since the Earth and the universe were created at the same time by God).
However, the first trip made to the Moon by Neil Armstrong and his team showed that there was not a billion years’ worth of cosmic dust on the moon, rather only a few thousand years’ worth of cosmic dust, hence proving that the Moon and Earth are not in fact 4.5 billion years old, but less than 10 000 years old.
Meteor-shower gauge
The meteor-shower gauge works on the same theory as cosmic dust: meteorites reaching the Earth’s surface should be accumulated throughout the supposed billions of years in the Earth’s geological column, and found embedded in rock layers. As a result, many meteorites should be found on Earth if it were 4.5 billion years old, with the number of meteorites acting as a “clock” to gauge the Earth’s age.
However, geologists are only able to find a small number of meteorites in the Earth’s geological column, thus reflecting that the Earth’s surface was not exposed to meteorites for a long time, supporting Creationism in saying that the Earth was created recently. This proves that God created the Earth recently, that is within the last 10 000 years.
Response to Creationism
Most scientists do not believe in Creationism, and have dismissed it as a religious dogma. According to Religioustolerance.org, 95% of the scientists support evolution, and believe that humans and apes did evolve from a common ancestor, as with other species of organisms.
Belief system Creationist view Theistic evolution Naturalistic Evolution
Group of adults God created man pretty much in his present form at one time within the last 10,000 years. Man has developed over millions of years from less advanced forms of life, but God guided this process, including man's creation. Man has developed over millions of years from less advanced forms of life. God had no part in this process.
(Source: http://www.religioustolerance.org/ev_publi.htm)
As can be seen from the above table (a survey conducted in November 1997), there is a vast difference in scientists’ belief in Creationism as compared to the public.
Also according Religioustolerance.org, a secularist would probably comment that Genesis is should not be interpreted literally, as those who wrote the Book lived in an era before science, and “adopted creation legends from their surrounding Pagan societies” (http://www.religioustolerance.org/ev_publi.htm, 22nd April 2007)
Conclusion
Having stated the above evidence to support the theory of Creationism, it can be seen that an existing Creator with intelligence far greater than any human indeed is the cause of diverse life on Earth.
He created the Earth in a position from the Sun such that the biodiversity of life can survive. God also equipped the different species of living things on Earth with the necessary tools for survival (through Intelligent Design), for instance instinct. By providing all organisms with such a tool to rely on for survival and by purposefully creating organisms in proportion (and maintaining such equilibrium), it is evident that God created this Earth and life, proving Creationism.
Reference
http://www.trueorigin.org/, 9th April 2007
http://www.talkorigins.org/, 9th April 2007
http://www.actionbioscience.org/evolution/nhmag.html, 10th April 2007
John Brockman, “Intelligent Thought: Science versus the Intelligent Design Movement”, 2006, 11th April 2007
http://www.creationism.org/, 15th April 2007
http://www.religioustolerance.org/evolutio.html, 15th April 2007
Dr. Paul D. Ackerman, “It’s A Young World After All”, 1986, chapter 1 – 2, 21st April 2007
Picture taken from http://www.phys.utas.edu.au/optastr/media_OB390_files/p060_x_bacon.jpg, 22nd April 2007
celine chia
Creationism
Creationism is the belief that there exists a supernatural Creator who possesses the wisdom and knowledge to create living things on Earth, instead of them evolving from natural selection. Creationism is based on the Book of Genesis (the Bible), which states that The Creator, also known as God, created the universe and organisms in 6 days, making the Earth less than 10 000 years old. Creationism is one of the main current opposing theories of evolution.
Intelligent Design Theory
The Intelligent Design Theory, in support of Creationism, also claims that God creates and perfects His design of organisms so that they are purposefully given the abilities, characteristics, body parts etc. to carry out different processes necessary for their survival.
Such a theory is supported by English theolgian, William Paley made the famous watchmaker analogy:
"If we find a pocket watch in a field, we immediately infer that it was produced not by natural processes acting blindly but by a designing human intellect. Likewise, the natural world contains abundant evidence of a supernatural creator." (http://www.actionbioscience.org/evolution/nhmag.html, 9th April 07)
Evidence
A Creator
Creationism explains that everything is created by God for a purpose. As Paley said, there is much evidence that such a Creator exists, and such can be seen from the evidence provided:
Position of Earth from the Sun
The light and heat from the Sun is of paramount importance to organisms on Earth; processes such as photosynthesis depend greatly on the energy from the Sun. In fact, all life on Earth is linked very closely to the energy (light and heat) received by the Sun, without which would cease to exist.
Approximately 93 million miles away from the earth, the Sun is at exactly the right distance for Earth to bear life, which is not possible on any other planet in the solar system due to their positions from the Sun (either too near therefore making it too hot, or too far away, making it much too cold). The Earth is the only planet that is at a precise climatic distance such that the production and maintenance of life is possible. With reference to Genesis 1:1 “In the beginning God created the heavens and the earth”, the Earth’s positioning from the Sun is the creation of God, who purposefully placed the planet from the Sun, such that life could be supported by the energy received. This is evidence that a supernatural Creator exists, and proves the theory of Creationism.
Instinct
Instincts are evidence of God’s creation of organisms. For a plant to grow towards an area with a higher intensity of light due to the need for light energy for photosynthesis, explains how God created natural reactions in organisms to aid in their survival. Instincts are part of the Intelligent Design of organisms by God, which ultimately helps them to live on.
