As of 2016, approximately 40% of the world’s men are circumcised, including half of men under the age of 30. In addition, approximately 40% of uncircumcised Chinese men and men from non-circumcising countries of South East Asia have foreskin shortened to the point of where all or almost all of the glands of the penis are exposed when flaccid. China and non-circumcising South East Asia countries account for about 20% of the worlds population. This rate of circumcision is higher than the 33% 2007 estimate by the World Health Organization (WHO) and UNAIDS for a number of reasons. Firstly, the WHO’s estimate only looked at people over the age of 15. Since the average age of a Muslim is 23 compared to 30 years old for a non Muslim, Muslims make up a larger percentage of people under the age of 15 than the 24% of people world wide that are Muslim. Secondly, the Muslim population has gained a higher percentage of the worlds population over the last 10 years. Thirdly, since circumcision’s ability to reduce of men contracting HIV has been put on rigorous medical grounding, the World Health Organization has incorporated circumcision into a comprehensive package of tools to reduce HIV[2,4], which has resulted in a large increase in in circumcision rates in areas that traditionally had a low circumcision prevalence. Lastly, since the importance of circumcision in the fight against HIV has been revealed, circumcision rates in many countries have now been well documented, allowing for a more accurate estimate.
The circumcision rate among younger men (under 30) is higher than the world’s rate for the same reasons as stated before. The Muslim population makes up a much larger portion of men under 30, and circumcision has become popular in many countries among young men where it previously was not practiced in order to prevent HIV infections. Some examples are China, where just around 5% of older adults are circumcised, but half of Chinese youth in western provinces are , and almost 90% of 20 year olds in South Africa are circumcised, up from just 50% a few years prior .
Now we will try to estimate the circumcision rates of males in this coming generation. First we will look at what percentage of males will be born into the Muslim population. While Muslims make up 24% of the world population, 28% of women in their child bearing years are Muslim and thus 72% of women in child bearing years being non-Muslim. In addition, the birth rate of Muslim women is 3.1 to 2.3 of non-Muslims. This yields [(.28*3.1)/(.28*3.1+.72*2.3)]*100% = 34.4% of kids today are born into Muslim families. Second, we estimate the percentage of children born into non-Muslim African families. Since the world health organization has set a goal of 90% circumcision rate among non-Muslims in African countries with the highest HIV rates (which, not coincidentally, corresponds to which African countries don’t already have near universal circumcision rates), this population will have a circumcision rate of approximately 95%.
Africa has a population of approximately 1,230,000,000 with 55% of the population being non-Muslim, i.e. 676,500,000 non-Muslims live in Africa, which is 676,500,000/7,400,000,000 = 9.1% of the world population (assuming a world population of 7.4 billion). Like Muslims though, the non-Muslim population in Africa is younger than the world’s population, and so approximately 10.5% of the worlds women in child bearing age belong to the non-Muslim African population and thus 88.5% of the worlds women in child bearing years do not fall into this population. Also like Muslims, this population has a much higher birth rate (4.5) than those not in this population (approximately 2.5). This gives [(.105*4.5)/(.105*4.5+.885*2.5)]*100% = 17.6% of children are born into this population, with approximately 95% of these males eventually undergoing circumcision. This yield 17.6%*.95 = 16.7%. Lastly we take into account non-Muslim and non-African populations that have practiced circumcision for hygiene and culture reasons, as well as countries outside of Africa that have begun implementing circumcision programs to stop the progress of HIV in their countries or lower the HIV rates in their countries, as recommended by the World Health Organization. These countries include (but not limited to) Canada/USA (pop. 355 million), the Philippines (pop. 100m), non-Muslims in Indonesia (non-Muslim pop. 25 million), China (pop. 1357 million), South Korea (pop. 51 million), Thialand (pop. 70 million), Caribbean countries (Haiti, Jamaica, Dominican Republic ect.) (pop. 42 million), India (pop. 1252 million), and many other smaller countries [2,7-14]. The circumcision rates vary highly by country (nearly 100% in countries like the Philippines and only around 15% in India, where is being introduced as an effective method to prevent HIV to populations that would benefit from circumcision) and approximately 50% of non-Muslims in these populations will undergo circumcision. These places make up about [(355+100+1357+51+70+42+1252+ 25+ 20(for the smaller countries))/7400]*100% = 44.2% of the worlds population. Since most of these countries have a birth rate somewhat below the worlds average and some of this population is Muslim, about 35% of children will be born into the non-Muslim population of these countries. So since about half will be getting circumcised, and additional 35%*.5 = 17.5% of males this coming generation will be getting circumcised. In total now we have 34.4%(Muslims) + 16.7%(non-Muslim Africans) + 17.5%(other countries) = 68.6%. In addition, about 5% of the remaining 21.4% of the population would be undergoing circumcision for medical reasons, converting to a religion that circumcises, or for protection from HIV. This gives 68.6% + 21.4%*.05 = 69.7%. So, this coming generation will have a circumcision rate of approximately 70%. The rate that is most subject to variation would be the non-Muslim, non-African circumcision rate. I approximated 17.5% of males world wide would belong to this population and undergo circumcision. This number will very likely fit in the range of 15% and 20%, thus the circumcision rate of this coming generation can be placed in the range of 67.5% and 72.5%.
