Jean Baptiste de Lamarck was born in 1744 in Bazetin le Petit.Very young he entered the army, which by their valor in combatquickly rose to officer. In 1768 due to a wound in the neck had to leave the profession of arms, as he was only a small pension to live, and given its position as a gentleman decided to study medicine, a profession he never came to practice. In those years was closely linked to botanical medicine, and was a very popular hobby among the nobility who grew in their properties many species of flowers and plants brought from abroad, this meant that Lamarck was devoted to botany, but a scientific spirit. Soon to write a great bookentitled "Flora of France" that issued the naturalist Georges LouisBuffon, which began implementing dichotomous keys in classifyingspecies. Thanks to the prestige gained through her book and her friendship with Buffon was elected member of the French Academy of Sciences, earning a spot in the Museum of Natural History. In 1793, motivated by a reorganization of the museum, he became professorof the area of insects and worms, which he then renombraríadepartment of zoology as invertebrados.Lamarck was the first touse the term to refer to biological life sciences and he who coined the word invertebrates. On this new field has written an importantbook in seven volumes "Natural history of invertebrate animals"(1815-1822) very advanced for its time.
Lamarck was interested in unicellular organisms and invertebrates.His observations led him to think that species are becomingincreasingly complex as they evolve. According to their hypothesis, the evolution is the result of two forces combined: acquired characteristics, which in its opinion may be transmitted from father to son, and the existence of a universal creative principle which makes the species reach increasing complexity in its evolution.Regarding the first of these forces, Lamarck held that an individualorgans are strengthened or weakened, as do regular use of them ornot, but also believed that these characteristics of a particular individual can be transmitted to your offspring. Along with that engine of evolution was a universal creative principle, which was, according to Lamarck, the species had to meet increasingcomplexity.
Lamarck had noticed a clear relationship between fossil andmodern organisms. From these observations concluded that themost recent fossils were related to modern organisms. He outlineda theory of biological evolution can be summarized as follows: individuals change physically during his life to adapt to the environment they live; +organisms acquired characters had no parents. These changes oracquired characteristics +are due to the use or disuse of organs; +acquired characteristics are transmitted by heredity to their offspring +the sequence of adaptive changes shows a tendency towardcomplexity and perfection.
Lamarck's theory was strongly criticized by the scientific communityof his time, mainly by Cuvier, who, besides being an eminent scientist, he served as Inspector General of Education in France.This and his contemporaries insisted that the species had beenindependently created and were immutable. To prove it, made several experiments. One of them was to amputate the tail of mice,even after 20 generations have been subjected to such change,produced offspring with tail. In other words, showed that the characters acquired by interaction with the environment (such as loss of tail) is not transmitted by heredity. In this, the vision ofLamarck, based on the process of inheritance of acquired characteristics was not appropriate, but the general intuition thatspecies evolve was correct.
How Lamarck explain why giraffes have the neck and legs so long? A population of antelope neck and legs of normal length, beset by lack of forage because of drought, tried to change your diet byacacia leaves, which abounded in the treetops. The efforts of theseanimals made their way to lengthen their necks and legs to reachthe green leaves of the acacias. As time went on accessible leaveswere dried up and only those who were on higher ground. The necks and legs could grow a few centimeters in these animals by the principle of developing adaptations. As their descendants in the next generation and were born with the neck and legs a little longer,according to the principle of inheritance of acquired characteristicscould be better adapted and continue efforts to stretch their limbs.As time passed and succeeded generations, these animals werebecoming more like today's giraffes.
1. The primitive primitive antelope giraffes came from, who lived in the bush and fed on the lower leaves of the acacias.
2.The times of drought, decreased food and giraffes need to stretch the neck and legs to reach leaves on the top of the acacias. Due to the use, these bodies were lengthening.
3.The acquired characters, neck and legs getting longer, weretransmitted to offspring from generation to generation.