Until the 1800s, population growth was incredibly slow on a global level. The global population was estimated to have been around 188 million people in the year 1CE, and did not reach one billion until around 1803. However, since the 1800s, a phenomenon known as the demographic transition has seen population growth skyrocket, reaching eight billion people in 2023, and this is expected to peak at over 10 billion in the 2080s.

In 2024, around **** million babies were born in China. The number of births has increased slightly from **** million in the previous year, but is much lower than the ***** million births recorded in 2016. Demographic development in China In 2022, the Chinese population decreased for the first time in decades, and population decline is expected to accelerate in the upcoming years. To curb the negative effects of an aging population, the Chinese government decided in 2013 to gradually relax the so called one-child-policy, which had been in effect since 1979. From 2016 onwards, parents in China were allowed to have two children in general. However, as the recent figures of births per year reveal, this policy change had only short-term effects on the general birth rate: the number of births slightly increased from 2014 onwards, but then started to fell again in 2018. In 2024, China was the second most populous country in the world, overtaken by India that year. China’s aging population The Chinese society is aging rapidly and facing a serious demographic shift towards older age groups. The median age of China’s population has increased massively from about ** years in 1970 to **** years in 2020 and is projected to rise continuously until 2080. In 2020, approximately **** percent of the Chinese were 60 years and older, a figure that is forecast to rise as high as ** percent by 2060. This shift in demographic development will increase social and elderly support expenditure of the society as a whole. One measure for this social imbalance is the old-age dependency ratio, measuring the relationship between economic dependent older age groups and the working-age population. The old-age dependency ratio in China is expected to soar to ** percent in 2060, implying that by then three working-age persons will have to support two elderly persons.

Whereas the population is expected to decrease somewhat until 2100 in Asia, Europe, and South America, it is predicted to grow significantly in Africa. While there were 1.5 billion inhabitants on the continent at the beginning of 2024, the number of inhabitants is expected to reach 3.8 billion by 2100. In total, the global population is expected to reach nearly 10.4 billion by 2100. Worldwide population In the United States, the total population is expected to steadily increase over the next couple of years. In 2024, Asia held over half of the global population and is expected to have the highest number of people living in urban areas in 2050. Asia is home to the two most populous countries, India and China, both with a population of over one billion people. However, the small country of Monaco had the highest population density worldwide in 2021. Effects of overpopulation Alongside the growing worldwide population, there are negative effects of overpopulation. The increasing population puts a higher pressure on existing resources and contributes to pollution. As the population grows, the demand for food grows, which requires more water, which in turn takes away from the freshwater available. Concurrently, food needs to be transported through different mechanisms, which contributes to air pollution. Not every resource is renewable, meaning the world is using up limited resources that will eventually run out. Furthermore, more species will become extinct which harms the ecosystem and food chain. Overpopulation was considered to be one of the most important environmental issues worldwide in 2020.

In China, hair loss problems begin at young age. In 2018, over 43 percent of people developing hair loss were below 30 years old. In 2019, there were around 250 million people affected by the condition in China, with an almost 90 million female population.

Kawasaki disease (KD) is an acute systemic vasculitis syndrome that primarily affects infants and young children. Its etiology is unknown; however, epidemiological findings suggest that genetic predisposition underlies disease susceptibility. Taiwan has the third-highest incidence of KD in the world, after Japan and Korea. To investigate novel mechanisms that might predispose individuals to KD, we conducted a genome-wide association study (GWAS) in 250 KD patients and 446 controls in a Han Chinese population residing in Taiwan, and further validated our findings in an independent Han Chinese cohort of 208 cases and 366 controls. The most strongly associated single-nucleotide polymorphisms (SNPs) detected in the joint analysis corresponded to three novel loci. Among these KD-associated SNPs three were close to the COPB2 (coatomer protein complex beta-2 subunit) gene: rs1873668 (p = 9.52×10−5), rs4243399 (p = 9.93×10−5), and rs16849083 (p = 9.93×10−5). We also identified a SNP in the intronic region of the ERAP1 (endoplasmic reticulum amino peptidase 1) gene (rs149481, pbest = 4.61×10−5). Six SNPs (rs17113284, rs8005468, rs10129255, rs2007467, rs10150241, and rs12590667) clustered in an area containing immunoglobulin heavy chain variable regions genes, with pbest-values between 2.08×10−5 and 8.93×10−6, were also identified. This is the first KD GWAS performed in a Han Chinese population. The novel KD candidates we identified have been implicated in T cell receptor signaling, regulation of proinflammatory cytokines, as well as antibody-mediated immune responses. These findings may lead to a better understanding of the underlying molecular pathogenesis of KD.

