logo

More or Less: Behind the Stats Is the UN underestimating the global fall in fertility?

BBC News24-05-2025
Every two years, the UN release their predictions for the future population of humanity – currently expected to peak in the 2080s at around 10.3 billion people.
One of the things they use to work this out is the fertility rate, the number of children the average woman is expected to have in her lifetime. When this number falls below 2, the overall population eventually falls.
In this episode of More or Less, we look at the fertility estimates for one country – Argentina. The graph of the real and predicted fertility rate for that country looks quite strange.
The collected data – that covers up to the present day – shows a fertility rate that's falling fast. But the predicted rate for the future immediately levels out.
The strangeness has led some people to think that the UN might be underestimating the current fall in global fertility.
To explain what's going on we speak to Patrick Gerland, who runs the population estimates team in the United Nations Population Division.
Presenter / producer: Tom Colls
Production co-ordinator: Brenda Brown
Sound mix: Sue Maillot
Editor: Richard Vadon
Orange background

Try Our AI Features

Explore what Daily8 AI can do for you:

Comments

No comments yet...

Related Articles

Teeth marks suggest 'terror bird' was killed by reptile 13 million years ago
Teeth marks suggest 'terror bird' was killed by reptile 13 million years ago

BBC News

time10 hours ago

  • BBC News

Teeth marks suggest 'terror bird' was killed by reptile 13 million years ago

Teeth marks made on the leg bone of a large avian reptile known as a terror bird 13 million years ago suggest an even bigger predator may have killed it, scientists birds were top predators - they could be taller than a human and had powerful legs and hooked, flesh-ripping beaks. Palaeontologists in Colombia matched teeth marks on the fossilised leg bone of one of these fearsome birds to a caiman, or a crocodile-like reptile. 3D digital scans of the bites allowed the scientists to reconstruct what they believe was a "battle to the death" that the terror bird did not survive. The new study, published in the journal Biology Letters, compared the size and shape of the teeth marks to the skulls and teeth of crocodile-like predators in museum provides rare evidence, the researchers say, of an interaction between two extinct top predators at the leg bone the scientists studied was first unearthed more than 15 years ago in Colombia's Tatacoa Desert. When the bird lived in the swamps of that area 13 million years ago, it would have been about 2.5m tall and would have used its legs and beak to hold down and rip at its prey. What the scientists are not able to prove conclusively is whether this particular, unfortunate terror bird was killed in the attack, or if the caiman scavenged its remains. "There is no sign of healing in the bite marks on the bone," explained lead researcher Andres Link from the Universidad de Los Andes in Bogotá, Colombia. "So if it wasn't already dead, it died in the attack. That was the last day that bird was on this planet - then a piece of its leg bone was found 13 million years later." The Tatacoa Desert is home to rich deposits of fossils from an epoch known as the Middle Miocene. At that time, it was a humid swamp, where river sediments trapped and fossilised the bones of dead animals, resulting in the preserved remains found there today. This particular bone was first discovered about 15 years ago by local fossil collector César Augusto Colombian scientists worked closely with Mr Perdomo, studying and cataloging fossils that he has gathered in his museum. It was when scientists were working in the museum that they realised that this fist-sized piece of leg bone came from a terror bird. That was an exciting discovery - terror bird fossils are rare. But Dr Link and his colleagues were also fascinated by the puncture marks in the bone, which had clearly been made by the teeth of another powerful predator. This new analysis of the marks revealed that they most closely match an extinct caiman species called Purussaurus neivensis, a crocodilian that would have been up to five metres long. The researchers say it would have ambushed its prey from the water's edge, much like crocodiles and caimans do today. "I would imagine it was waiting for prey to to be nearby," said Dr Link. If this was indeed a battle between two apex predators, Dr Link says that provides insight into an ancient ecosystem. It reveals that ferocious terror birds were much more vulnerable to predators than previously thought. "Every piece of a body helps us to understand so much about life on the planet in the past," Dr Link told BBC News. "That's something that amazes me - how one tiny bone can complete the story."

