Considering the current shift in warfare methodology it is not unlikely to anticipate new imaginative ways to replace the rifles and tanks of the XX century. Most recent major shift in warfare strategy progressed throughout the period of World War II when every faction tried to best its enemies in most original and efficient ways possible. As dark as this period might have been, it was a catalyst for the exponential spring in technological and scientific progress. Many comforts and necessities of today would possibly not have been invented for a long time if not for the WWII; from penicillin to computers, countries were forced to compete against each other on a wide array of aspects in order to have an edge over the rival. Although conflicts of the XXI century may not be that obvious to the general public, national budget expenditure for national defense of the major powers of the world show that a great deal of countries` GDP is still dedicated to possible war effort and eradication of national and international threats. Comparing what part of the national budget country allocates to war throughout history is indeed interesting and it does help to take the current international tension into the perspective. USA today has a significant lead on expenditures on national defense, allocating 596 billion dollars to the cause in 2015. That translates to 3.3% of country‘s GDP and 16% of national budget. That is almost 3 times more than the ammount of money China allocates to the same cause and is considered to be second in that regard. Russia, while spending considerably less than USA, gives up 5.4% of their GDP for the war effort. Only countries that allocate such giant pieces of their national budget to the military are Israel, Saudi Arabia, United Arab Emirates and possibly Iraq.
Going back a century to the years 1939-1945 during the World War II, numbers I have mentioned above pale in comparison. USA cut their military expenses the least compared to the ammount today and had spent ~32% of their national GDP. Soviet Union and UK were allocating close to whooping 45% GDP, while Germany had had to give up half of its GDP to the war effort. Finally, considering the military expenditures during the middle ages and reneissance, single digit shares of GDP nowadays do seem almost insignificant.
In the period of 1535-1547 England allocated a mean of 30% of its central government expenditures to military expenditures every consecutive year. Situation during 1658-1813 period England is even more difficult to imagine, when a mean of 74.6% of national budget had been allocated to military expenditures! Then again, considering that we have a free access to education and healthcare here in Europe and most of us own a smartphone and a car, it may not seem to be that difficult to understand the situation back then, compared to the current century.
Another thing to keep in mind is the fact that the current evaluation of expenditures for national defense may not fully reflect the true picture. Lack of long term data from the key warmongers of today, namely North Korea, Syria and Somalia, is missing. We could only speculate the amount of national budget North Korea spends on their war machine, but it is likely to be over 20% GDP. Numbers also differ from source to source. Comparison between data from different sources is a good idea to evaluate the transparency of every country in this regard. If the number is stable enough throughout all of the sources, it is more likely to be legitimate. The greater the fluctuation of numbers between sources, the more likely it is that the data from that country is unreliable. Latter examples would be Russia, where number fluctuates between 3% and 6%, or Iraq, where military expenditures could be portrayed as different as 13% and 8% depending on the source.
One more thing to keep in mind is the fact that national defense expenses may not necessarily reflect the true extent of budget dedication to named cause. Other fields may be indirectly connected to the possible expenses of war. An example would be money allocated to scientific research or education. A lot of new findings could be applicable to warfare context. That was actually the case in World War II when the greatest physicists of the time (namely J.R. Oppenheimer, E. Fermi and R. Feynman) applied their theoretical findings to the construction of the nuclear weapon. Education could also be easily utilized for military means: professional scientists, medics, programmers, psychologists, etc. are a far greater advantage to the country at the time of war compared to uneducated civilians with only rudimentary knowledge of those fields. Education thus is a long term investment and insurance.
Scientific progress in recent decades opened up many possible ways to indirectly wage war against fellow human beings. Some of them can be borrowed from other aspects of applied science, like pest control. Sterile insect technique (SIT) is one such contemporary biological pest control method. Throughout history eradication programs utilizing SIT were mostly focused on destroying different species of pest flies around the world with varying degree of success. The concept of such method is rather simple: a number of sterile (unable to sexually reproduce) individuals of a target species are bred in the laboratory and are released to the wild in huge numbers. If said number is high enough, sterile individuals gradually overwhelm the wild population of the same species. Individuals may mate with each other, but may not produce any offspring.
Fruitless copulations eventually ensure that the dead members of the populations will not be replaced by their offspring and the total number of individuals will decrease. Although this method is fairly effective against small populations, larger ones usually recover after some time. I will take my time to try and explain this technique in simpler terms.
Imagine a very small village consisting of 3 human females and 3 males. This village can represent a single population. All 3 females are fertile and able to conceive a child, while only 1 of the males is fertile. Other 2 will not be able to inseminate a female. All 6 individuals are not aware of their condition. It so happens that all 6 individuals engage in a relationship with each other and thus form 3 couples. They also engage in sexual relationship (let’s also assume that inhabitants of this village do not have access to any form of contraception. Now it really does sound like a very stereotypical redneck village, doesn’t it?). After a while, one of the village’s women became pregnant. The remaining 2 couples, despite their effort, are not able to have children, but remain loyal to each other and die of old age after a few decades without direct descendants. The lucky couple had two children by that time – both girls. But since the remaining 2 couples were childless, the girls have no one to engage in a sexual relationship with. They are the only remaining inhabitants of the village. After a few more decades they both die. The village remains uninhabited because the population died of.
This is a good example of how the majority of sterile single gender individuals can lead to the eradication of a population. Of course, we are dismissing a possibility of any outside introduction of new inhabitants, which is not uncommon in mobile animal populations, especially winged ones. We are also dismissing inbreeding – sexual reproduction of relatives – because human reproduction is highly selective, while lower case animals like nonsocial insects engage in more random selection of mates. Despite that this example still stands to show what devastating result sterile individuals can have on small populations.
Now if we repopulate our village with 100 males and 100 females, out of which 60 males are sterile, things can end up very differently. If the remaining 40 males are fertile, and all of them engage in sexual relationship with the female and have one child, we end up with 40 more individuals that can mate with each other. That is a decent enough pool for the population not to go extinct. Sterile males die without any descendants, but their female partners may engage in sexual relationship with other males; if the population is big enough, they have a choice, unlike in the first example. Newborn individuals surpass the number of dead individuals and the population persists. Of course, we are dismissing the possibility of random death before the sexual relationship or any other disaster that may strike the village (like a viral disease of high mortality). In that case there may not be enough newborns to replace the dead individuals. This point is applicable to the pest control program as well, arguing that SIT used against huge populations of insects can only be effective if other types of complementary pest control (e.g. chemical) is used.