Understanding Disease and Evolutionary Biology

Posted on May 16, 2025 in Biology

Disease Concepts and Control

Re-emerging and Emerging Diseases

Re-emerging diseases: Caused by germs in an unknown state that may have been hidden for a long time and then appear suddenly, like Ebola or tuberculosis.

Emerging diseases: Mutations may occur. Includes past illnesses that remain with us, such as cholera, tuberculosis, dengue, malaria.

Infectious Agents

Infectious agents: Pathogenic microorganisms that cause diseases. They are those that invade our body, called the host, and reproduce within them. They are responsible for the symptoms. Include viruses, bacteria, protozoa, and fungi.

Sources of Infection

  • Direct: Through direct contact between people.
  • Indirect: Via food, water.

The Immune Response

Immune response: The body already has natural barriers. If pathogens pass these, the immune system involves organs and cells that spread throughout the body. White blood cells make a response to protect the body, called the immune response, which kills germs (for example, cold germs).

Types of Immunity

  • Natural immunity: Such as chickenpox, which only happens once in a lifetime.
  • Artificial immunity: Introducing pathogens without potential for harm to cause an immune response; this is called vaccination.

Antibiotics and Antivirals

Antibiotics: Chemical substances that kill bacteria and prevent multiplication. Their discovery was revolutionary in the fight against diseases. Penicillin was the first.

Antivirals: Unlike antibiotics that act on bacteria, antivirals act on groups such as viruses.

Drug Resistance

Drug resistance: Factors contributing to the resistance of bacteria to antibiotics: mutated gene or gene exchange.

Drug Development Stages

Stages of drug development:

  • Pre-clinical stage: Research and a series of tests with new molecules. Here, it is checked if it works and is not toxic through animal testing.
  • Clinical stage: Done with volunteers, the longest stage, with 3 phases:
    • Phase 1: Tests on healthy volunteers to check for negative effects.
    • Phase 2: With a small group of patients to check effectiveness.
    • Phase 3: With a larger group of patients; results are compared with other drugs.

Theories and Mechanisms of Evolution

Fixism

Fixism: Characterized by an “anthropological vision of the world.” Idea of an Earth that was just 6,000 years old, based on Genesis. Relied on “some false evidence of common sense.” Championed by G. Cuvier.

Lamarckism

Lamarckism: Idea of complexity and progress, transformation (Lamarck). Characteristics:

  • Organisms necessarily change.
  • Changes are caused by environmental needs.
  • “The habits of the organisms cause changes.”
  • “The acquired changes will be inherited.”

Darwinism

Darwinism: Ideas:

  • More individuals are born than can survive.
  • Among individuals, mutations occur that cause changes.
  • There is a natural selection of the fittest.
  • The population gradually changes.

Synthetic Theory of Evolution

Synthetic Theory of Evolution: Contributions:

  • The evolutionary unit is not the individual but the population.
  • Origin of this variability is in mutations, which are changes in DNA that cause the body to acquire different characteristics. They can produce advantage, disadvantage (most times), or be neutral.

Evo-Devo

Evo-Devo: Hierarchy of genes; some are more important. If changes occur in an important gene, the change will be more meaningful. Helps explain evolutionary leaps by involving variability (Darwinian).

How Species Change

How Species Change:

  • Two populations of the same species become separated.
  • Both undergo independent evolution.
  • The accumulation of differences eventually leads to a new species.

Human Evolution: Homo Species

  • Homo habilis: First Homo. 2.5 to 1.5 Ma. Africa.
  • Homo ergaster: 1.8 to 1.2 Ma. 800 to 1000 cm³ brain.
  • Homo erectus: 1.7 Ma to 50,000 years ago. 800 to 1100 cm³ brain. Browser.
  • Homo antecessor: 1.2 Ma to 300,000 years ago. 1000 to 1100 cm³ brain. Europe. Evolved into Homo neanderthalensis.
  • Homo neanderthalensis: From 300,000 years ago. 1500 cm³ brain. No chin and no forehead. Physically strong but short. Knew fire, cared for the elderly, and buried the dead.