Throughout the Cold War, the United States and the Soviet Union had relatively similar total populations. The U.S.' population grew from around 205 million to almost 250 million people between 1970 and 1990, while the USSR's population grew from around 240 to 290 million in this time. In these years, the Soviet Union had the third largest population in the world, and the U.S. had the fourth largest (behind China and India respectively). Despite their similar sizes, these populations differed in terms of distribution as the U.S.' population was approximately three quarters urban in this period, whereas the Soviet Union's urban population was just 56 percent in 1970 and 66 percent in 1989. Additionally, the Soviet Union's population was much younger than that of the U.S. due to a higher birth rate and lower life expectancy.

This graph shows the population of the U.S. by race and ethnic group from 2000 to 2023. In 2023, there were around 21.39 million people of Asian origin living in the United States. A ranking of the most spoken languages across the world can be accessed here. U.S. populationCurrently, the white population makes up the vast majority of the United States’ population, accounting for some 252.07 million people in 2023. This ethnicity group contributes to the highest share of the population in every region, but is especially noticeable in the Midwestern region. The Black or African American resident population totaled 45.76 million people in the same year. The overall population in the United States is expected to increase annually from 2022, with the 320.92 million people in 2015 expected to rise to 341.69 million people by 2027. Thus, population densities have also increased, totaling 36.3 inhabitants per square kilometer as of 2021. Despite being one of the most populous countries in the world, following China and India, the United States is not even among the top 150 most densely populated countries due to its large land mass. Monaco is the most densely populated country in the world and has a population density of 24,621.5 inhabitants per square kilometer as of 2021. As population numbers in the U.S. continues to grow, the Hispanic population has also seen a similar trend from 35.7 million inhabitants in the country in 2000 to some 62.65 million inhabitants in 2021. This growing population group is a significant source of population growth in the country due to both high immigration and birth rates. The United States is one of the most racially diverse countries in the world.

The statistic shows the total population of India from 2019 to 2029. In 2023, the estimated total population in India amounted to approximately 1.43 billion people.

Total population in India

India currently has the second-largest population in the world and is projected to overtake top-ranking China within forty years. Its residents comprise more than one-seventh of the entire world’s population, and despite a slowly decreasing fertility rate (which still exceeds the replacement rate and keeps the median age of the population relatively low), an increasing life expectancy adds to an expanding population. In comparison with other countries whose populations are decreasing, such as Japan, India has a relatively small share of aged population, which indicates the probability of lower death rates and higher retention of the existing population.

With a land mass of less than half that of the United States and a population almost four times greater, India has recognized potential problems of its growing population. Government attempts to implement family planning programs have achieved varying degrees of success. Initiatives such as sterilization programs in the 1970s have been blamed for creating general antipathy to family planning, but the combined efforts of various family planning and contraception programs have helped halve fertility rates since the 1960s. The population growth rate has correspondingly shrunk as well, but has not yet reached less than one percent growth per year.

As home to thousands of ethnic groups, hundreds of languages, and numerous religions, a cohesive and broadly-supported effort to reduce population growth is difficult to create. Despite that, India is one country to watch in coming years. It is also a growing economic power; among other measures, its GDP per capita was expected to triple between 2003 and 2013 and was listed as the third-ranked country for its share of the global gross domestic product.

