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What Was Lamarck's Theory Of Evolution?

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Kath Senior Profile
Kath Senior answered
Jean-Baptiste Lamarck lived from 1744 until 1829 and was a scientist from France. He lived before Charles Darwin (1809 – 1882) and was also interested in how organisms had developed into the form that they had. His ideas were the start of scientists thinking about evolution but he did manage to get it wrong in a rather major way.

He thought that animals and plants adapted to their changing surroundings in their lifetime and then passed on these changes to their offspring. The classic example that he cited was a giraffe – he said that a giraffe's neck got longer as it stretched for leaves higher up on trees. This made its neck and bit longer, so its offspring had necks a bit longer too.

This theory, often called Lamarckism, is a mistake often repeated by biology students when they first learn about evolution. The true mechanism of natural selection was explained by Darwin and others a few decades later.
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lizzii
lizzii commented
He believed that giraffes have long necks because they have to strech upwards to reach the leaves on the high trees. Lamarck said that the stretched neck of the giraffe would be passed on to it's children and that this explained the gradual lengthening of the neck of the giraffe over many years.
Anonymous Profile
Anonymous answered
That life evolved from simple organisms which then developed into more complex organisms.
Anonymous Profile
Anonymous answered
There may be a small grain of accidental truth in Lamarck's theory. Geneticists have recently discovered that regions of so called 'junk DNA' found in the tails of most chromosomes can act as a built-in 'flight recorder' or genetic 'black box'. They may register cellular trauma on the genotype in an organisms lifetime and the resultant damage could equate to an obvious phenotypic expression. Although this is purely speculation based on observations of several organisms, including humans. It is thought that cervical trauma during child birth could lead to a second child from the same mother inheriting a slightly altered genetic code that may be expressed as a wider cervix. If this theory is true then it will serve to add massive weight to Darwin's theory of evolution and dramatically cut down the time it would take for speciation to occur.
(This so-called 'junk DNA' or 'telomeres' are also thought to be involved in the premature ageing and subsequent death of Dolly the sheep).
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Anonymous
Anonymous commented
I think you are being a bit hard on Lamarck to say a 'grain of truth'. Lamark thought as most scientists do today, that species may be subject to change over time. His proposed mechanism was plausible given the state of science at the time and does get re-examined from time to time (for a recent example search epigenetics on the net).

The importance of Lamarck is that he was an indicator of the growing popularity of evolutionary thought - not how evolution may specifically occur.
Anonymous Profile
Anonymous answered
Jean-Baptiste Lamarck was a French scientist  born  1st August 1744 and died 18th December 1829. He developed an alternative theory at the beginning of the 19th century. His theory stated that a characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears. Lamarck used giraffes to explain his theory he said that a giraffes neck stretches to reach higher up food and gets longer because it is used a lot then the giraffes offspring inherit its neck length. This theory has been disproved by Darwin who gave a more reasonable theory
Anonymous Profile
Anonymous answered
Lamarck thought that evolution occurred and this is probably the most important thing to understand. The main reason he should be mentioned in Biology is to ensure Darwin doesn't appear out of thin air, but he existed in a context that started well before he was born.Lamarck proposed two mechanisms for evolution:that unused organs and abilities would disappear after a whilethat capabilities could emerge graduallyWhat is currently thought to be wrong about these proposals is that Lamarck thought of these mechanisms in terms of individuals, rather than at a species level. He further imagined that capabilities acquired or lost by an individual would be transmitted to any offspring.
Shubham Bansal Profile
Shubham Bansal answered
According to Lamarck's theory:
In every animal which has not passed the limit of its development, a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears.
All the acquisitions or losses wrought by nature on individuals, through the influence of the environment in which their race has long been placed, and hence through the influence of the predominant use or permanent disuse of any organ; all these are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young.
Anonymous Profile
Anonymous answered
Lamarck's theory can be described in one sentence: The function creates the organ. He believed that organisms tried to make themselves better in their lifetimes and these improvements were passed onto their offspring. This theory has been disproved by Darwin who gave a more reasonable theory.
Anonymous Profile
Anonymous answered
He believed that for example all giraffes had short necks and stretched them out themselves to reach for food or something....
But I'm not sure...yan lang ang alam ko....
I'd hope na-answer ko ang question mo!!!
God bless!!1
Katlego Mali Profile
Katlego Mali answered
He said snake had a legs, bt while legs again dissapeared bcoz snake like 2 go in 2 small places

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