Utafiti wa kisasa kuhusu muundo wa kijeni wa idadi ya binadamu unapendekeza kwamba takriban miaka 15,000 iliyopita idadi ya watu duniani ilikuwa milioni 15 (idadi ya sasa ya jiji la Delhi, India). Kufikia wakati wa Nabii Isa (Yesu) zaidi ya miaka 2000 iliyopita, idadi hiyo ilikuwa imeongezeka hadi milioni 250 (karibu sawa na idadi ya sasa ya Indonesia). Ilipofika usiku wa mapinduzi ya viwanda katika karne ya 18, idadi ya watu duniani ilikuwa imeongezeka mara tatu hadi takriban milioni 700 (karibu ukubwa wa Ulaya ya sasa). Katika karne mbili zilizofuata, idadi ya watu duniani iliongezeka kwa kiwango cha 6% kila mwaka na kufikia bilioni 2.5 kufikia mwaka 1950, kisha ikaongezeka zaidi ya mara mbili katika miaka 50 iliyofuata, kwa kiwango cha 18%, hadi kufikia bilioni 6 usiku wa kuingia karne ya 21. Ingawa viwango vya ukuaji vinapungua, isipokuwa kukiwa na janga kubwa la kidemografia, idadi ya watu duniani inatarajiwa kufikia bilioni 9 kufikia mwaka 2050. Idadi ya sasa ya watu duniani, kufikia Septemba 2008, ni bilioni 6.72.

Modern research on the genetic structure of human populations suggests that nearly 15,000 years ago the world population was 15 million (the present population of Delhi, India). The population by the time of Jesus (Isa) over 2000 years ago had increased to 250 million (about the same as present day Indonesia). On the eve of the industrial revolution in the 18th century world population had tripled to about 700 million (nearly the size of current day Europe). In the two centuries that followed, the global population increased at an annual rate of 6% reaching 2.5 billion by 1950 and more than doubled in the next 50 years at a rate of 18% to reach 6 billion on the eve of the 21st century. Although growth rates are slowing, barring some demographic catastrophe the world population should reach 9 billion by 2050. The current population of the world stands as of September 2008 at 6.72 billion.

Kiwango cha ukuaji wa idadi ya watu katika karne iliyopita kimetajwa kuwa chanzo kikuu cha ulimwengu kusimama kwenye ukingo wa maafa; inasemwa kwamba tunaishiwa chakula cha kulisha idadi hiyo inayoongezeka. Wanaounga mkono hoja ya ongezeko kubwa la watu wanasema kwamba ukuaji mkubwa wa idadi ya watu duniani ndio unaosababisha umaskini, uharibifu wa mazingira na machafuko ya kijamii, na kwamba maendeleo ya kiuchumi katika nchi za ulimwengu wa tatu hayawezekani mradi idadi ya watu inaendelea kuongezeka. Kwa sababu hiyo, mashirika ya kimataifa na serikali zimeandaa na kutekeleza programu nyingi katika nchi za ulimwengu wa tatu ili kupunguza kasi ya ukuaji wa idadi ya watu.

The rate of population growth over the last century has been labelled as the underlying cause of the world standing on the brink of disaster; it is argued we are running out of food to sustain such a growing population. It is argued by the proponents of overpopulation that the huge growth in world population is responsible for poverty, environmental destruction and social unrest and that economic development in the third world is impossible as long as populations continue to grow. As a result international agencies and governments have developed and implemented numerous programmes in the third world to curtail the rate of population growth.

Ongezeko hili la watu linalodaiwa linapaswa kuhusishwa na kitu fulani ili kuthibitisha kwamba ni kubwa kupita kiasi. Kitu hicho ni matumizi ya rasilimali. Ukosefu wa uwiano duniani unaotokana na rasilimali zinazotumiwa unahusishwa na idadi ya watu.

This alleged overpopulation has to be in relation to something to qualify it being over. That something is the use of resources. The resources being consumed leading to global imbalances are attributed to population sizes.

Hata hivyo, wakati dhana zote kuhusu athari za ongezeko la watu zinapochunguzwa kwa makini, inadhihirika kwamba ongezeko la idadi ya watu halijawahi kuchangia katika matatizo mengi ya dunia ya leo. Kinachoonekana wazi ni kwamba kuna ajenda ya kisiasa katika kuhusisha ongezeko la idadi ya watu duniani na chanzo cha hatari inayoweza kuikumba dunia. Ajenda hii inalenga kuhamisha sababu halisi mbali na mitindo ya maisha, mifumo ya kuishi, kutokuwa endelevu kwa utumiaji wa mali kupita kiasi, umaskini, na unyanyasaji wa wazi unaofanywa dhidi ya ulimwengu wa tatu, ili ulimwengu wa Magharibi uweze kuishi kwa kutegemea ulimwengu wa tatu.

