Hypothesis of early Earth. About 4.4 billion years ago, Earth might have cooled enough for the water in its atmosphere to condense. This might have led to millions of years of rainstorms with lightning, enough rain to fill depressions that became Earth’s oceans.
Today, penicillin no longer affects as many species of bacteria because some species have evolved physiological adaptations to prevent being killed by penicillin.
When the population is exposed to an antibiotic, only the resistant bacteria survive.
The resistant bacteria live and produce more resistant bacteria.
If bacteria can develop drug resistance in just a few generations, imagine the changes to some bacteria over millions of years.
Homologous structures can be similar in arrangement, in function, or in both.Comparing anatomy
Pig fetus – 21 days
Human fetus – 31 days