Carrying Capacity and Birth Control

Reproduction is perhaps one of the most important life processes that ensure continuity of life. Imagine if all the humans presently on earth decides to stop reproducing starting from today, very few or no humans would remain on the planet; let's say in a hundred years to come. Such is the indispensability of the process.

Hence, it usually amazes me when folks say they do not have any plan to have kids throughout their lives. Much as I respect their decisions as a layman, I see it as an unconscious attempt to promote discontinuity of human life and disrupt one of the processes that ensure equilibrium in the ecosystem; especially in terms of gene pool flux and genetic diversity. Though such people sometimes argue that a whole lot of other humans are giving birth to more kids than necessary and that the world actually has more than enough population already.

The current world population stands at a staggering figure of 7.6 billion individuals which represents a significant increase in the last 10 years. It is hypothesized that if the human population is allowed to continue without checks and balances, a time might come when the earth itself would no longer be able to support more individuals. At this point, we say the earth has reached its carrying capacity.

According to several scientists, the maximum figure the earth can support oscillates around 9 to 10 billion and if the current trend of population increase continues, the carrying capacity would be reached somewhere between the year 2050 and 2100. Should we be scared?

Often times, I get into argument with proponents of birth control. Most believe that humans should not be allowed to proliferate according to their capacities, citing limited resources as the main reason. China as a country happened to have criminalized excessive fecundity in the past, putting a cap of one or two kids per family as the case may be. I always like to play the devil in this kind of argument. In a world where we keep hammering on fundamental human rights, I am of the opinion that dictating to fellow humans when and how (and probably where) to have sex is a gross violation of it. I usually like to end the argument by telling my opponents that I am going to give birth to as many kids as my resources can cater for (and yea, I am serious about this). Thank goodness I do not live in China.

Some would probably consider my stands as grossly unscientific and counterproductive to the efforts being channeled towards saving the planet. I really do not believe so. My reasons are not far fetched. I can say it categorically that no matter how high the birth rate of the human population is, the earth cannot and would never get to its carrying capacity. It can only oscillate around it. Let's have a look at some concepts that fully explain this hypothesis of mine.

Population has been defined in a variety of ways, perhaps depending on the field the definer operates. But for the purpose of today's discussion and to simplify it, a population can be viewed as an assemblage of individuals of the same species which possess the inherent ability to produce fertile progenies through breeding. Ipso facto, a human-animal hybrid would neither be considered a part of human population nor part of animal population.

Since the discussion is about the global human population, migration does not have any resultant effect. Hence, birth and death rate are the main factors that determine whether a population would increase or otherwise. When the birthrate outweighs the death rate, population increases and when otherwise, it decreases. Therefore, the argument has always been that if the birthrate is left unchecked, the world population would shoot up rapidly and the carrying capacity of the earth would be reached soon enough.

Basically, there are two types of population growth. A population will continue to grow indefinitely as long as the birthrate keep outweighing the death rate with all other factors being constant. This is generally referred to as exponential population growth. More realistically, however, is the fact that even if birthrate outstretches death rate, populations cannot continue to increase indefinitely due to a host of biotic and abiotic environmental factors otherwise known as limiting factors of the population.

Just as machines cannot achieve 100% efficiency due to friction, no population of any species of organism can continue to grow indefinitely. A lot of factors operate naturally that tend to keep the population in checks and keep it oscillating just around its carrying capacity at best.

On one hand, some of these factors tend to have strong correlations with population size and are therefore referred to as density-dependent limiting factors. For example, epidemic disease outbreaks are quite common in heavily populated areas and less common in sparsely populated areas. Also, intra-species competition tends to increase with an increase in population density and vice versa. These two factors along with some others limit population by either by influencing the reproductive capacity of the population or the mortality rate.

On the other hand, some limiting factors are quite independent of population density. No matter how sparsely or heavily populated an area is, they randomly operate and work to limit population size. Inadequate food or nutrient, environmental pollutants, natural disasters and several other factors all operate and limit population size irrespective of the population density. Just like the density-dependent factors, they also influence the reproductive capacity and mortality to regulate population size. If local populations were to be considered, these factors also cause a flux in the immigration-emigration equilibrium. However, as I said earlier, migration has no resultant effect on the global population size, unless humans are migrating to another planet.

As I said earlier, I am really not an advocate of telling people the number of kids to have. Without being told, the socio-economic status quo of a lot of countries has actually enforced self-birth control on some couple without the intervention of government. No matter how hard some humans try, they cannot reproduce without being assisted technologically while some are irreversibly sterile.

However, if all the fertile human population decide to reproduce at their maximum capacity, competition for resources would increase, disease outbreak would increase, war and pestilence would increase among a host of other density-dependent and independent factors. This would definitely mean more death rate and if the theory of natural selection is anything to go by, only the weak would die off and the strong would survive at the end of the day. Hence, I personally do not see the carrying capacity as a disaster, rather a point of equilibrium between population and available resources.

I am a respecter of fundamental human rights and of the opinion that no one should dictate to fellow humans how to use his/her body. I have seen folks given birth to several kids and effectively took care of them all while someone with a single kid did not give a hoot about the kid. I also feel some of these policies or ideologies promoting birth controls are often targeted at the proletariat in the society all because the bourgeoisie feels somehow threatened by the limiting factors that could come into play in the population.

The earth as a planet is blessed with huge resources which are kind of skewed in distribution. A large percentage of the world's wealth is in the hands of few. Hence, it is probable that the carrying capacity of the planet has been underestimated.