Climate change may have diverse and complex impacts on species interactions, destabilizing food webs and ecosystem services. The effects of warming on the top-down biological control of crop pests have been considerably less studied than bottom-up effects through crop physiological changes. We studied the effect of a 2 °C warming in the laboratory and in wheat fields on the predation and metabolism of Harmonia axyridis on wheat aphids using molecular gut content analysis. We also measured the effects of warming on the predation rate and functional response of H. axyridis on each aphid species in the laboratory, as well as on DNA degradation rate. Field densities of Sitobion avenae and Rhopalosiphum padi, the two most abundant wheat aphid species, were increased by 2 and 2.5 times, respectively, under experimental warming, but densities of H. axyridis were not. Field predation rate of H. axyridis on these two aphids was found to be about 25% lower under elevated temperature. This could have been due to faster prey digestion, since degradation of the preferred aphid species, Sitobion avenae, was 1.5 times faster under elevated temperature. However, the functional response of H. axyridis larvae on these two species was 1.5 times higher under warming over the range of prey densities tested (50 to 250 over 24 h). The total predation rate of H. axyridis larvae on a mixture of S. avenae, R. padi and Schizaphis graminum aphid prey was also increased by 1.4 times, but consumption of R. padi aphids was increased while that of S. graminum was decreased under warming. Overall, our results show that global warming could strongly increase pest outbreaks and destabilize biological pest control, which would likely result in accrued yield losses.

Methods Experimental design Field experiments were conducted in Langfang, Hebei Province (Langfang Research Station, Institute of Plant Protection, Chinese Academy of Agricultural Sciences; 39°30’N, 116°36’E) and in Yuanyang, Henan Province (Modern Agricultural Science and Technology, Henan Academy of Agricultural Sciences; 34°55’N, 114°15’E). The climate at both stations is continental warm temperate with a monsoon season from April to September and mean annual precipitations of 550 mm; the mean annual temperature is 12.3 °C in Langfang and 14.4 °C in Yuanyang (http://data.cma.cn/). In each station, one field (23 × 16m) was selected and grown with wheat Triticum aestivum L. variety Hengguan 35, which is adapted to dry conditions. In each field, twelve plots of 2 m × 2 m were selected and randomly assigned to control (ambient temperature; six plots) or to treatment (warming; six plots). Plots were separated by a buffer of at least 5 m of bare ground. MSR-2420 infrared heaters (Kalglo Electronics Inc., Bethlehem, Pennsylvania, USA; 165 cm × 15 cm) were placed above treatment plots, setting a radiation output of 2000 W and with a 4 m2 effective area (Han et al., 2019). Air temperature and relative humidity were monitored hourly 80 cm above ground using a data logger (JL-17; Hebei Qingsheng Electricity Company, Hebei, China) placed in the middle of each plot. Wheat was sown in mid-October 2014, 2015 and 2016, and harvested in early June 2015, 2016 and 2017. Two months after wheat planting, infrared heaters were set up until harvesting the wheat. Bare ground borders between plots were regularly manually weeded, and no pesticides were applied. Field population dynamics of wheat aphids and of H. axyridis

To evaluate the influence of warming on insect population dynamics, aphids and H. axyridis numbers were recorded every seven days from the beginning of March to harvest each year in the twelve experimental plots. In each plot, a ‘Z-shaped’ sampling pattern was used, along which five sampling sites were selected. At each sampling site, ten wheat tillers were randomly selected and carefully inspected, and the number of aphids (adults and nymphs) and of H. axyridis were counted on those tillers.