Exposure to a mix of pesticides raises risk of pregnancy complications, study suggests
Exposure to a mix of pesticides raises risk of pregnancy complications, study suggests

The Guardian

time4 days ago

  • The Guardian

Exposure to a mix of pesticides raises risk of pregnancy complications, study suggests

Exposure to multiple pesticides increases the chances of pregnancy complications compared to exposure to just one pesticide, new peer-reviewed research suggests. The findings raise new questions about the safety of exposure to widely used pesticides and herbicides in food and agricultural communities. The study, which bio-monitored pregnant women in a heavily agricultural state in Argentina, adds to recent-but-limited evidence pointing to heightened dangers in mixtures of pesticides. The authors say research into how pesticide mixtures impact human health is important because the vast majority of studies look at exposure to a single pesticide, and regulations on the substances' use are developed based on toxicity to just one. However, people are frequently exposed to multiple pesticides in non-organic meals, or when living in agricultural regions around the world. Studying exposure to those mixtures and other environmental factors is 'essential' to protecting people's health, said the authors, with the National University of the Littoral in Argentina. 'The concept of the exposome, which encompasses all lifetime environmental exposures, underscores the importance of studying pesticides as mixtures rather than in isolation,' the authors wrote. The study comes on the heels of University of Nebraska research that found state cancer records and bio-monitoring data showed that exposure to multiple pesticides could increase the chances of children developing brain cancer by about 36%. The new study checked for pesticides in the urine of nearly 90 pregnant women in Santa Fe, Argentina, a heavily agricultural region, and monitored their pregnancy outcomes. About 40 different pesticides were detected. At least one pesticide was found in the urine of 81% of women, and 64% showed multiple pesticides. Of those, 34% had pregnancy complications. The number of women living in urban areas who had at least one pesticide in their body was only slightly lower than those in rural districts, suggesting that food is also a meaningful exposure route. But about 70% of women in rural settings showed multiple pesticides, compared to 55% of women in urban settings, highlighting a greater risk among the former. Rural participants were over twice as likely to have pregnancy-related complications compared to urban, in part because they are more frequently exposed to mixtures. The Santa Fe region grows dozens of crops, including lettuce, cabbage, chicory, tomato, parsley, spinach, carrot, bell pepper, potato and strawberry, and the wide range of crops leads to the use of more pesticides, the authors wrote. 'The increased prevalence of pregnancy-related complications among rural participants highlights the need for a comprehensive review of pesticide use protocols, exposure limits and health risk assessments in agriculture and horticulture programs,' the authors said. Gestational hypertension was among the most common pregnancy-related complications, and the most common outcome was intrauterine growth restriction, a condition in which the fetus does not grow to a normal weight during pregnancy. The findings may also point to dangers in the type of pesticide to which women are exposed, the authors wrote. Those who had complications showed higher levels of triazole fungicides, a pesticide class that is widely used on crops like corn, soybeans and wheat. Some previous evidence suggests it's a reproductive toxicant, and the authors say their findings show the need for more research on the class's potential effects. Though not all the same pesticides are used in the US or other countries as in Argentina, the use of triazole fungicides increased four-fold in the US between 2006 and 2016, especially in the southeast and midwest. Still, it has drawn little regulatory scrutiny. Exposure to mixtures of pesticides in general 'is the rule, not the exception', said Nathan Donley, a pesticides researcher with the Center for Biological Diversity, who was not involved with the study. 'For the most part we have absolutely no clue how different mixtures interact in utero, in a child or in an adult,' Donley said. 'Some mixtures probably aren't doing much of anything, others are probably causing significant harm that we have not identified yet.' There is little regulatory oversight of pesticide mixtures in the US, in part because determining health impacts of mixtures is complicated, Donley added. 'The US tends to just default that it's all safe until proven otherwise, and since there is very little research on pesticide mixtures, it's rarely proven otherwise,' Donley said, adding that the unknown risks calls for the use of greater precaution. The authors note that the paper's sample size is small, and the findings point to the need for a larger bio-monitoring study. 'Greater efforts are required to deepen and expand the evaluation of human exposure to pesticides in vulnerable populations,' the authors wrote.

