When bacteria is grown in a liquid nutrient medium, the population is counted at many time intervals, and we get a bacterial growth curve that represents growth of cells over time.
Why bacterial growth curve is so important?
It gives the idea to learn about the impact of competition in the simplest way. It gives the answer what happens to a population when resources are limited.
Bacterial growth best suits even to describe the human population.
In science, there are 4 phases, but for simplistic understanding, without any scientific jargon it can be three stages: Thrive, Survive, and Deteriorate
|Image from wikipedia (A: Lag phase, B: Log phase, C: Stationary phase, D: Death phase)|
Stage 1: Thrive
In this phase bacteria has sufficient resources, so bacteria flourish, prosper or grow vigorously.
In science, it's the lag phase and log phase.
In the lag phase, there is no cell division, but cells are not dormant, they undergo intense metabolic activity, synthesizing enzymes and various molecules
In log phase, cells begin to divide. Cellular reproduction is most active during this period.
Stage 2: Survive
When the population growth is unchecked, we reach a stage, where no more population growth is allowed, because of exhaustion of nutrients, accumulation of waste products, and harmful changes in pH etc. In science, it's called stationary phase.
Stage 3: Deteriorate
It's called death phase, in which population is diminished to a tiny fraction of the number of cells in the previous phase or there is an entire death of population. It could be caused by lack of nutrients, due to lethal toxic conditions
This is true for all living organisms. All organisms compete for resources till it gets depleted or environment gets noxious.
In the case of humans, we can see all the three stages in different places. Some thrive, some manage to survive, and those who can't deteriorate.
The disparity in the case of human can be compared with bacteria who use of antibiotics, which kills other bacterias so that it itself can thrive and overcome competition of resources.
If we ask for anyone which of the stage will you choose, it would be "thrive" without any question.
So can we perpetually stay in the thriving stage?
Bacteria and humans have one big different, we have got a brain with a huge amount of memory. A brain that can learn and understand things looking at the environment and other organisms, and take decisions accordingly. A brain that searches for reproducibility to predict what will happen if these conditions are met. Bacteria can't decide to stop reproduction so that it doesn't go to the "survive" or "deteriorate" stage. But we can.
We can't grow our population infinitely with limited resources and pollute our environment if you do get ready to deteriorate. We should have family planning based upon the available resources and income. Our kids need to thrive, not survive due to limited resources or deteriorate due to malnutrition. There must be a feedback mechanism, that decides, how much kids do a parent can have based upon income and time of parent, how much a country can have based upon its resources, how much the earth can withstand?
What policies should we make for family planning?