H. axyridis specimen collection and DNA extraction Twenty-seven and 33 larvae of H. axyridis were collected in 2018–2021 at the Yuanyang station in ambient versus elevated temperature plots, respectively, and placed individually in 50 mL centrifuge tubes sealed with gauze. Brought back in the laboratory, their guts were immediately dissected under a stereoscope, and placed individually in a DNA Preservation Solution (Phygene Biotech, Fuzhou, China) to protect DNA from degradation and contamination, then stored at -80 ℃ until DNA extraction. Later, collected guts were placed individually in 1.5 mL microcentrifuge tubes and homogenized in 500 µl of DNA extraction buffer (100 mM NaCl, 50 mM Tris–HCl, 100 mM EDTA, 5% SDS, and 20 mg.mL-1 proteinase K, pH 8.0) using a TGrinder homogenizer (OSE-Y50, Tiangen Biotech, Beijing, China) at 11,000rpm.min-1 for 2 min. The mixture was agitated at 1,000 rpm.min-1 for 30 s using a BS14-Vortex 3000 (Wiggens, Straubenhardt, Baden-Württemberg, Germany) and incubated at 56 °C for 30 min. Then, 300 µl of phenol reagent for DNA extraction (Solarbio biotech, Beijing, China) and 300 µl of chloroform were added, mixed, and centrifuged at 14,000 rpm for 10 min. This last step was repeated another time to remove all impurities and obtain pure DNA. Once the supernatant was transferred into a new 1.5 mL centrifuge tube, 600 µl of chloroform were added, mixed, and centrifuged at 14,000 rpm for 10 min. The aqueous phase was mixed with 0.13 volumes of ammonium acetate (7.5 M) and two volumes of 100% ethanol, and placed for 20 min at -80 °C. The precipitated DNA was centrifuged, dried, resuspended in 25 µl of ultrapure water, quantified using a spectrophotometer (NanoDrop 2, Thermo Fisher Scientific, Massachusetts, USA), and stored at -40 °C. The same DNA extraction procedure was used for both the field and laboratory samples. Primer design and specificity tests To analyse H. axyridis gut content and quantify the relative consumption of the three main aphid species, a molecular analysis was conducted. Three pairs of primers specific to the cytochrome C Oxidase subunit I (COI) sequences of each aphid species were designed using the online Eurofins Genomics qPCR Assay Design tool (https://eurofinsgenomics.eu/en/ecom/tools/qpcr-assay-design/), and using GenBank reference sequences for each aphid species. The screening conditions were set as follows: primer length 15-30 bp, GC content 40-80%, Tm > 55 °C, qPCR product 150-400 bp. The specificity of each primer to its target species was verified by PCR amplification of the DNA extract of each species (S. avenae, S. graminum, R. padi and H. axyridis) using each pair of primer (from each aphid species) in separate PCRs. For each PCR, 1 µL of DNA extract was mixed into 12.5 μL of 2×F8 PCR MasterMix (Aidlab, Beijing), 0.5 µL COI-F (10µM), 0.5 µL COI-R (10µM), and ddH2O up to 25 µL. The PCR steps were as such: initial denaturation at 94℃ for 2 min; 30 cycles at 94℃ for 10 s, 57℃ for 10 s, 72℃ for 10 s; and final extension at 72℃ for 5 min. Each PCR was carried out in a DNA engine gradient thermal cycler (Bio-Rad, USA). Sterile water was also included as a negative control in the PCR, for which no CT value was detected after amplification. The COI amplified products were purified using the DNA gel extraction kit (Aidlab, Beijing, China), then inserted and cloned into pTOPO-T vectors (Aibosen biology, Beijing, China) and propagated into DH5α competent cells, resulting in the production of pTOPO- S. avenae, pTOPO- S. graminum and pTOPO- R. padi plasmids. The plasmids were then purified with a High purity plasmid extraction kit (Aidlab, Beijing, China), and run on 1% agarose gels to check fragment purity and amplification success. Positive clones were sequenced in both forward and reverse orientations to verify that the fragment sequences were correct, using the Dnaman (2004) software. The cloned plasmids were then used to generate the standard calibration curves. The three wheat aphid species – S. avenae, R. padi and S. graminum – together account for more than 99% of all aphid individuals found in the field. In addition, the remaining extremely rare species, including Metopolophium dirrhodum (Walker) belong to other aphid genus, and we found that the three primer pairs for each aphid species were very specific to their target species. Therefore, we did not test the specificity of these three primer pairs towards other, locally extremely rare aphid species. Molecular gut content quantification from field individuals of H. axyridis