However, when all assumptions on the effects of population growth are scrutinised population increase in no way has ever contributed to the many ills of the world today and what becomes clear is that there is a clear political agenda in attributing the increasing global population as the cause of the worlds potential disaster. This agenda is to shift the real cause away from the lifestyles, living patterns, un-sustainability of consumerism, poverty and blatant abuse of the third world in order that the Western world can live off the third world.

Ulimwenguulioendelea pia unakabiliwa na tatizo gumu sana; Japani, Urusi, Ujerumani, Uswisi na sehemu kubwa ya Ulaya Mashariki vinapitia kupungua kwa idadi ya watu, kutokana na kupungua kubwa kwa kuzaliwa kwa watoto.

The developed world also faces a very serious conundrum; Japan, Russia, Germany, Switzerland and much of Eastern Europe are experiencing population decline, due to a huge reduction in births.

Idadi ya watu katika nchi nyingine za Magharibi nayo ingepungua kama isingekuwa uhamiaji. Kadiri idadi ya watu inavyopungua Magharibi ikilinganishwa na ulimwengu wa tatu na nchi za Kiislamu, nchi hizo zitakuwa na haki halali, kutokana na idadi yao, ya kudai sauti kubwa zaidi katika taasisi zinazoitwa za kimataifa na uwakilishi katika mashirika ya kimataifa. Suala la ongezeko kubwa la watu ni chombo chenye manufaa makubwa cha kuzishutumia nchi zenye idadi ya watu inayoongezeka, na wakati huo huo kulinda hatari ya kupoteza ushawishi wake wa baadaye. Hili linaonekana wazi katika suala la Uturuki kujiunga na Umoja wa Ulaya; Uturuki yenye wakazi karibu milioni 70 ingeipa nafasi ya pili kwa wingi wa Wabunge wa Bunge la Ulaya (MEP) baada ya kujiunga na EU. Zaidi ya hayo, makadirio ya idadi ya watu yanaonyesha kwamba Uturuki ingeipita Ujerumani kwa idadi ya viti ifikapo mwaka 2020. Uanachama wa Uturuki ungekuwa na athari pana kwa mwelekeo wa baadaye wa EU, ikiwemo suala gumu la mipango ya upanuzi wa baadaye, sababu ambazo Valéry Giscard d'Estaing wa Ufaransa ameitumia kupinga kukubaliwa kwa Uturuki. D'Estaing ameeleza kwamba hilo lingeleta madai ya kujiunga kutoka Morocco.

The rest of the Western world would also have declining populations were it not for immigration. As population numbers decline in the West relative to the third world and Muslim nations, such countries will have a legitimate right based upon their numbers to demand greater say in so called international institutes and representation on international bodies. The issue of overpopulation is a very useful tool to vilify nations with rising populations and at the same time protecting its potential loss of future influence. This can be seen clearly with Turkish EU accession; upon joining the EU, Turkey's almost 70 million inhabitants would bestow it the second largest number of MEP’s in the European Parliament. In addition, demographic projections indicate Turkey would surpass Germany in the number of seats by 2020. Turkey's membership would have wide ranging consequences for the future direction of the EU including the thorny issue of future enlargement plans, grounds by which Valéry Giscard d'Estaing of France has opposed Turkey's admission.5 D’Estaing has suggested that it would lead to demands for accession by Morocco.

Ingawa hakuna makubaliano kuhusu sababu ya Uingereza kuwa taifa la kwanza duniani kuingia katika viwanda, sababu zake kwa ujumla zinakubalika kuwa huenda ni nane, mojawapo ikiwa ni ukuaji wa idadi ya watu. Baada ya muungano na Scotland mwaka 1707, idadi ya watu wa Uingereza ilikuwa milioni 6.5; karne moja baadaye ilikuwa imeongezeka mara mbili na kufikia zaidi ya milioni 16. La muhimu zaidi, ukuaji huo mwingi ulitokea baada ya mwaka 1750, katika mojawapo ya milipuko mikubwa zaidi ya idadi ya watu katika historia ya Uingereza. Ongezeko hili lilikuwa la muhimu kwa kuwa liliongeza nguvu kazi inayoweza kupatikana na idadi ya watumiaji wa bidhaa.