Summary of the lecture on 07-31-96

Some theories for the origin of life are:

• creation by supernatural being
• spontaneous generation (just put an old sock in a plastic bag, wait a week, and ... there you go)
• panspermia (life didn't originate on Earth but was brought in by interstellar dust)

Some common properties of life (as we know it) are

• ability to copy information about itself (reproduction)
• the "drive" to do so
• copying is not exact

Four basic incredients necessary for life on Earth are

1. carbohydrates (energy storage)
2. lipids (cell walls)
3. amino acids (ploymers, proteins)
4. nucleic acids (DNA/RNA; ability to copy itself)

Some important questions that haven't been completely answerde, yet:

• Where did the cell walls come from? (primordial oil slick?)
• Why are all amino acids left-handed?
• Where did life first occur? (tide pools -> high concentration of necessary incredients, constant energy input, "clay world" -> clay as template and catalyst, under water -> shielded from UV, "Smokers" = small vulcanoes on bottom of the ocean, energy from hydrogen sulfide

Since the 1950's, experiments have been conducted that show that it is easy to make the basic incredients for life in the conditions of the early earth (first attempt by Miller & Uri). From craters on the Moon and Mercury, we know that heavy bombardment of the inner solar system stopped ~3.8 Gyr ago. The oldest evidence for life is about 3.6 Gyr old, so life emerged very fast as soon as the conditions allowed it. It may not have been an accident but inevitable.

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