Every December, Christians around the world celebrate the birth of a baby to a woman who never had sex.
We’ve seen the phenomenon of ‘virgin births’ among pythons, turkeys and even flies.
And just this week, a female crocodile gave birth to 14 fertilised eggs in Costa Rica, despite living alone for more than a decade.
But are ‘virgin births’ really possible in humans?
MailOnline spoke to an expert to find out if this really is the beginning of the end for men.
Virgin births can occur among reptiles, fish and even flies, but what about humans? (stock image)
How does a ‘virgin birth’ work?
‘Virgin birth’ is a natural process called facultative parthenogenesis, meaning a female is able to produce young without any involvement from a male.
It’s extremely rare in nature, although it is found in some other species, most notably mayflies, turkeys, pythons, and boa constrictors.
The case of the crocodile involved a mechanism called ‘terminal fusion automixis’, meaning the female fertilizes her own eggs using a genetic by-product called the second polar body.
This means that both parents are the mother and they have two pairs of the mother’s DNA.
Animals in the wild generally do not reproduce in this way, however, some research now suggests that endangered animals might do so more frequently as finding a mate becomes harder.
A virgin birth, or facultative parthenogenesis, is a rare ability among some animals that allows for the production of offspring without sex.
This is common among fish and reptile species, but scientists are still unsure what makes it possible.
‘We actually still don’t know exactly what it is that makes virgin birth possible in some animals but not in others,’ Professor Russell Bonuriansky, an ecologist at the University of South Wales in Australia, told MailOnline.
‘But we do have some idea of what is required. A normal cell in your body has 46 chromosomes, 23 from the egg and 23 from the sperm. Other animals have different numbers, but half of the chromosomes typically come from the mother and half from the father.’
For humans to form a viable embryo without sperm, the egg would need to replicate its chromosomes to end up with the ‘normal’ number.
The egg would also need to trigger a process of fertilisation – which is usually the role of sperm – and develop the embryo.
But the chances of this occurring are perhaps one in a billion, according to State – making it virtually impossible.
Professor Bonduriansky believes this inability could also be linked to a protective mechanism.
‘Some animals can do this but, for some reason, most can’t,’ he said.
‘[It] functions to prevent eggs from developing into embryos inside the ovaries, which would be lethal to female mammals,’ he continued.
‘However, scientists have devised ways to modify development in mammals so as to allow unfertilised eggs to develop.
‘The most famous example is Dolly the cloned sheep. Artificial cloning is probably possible in humans as well, but of course it presents complex ethical issues.’
Scientists have found the first known crocodile to produce fertilized eggs on its own (stock image)
Despite its rarity, one strange case took place in 1995, with a young boy that was believed to have been partially derived from an unfertilised egg.
As a result, the boy reportedly had a strange number of chromosomes which would typically signify that he was female, according to the New Scientist.
But Professor Bonuriansky says this was not a real example of a virgin birth.
He told MailOnline: ‘This boy is an example of an extremely rare type of genetic mosaic. In people, different body parts sometimes end up being genetically different as a result of accidents in cell division early in embryonic development, or as a result of the fusion of two embryos in the womb. For example, some cells might have an extra chromosome.
‘This boy is very unusual in that some of his cells have no paternal genes at all. This might have occurred because the sperm entered the egg after the first cycles of cell division had already occurred spontaneously.
‘As a result, some of his cells only contain genes from his mother. Nonetheless, his body does have some cells with both maternal and paternal genes, so he is not a true example of virgin birth.’
The British Medical Journal has also recorded around 45 bizarre ‘virgin pregnancies’ in the US since the mid-90s.
While the women did not directly claim to have experienced this, they reported characteristics that were synonymous.
This followed a survey of questions that enquired about vaginal intercourse and sexual history.
‘We weren’t looking for virgin births at all,’ Professor Amy Herring at Gillings School of Global Public Health in North Carolina, said.
‘While analyzing data for a separate project that examined correlates of virginity in adulthood, we were surprised to discover that a number of these individuals who stated they were virgins also reported pregnancies.
‘Once we confirmed these were not programming errors, we became interested in understanding factors related to this type of response pattern.’
Of 7,870 women, 0.8 per cent of those who conceived without sex said they had not used birthing technology to assist their pregnancies.
But, importantly, these results were not medically validated, which could point to biases among respondents.
So what’s the biological point of sex if there’s an option to give birth alone?
Professor Jenny Graves at Australia’s La Trobe University, told The Conversation that parthenogenesis is actually worse in the long run due to risks of disease.
She said: ‘The answer seems to be that although parthenogenesis works fine in the short term, it will always lose out in the long run because recombining two genes each generation is a great way of scrambling the combinations of proteins that pathogens see.
‘A pathogen that can infect one individual can also infect others with the same genes, so it’s no point in having many cloned copies. For instance, the female-only Australian gecko is very susceptible to mite infestation.
‘So the answer to the question of whether virgin birth is a real possibility is: yes, unless you are a mammal.’
HOW DO SPERM MOVE?
Sperm are vital in human reproduction and the motility of the male cells is crucial.
In order to help the sperm cells move, they evolved a ‘tail’ which is called a flagellum.
Sperms’ tails play a critical role in their ability to swim and consequently fertilise an egg.
Sperm are vital in human reproduction and the motility of the male cells is crucial. Sperms’ tails play a critical role in their ability to swim and consequently fertilise an egg
Sperm tails consist of around 1,000 building blocks, including structures known as tubulins, which form long tubes.
Attached to these tubes are moving molecules called motorproteins.
These pull and bend sperm tails, enabling them to swim.
The movement of the tail is powered by a mitochondria, the powerhouse of a cell, which produces energy.
Read the full article here