One is to use it to waste it; One is to obtain trait inheritance. It is considered that both of them are the causes of variation and the process of adaptation. He proposed that "species can be changed, and the stability of species is only relative". The reason of biological evolution is the direct influence of environmental conditions on biological organism. It is believed that under the direct influence of the new environment, the habits of organisms have changed, and some "commonly used organs have developed and increased, while those that are not commonly used have gradually deteriorated". It is believed that a species can gradually become a new species by constantly strengthening and perfecting its adaptive traits, and these "acquired traits can be passed on to future generations", which makes the organism gradually evolve. People think that adaptation is the main process of biological evolution. He believes that this evolutionary process is repeated and continues to this day. In other words, to this day, intelligent orangutans are still trying to evolve into adults. Lamarck was also the first person who tried to explain the phenomenon of evolution, and he gave the first theory to explain the motivation and reason of evolution.
What is the main content of Darwin's theory?
Individuals of any species are different and have variations. These variations may be neutral, and may also affect the viability of individuals, leading to the strength of individual viability. In the competition for survival, individuals with strong viability have the opportunity to produce more offspring, the race can be multiplied, and their genetic traits gradually gain advantages in quantity, while individuals with weak viability are gradually eliminated, which is called' survival of the fittest'. As a result, biological species gradually changed because they adapted to the environment. "
What are the similarities and differences between them?
For the proposition of evolution, there are only two basic questions: "change and invariance" and "if change, how to change". On the former question, Lamarck and Darwin have the same answer, but there are differences on the latter question, that is, their explanations of the change mechanism are different.
As early as the16th century, after the Renaissance, people began to accumulate quite a lot of factual materials in comparative anatomy, embryology, morphology and taxonomy, paleontology fossils and geology, etc. By Darwin's time, the proposition of species variability was irrefutable in the face of a large number of factual materials. However, there are obvious differences in mutation mechanism and evolutionary dynamics. On this issue, the only thing they have in common is Darwin's neutral attitude towards the inheritance of acquired traits: he explicitly mentioned "the influence of habits and organ use and non-use" in Variation under Domestic Conditions.
Lamarck acknowledged the universality of variation, but denied the randomness of variation: "Lamarck believes that the primary reason for evolution is to seek more complex (perfect) talents. When all kinds of animals are produced one after another, they naturally start from the most imperfect or simplest and end in the most perfect, which makes the structure of animals gradually complicated. This more complicated tendency comes from' God-given power'. "It can be seen that Lamarck believes that variation is directional and occurs out of some need.
Darwin wrote in "Variation under Domestic Conditions": "Similar variation occurs under different conditions, while dissimilar variation occurs under the same conditions ... Under changing conditions, non-directional variation is more common than directional variation". He also wrote in "Variation under Natural Conditions": "Individual differences refer to many small differences among the descendants of the same parent ... Individual differences are very important, and they are usually heritable ... The most experienced naturalist will be surprised by so many examples of variation ..." It can be seen that Darwin not only realized the universality of variation, but also had a deep understanding of the randomness (directionality) of variation.
In the famous giraffe example, Lamarck explained the origin of giraffe's long neck in this way: giraffe's ancestors often craned their necks to eat leaves high in trees, and their necks were exercised and lengthened (used and discarded), which can be inherited and strengthened, so their offspring will be longer than their parents' necks (acquired trait inheritance), and giraffe's necks will get longer and longer from generation to generation. But in Darwin's view, the origin of long neck is not the result of waste, but the variation of long neck and short neck in giraffe ancestors (excessive reproduction, the source of variation). When the environment changes or food is scarce, the long neck has the survival advantage because it can eat leaves from higher places, and the short neck is gradually eliminated because of food shortage (struggle for existence). Due to the selection from generation to generation, the characteristics of long neck spread in the group.
The emergence and main points of Lamarckian evolution theory and Darwin evolution theory, and compare their similarities and differences. Both of them believe that biology is changeable and support evolution theory; They have different views on the mechanism of evolution. Lamarck advocates "using, discarding and obtaining trait inheritance" and emphasizes the "induction" of environmental change on biological variation, but thinks that variation is mainly caused by biological nature (a demand for perfection). Although Darwin also agreed that biological nature is more important than environment, Darwin believed that variation and environment are independent of each other. Variation occurred before the environment took effect, and the environment only played a role in the selection of variation. When organisms (as far as species are concerned) pass through struggle for existence, the characteristics of adapting to the environment are preserved, while the characteristics of adapting to the environment are eliminated (survival of the fittest). Due to the limitation of knowledge, Darwin failed to explain the mechanism of variation through genetics, nor did he clearly show his attitude towards "acquired trait inheritance", but on the whole, the theoretical system of natural selection is more complete, scientific and convincing than Lamarckianism.
What are the main schools of thought about biological evolution?
There are many schools of modern biological evolution, such as comprehensive evolution (modern Darwinism), neo-Darwinism, neo-Lamarconism, neutrality, catastrophe theory and so on.