An example of instinct present in organisms can be seen in spiders. All web-weaving spiders are perfectly able to weave their own webs without being taught how. Such an instinct cannot be explained by evolution, but Creationism is able to explain this. As God created creatures and their complex reactions for a purpose, the spider’s ability to weave its web based on its instinct created by God for it to survive.
Proportion of roles of bees
There is diversity in the roles of bees in a hive. In an article by Jean George, which appeared in the Reader's Digest, 1966, it is explained that nurse bees, which feed the queen bee and the larvae, have special glands in their heads to form milk. Other bees with different roles have different abilities, for example to turn honey into beeswax. The proportion of the roles of bees in a hive has always been maintained at equilibrium, such that there are not too many queen bees or too few nurse bees.
Evolution by natural selection cannot explain how this correct proportion of the roles of bees is maintained. It is only through Creationism that such a phenomenon can be explained: God has created bees with the design and purpose, so that the maintenance of the equilibrium of the roles of bees is possible, hence the different productions can be carried out at suitable proportions, enabling the entire hive to survive.
A Young Earth
As from the Book of Genesis, it is said that God created the universe in 6 days, and the Earth is less than 10 000 years old, instead of the generally-believed 4.5 billion years old by evolutionists.
Cosmic dust on the Moon
It is believed by scientists that cosmic dust is like dust on Earth; it collects on the surface of heavenly bodies over time. As such, the measure of cosmic dust on the Moon has been used as a measure of the Earth’s age (since the Earth and the universe were created at the same time by God).
However, the first trip made to the Moon by Neil Armstrong and his team showed that there was not a billion years’ worth of cosmic dust on the moon, rather only a few thousand years’ worth of cosmic dust, hence proving that the Moon and Earth are not in fact 4.5 billion years old, but less than 10 000 years old.
Meteor-shower gauge
The meteor-shower gauge works on the same theory as cosmic dust: meteorites reaching the Earth’s surface should be accumulated throughout the supposed billions of years in the Earth’s geological column, and found embedded in rock layers. As a result, many meteorites should be found on Earth if it were 4.5 billion years old, with the number of meteorites acting as a “clock” to gauge the Earth’s age.
However, geologists are only able to find a small number of meteorites in the Earth’s geological column, thus reflecting that the Earth’s surface was not exposed to meteorites for a long time, supporting Creationism in saying that the Earth was created recently. This proves that God created the Earth recently, that is within the last 10 000 years.
Response to Creationism
Most scientists do not believe in Creationism, and have dismissed it as a religious dogma. According to Religioustolerance.org, 95% of the scientists support evolution, and believe that humans and apes did evolve from a common ancestor, as with other species of organisms.
Belief system Creationist view Theistic evolution Naturalistic Evolution
Group of adults God created man pretty much in his present form at one time within the last 10,000 years. Man has developed over millions of years from less advanced forms of life, but God guided this process, including man's creation. Man has developed over millions of years from less advanced forms of life. God had no part in this process.
(Source: http://www.religioustolerance.org/ev_publi.htm)As can be seen from the above table (a survey conducted in November 1997), there is a vast difference in scientists’ belief in Creationism as compared to the public.
Also according Religioustolerance.org, a secularist would probably comment that Genesis is should not be interpreted literally, as those who wrote the Book lived in an era before science, and “adopted creation legends from their surrounding Pagan societies” (http://www.religioustolerance.org/ev_publi.htm, 22nd April 2007)
Conclusion
Having stated the above evidence to support the theory of Creationism, it can be seen that an existing Creator with intelligence far greater than any human indeed is the cause of diverse life on Earth.
He created the Earth in a position from the Sun such that the biodiversity of life can survive. God also equipped the different species of living things on Earth with the necessary tools for survival (through Intelligent Design), for instance instinct. By providing all organisms with such a tool to rely on for survival and by purposefully creating organisms in proportion (and maintaining such equilibrium), it is evident that God created this Earth and life, proving Creationism.
Reference
http://www.trueorigin.org/, 9th April 2007
http://www.talkorigins.org/, 9th April 2007
http://www.actionbioscience.org/evolution/nhmag.html, 10th April 2007
John Brockman, “Intelligent Thought: Science versus the Intelligent Design Movement”, 2006, 11th April 2007
http://www.creationism.org/, 15th April 2007
http://www.religioustolerance.org/evolutio.html, 15th April 2007
Dr. Paul D. Ackerman, “It’s A Young World After All”, 1986, chapter 1 – 2, 21st April 2007
Picture taken from http://www.phys.utas.edu.au/optastr/media_OB390_files/p060_x_bacon.jpg, 22nd April 2007
celine chia
Opposing Evolution: Catastrophism
Introduction
Catastrophism is the belief that Earth was affected by sudden violent catastrophic natural disasters, causing mass extinctions followed by rapid bursts of new species. Such a theory is supported by the Book of Genesis, which also supports Creationism, whereby The Great Flood was said to have happened.
Evidence
Meteorite showers
Catastrophism is the belief that Earth was affected by sudden violent catastrophic natural disasters, causing mass extinctions followed by rapid bursts of new species. Such a theory is supported by the Book of Genesis, which also supports Creationism, whereby The Great Flood was said to have happened.
