Scientist reveals exactly how long it would take for humans to go EXTINCT if we stopped having babies

Daily Mail​

2 days ago

It is a terrifying prospect right out of a dystopian science fiction movie.
But a scientist has now revealed exactly how long it would take for humanity to go extinct if we stopped having babies.
Since very few people live beyond a century, you might think that humanity would take around 100 years to vanish.
However, according to Professor Michael Little, an anthropologist at Birmingham University, we would probably disappear even faster.
That's because there would eventually not be enough young people of working age to keep civilisation functioning.
Writing in The Conversation, Professor Little explained: 'As an anthropology professor who has spent his career studying human behavior, biology and cultures, I readily admit that this would not be a pretty picture.
'It's likely that there would not be many people left within 70 or 80 years, rather than 100, due to shortages of food, clean water, prescription drugs and everything else that you can easily buy today and need to survive.
'Eventually, civilization would crumble.'
If all of humanity suddenly lost the ability to have children, the world would not end overnight.
Instead, the world's population would gradually shrink as the older generations die and fail to be replaced by the next.
If there were enough food and supplies to go around, the world's population would simply get older until everyone currently on Earth died of old age.
The countries that would show the most rapid declines would be those with already ageing populations such as Japan and South Korea.
Meanwhile, countries with younger populations such as Niger, where the median age is just 14.5, would remain well-populated for longer.
However, much like in the science fiction classic Children of Men, Earth's extinction would not follow such a smooth trajectory into oblivion.
Professor Little says: 'Eventually there would not be enough young people coming of age to do essential work, causing societies throughout the world to quickly fall apart.
'Some of these breakdowns would be in humanity's ability to produce food, provide health care and do everything else we all rely on.
'Food would become scarce even though there would be fewer people to feed.'
This societal collapse would likely lead to Earth's depopulation well before most people live out their natural lifespans.
Luckily, Professor Little says that an abrupt halt in births is 'highly unlikely unless there is a global catastrophe'.
One possible scenario that could lead to such a disaster is the spread of a highly contagious disease which causes widespread infertility.
Studies suggest there are only a small number of viruses which have an impact on male fertility, including deadly strains such as Zika virus and HIV.
But none of these cause infertility in 100 per cent of cases and many only have mild impacts on fertility-related issues such as reduced sperm count.
This means that a virus which wipes out the world's ability to reproduce thankfully remains a matter for science fiction.
However, the possibility of facing a rapidly ageing population due to a declining birth rate is a far more pressing concern.
The world's population has boomed in the last 100 years, expanding from just 2.1 billion in 1930 to 8.09 billion today.
Current estimates suggest that humanity will continue to expand until the mid-2080s, reaching a peak of 10 billion.
But as humanity reaches its peak size, the number of babies being born each year is already beginning to fall.
In some cases, fertility rates have now fallen below the 'replacement rate' of 2.1 children per woman needed to maintain a stable population.
Combined with growing life expectancy, this means the average age of many countries has begun to increase.
Billionaire Elon Musk - who has 14 children with four women - has for years warned about population collapse caused by a 'baby bust' in America and the West.
In the UK, the Office for National Statistics found that the fertility rate fell to just 1.44 children per woman in 2024 down from the 'Baby Boom' of 2.47 children per woman in 1946.
This is leading to a rapid increase in the average age, reaching 40.7 years in 2022 from 39.6 years in 2011.
England and Wales only recorded 591,072 live births in 2023, the lowest number since 1977. This has brought the UK's fertility rate below the 'replacement rate' - the number of babies per woman needed to maintain a stable population
Other countries are facing an even greater birth rate crisis, sparking serious concerns for economic growth.
China, which artificially dropped its birth rate through the 'one child policy', has a fertility rate of just 1.18 children per women.
This has led many to worry about how a dwindling working-age population will be able to care for a growing number of elderly people.
While falling birth rates alone aren't likely to destroy humanity, Professor Little cautions that humans should be wary.
Professor Little says: 'Our species, Homo Sapiens, has been around for at least 200,000 years. That's a long time, but like all animals on Earth we are at risk of becoming extinct.'
He points to the example of the Neanderthals, a close relative of Homo sapiens, which lasted over 350,000 years before gradually declining and becoming extinct.
Professor Little added: 'Some scientists have found evidence that modern humans were more successful at reproducing our numbers than the Neanderthal people.
'This occurred when Homo sapiens became more successful at providing food for their families and also having more babies than the Neanderthals.'
So what is behind the West's baby bust?
Women worldwide, on average, are having fewer children now than previous generations.
The trend, down to increased access to education and contraception, more women taking up jobs and changing attitudes towards having children, is expected to see dozens of countries' population shrink by 2100.
