Jean lamarck’s theory of evolution


   Jean lamarck's theory of evolution
Jean-Baptiste Lamarck on the other hand was a French scientist who evolved an alternative theory of evolution at the start of the 19th century. His theory included two ideas:

  1. A trait which is made use of more frequently by an organism grows bigger and stronger, and one that is not being utilized gradually and at the end becomes extinct.
  2. Any feature of an organism that is enhanced through use is transferred to the s offspring of the organism.

Nevertheless, we now know that in majority of cases this type of inheritance cannot occur.

Lamarck’s theory cannot take care of every observation made consigning life on Earth.

For example, his theory implies that every organism would slowly and surely turns composite and simple organisms become extinct.On the contrary, Darwin’s theory can account for the continued presence of simple organisms.

Darwin was not the first naturalist to suggest that species altered over time into fresh species—that life, as we would say currently, evolves.

In the eighteenth century, Buffon and other naturalists started to initiate the idea that life may not have been constant or permanent since creation.

By the end of the 1700s, paleontologists had puffed up the fossil collections of Europe, offering a picture of the ancient times at odds with an unchanging natural world.

And in 1801, a French naturalist named Jean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck took a great theoretical step and proposed a full-blown theory of evolution.

Lamarck started his scientific career as a botanist, but in 1793 he became one of the founding professors of the Musee National d’Histoire Naturelle as an expert on invertebrates.

His work on classification of worms, spiders, molluscs, and other boneless creatures was far above the findings of his time.

Change through use and disuse

Lamarck was hit by the similarities of a lot of the animals he examined and was highly impressed by the escalating fossil record.

It led him to dispute that life was not rigid or stable. When environments are altered, organisms had to alter their behavior to remain alive.

If they start to make use of an organ more than they did in the past, it would gradually increase in size during its lifetime.

If a giraffe stretched its neck for leaves, for instance, a “nervous fluid” would flow into its neck and cause it to grow longer.

Its offspring would inherit the longer neck, and extra and improved stretching would make it longer still over a lot of generations.

In the meantime organs that organisms stopped making use of would shrink.

Organisms moved to higher complexity

This type of evolution, for which Lamarck is majorly well known today, was only one of two mechanisms he projected. As organisms adapted to their surroundings, nature as well drove them inescapably upward from simple forms to progressively more composite ones.

Like Buffon, Lamarck is of the thought that life had started via spontaneous generation. But he maintained that fresh prehistoric living things sprang up throughout the history of life; today’s microbes were merely “the fresh kids on the block.”

Lamarck as well postulated that organisms were driven from simple to increasingly more complex forms.

The characteristic example used to illustrate the concept of use and disuse is the extended neck of the giraffe. According to Lamarck’s theory, a given giraffe could, over a lifetime of twisting to reach high branches, grow an elongated neck.

A key fault of his theory was that he could not illustrate the way this could occur even though he discussed a “natural tendency toward perfection.”

Another example Lamarck made use of was the toes of water birds.

He postulated that from years of straining their toes to swim through water, these birds grew elongated, webbed toes to enhance their swimming.

These two examples illustrate the way use could change a characteristic or a feature.

In the same way, Lamarck believed that disuse would result in a character or feature becoming reduced.

The wings of penguins, for instance, would be smaller than those of other birds for the fact that penguins do not use them to fly.

The second part of Lamarck’s mechanism for evolution is the inheritance of acquired traits.

He believed that traits altered or acquired over an individual’s lifetime could be transferred down to its offspring.

Giraffes that had acquired long necks would have offspring with long necks instead of the short necks their parents were born with.

This type of inheritance, every now and then known as Lamarckian inheritance, has since been disproved through the discovery of hereditary genetics.

An extension of Lamarck’s ideas of inheritance that has stood the test of time, though, is the idea that evolutionary change occurs slowly and steadily.

He studied antique seashells and observed that the older they were, the simpler they looked. From that, he concluded that species began simple and constantly moved toward complexity, or, as he phrased it, closer to perfection.

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