Evidence
Meteorite showers
According to historians, a huge meteor wiped out all the dinosaurs on Earth, after which other species appeared. A whole shower of meteorites landed on Earth in 1803, causing many large craters on the Earth’s surface, proving that such catastrophic events do happen, thus supporting Catastrophism.
Noachian Flood
Tree stumps in coal
In Nova Scotia, the coal measures of stumps and trunks of many trees have been preserved standing upright as they grew, showing that before they had time to fall and decay, they were buried. The accumulated sediment seems to have accumulated many feet deep within the span of a couple of years.
This therefore shows that there probably was a Great Flood that swept rock and mud over the trees, causing them to remain in the “petrified” position under the layers of rock, and becoming coal.
Peculiar clam fossils
A three-foot thick stratum composed mainly of millions of closed fossil clams was found on the Paluxy River near Glen Rose, Texas. However, based scientific research today, clams do not live crammed together in a thick layer, unlike what was observed in the stratum. Neither are clam shells usually found in one piece in a closed position, but rather the 2 valves are found unhinged most of the time.
As can be observed from the peculiar fossilization of the clams, the only possible explanation is turbulent waters from the Noachian Flood washing the clams into their present location, and buried them in that thick layer, alive.
Sedimentary Rock: Conglomerate
Conglomerate, a type of sedimentary rock (rock that is made up of sediments cemented together from pressure exerted by river beds), is usually made up of cemented gravel and pebbles. A conglomerate formation, the Shinarump of the Colorado Plateau however shows signs of vari-coloured quartz and quartzite, which is not usually present in sedimentary rock, but rather in igneous or metamorphic rock on land. The size of the Shinarump is also very great: it can reach up to 300 feet thick. Such formations have also been found over wide areas in northern Arizona and southern Utah.
The Great Flood can explain the occurrence of such a conglomerate formation: fast-flowing water can easily deposit large amounts of coarse material with sand. Minerals like quartz and quartzite could have been swept away by the waters of The Flood and deposited with the sediments, which were then cemented under the pressure of water (from The Flood) to form Shinarump. Conglomerate "blankets" even more extensive than the Shinarump exist, and a blanket of this size is not possible to have been formed by normal stream processes, proving that the Great Flood must have happened.
Response to Catastrophism
Scientists have denied that Catastrophism is the explanation for life on Earth, and feel that it is a religious theory supporting the Book of Genesis, like Creationism. Scientists, namely astronomers, have concluded that Catastrophism cannot explain life on Earth as they do not agree with the astronomical evidence produced by Catastrophists to support the theory.
Conclusion
Having presented some evidence (above) for the occurrence of the Noachian Flood, it can be seen that life on Earth was destroyed by catastrophic events (for example the Flood) that happened on Earth in the past, and was replaced by the rapid bursts and replacements of new species.
Noachian Flood
Tree stumps in coal
In Nova Scotia, the coal measures of stumps and trunks of many trees have been preserved standing upright as they grew, showing that before they had time to fall and decay, they were buried. The accumulated sediment seems to have accumulated many feet deep within the span of a couple of years.
This therefore shows that there probably was a Great Flood that swept rock and mud over the trees, causing them to remain in the “petrified” position under the layers of rock, and becoming coal.
Peculiar clam fossils
A three-foot thick stratum composed mainly of millions of closed fossil clams was found on the Paluxy River near Glen Rose, Texas. However, based scientific research today, clams do not live crammed together in a thick layer, unlike what was observed in the stratum. Neither are clam shells usually found in one piece in a closed position, but rather the 2 valves are found unhinged most of the time.
As can be observed from the peculiar fossilization of the clams, the only possible explanation is turbulent waters from the Noachian Flood washing the clams into their present location, and buried them in that thick layer, alive.
Sedimentary Rock: Conglomerate
Conglomerate, a type of sedimentary rock (rock that is made up of sediments cemented together from pressure exerted by river beds), is usually made up of cemented gravel and pebbles. A conglomerate formation, the Shinarump of the Colorado Plateau however shows signs of vari-coloured quartz and quartzite, which is not usually present in sedimentary rock, but rather in igneous or metamorphic rock on land. The size of the Shinarump is also very great: it can reach up to 300 feet thick. Such formations have also been found over wide areas in northern Arizona and southern Utah.
The Great Flood can explain the occurrence of such a conglomerate formation: fast-flowing water can easily deposit large amounts of coarse material with sand. Minerals like quartz and quartzite could have been swept away by the waters of The Flood and deposited with the sediments, which were then cemented under the pressure of water (from The Flood) to form Shinarump. Conglomerate "blankets" even more extensive than the Shinarump exist, and a blanket of this size is not possible to have been formed by normal stream processes, proving that the Great Flood must have happened.
Response to Catastrophism
Scientists have denied that Catastrophism is the explanation for life on Earth, and feel that it is a religious theory supporting the Book of Genesis, like Creationism. Scientists, namely astronomers, have concluded that Catastrophism cannot explain life on Earth as they do not agree with the astronomical evidence produced by Catastrophists to support the theory.
Conclusion
Having presented some evidence (above) for the occurrence of the Noachian Flood, it can be seen that life on Earth was destroyed by catastrophic events (for example the Flood) that happened on Earth in the past, and was replaced by the rapid bursts and replacements of new species.