Dr Jennifer Sciubba, author of 8 Billion and Counting: How Sex, Death, and Migration Shape Our World, told MailOnline that people are choosing to have smaller families and the change 'is permanent'.
'So it's wise to focus on working within this new reality rather than trying to change it,' she said.
Sex education and contraception
A rise in education and access to contraception is one reason behind the drop off in the global fertility rate.
Education around pregnancy and contraception has increased, with sex education classes beginning in the US in the 1970s and becoming compulsory in the UK in the 1990s.
'There is an old adage that 'education is the best contraception' and I think that is relevant' for explaining the decline in birth rates, said Professor Allan Pacey, an andrologist at the University of Sheffield and former chair of the British Fertility Society.
Elina Pradhan, a senior health specialist at the World Bank, suggests that more educated women choose to have fewer children due to concerns about earning less when taking time off before and after giving birth.
In the UK, three in 10 mothers and one in 20 fathers report having to cut back on their working hours due to childcare, according to ONS data.
They may also have more exposure to different ideas on family sizes through school and connections they make during their education, encouraging them to think more critically about the number of children they want, she said.
And more educated women may know more about prenatal care and child health and may have more access to healthcare, Ms Pradhan added.
Professor Jonathan Portes, an economist at King's College London, said that women's greater control over their own fertility means 'households, and women in particular, both want fewer children and are able to do so'.
More women entering the workplace
More women are in the workplace now than they were 50 years ago — 72 vs 52 per cent — which has contributed to the global fertility rate halving over the same time period.
Professor Portes also noted that the drop-off in the birth rate may also be down to the structure of labour and housing markets, expensive childcare and gender roles making it difficult for many women to combine career aspirations with having a family.
The UK Government has 'implemented the most anti-family policies of any Government in living memory' by cutting services that support families, along with benefit cuts that 'deliberately punish low-income families with children', he added.
As more women have entered the workplace, the age they are starting a family has been pushed back. Data from the ONS shows that the most common age for a women who were born in 1949 to give birth was 22. But women born in 1975, were most likely to have children when they were 31-years-old.
In another sign that late motherhood is on the rise, half of women born in 1990, the most recent cohort to reach 30-years-old, remained childless at 30 — the highest rate recorded.
Women repeatedly point to work-related reasons for putting off having children, with surveys finding that most women want to make their way further up the career ladder before conceiving.
However, the move could be leading to women having fewer children than they planned. In the 1990s, just 6,700 cycles of IVF — a technique to help people with fertility problems to have a baby — took place in the UK annually. But this skyrocketed to more than 69,000 by 2019, suggesting more women are struggling to conceive naturally.
Declining sperm counts
Reproductive experts have also raised the alarm that biological factors, such as falling sperm counts and changes to sexual development, could 'threaten human survival'.
Dr Shanna Swan, an epidemiologist at Icahn School of Medicine at Mount Sinai in New York City, authored a ground-breaking 2017 study that revealed that global sperm counts have dropped by more than half over the past four decades.
She warned that 'everywhere chemicals', such as phthalates found in toiletries, food packaging and children's toys, are to blame. The chemicals cause hormonal imbalance which can trigger 'reproductive havoc', she said.
Factors including smoking tobacco and marijuana and rising obesity rates may also play a role, Dr Swan said.
Studies have also pointed to air pollution for dropping fertility rates, suggesting it triggers inflammation which can damage egg and sperm production.
However, Professor Pacey, a sperm quality and fertility expert, said: 'I really don't think that any changes in sperm quality are responsible for the decline in birth rates.
'In fact, I do not believe the current evidence that sperm quality has declined.'
He said: 'I think a much bigger issue for falling birth rates is the fact that: (a) people are choosing to have fewer children; and (b) they are waiting until they are older to have them.'
Fears about bringing children into the world
Choosing not to have children is cited by some scientists as the best thing a person can do for the planet, compared to cutting energy use, travel and making food choices based on their carbon footprint.
Scientists at Oregon State University calculated that the each child adds about 9,441 metric tons of carbon dioxide to the 'carbon legacy' of a woman. Each metric ton is equivalent to driving around the world's circumference.
Experts say the data is discouraging the climate conscious from having babies, while others are opting-out of children due to fears around the world they will grow up in.
Dr Britt Wray, a human and planetary health fellow at Stanford University, said the drop-off in fertility rates was due to a 'fear of a degraded future due to climate change'.
She was one of the authors behind a Lancet study of 10,000 volunteers, which revealed four in ten young people fear bringing children into the world because of climate concerns.