To quantify the relative consumption of H. axyridis on the three main aphid species based on molecular gut content (COI copy numbers), standard calibration curves were produced using the three recombinant plasmids pTOPO- R. padi, pTOPO- S. avenae and pTOPO- S. graminum. Each plasmid was first diluted in sterile Millipore water resulting in a stock preparation containing 1010 copies per μL, aliquoted and stored at -80 °C, respectively. From this stock, serial 10-fold dilutions containing from 109 to 100 copies of plasmids per μL were prepared for each plasmid. Then, 1 µL of each dilution was mixed into 10 μL of SYBR qPCR Mix (Aibosen, Beijing, China), 0.6 μL of each of the three primers, 7.8 μL ultra-pure H2O, and 0.01 μL ROX Reference Dye (Aidlab, Beijing, China). A negative control was also prepared by adding 1 µL of ultra-pure water instead of plasmid dilution. qPCR amplifications were then performed for each sample using an Applied Biosystems 7500 (ThermoFisher, Massachusetts, USA). The qPCR steps were as such: pre-denaturation at 95°C for 2min; 40 cycles at 95°C for 15 s, 57°C for 20 s, 72°C for 40 s. After each reaction, a melting curve analysis was performed to verify amplicon purity. Primers’ amplification efficiency was calculated based on standard curves’ slopes. The copy number of plasmids per µL in each sample was calculated as

*Medians were compared between fatal and survival cases with the Wilcoxon rank sum test. For categorical variables, percentages of cases in each category were compared with Fisher's exact test.†NA demotes not applicable.‡Two fatal H5N1 cases had underlying medical conditions, including a 24-year-old pregnant woman [28] and a 16-year-old male with a 10-year history of minimal change glomerulopathy. Two surviving H5N1 cases had underlying medical conditions, including a 26-year-old pregnant woman and a 44-year-old female with a ten-year history of chronic bronchitis [unpublished data, China CDC].#A higher proportion of cases survived that received any antiviral treatment compared to those that did not receive antivirals (67% [8/12 patients] vs 7% [1/14 patients], p = 0.003), and with a positive linear association: the Gamma coefficient equals 0.664 (p = 0.005) which indicate a positive correlation between antiviral therapy and disease outcome.$High-dose corticosteroid use was defined as ≥250 mg hydrocortisone or equivalent intravenous (IV) administration daily. For children

Chr, chromosome; Risk allele, allele with higher frequency in cases compared to controls; RAF (KD) and RAF (control), risk allele frequencies in cases and controls, respectively; OR, odds ratio for risk allele; p-value (best), minimal p-value of the five association tests: genotype, allele, trend, dominant, and recessive. Stage 1 (genome scan) included 250 cases and 446 controls. Stage 2 (replication stage) included 208 cases and 366 controls. Alleles were indexed to the forward strand of NCBI Build 36.

In 2024, the average annual per capita disposable income of rural households in China was approximately ****** yuan, roughly ** percent of the income of urban households. Although living standards in China’s rural areas have improved significantly over the past 20 years, the income gap between rural and urban households is still large. Income increase of China’s households From 2000 to 2020, disposable income per capita in China increased by around *** percent. The fast-growing economy has inevitably led to the rapid income increase. Furthermore, inflation has been maintained at a lower rate in recent years compared to other countries. While the number of millionaires in China has increased, many of its population are still living in humble conditions. Consequently, the significant wealth gap between China’s rich and poor has become a social problem across the country. However, in recent years rural areas have been catching up and disposable income has been growing faster than in the cities. This development is also reflected in the Gini coefficient for China, which has decreased since 2008. Urbanization in China The urban population in China surpassed its rural population for the first time in 2011. In fact, the share of the population residing in urban areas is continuing to increase. This is not surprising considering remote, rural areas are among the poorest areas in China. Currently, poverty alleviation has been prioritized by the Chinese government. The measures that the government has taken are related to relocation and job placement. With the transformation and expansion of cities to accommodate the influx of city dwellers, neighboring rural areas are required for the development of infrastructure. Accordingly, land acquisition by the government has resulted in monetary gain by some rural households.

Nigeria has the largest population in Africa. As of 2025, the country counted over 237.5 million individuals, whereas Ethiopia, which ranked second, has around 135.5 million inhabitants. Egypt registered the largest population in North Africa, reaching nearly 118.4 million people. In terms of inhabitants per square kilometer, Nigeria only ranked seventh, while Mauritius had the highest population density on the whole African continent in 2023. The fastest-growing world region Africa is the second most populous continent in the world, after Asia. Nevertheless, Africa records the highest growth rate worldwide, with figures rising by over two percent every year. In some countries, such as Niger, the Democratic Republic of Congo, and Chad, the population increase peaks at over three percent. With so many births, Africa is also the youngest continent in the world. However, this coincides with a low life expectancy. African cities on the rise The last decades have seen high urbanization rates in Asia, mainly in China and India. However, African cities are currently growing at larger rates. Indeed, most of the fastest-growing cities in the world are located in Sub-Saharan Africa. Gwagwalada, in Nigeria, and Kabinda, in the Democratic Republic of the Congo, ranked first worldwide. By 2035, instead, Africa's fastest-growing cities are forecast to be Bujumbura, in Burundi, and Zinder, Nigeria.