References
http://www.creationism.org/symposium/symp3no2.htm, 15th April 2007
http://www.catastrophism.net/, 21st April 2007
http://www.knowledge.co.uk/sis/controv.htm, 21st April 2007
http://www.knowledge.co.uk/sis/catneo.htm, 22nd April 2007
http://www.creationism.org/symposium/symp3no2.htm, 15th April 2007
http://www.catastrophism.net/, 21st April 2007
http://www.knowledge.co.uk/sis/controv.htm, 21st April 2007
http://www.knowledge.co.uk/sis/catneo.htm, 22nd April 2007
Picture taken from http://www.creationism.org/images/DoreBibleIllus/aGen0724Dore_TheWorldDestroyedByWater.jpg, 22nd April 2007
celine chia
Evidence from comparative anatomy
Evolutionary theory predicts that related organisms will share similarities that are derived from common ancestors. Therefore, comparative anatomy is used to determine relationships between different species of organisms which may link them to a common origin.
Homologous structures are usually present in the organism’s stage of embryonic development, but it is sometimes absent in the adult organism. In cases where the similar structures serve different functions in adults, it may be necessary to trace their origin and embryonic development. Species that look very different from each other in their adult form may have similar embryonic stages.
Homologous structures and divergent evolution
Widely separated groups of organisms would share certain basic features if they have common ancestors. The degree of how closely two organisms are related in evolution can be determined by the extent of resemblance between them.
Groups with little in common are assumed to have diverged from a common ancestor much earlier in geological history than groups which have a lot in common.
Fundamentally similar structures are used in deciding how closely related the two organisms are, even though they may serve different functions in the adult stage of the organism’s life cycle. Such structures are described as homologous and suggest a common origin.
These homologous structures are different in the way that each structure is specialized to perform a variety of functions in order to adapt to different environmental conditions unique to the organism. The gradual spreading of the different structures is called divergent evolution.
Example: Pentadactyl limb
All of the animals’ forelimbs as shown in the picture above conform to the basic pentadactyl pattern but are modified for different usages.
The pentadactyl limb is found in all classes of tetrapods (i.e. from amphibians to mammals), and can even be traced back to the fins of certain fossil fishes from which the first amphibians are thought to have evolved. The different forelimbs of all the animals all share the same set of bones - the humerus, the radius, and the ulna. This suggests that even though the bones may be slightly different in shape and size (due to the animals’ different lifestyles), the animals may have all descended from a common ancestor. In the course of evolution, these fundamental structures have been modified to serve different functions and to adapt to different environments and modes of life.
One example is the bat, whereby 4 of the bones in the forelimbs have been elongated and turned into wings for flying, whilst another bone is hooked to allow the bat to hang from trees.
Embryology
Homologous structures are usually present in the organism’s stage of embryonic development, but it is sometimes absent in the adult organism. In cases where the similar structures serve different functions in adults, it may be necessary to trace their origin and embryonic development. Species that look very different from each other in their adult form may have similar embryonic stages. One such example is the human foetus. The embryo has gill-like structures like those of the fish in one of its developing stages. The embryo also has a tail for a long period of the time during its development, similar to those of our primate relatives. Hence, it can be said that humans and primates or humans and fish share homologous structures.
Source:
http://en.wikipedia.org/wiki/Evidence_of_evolution, 11th April 2007
http://www.sparknotes.com/biology/evolution/evidence/section3.rhtml, 11th April 2007
Ilisa Ishak [Science Investigator]
Saturday, April 21, 2007
The History of the Theory of Evolution
BEFORE DARWIN
Before Charles Darwin formulated his theory of evolution, there appears to be many theories existing at the time.
From ancient times, there were scientists such as Aristotle who classified organisms with similar characteristics with one another into what is called genera before dividing the organism in each genera into different species. Following his lead, there were others such as John Ray who proposed that the organisms on Earth could be examined to determine the creation, association and the destiny of the Earth which is ultimately decided by God.
After these scientists, there were many others who seek to provide an explanation for the origin of life. In the 18th century, Georges-Louis Leclerc, Comte de Buffon observed that Man had many characteristics in common with the apes and even proposed that we could have descended from a common ancestor. He did not, however, provide an acceptable explanation for this idea. At this same time, Carl Linnaeus proposed the Linnaean classification in which animals are ranked in a type of hierarchical classification. This classification is still being used in today’s society. Erasmus Darwin, grandfather to Charles Darwin, had in his grandson’s words anticipated Lamarck’s theory at this point of time in the history of evolutionary thought.
The main theory before natural selection would be that proposed by Jean-Baptise Pierre Antoine de Monet, Chevalier de Lamarck. Lamarck formulated the theory of inheritance of acquired traits in which he points out that organisms would pass on the traits they have acquired within their lifespan to their offsprings. Lamarck built his theory based on two observations he made, mainly using the giraffe as an example to support his theory. The two observations are as follows:
1. Use and Disuse
2. Inheritance of Acquired Traits
Lamarck observed that organisms will eventually lose the characteristics which they do not have a need for or which they do not use and will develop the traits which will be useful for their survival. He uses the giraffe as an example to support this. Lamarck states that giraffes require the trait of having long necks as they have to reach for the leaves in the trees, thus their necks would strengthen and lengthen after a period of time. Also, Lamarck states that all organisms would inherit their traits from their ancestors. Thus the giraffes would pass on the traits they have acquired to their offspring resulting in the development of slightly longer necks in the next generation.
