Here's why:

* Increased genetic diversity: Combining genetic material from two parents (through the fusion of gametes) creates offspring with unique combinations of genes. This variation makes it more likely that some offspring will be better suited to survive and reproduce in a changing environment.

* Adaptive advantage: In a changing environment, a diverse population is more likely to have individuals with traits that help them cope with challenges like disease, predation, or climate change. Those with advantageous traits are more likely to survive and pass those traits on, allowing the population to adapt as a whole.

Here's a simplified analogy:

Imagine a population of bacteria living in a petri dish. All the bacteria are identical. Then, a new antibiotic is introduced. The antibiotic kills off all the bacteria except for a few that have a gene for antibiotic resistance. These resistant bacteria reproduce, and their offspring inherit the resistance gene. The population now has a higher chance of surviving future antibiotic challenges.

While this example is simplified, it illustrates the point that sexual reproduction provides a mechanism for generating genetic diversity, which allows organisms to adapt to changing environments.

Note: While the origins of sexual reproduction are complex and not fully understood, the benefits of increased genetic diversity and adaptability are widely accepted as key drivers for its evolution.