Understanding Evolutionary Theories and Current Debates

Evolutionary Theories: The new science emerges, taxonomy, which was visible and obvious similarities between living organisms in different parts of the world. Lamarck: Theory of the Inheritance of Acquired Characteristics states that organisms react against environmental change by developing, creating, or enhancing a particular organ, while abandoning the use of an organ leads to its atrophy or disappearance. Key Aspects of Evolutionary Theory by Darwin and Wallace:

• Changes by Chance: In a population, there are different characters or varieties among individuals.
• Selection: This mechanism chooses the characters that confer an adaptive advantage, allowing reproduction and transmission to the next generation.
• Gradualism: Individuals carrying adaptive traits will become the majority in the population.

Consequences Impacting Darwin's Theory: The source of variation is random; natural selection acts as a filter on the characters that are adaptive in a particular environment. This places humans in nature as a species, subject to the same principles as other living beings.
Current Debates About Evolution: These are some of the points we are currently discussing:

• The Direction of Evolution: Is evolution a non-directional phenomenon or a random one?
• The Causes of Evolution: Is evolutionary change due to environmental influences on organisms or domestic factors driving this change?
• The Pace of Change: Is change slow and steady or fast and discontinuous?
• The Role of Natural Selection: Is natural selection the main and almost the only agent of evolution, or does it act together with other causes such as genetic drift or migration?
• The Adaptive Value: Do all characters of an organism serve to improve fitness, or are there characters with no adaptive value?

Principles of the Synthetic Theory of Evolution: There are two sources of variation in organisms: mutations and the almost unlimited combinations of genes resulting from sexual reproduction. Natural selection acts on these gene combinations, so those best adapted to a particular environment will advance to the next generation, while others are eliminated. Natural selection acts on populations, not individuals. The accumulation of small variations in gene frequency changes from almost imperceptible to significant over time, leading to the emergence of new species. This transformation process is called anagenesis.