In 2025, there were around 1.53 billion people worldwide who spoke English either natively or as a second language, slightly more than the 1.18 billion Mandarin Chinese speakers at the time of survey. Hindi and Spanish accounted for the third and fourth most widespread languages that year. Languages in the United States The United States does not have an official language, but the country uses English, specifically American English, for legislation, regulation, and other official pronouncements. The United States is a land of immigration, and the languages spoken in the United States vary as a result of the multicultural population. The second most common language spoken in the United States is Spanish or Spanish Creole, which over than 43 million people spoke at home in 2023. There were also 3.5 million Chinese speakers (including both Mandarin and Cantonese),1.8 million Tagalog speakers, and 1.57 million Vietnamese speakers counted in the United States that year. Different languages at home The percentage of people in the United States speaking a language other than English at home varies from state to state. The state with the highest percentage of population speaking a language other than English is California. About 45 percent of its population was speaking a language other than English at home in 2023.

In 1800, the population of the region of present-day India was approximately 169 million. The population would grow gradually throughout the 19th century, rising to over 240 million by 1900. Population growth would begin to increase in the 1920s, as a result of falling mortality rates, due to improvements in health, sanitation and infrastructure. However, the population of India would see it’s largest rate of growth in the years following the country’s independence from the British Empire in 1948, where the population would rise from 358 million to over one billion by the turn of the century, making India the second country to pass the billion person milestone. While the rate of growth has slowed somewhat as India begins a demographics shift, the country’s population has continued to grow dramatically throughout the 21st century, and in 2020, India is estimated to have a population of just under 1.4 billion, well over a billion more people than one century previously. Today, approximately 18% of the Earth’s population lives in India, and it is estimated that India will overtake China to become the most populous country in the world within the next five years.

In 2023, roughly 1.49 billion adults worldwide had a net worth of less than 10,000 U.S. dollars. By comparison, 58 million adults had a net worth of more than one million U.S. dollars in the same year. Wealth distribution The distribution of wealth is an indicator of economic inequality. The United Nations says that wealth includes the sum of natural, human, and physical assets. Wealth is not synonymous with income, however, because having a large income can be depleted if one has significant expenses. In 2023, nearly 1,700 billionaires had a total wealth between one to two billion U.S. dollars. Wealth worldwide China had the highest number of billionaires in 2023, with the United States following behind. That same year, New York had the most billionaires worldwide.

A global phenomenon, known as the demographic transition, has seen life expectancy from birth increase rapidly over the past two centuries. In pre-industrial societies, the average life expectancy was around 24 years, and it is believed that this was the case throughout most of history, and in all regions. The demographic transition then began in the industrial societies of Europe, North America, and the West Pacific around the turn of the 19th century, and life expectancy rose accordingly. Latin America was the next region to follow, before Africa and most Asian populations saw their life expectancy rise throughout the 20th century.

As of February 2025, India was the country with the largest YouTube audience by far, with approximately 491 million users engaging with the popular social video platform. The United States followed, with around 253 million YouTube viewers. Brazil came in third, with 144 million users watching content on YouTube. The United Kingdom saw around 54.8 million internet users engaging with the platform in the examined period. What country has the highest percentage of YouTube users? In July 2024, the United Arab Emirates was the country with the highest YouTube penetration worldwide, as around 94 percent of the country's digital population engaged with the service. In 2024, YouTube counted around 100 million paid subscribers for its YouTube Music and YouTube Premium services. YouTube mobile markets In 2024, YouTube was among the most popular social media platforms worldwide. In terms of revenues, the YouTube app generated approximately 28 million U.S. dollars in revenues in the United States in January 2024, as well as 19 million U.S. dollars in Japan.