With this in mind, Lamarck developed two laws for his theory:
1. In every organism which has not hit its limit for development, the often and continuous use of a particular organ would slowly strengthen and develop it and the disuse of an organ permanently will result in its weakening until it stops functioning. This organ will then cease to exist in the organism.
2. All acquisitions and losses of characteristics, due to the changes in the environment, of an organism will be passed on through reproduction to its offspring, given the condition that the acquired changes in traits are applicable to both sexes, or at least to the individuals which produce the offspring.
Alongside Lamarck, Thomas Malthus had observed that there was an overproduction of offspring in organisms and that this would eventually lead to competition for the limited amount of resources found here on Earth. This was what eventually paved the way for Darwin’s proposal of his theory on natural selection.
Before Darwin proposed his theory on natural selection, there was one other scientist who had a theory similar to that of Darwin. Through the study of trees, Patrick Matthew observed that trees were different from one to another and was able to derive a theory of natural selection which was not as fully developed as that of Darwin’s.
DURING DARWIN
Along with Darwin who formulated the theory of evolution through natural selection, there was one other person who formulated a theory strikingly similar to it. This person would be known as Alfred Russel Wallace and he proposed the theory that natural selection is an environmental weeding out process of those which could not adapt. This is where his theory would differ from that of Darwin who theorized that competition for the limited resources is the genuine weeding out process.
He travelled and collected plant samples in the Amazon basin together with Henry Walter Bates (1842-52) and was similarly employed in the Malay Archipelago and the Spice Islands (1854-62).
Wallace theorized on the basis of his findings and was influenced by Thomas Malthus' Essay on Population. These later allowed him to propound a theory of the evolutionary origin of species by natural selection.
In 1858, Wallace sent an essay he had written to Darwin - On the Tendency of Varieties to depart indifenitely from the Original Type. It is this that prompted Darwin to make known his findings on natural selection.
Also, Darwin was very much influenced by the geologist Charles Lyell. Lyell proposed a theory very much different from all the prevailing theories of geology at the time. According to him, the theories at the time were prejudiced, being based on the interpretation of Genesis. He thought that we should exclude sudden geological catastrophes to account for fossil remains of extinct species and believed it was necessary to know that Earth’s history went back a long way. This concept was called Uniformitarianism.
Lyell stated that the origin of human species was far beyond the prevailing theories of that time, that the origin of the human species went a very long way back.
All these eventually led Darwin to construct his theory of evolution based on natural selection and make it known to the public.
RELIGIOUS CONTEXT
At the time, there was the interpretation of the Book of Genesis in which God had created the world as how it is now and the distinguishable living organisms along with it. People at the time, mainly Christians, believed that the world was as God had created it with no changes, meaning that there were no extinct species as well as no new species. It was extremely dangerous for Darwin to even begin to suggest that the human species was evolved from the apes.
However, the response to the publication of his book appeared to be of less ferocity as he had anticipated.
This theory proposed by Darwin, however is widely accepted today.
Sources:
http://en.wikipedia.org/wiki/Jean-Baptiste_Lamarck
http://www.ucmp.berkeley.edu/history/evothought
Evon
Before Charles Darwin formulated his theory of evolution, there appears to be many theories existing at the time.
From ancient times, there were scientists such as Aristotle who classified organisms with similar characteristics with one another into what is called genera before dividing the organism in each genera into different species. Following his lead, there were others such as John Ray who proposed that the organisms on Earth could be examined to determine the creation, association and the destiny of the Earth which is ultimately decided by God.
After these scientists, there were many others who seek to provide an explanation for the origin of life. In the 18th century, Georges-Louis Leclerc, Comte de Buffon observed that Man had many characteristics in common with the apes and even proposed that we could have descended from a common ancestor. He did not, however, provide an acceptable explanation for this idea. At this same time, Carl Linnaeus proposed the Linnaean classification in which animals are ranked in a type of hierarchical classification. This classification is still being used in today’s society. Erasmus Darwin, grandfather to Charles Darwin, had in his grandson’s words anticipated Lamarck’s theory at this point of time in the history of evolutionary thought.
The main theory before natural selection would be that proposed by Jean-Baptise Pierre Antoine de Monet, Chevalier de Lamarck. Lamarck formulated the theory of inheritance of acquired traits in which he points out that organisms would pass on the traits they have acquired within their lifespan to their offsprings. Lamarck built his theory based on two observations he made, mainly using the giraffe as an example to support his theory. The two observations are as follows:
1. Use and Disuse
2. Inheritance of Acquired Traits
Lamarck observed that organisms will eventually lose the characteristics which they do not have a need for or which they do not use and will develop the traits which will be useful for their survival. He uses the giraffe as an example to support this. Lamarck states that giraffes require the trait of having long necks as they have to reach for the leaves in the trees, thus their necks would strengthen and lengthen after a period of time. Also, Lamarck states that all organisms would inherit their traits from their ancestors. Thus the giraffes would pass on the traits they have acquired to their offspring resulting in the development of slightly longer necks in the next generation.
