Evolution Theories Quiz

Evolution Theories

• Evolution is the change in heritable characteristics of biological populations over successive generations.
• The image shows a visual representation of different stages in human evolution, depicting changes in physical characteristics and skeletal structures over time.
• This illustrates the concept of evolution, emphasizing morphological changes across generations.

Lamarck's Theory

• Jean-Baptiste de Lamarck proposed the first significant evolutionary theory.
• His theory asserted that organisms evolve in response to their environment, adapting and changing themselves over time to suit their surroundings.
• Lamarck proposed that acquired characteristics — traits gained during an organism’s lifetime—could be passed down to offspring.

Theory of Need

• This theory emphasizes that organisms adapt to their environments by responding to their fundamental needs.
• For example, a giraffe's neck lengthening is explained by the giraffe's constant stretching to reach higher leaves over generations.

Theory of Use and Disuse

• This theory states that organs actively used by organisms will strengthen and grow over time, while organs not used will weaken and disappear.
• An example of this theory, also focusing on the giraffe's neck, suggests that constant stretching strengthened the neck.

Theory of Acquired Characteristics

• This aspect of Lamarck’s theory postulates that changes acquired during an organism's life, are heritable and passed on to future generations.
• The text elaborates on how this theory suggests that attributes gained throughout the life of an organism are directly transmitted to their offspring.

Critique of Lamarck's Theories

• Modern biologists largely reject the idea that acquired characteristics are inheritable, a significant critique of Lamarck's theories.
• The concept is now understood that genetic modifications are necessary for heritable changes, and acquired characteristics are not directly passed on.

Darwin's Theory of Natural Selection

• Charles Darwin proposed a comprehensive theory of evolution based on natural selection.
• The theory posits that organisms with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring.
• Darwin's theory, also known as the theory of natural selection, explains how species change over time, based on the concept of "survival of the fittest."

Darwin's Observations in the Galapagos Islands

• Darwin observed finches with different beak shapes adapted to different food sources on various Galapagos Islands.
• These diverse beak structures are clear evidence of adaptation through natural selection.
• This highlights how variations in traits arise within species due to environmental pressures.