Chemical barriers at these surfaces include specialized soluble substances that possess antimicrobial activity as well as acid pH.

TLS Online TPP Program

#Id: 4316

#Unit 11. Evolution and Behavior

Theories to explain origin of life

Special Creation

Panspermia/ Cosmozoic theory/ Interplanetary theory

Spontaneous Generation

TLS Online TPP Program

#Id: 4317

#Unit 11. Evolution and Behavior

The Theory of Spontaneous Generation

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation, the notion that life can arise from nonliving matter.

TLS Online TPP Program

#Id: 4318

#Unit 11. Evolution and Behavior

Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”).

TLS Online TPP Program

#Id: 4319

#Unit 11. Evolution and Behavior

As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water.

TLS Online TPP Program

#Id: 4320

#Unit 11. Evolution and Behavior

When the roof leaked and the grain molded, mice appeared. Jan Baptista van Helmont, a seventeenth century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. 

TLS Online TPP Program

#Id: 4321

#Unit 11. Evolution and Behavior

Italian physician Francesco Redi (1626–1697),

His hypothesis was supported when maggots developed in the uncovered jars, but no

maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that

maggots could only form when flies were allowed to lay eggs in the meat, and that the

maggots were the offspring of flies, not the product of spontaneous generation.