With this in mind, Lamarck developed two laws for his theory:
1. In every organism which has not hit its limit for development, the often and continuous use of a particular organ would slowly strengthen and develop it and the disuse of an organ permanently will result in its weakening until it stops functioning. This organ will then cease to exist in the organism.
2. All acquisitions and losses of characteristics, due to the changes in the environment, of an organism will be passed on through reproduction to its offspring, given the condition that the acquired changes in traits are applicable to both sexes, or at least to the individuals which produce the offspring.
Alongside Lamarck, Thomas Malthus had observed that there was an overproduction of offspring in organisms and that this would eventually lead to competition for the limited amount of resources found here on Earth. This was what eventually paved the way for Darwin’s proposal of his theory on natural selection.
Before Darwin proposed his theory on natural selection, there was one other scientist who had a theory similar to that of Darwin. Through the study of trees, Patrick Matthew observed that trees were different from one to another and was able to derive a theory of natural selection which was not as fully developed as that of Darwin’s.
DURING DARWIN
Along with Darwin who formulated the theory of evolution through natural selection, there was one other person who formulated a theory strikingly similar to it. This person would be known as Alfred Russel Wallace and he proposed the theory that natural selection is an environmental weeding out process of those which could not adapt. This is where his theory would differ from that of Darwin who theorized that competition for the limited resources is the genuine weeding out process.
He travelled and collected plant samples in the Amazon basin together with Henry Walter Bates (1842-52) and was similarly employed in the Malay Archipelago and the Spice Islands (1854-62).
Wallace theorized on the basis of his findings and was influenced by Thomas Malthus' Essay on Population. These later allowed him to propound a theory of the evolutionary origin of species by natural selection.
In 1858, Wallace sent an essay he had written to Darwin - On the Tendency of Varieties to depart indifenitely from the Original Type. It is this that prompted Darwin to make known his findings on natural selection.
Also, Darwin was very much influenced by the geologist Charles Lyell. Lyell proposed a theory very much different from all the prevailing theories of geology at the time. According to him, the theories at the time were prejudiced, being based on the interpretation of Genesis. He thought that we should exclude sudden geological catastrophes to account for fossil remains of extinct species and believed it was necessary to know that Earth’s history went back a long way. This concept was called Uniformitarianism.
Lyell stated that the origin of human species was far beyond the prevailing theories of that time, that the origin of the human species went a very long way back.
All these eventually led Darwin to construct his theory of evolution based on natural selection and make it known to the public.
RELIGIOUS CONTEXT
At the time, there was the interpretation of the Book of Genesis in which God had created the world as how it is now and the distinguishable living organisms along with it. People at the time, mainly Christians, believed that the world was as God had created it with no changes, meaning that there were no extinct species as well as no new species. It was extremely dangerous for Darwin to even begin to suggest that the human species was evolved from the apes.
However, the response to the publication of his book appeared to be of less ferocity as he had anticipated.
This theory proposed by Darwin, however is widely accepted today.
Sources:
http://en.wikipedia.org/wiki/Jean-Baptiste_Lamarck
http://www.ucmp.berkeley.edu/history/evothought
Evon
Monday, April 16, 2007
Evidence for Evolution: Paleontology
Paleontology is the study of past life based on fossil records and their associations to different geologic time periods.When organisms die, they usually do not leave any traces of their existence as most of them are decomposed or consumed. However, some organisms are preserved as fossils, which are the remains of organisms from a past geologic age embedded in rocks by natural processes. These fossils are play an important role in understanding the evolutionary history of life on Earth, as they provide direct evidence of evolution and detailed information on the ancestry of organisms.
Fossil records
By organising fossils records in a chronological sequence, we are able to find out how a particular group of organisms, for example animals and plants, evolved.
Fossil evidence shows that organisms tend to gradually become more complex. The reason for this is that the organisms are constantly adapting to the ever-changing conditions in the environments, due to the varying geographical regions and climatic conditions. By studying the number and complexity of different fossils at different stratigraphic levels, it has been shown that older fossilized organisms have simpler structures, whereas younger fossils often have more complex structures.
This supports Darwin’s theory that organisms will develop certain characteristics to aid in their survival due to the competition for the limited resources. These characteristics would be passed down from generations to generations. Hence, in light of this evidence presented by fossil records, scientists readily accept the theory of evolution.
Example: Evolution of the horse
An almost-complete horse fossil record was found in North American sedimentary deposits from the early Eocene to the present, which provides one of the best examples of evolutionary history (phylogeny).
The course of development of horses from Hyracotheium to Equus (the modern horse) involved at least 12 genera and several hundred species. The major changes seen in the horse’s adaptation to changing environmental conditions may be summarized as follows:1.Increase in size (from 0.4 m to 1.5 m);
2.Lengthening of limbs and feet;
3.Reduction of lateral digits (refer to picture);
4.Increase in length and thickness of the third digit (refer to picture);
5.Increase in width of incisors;
6.Replacement of premolars by molars; and
7.Increases in tooth length, crown height of molars.
The marshy, wooded country in which the Hyracotherium used to live in had become dryer, and thus the Hyracotherium adapted to the drier environment by means of an elevated head for gaining a good view of the surrounding countryside; and a larger hoofed foot to increases its speed so as to escape from predators. The original splayed-out foot would not be able to support the Hyracotherium on the drier, harder ground. The probable explanation for the changes in the teeth may be that the animal’s diet changed from soft vegetation to grass, and thus would need stronger teeth.
