Driving Adaptation in the Immune System

Which processes in the human body depend on natural selection among cells?

Natural selection primarily operates at the level of individuals and populations rather than individual cells. However, there are some processes in the human body where natural selection among cells can play a role. Here are a few examples:

1. Immune system: The immune system relies on natural selection among immune cells to recognize and eliminate foreign invaders such as pathogens. Within the immune system, B cells and T cells undergo a process called somatic hypermutation, where their antibody receptors undergo random mutations. Cells with receptor mutations that improve their ability to recognize and bind to pathogens are positively selected, allowing the immune system to adapt and mount a more effective response against specific infections.

2. Cancer development: Cancer is caused by the uncontrolled growth and accumulation of abnormal cells. Within a tumor, natural selection can occur among different <a href="https://www.<a href="https://www.cancer.gov/about-cancer/understanding/what-is-cancer” target=”_blank”>cancer.gov/about-<a href="https://www.cancer.gov/about-cancer/understanding/what-is-cancer” target=”_blank” rel=”noopener”>cancer/understanding/what-is-<a href="https://www.cancer.gov/about-cancer/understanding/what-is-cancer” target=”_blank” rel=”noopener”>cancer” target=”_blank” rel=”noopener”><a href="https://www.cancer.gov/about-cancer/understanding/what-is-cancer” target=”_blank” rel=”noopener”>cancer cells, leading to the survival and proliferation of cells with certain advantageous genetic mutations. Cells with mutations that confer resistance to chemotherapy, for example, may survive treatment and give rise to a chemotherapy-resistant tumor.

3. Evolution of drug resistance: In the context of infectious diseases, some microbes, such as bacteria, can evolve resistance to drugs through natural selection among individual cells. When exposed to antibiotics, certain bacteria may have mutations that make them more resistant to the drug. These resistant cells survive and multiply, leading to the growth of a population that is less susceptible to the antibiotic treatment.

4. Tissue regeneration: In certain tissues that have the capacity to regenerate, such as the liver and skin, natural selection among cells can occur during the healing process. Stem cells and progenitor cells in these tissues can undergo proliferation and differentiation to replace damaged cells. The cells that can divide and differentiate most effectively are more likely to contribute to the restoration of tissue structure and function, thus being naturally selected for their regenerative capacity.

It’s important to note that while natural selection can influence the behavior and characteristics of cells within these processes, most evolutionary changes occur at the level of populations over long periods of time.

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