Infectious Disease: Evolving Challenges to Human Health

Rapid Evolution Interactive -- Text-only Version


This interactive contains an animated time-based chart on the left, and an animation of a population of bacteria on the right.  The lines on the chart show the increases and decreases in the bacteria population over time, which is also shown graphically in the animation.

The text below the animation reads:

Evolution is a continuous process.

New genetic traits appear randomly and the environment selects for individuals with traits that help them survive and grow.

The process can be seen as a population grows from an individual organism.

A random mutation occurs as one bacterium divides into daughter cells.

The animation shows one yellow bacterium in the middle of many blue ones.

The mutant bacteria divide into daughter cells, each of which has this mutation.

Another random mutation occurs as a mutant bacterium divides into daughter cells.

The animation shows red  bacteria appearing among the blue and yellow ones.

A chemical, such as an antibiotic, is introduced to the entire population.

A ripple moves through the field of bacteria.

The chemical prevents blue bacteria from building new cell walls when they divide, and they die. Only red and yellow bacteria remain.

All of the mutant bacteria are resistant to the chemical, so they continue to grow.

Another mutation occurs.

A green bacterium appears amid the red ones.

A new chemical, such as a different antibiotic, is introduced to the entire population.

Another ripple moves through the animation.

Only the red bacteria are resistant to this chemical. All of the others die as they divide.

Only red bacteria remain.

As the bacteria grow, new mutations will occur and the population will continue to evolve.