In addition to a global circumcision rate of around 70%, studies have shown the some groups of humans have begun to evolve out of foreskin (as mentioned before) which will discussed in the next few paragraphs.
Studies now from China indicate that humans are in fact evolving out of foreskin. One study  measured the foreskin length of a large cohort of uncircumcised Chinese men using the following classification.
The study found that the general Chinese male population (‘the control group’) fell into the following classifications.
As is shown, 22.9% of men in the general population, (‘control group’) have level 1 foreskin length, which means their foreskin is shortened to the point of where all the glands of their penis are exposed when flaccid (naturally circumcised). Another 18.2% of the population have their foreskin cover some, but less than half of the glands of their penis, which is quit close to being naturally circumcised. All together over 40% of Chinese men are more or less naturally circumcised. This study as well as others [16,17] also find that men that test positive for STD’s have longer foreskin on average, and the difference grows greater when accounting for frequency of sex and for age. All together these studies show that, especially in the Chinese population, natural selection favors men with shortened foreskin and humans are becoming natural circumcised.
Estimation of country-specific and global prevalence of male circumcision. Wamai et. al. https://www.ncbi.nlm.nih.gov/pubmed/27051352
World Health Organization and UNAIDS on circumcision http://www.unaids.org/sites/default/files/media_asset/jc1360_male_circumcision_en_0.pdf
Pew Research Center: The Future of the Global Muslim Population http://www.pewforum.org/2011/01/27/the-future-of-the-global-muslim-population/
 World Health Organization and UNIADS: New Data on Male Circumcision and HIV Prevention: Policy and Programme Implications http://apps.who.int/iris/bitstream/10665/43751/1/9789241595988_eng.pdf
Africa Population (live) http://www.worldometers.info/world-population/africa-population/
Pew Research Center: Why Muslims are the Worlds Fastest Growing Religious Group http://www.pewresearch.org/fact-tank/2015/04/23/why-muslims-are-the-worlds-fastest-growing-religious-group/
A Clinical trial to Introduce Voluntary Medical Male Circumcision for HIV Prevention in Areas of High Prevalence in the Dominican Republic. Volquez et al https://www.ncbi.nlm.nih.gov/pubmed/26367187
Knowledge, Attitues, Practices and Beliefs about Medical Male Circumcision (MMC) among a Sample of Health Care Providers in Haiti. Devieux et al https://www.ncbi.nlm.nih.gov/pubmed/26237217
Comparison of Three Intervention Models for Promoting Circumcision Among Migrant Workers in Western China to Reduce Local Sexual Transmission of HIV. Ning et al https://www.ncbi.nlm.nih.gov/pubmed/24098770
Prevalence and Determinants of High-Risk Human Papillomavirus Infection in Male Genital Warts.(over 90% circumcision rate found in table 1) Park et al https://www.ncbi.nlm.nih.gov/pubmed/24648877
Acceptability of male circumcision among mothers with male children in Mysore, India https://www.ncbi.nlm.nih.gov/pubmed/18453858
Why Thailand Should Consider Promoting Circumcision. Srithanaviboonchai et al https://www.ncbi.nlm.nih.gov/pubmed/23431830
 Factors Associated with the Acceptability of Male Circumcision Among Men in Jamaica. Maung et al https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3774608/
 Parental Factors Affecting the Circumcision of Non-Muslim Chinese Boys Include Education and Family History. Yan et al. https://www.ncbi.nlm.nih.gov/pubmed/26215895
 Sequential Cross-Sectional Surveys in Orange Farm, a Township of South Africa. Marshall et al. https://www.ncbi.nlm.nih.gov/pubmed/27427957
 Redundant Prepuce Increases the Odds of Chronic Prostate/Chronic Pelvic Pain Syndrome. Zhao et al. (the table with foreskin lengths is the 4th image and 3rd table given in the paper. it is labeled ‘OR for CP/CPPS with respect to foreskin length’. The general Chinese population is the control group.) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4215657/
 Acceptability of Voluntary Medical Male Circumcision Among Male Sexual Transmitted Disease Patients in China. Wang et al. https://www.ncbi.nlm.nih.gov/pubmed/26905739