Exposure to a mix of pesticides raises risk of pregnancy complications, study suggests
Exposure to a mix of pesticides raises risk of pregnancy complications, study suggests

The Guardian

time4 days ago

  • The Guardian

Exposure to a mix of pesticides raises risk of pregnancy complications, study suggests

Exposure to multiple pesticides increases the chances of pregnancy complications compared to exposure to just one pesticide, new peer-reviewed research suggests. The findings raise new questions about the safety of exposure to widely used pesticides and herbicides in food and agricultural communities. The study, which bio-monitored pregnant women in a heavily agricultural state in Argentina, adds to recent-but-limited evidence pointing to heightened dangers in mixtures of pesticides. The authors say research into how pesticide mixtures impact human health is important because the vast majority of studies look at exposure to a single pesticide, and regulations on the substances' use are developed based on toxicity to just one. However, people are frequently exposed to multiple pesticides in non-organic meals, or when living in agricultural regions around the world. Studying exposure to those mixtures and other environmental factors is 'essential' to protecting people's health, said the authors, with the National University of the Littoral in Argentina. 'The concept of the exposome, which encompasses all lifetime environmental exposures, underscores the importance of studying pesticides as mixtures rather than in isolation,' the authors wrote. The study comes on the heels of University of Nebraska research that found state cancer records and bio-monitoring data showed that exposure to multiple pesticides could increase the chances of children developing brain cancer by about 36%. The new study checked for pesticides in the urine of nearly 90 pregnant women in Santa Fe, Argentina, a heavily agricultural region, and monitored their pregnancy outcomes. About 40 different pesticides were detected. At least one pesticide was found in the urine of 81% of women, and 64% showed multiple pesticides. Of those, 34% had pregnancy complications. The number of women living in urban areas who had at least one pesticide in their body was only slightly lower than those in rural districts, suggesting that food is also a meaningful exposure route. But about 70% of women in rural settings showed multiple pesticides, compared to 55% of women in urban settings, highlighting a greater risk among the former. Rural participants were over twice as likely to have pregnancy-related complications compared to urban, in part because they are more frequently exposed to mixtures. The Santa Fe region grows dozens of crops, including lettuce, cabbage, chicory, tomato, parsley, spinach, carrot, bell pepper, potato and strawberry, and the wide range of crops leads to the use of more pesticides, the authors wrote. 'The increased prevalence of pregnancy-related complications among rural participants highlights the need for a comprehensive review of pesticide use protocols, exposure limits and health risk assessments in agriculture and horticulture programs,' the authors said. Gestational hypertension was among the most common pregnancy-related complications, and the most common outcome was intrauterine growth restriction, a condition in which the fetus does not grow to a normal weight during pregnancy. The findings may also point to dangers in the type of pesticide to which women are exposed, the authors wrote. Those who had complications showed higher levels of triazole fungicides, a pesticide class that is widely used on crops like corn, soybeans and wheat. Some previous evidence suggests it's a reproductive toxicant, and the authors say their findings show the need for more research on the class's potential effects. Though not all the same pesticides are used in the US or other countries as in Argentina, the use of triazole fungicides increased four-fold in the US between 2006 and 2016, especially in the southeast and midwest. Still, it has drawn little regulatory scrutiny. Exposure to mixtures of pesticides in general 'is the rule, not the exception', said Nathan Donley, a pesticides researcher with the Center for Biological Diversity, who was not involved with the study. 'For the most part we have absolutely no clue how different mixtures interact in utero, in a child or in an adult,' Donley said. 'Some mixtures probably aren't doing much of anything, others are probably causing significant harm that we have not identified yet.' There is little regulatory oversight of pesticide mixtures in the US, in part because determining health impacts of mixtures is complicated, Donley added. 'The US tends to just default that it's all safe until proven otherwise, and since there is very little research on pesticide mixtures, it's rarely proven otherwise,' Donley said, adding that the unknown risks calls for the use of greater precaution. The authors note that the paper's sample size is small, and the findings point to the need for a larger bio-monitoring study. 'Greater efforts are required to deepen and expand the evaluation of human exposure to pesticides in vulnerable populations,' the authors wrote.

DOWNLOAD THE APP

Get Started Now: Download the App

Ready to dive into a world of global content with local flavor? Download Daily8 app today from your preferred app store and start exploring.
app-storeplay-store