Origin of Life Theories

• There are multiple theories about the origin of life on Earth, including creationism, spontaneous generation, panspermia, and Oparin's theory.

Creationism

• It attributes the origin of life to an unknown force or the will of divine beings.
• This belief originated from primitive humans and was reinforced by early cultures like the Egyptian and Mesopotamian civilizations.
• Several branches exist, including classical creationism, fixism, and intelligent design

Classical Creationism

• Denies biological evolution and scientific evidence of the origin of life.
• Based on a literal interpretation of sacred texts.

Fixism

• Describes nature as a definite, unchangeable reality.
• According to fixism living beings have remained unchanged since creation.
• Formally developed in the 17th century by Carl Linnaeus, who stated that species were created separately and independently, denying a common origin.

Intelligent Design

• Argues that the origin of the universe and living beings is the result of deliberate, rational actions by one or more intelligent agents.

Spontaneous Generation

• It claims that some living beings can originate from inert materials like mud, sweat, or rotting meat.
• Aristotle supported this theory (384-322 BC)
• In the 17th century, Jean Baptiste van Helmont claimed mice could be created by wrapping wheat grains in a dirty, sweaty shirt and waiting 21 days.
• Francesco Redi (1626-1698) later disproved spontaneous generation showing it was wrong.
• In 1860, Louis Pasteur explained that microbes and spores caused the decomposition of organic matter, proving that all living beings come from other living beings.

Panspermia

• It suggests that the elements for the origin of life were distributed throughout the universe.
• They arrived on Earth via meteorites after being ejected from other planets due to volcanic eruptions or asteroid impacts.
• Anaxágoras (500 BC-428 BC) first proposed it in the 6th century BC.
• German biologist Hermann Richter defended the term panspermia, from Greek pan meaning all, and sperma meaning seed, in 1865
• Svante Arrhenius, Nobel Prize winner in Chemistry, popularized it in 1903.
• Nobel laureate Francis Crick and British astronomer Fred Hoyle supported Panspermia.
• Directed panspermia suggests intelligent beings controlled the process, seeding life where they chose.
• Molecular panspermia states that complex organic molecules are the material basis for the genesis of life.

Oparin's Theory

• Alexander Oparin proposed in 1924 the abiotic synthesis theory.
• The primitive environment of the seas, rich in electrical discharges, volcanic eruptions, and substances like oxygen, gas, methane, and hydrogen, combined to form organic compounds called coacervates.
• Coacervates are systems of diverse macromolecules that formed in aqueous conditions and evolved into cells and characteristics of living organisms.
• In the mid-20th century, Stanley Miller created a primitive soup simulating Oparin's proposed conditions and subjected it to electrical discharges.
• Miller found amino acids which are precursors to proteins forming the building blocks of organisms.

Theory of Evolution

• Charles Darwin explained his hypothesis of how today's animal and plant species are derived from similar passed species, in his book "The Origin of Species" (1859).
• Understanding of evolution requires considering geological events, climate changes, radiation of organisms to new habitats, changes in ecosystems, continental positions, and mass extinctions.
• Natural Selection: Continuous, gradual adaptation needed for survival.
• Phylogenetic tree: Shows evolution relationships among species that are believed to have a common ancestor.
• Human Evolution: Humans are descended from human-like apes.

Key milestones in the historyof life

• 4,600 million years ago: Earth forms and is bombarded by meteorites and comets.
• 3,800 million years ago: Replicating molecules, precursors of DNA, are created
• 3,500 million years ago: The unicellular life begin and phtosynthetic bacteria begin releasing Oxygen to the atmosphere
• 555 million years ago: Multicellular marine organisms where common, with strange looking animals
• 500 million years ago: vertebrated appeared like fish with invertebrates
• 450 million years ago: Arthropods colonize the terrestrial environment evolving into scorpions, spiders, mites and centipedes.
• 420 million years ago: Land plants evolve, dramatically changing Earth landscape and creating new habitats
• 360 million years ago: Tetrapodes vertebrates colonize The Earth where seeded plant and big wood appear with huge coral reef.
• 250 million years ago: Pangea supercontinent formed. Conifer-like tree forests, reptiles, and synapsids are the ancestors to mammals.
• 248 million years ago: most of the marine life and 70% on terrestrial life dissapear on the most important extinction on Earth with ammonites getting over the extinction
• 225 million years ago: Evolution of dinosaurs and mammals. Pangea strats breaking apart.
• 130 million years ago: Flowering plants appears while dinosaurs dominate the landscape
• 65 million years ago: Yucatán Peninsula asteroid impacted and the ammonites and non-avian dinosaurs went extinct with birds and mammals between survivors.
• 4 million years ago: In Africa, one of the first hominids, Lucy, lived where ice age began.
• 130 thousand years ago: Anatomical modern humans evolve.
• 70 thousand years ago: Descendants create paintings.

Mayan Quiché "Theory of Creation"

• The Popol Vuh explains the origins of the universe from a cultural perspective.
• Figure of the twin heroes, Hunaphú e Ixbalanqué,
• Three part classification of the content of Mayan creation
• Silcence is when The Earth has been bombarded by meteorites and comets.
• No man animal etc.
• The first men, how did they apear on the Land and relation with the gods.
• Hunahpú e Ixnalanqué is one of the source of Mayan culture that explains the origins of universe
• 4 human bodies are made on earth.