Example: Human Evolution
Human fossils show that the oldest human ancestor was an apelike creature that lived about 40 million years ago in Egypt. However, a gap in the fossil record means it is difficult to follow human evolution over the next 20 million years. Humanlike fossils have been found 4- to 5-million-year-old sediments in Ethopia and East Africa. It has been said that everyone can trace their family trees back to a common ancestor – one woman who lived in Africa. She has been called Eve, after the first woman in the Bible. The idea about ‘Eve’ has led to arguments among scientists.
Additional clues from fossils
Each new fossil contains additional clues that allow us to better understand our life's history and help us to learn about the evolutionary story of different organisms. Examples include:
Indication of interactions
This ammonite fossil (see right) shows punctures in an ammonite fossil have been interpreted by scientists as the bite mark of a mosasaur, which corresponds to the shapes and capabilities of mosasaur teeth and jaws.
Clues at the cellular level
Fossils contain clues about growth patterns in ancient animals. The cross-section through a sub-adult thigh bone of the duckbill dinosaur Maiasaura shows that it was a fast-growing bone as there were lots of blood vessels running through it, which can be seen from the white spaces.
Limitations
The fossil record is an important source for scientists when tracing the evolutionary history of organisms. However, there is a lack of continuous fossils in record and there are large gaps between major evolutionary ancestries (“missing links”). One of the reasons for this is that in general, the probability that an organism becomes fossilized after death is very low, and thus is a major limitation in tracing the descent of biological groups.
Source:
S Gater & V Wood-Robinson, "G.C.S.E Science Double Award-Biology", 1996, p. 154-155,
10th April 2007
Source:
S Gater & V Wood-Robinson, "G.C.S.E Science Double Award-Biology", 1996, p. 154-155,
10th April 2007
Marshall Cavendish, "Exploring Life Science 4", 2000, p. 310, 10th April 2007
http://en.wikipedia.org/wiki/Evidence_of_evolution, 10th April 2007
http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_02, 10th April 2007
Ilisa Ishak [Science Investigator]
http://en.wikipedia.org/wiki/Evidence_of_evolution, 10th April 2007
http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_02, 10th April 2007
Ilisa Ishak [Science Investigator]
Friday, April 13, 2007
EXAMPLES used to support Darwin's theory
Some examples Charles Darwin used to support his theory are the finches as well as the peppered moths.
DARWIN'S FINCHES
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Emberizidae
Darwin's finches (also known as the Galápagos Finches) are 13 or 14 different but closely related species of finches Charles Darwin collected on the Galapagos Island. The group consists of ground-dwelling birds (Geospiza) that feed on different sized seeds or cactus flowers as well as tree-dwelling birds (Camarynchus) that feed on different types of insects or types of fruit. The beaks belonging to each type or finch are adapted for a specialized feeding task. Thirteen of the finches reside on the Galápagos Islands and one on Cocos Island.
DARWIN'S FINCHES
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Emberizidae
Darwin's finches (also known as the Galápagos Finches) are 13 or 14 different but closely related species of finches Charles Darwin collected on the Galapagos Island. The group consists of ground-dwelling birds (Geospiza) that feed on different sized seeds or cactus flowers as well as tree-dwelling birds (Camarynchus) that feed on different types of insects or types of fruit. The beaks belonging to each type or finch are adapted for a specialized feeding task. Thirteen of the finches reside on the Galápagos Islands and one on Cocos Island.
All the species of finches on the Galápagos Islands appear morphologically very alike, varying mostly in terms of beak size and behaviour. All of them appear very much like a type of finch which can be found in the mainland of South America. This insinuates that all the finches on the Galápagos Island descended from one original colonist species that adapted to a variety of feeding conditions went. Also, this seems to show that when different populations of species become reproductively isolated from one another by adapting to differing ecological niches, they ultimately become distinct and individual species. This process is as adaptive radiation whereby one species diversifies into several other species in order to utilize the extensive range of habitats.
This diagram shows the relationship between the diet of the birds, the purpose of the beaks, the usual location of the birds as well as the shape and size of the beaks
This diagram shows the types of beaks in relation to its purpose
1) Source: http://en.wikipedia.org/wiki/Darwin's_finches, 14th April 2007
2) Source: http://www.ncseweb.org/icons/icon7finches.html, 7th April 2007
4) Source: http://anthro.palomar.edu/evolve/evolve_2.htm, 17th April 2007
5) Source [1st picture]: http://www.pbs.org/wgbh/evolution/library/01/6/l_016_02.html, 7th April 2007
PEPPERED MOTHS- Biston betularia
PEPPERED MOTHS- Biston betularia
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Geometridae
Genus: Biston
Species: B. betularia
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Geometridae
Genus: Biston
Species: B. betularia
Evidence for selection over a much shorter time, from 1848 onwards, comes from looking at the population of the peppered moth. There are two different kinds of moths, dark and light coloured. The colour of the moth offers camouflage against the tree barks, as can be seen from the photographs below.
