Origins of Life

 How old is the universe? about 15 billion years since Big Bang  How old is the Earth? about 4.5 billion years  How long has there been life on Earth? about billion years  How old is the human species (Homo sapiens)? 100,000 to 200,000 years old  What do you think conditions were like on early Earth? Weather? Atmosphere? Appearance?

If earth's history were compressed into one calendar year, earth forms, cools and develops an atmosphere during January. Late January into February sees global volcanic activity as oceans fill the great basins. Life begins somewhere in March. All of human history occurs in the last 7 minutes of December 31, and Columbus "discovers" America only 3 seconds before the clock strikes midnight (midnight = today).

How did life originate?  Spontaneous Generation Idea that nonliving material can produce life

Recipe for bees: Kill a young bull, and bury it in an upright position so that its horns protrude from the ground. After a month, a swarm of bees will fly out of the corpse. Jan Baptista van Helmont’s recipe for mice: Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat or some wheat bran, and in 21 days, mice will appear. There will be adult males and females present, and they will be capable of mating and reproducing more mice. Recipe for bees: Kill a young bull, and bury it in an upright position so that its horns protrude from the ground. After a month, a swarm of bees will fly out of the corpse. Jan Baptista van Helmont’s recipe for mice: Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat or some wheat bran, and in 21 days, mice will appear. There will be adult males and females present, and they will be capable of mating and reproducing more mice.

Spontaneous Generation  Francesco Redi was the first to disprove this idea.

Spontaneous Generation  Louis Pasteur went on to disprove it as well.  Air can still get in but microorganisms cannot

So where did life come from???  Before life can begin, what molecules would we need to make??? CO2 O2 Nucleic Acids Proteins Glucose ATP

Meteorites  Living organisms may have arrived from an extraterrestrial source

Primordial Soup  Earth’s atmosphere was probably made up of gases that contained organic elements. CO 2, CH 4, NH 3 …

Primordial SoupPrimordial Soup  The mix of atmospheric molecules and water  Rain washed atmospheric molecules into the ocean making “the soup”  A particular mix of inorganic chemicals could have reacted together to produce small organic molecules.  Glucose  Amino Acids  Nucleic Acids

Can we prove it?  Harold Urey and Stanley Miller provided evidence to support this.