Life Comes From LifeExperiments to disprove Spontaneous Generation

Where Does Life Come FromObservation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times.

Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs.

Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.

Conclusion: It was obvious to them that the mice came from the moldy grain.

Recipe for Bees

1. Kill a bull during 1st thaw of winter

2. Build a shed

3. Place dead bull on branches and herbs inside shed

4. Wait for summer. The decaying body of the bull will produce bees.

Where Does Life Come From

Spontaneous generation: mistaken idea that living things could arise from nonliving sources

Redi and Pasteur Beat the Odds

It took hundreds of years to convince people that spontaneous generation does not occur.

Louis Pasteur

Francesco Redi

Meat & Maggots…Yummmmm!•mid-1600s•Redi designed controlled experiment to prove that flies do not spontaneously arise from decaying meat

Controlled experiment: two tests are carried out, they are identical in every way except for ONE factorVariable: one factor changed in controlled experiment

Louis, Louis

Even after Redi’s work, people still had a difficult time with spontaneous generation.

• Louis Pasteur’s experiments finally disproved SG!!

Pasteurization anyone??