Moths with light-colouration are well camouflaged against lichen-covered bark, but moths with dark-colouration are more noticeable against that background are hence are more likely to be spotted by predators and be eaten up. However, when soot increasingly caused the lichens to die out and the trunks of the trees to turn black in industrial areas during the Industrial Revolution in England, the dark moths, or melanic moths- carbonaria, were able to camouflage themselves better and as a result they usually live long enough to reproduce. On the other hand, the light-coloured moths, or typica, died off due to predation. Over generations, the environment continued to favor darker moths. Thus, they gradually became more common in comparison to light coloured moths. 98% of the moths in the vicinity of English cities like Manchester were largely black by the 1895.
Biston betularia f. typica, the white-bodied peppered moth.
Biston betularia f. carbonaria, the black-bodied peppered moth.
Since the 1950's, air pollution was drastically reduced and hence, the lichen grew back, making the colour of trees lighter. Additionally, the once blackened buildings were cleaned making them lighter in color. Presently, natural selection favors lighter moth varieties so they have become the most common.
With the dramatic variation in the peppered moth’s population, it has continued to be an issue of much interest and study and has led to coining of the phrase “industrial melanism” which refers to the genetic darkening of species in response to pollutants.
1) Source: S Gater & V Wood-Robinson, "G.C.S.E Science Double Award-Biology", 1996, p. 158-159
2) Source: http://anthro.palomar.edu/evolve/evolve_2.htm, 17th April 2007
3) Source: http://en.wikipedia.org/wiki/Peppered_moth, 19th April 2007
chan li ying [evolution expert]
Saturday, April 7, 2007
MAIN IDEAS of Darwin's theory
Darwin's Theory of Evolution
Darwin's Theory of Evolution briefly summarized are:
Darwin's Theory of Evolution briefly summarized are:
1. Variation: There is variation in every population
2. Competition: Organisms compete for limited resources
3. Offspring: Organisms produce more offspring that can survive
4. Genetics: Organisms pass genetic traits on to their offspring
5. Natural Selection: Those organisms with the most beneficial traits are more likely to survive and reproduce
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Darwin's Theory of Evolution is the widely held idea that all organisms is related and that they descended from a common ancestor. The theory makes the assumption that the development of life from non-life and stresses a purely naturalistic (undirected) "descent with modification". That is, complex creatures evolve from more simplistic ancestors naturally over time. To put it briefly, as random genetic mutations occur within an organism's genetic code, the valuable mutations are kept because they aid survival. This process is known as natural selection. These mutations are passed on to the next generation. Over time, the mutations accumulate and this results in a different organism which is not merely a variation of the original.
Darwin wrote, "…Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by short and sure, though slow steps."[1] As such, we can say that Darwin's Theory of Evolution is a slow gradual process.
[1] Charles Darwin, "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," 1859, p. 162.
1) Source: http://www.darwins-theory-of-evolution.com/, 31st march 2007
2) Source: http://www.spaceandmotion.com/Charles-Darwin-Theory-Evolution.htm, 19th April 2007
Darwin wrote, "…Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by short and sure, though slow steps."[1] As such, we can say that Darwin's Theory of Evolution is a slow gradual process.
[1] Charles Darwin, "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," 1859, p. 162.
1) Source: http://www.darwins-theory-of-evolution.com/, 31st march 2007
2) Source: http://www.spaceandmotion.com/Charles-Darwin-Theory-Evolution.htm, 19th April 2007
Darwin's theory: Natural selection [one of the main highlights of the theory]
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Ancient Greek philosophers such as Anaximander postulated the development of life from non-life and the evolutionary descent of man from animal. Charles Darwin brought something new to the old philosophy-a probable mechanism called "natural selection." Natural selection means the survival of organisms that are best suited to surviving and reproducing in their environment. The rationale of natural selection is to preserve and accumulate minor advantageous genetic mutations whereby favourable traits that are heritable become more common in successive generations of a population of reproducing organisms, and unfavourable traits that are heritable become less common.
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For example, if a member of a species developed a useful advantage (it grew fins and learned to swim). Its offspring would inherit that advantage the advantage would be passed down to future generations. The inferior (disadvantaged) members of the same species would gradually die out, leaving only the superior (advantaged) members of the species. Natural selection is the preservation of a useful advantage that allows a species to compete better in the wild. Basically, natural selection eliminates inferior species gradually over time. Over time, this process, which eliminates inferior species, can result in adaptations that specialize organisms for certain ecological niches and may ultimately result in the emergence of new type of species.
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Up till today, natural selection still remains as the single primary explanation for adaptive evolution.
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1) Source: http://www.darwins-theory-of-evolution.com/, 31st march 2007
2) Source: http://en.wikipedia.org/wiki/Natural_selection, 19th April 2007
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Charles Darwin- Source: http://www.rottweiler-dog.fsworld.co.uk/evolution_darwin.jpg, 17th April 2007
chan li ying [evolution expert]
definition of EVOLUTION
Evolution is the process that has led to the emergence and change of species which are alive on Earth. The earliest organisms were very basic cells, algae, or bacteria that appeared 3.8 billion years ago. Since then, life forms have diversified and adapted to their surroundings. Hence, all living species today share a common ancestor. Also, it can be the change in the genetic composition of a population during consecutive generations, resulting from natural selection acting on the genetic variation among individuals. The outcome will be that there will be the development of new species.
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Source: http://www.lexicon-biology.com/biology/definition_45.html, 8th April 2007
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chan li ying [evolution expert]
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