Scientific Method, Cosmic Origins, and Evolutionary Biology

The Scientific Method

The scientific method involves a systematic approach to discovery:

• Ask a question and find information.
• Observe, describe, measure, and classify.
• Identify variables of a phenomenon.
• Formulate hypotheses.
• Design experiments to test the hypothesis.
• Select proper instruments, tools, and techniques.
• Analyze results and propose conclusions.
• Invent laws and theories.
• Verify the operation of those laws or models.
• Communicate results.

Cosmological Theories

1. Slipher: Analyzed the light spectrum from distant galaxies, finding that light waves showed a peculiar elongation (redshift).
2. Gamow: Proposed the "law of recession of the galaxies," stating that galaxies are expanding and cooling over time.
3. Penzias and Wilson: Discovered cosmic microwave background radiation.

Origins of Life

Panspermia: The theory that life on Earth was seeded by spores from meteorites arriving from space; however, this is not considered reliable.

Chemical Evolution: Suggests that the first life forms arose as a culmination of an evolutionary process. Oparin concluded that the early atmosphere must have been reducing, as an oxidant atmosphere would degrade life. He described the oceans as a "primordial soup" rich in organic compounds.

Evidence for Evolution

• 1. Paleontological: Living species share characteristics with fossils. Intermediate forms, such as Archaeopteryx (half-bird, half-reptile), provide evidence.
• 2. Comparative Anatomy: Similar structures in different species indicate a common origin followed by adaptive divergence.
• 3. Embryological: Vertebrate embryos show striking similarities, suggesting a common origin.
• 4. Comparative Biochemistry: All living things are composed of the same molecules (e.g., lipids, sugars), indicating kinship.
• 5. Biogeographical: Shows that populations evolve due to geographical barriers, leading to gradual changes and speciation.

Homologous and vestigial organs: Homologous organs have the same structure but different functions. Vestigial organs are stunted structures that have lost their original function. Both demonstrate the common origin of many species.

Hominization

Hominization is the evolutionary process that resulted in the appearance of the genus Homo:

• Development of bipedalism.
• Elongation of legs, widening and shortening of the pelvis, and changes to the femur.
• Hands become more mobile with higher precision and thumb opposition.
• Dietary changes leading to a reduction in tooth size.