Evolutionary Biology and Cosmic Origins: Key Concepts

Darwinism and Natural Selection

Darwinism describes the struggle for survival caused by limited resources, resulting in a process of natural selection. The fittest individuals—those with the best characteristics to adapt to their environment—survive, while the least adapted perish. These survivors transmit their advantageous traits to their offspring.

Origin of the Cosmos: The Big Bang

The Big Bang was an initial expansion of the universe from all points of a field. This event did not occur in one specific location; rather, it was an amorphous state subjected to extreme temperatures that expanded simultaneously in all directions. As the universe expanded, space filled with light and matter, causing celestial bodies to separate.

Future Scenarios of the Universe

• Big Rip: The temperature of the universe drops permanently until stars extinguish and expansion becomes absolute.
• Big Crunch: Gravitational forces between matter eventually curb expansion, causing the universe to shrink and potentially trigger another Big Bang indefinitely.
• Static Universe: A theory suggesting the universe remains unchanging once it ceases to expand.

Origin of Life

Following the Big Bang, gas and dust condensed to form galaxies. Earth's primitive atmosphere, composed of methane, ammonia, and water vapor, reacted with ultraviolet radiation, lightning, and volcanic heat to create complex molecules. These molecules eventually accumulated in the oceans, where they associated to form more complex compounds capable of reproduction.

Anatomic and Physiological Changes in Humans

Anatomic Evolution

• Bipedalism: Climate change forced hominids to adapt to new habitats, moving on two hind legs. This allowed for an upright posture and better predator detection.
• Encephalization: Brain volume increased, leading to more complex neurological connections.
• Hand Morphology: The palm shortened while fingers and the thumb lengthened, increasing dexterity.

Physiological Adaptations

• Release of Hands: Hands were no longer required for locomotion, allowing for tool use and manipulation.
• Biological Plasticity: Human survival relies less on physical body traits and more on the culture and knowledge acquired over time.
• Reproductive Particularities: Unlike many species, humans have no specific mating season, allowing for reproductive capacity throughout the year.