Sperm Snatching as a Problem of Dynamic Inconsistency

Two articles have appeared recently on the topic of sperm snatching. The first is a new blog here at Big Think and the second is an article in yesterday’s Daily Mail by writer Liz Jones. In the Daily Mail article Ms. Jones describes how, over the course of two relationships, she snuck into the bathroom in the middle of the night in order to inseminate herself using sperm rescued from condoms. This despite the fact that both men had made their unwillingness to become fathers very, very clear (hence the condom usage).

According to the Daily Mail article, a 2001 survey showed that 42% of women would lie about their contraceptive use if they wanted to get pregnant and their partner did not.

None of Ms. Jones's attempts at self-fertilization worked (not surprisingly since condoms are full of spermicide) but if they had, and she had given birth, the unwilling baby daddy would have found himself paying child support for the next twenty years.

Maybe Ms. Jones would say that is not true, that she planned to raise her baby alone without any support from an unwilling father. But this contention of future independence by sperm snatchers creates a problem that economists call dynamic inconsistency. And, as any good economist will tell you, there is nothing irrational about claiming not to want support during pregnancy and then demanding it after the baby is born.

Before I tell you exactly how dynamic inconsistency works, let me tell you a story that illustrates this concept.

It concerns a friend of mine who had his sperm snatched under circumstances that were very similar to those described in the Daily Mail article. The difference in my friend’s case is that his sperm snatcher got lucky and became pregnant.

This is what happened from his perspective:


  • His ex-girlfriend contacted him to say that she was pregnant but that as far as she was concerned he was merely a sperm donor. She gave him her assurance that she would not ask him for support and planned to raise the baby on her own.
  • Some time after the baby was born she wrote him an email to tell him that she had had the baby and that it would be “nice to have some money for diapers.”
  • Six months later she hired a lawyer and successfully sued him for a significant amount of child support that he is now dutifully paying.
  • So, in theory at least this was a very bad outcome for my friend. I say, “in theory” because once his ex-girlfriend opened the door to making financial demand he reciprocated with demands to spend time with his daughter. Now, a few years later, she may be costing him a small fortune but he does love her dearly.

    Now, this is only half the story. Here is what I believe happened from her perspective:

  • He broke up with her when she was in her late thirties. It was fairly clear that her last few years of fertility were slipping away and that she had to act soon if she ever hoped to be a mother. She convinced him to have sex with her one more time, as a nice way to say goodbye, and that made her dreams come true.
  • During her pregnancy she felt good about her decision. She wanted the baby, while he did not (in fact he was very angry that he had been deceived – a fact she never denied) and since she had a good job she felt happy and confident in raising the baby without his help.
  • Once the baby was born friends and family started to press her on why she wasn’t getting child support. Of course she knew the whole story--they did not--but after a while their arguments made sense. After all, she could convince herself, the money wasn’t for her, it was for their baby.
  • At the six month mark, the small amounts of money he had been giving her no longer seemed fair. She was the one doing all the work. She was the one staying up late at night and putting her career on hold. He owed her for everything she was going through and their daughter deserved to have the best of everything that he could afford.

  • Just for the record, I did tell him while she was pregnant that this is exactly what would happen.

    Dynamic (or time) inconsistency is an economic concept that tells that preferences can change over time. What may seem like the optimal choice in period one (here during pregnancy) is not necessarily the optimal choice in period two (here when the baby is born).

    It may seem optimal to a woman to claim independence when pregnant, especially since the decision to have the baby was her own, yet once the child has been born child support legislation gives women an incentive to get support for her child.

    After all, it is true that the money is not for her – it is for their baby.

    Usually the best way to solve a dynamic inconsistency “problem”, where decisions are made today that are no longer optimal tomorrow, is to form unbreakable contracts. However, in most countries women cannot sign away her baby's right to support from his/her father because support from both parents is in the best interest of the child. So, even if a contract was written it would likely be unenforceable leaving us back where we started.

    In the article here at Big Think, blogger Pamela Haag tells the story of a woman who is a self described “sperm hunter.” In that piece the young woman claims both that she can’t afford a sperm bank and that when she gets pregnant she won’t contact the father.

    As I have already said, not contacting the father and not asking for child support after the baby is born is completely irrational behavior. What dynamic inconsistency tells us though is any man who is rational should be able to foresee this change in preferences for support and behave accordingly.

    Both of these articles suggest, to me at least, that now really is the right time for effective male birth control.

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    Experts argue the jaws of an ancient European ape reveal a key human ancestor.

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    • The jaw bones of an 8-million-year-old ape were discovered at Nikiti, Greece, in the '90s.
    • Researchers speculate it could be a previously unknown species and one of humanity's earliest evolutionary ancestors.
    • These fossils may change how we view the evolution of our species.

    Homo sapiens have been on earth for 200,000 years — give or take a few ten-thousand-year stretches. Much of that time is shrouded in the fog of prehistory. What we do know has been pieced together by deciphering the fossil record through the principles of evolutionary theory. Yet new discoveries contain the potential to refashion that knowledge and lead scientists to new, previously unconsidered conclusions.

    A set of 8-million-year-old teeth may have done just that. Researchers recently inspected the upper and lower jaw of an ancient European ape. Their conclusions suggest that humanity's forebearers may have arisen in Europe before migrating to Africa, potentially upending a scientific consensus that has stood since Darwin's day.

    Rethinking humanity's origin story

    The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)

    As reported in New Scientist, the 8- to 9-million-year-old hominin jaw bones were found at Nikiti, northern Greece, in the '90s. Scientists originally pegged the chompers as belonging to a member of Ouranopithecus, an genus of extinct Eurasian ape.

    David Begun, an anthropologist at the University of Toronto, and his team recently reexamined the jaw bones. They argue that the original identification was incorrect. Based on the fossil's hominin-like canines and premolar roots, they identify that the ape belongs to a previously unknown proto-hominin.

    The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape Graecopithecus, which the same team tentatively identified as an early hominin in 2017. Graecopithecus lived in south-east Europe 7.2 million years ago. If the premise is correct, these hominins would have migrated to Africa 7 million years ago, after undergoing much of their evolutionary development in Europe.

    Begun points out that south-east Europe was once occupied by the ancestors of animals like the giraffe and rhino, too. "It's widely agreed that this was the found fauna of most of what we see in Africa today," he told New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"

    He recently outlined this idea at a conference of the American Association of Physical Anthropologists.

    It's worth noting that Begun has made similar hypotheses before. Writing for the Journal of Human Evolution in 2002, Begun and Elmar Heizmann of the Natural history Museum of Stuttgart discussed a great ape fossil found in Germany that they argued could be the ancestor (broadly speaking) of all living great apes and humans.

    "Found in Germany 20 years ago, this specimen is about 16.5 million years old, some 1.5 million years older than similar species from East Africa," Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."

    Migrating out of Africa

    In the Descent of Man, Charles Darwin proposed that hominins descended out of Africa. Considering the relatively few fossils available at the time, it is a testament to Darwin's astuteness that his hypothesis remains the leading theory.

    Since Darwin's time, we have unearthed many more fossils and discovered new evidence in genetics. As such, our African-origin story has undergone many updates and revisions since 1871. Today, it has splintered into two theories: the "out of Africa" theory and the "multi-regional" theory.

    The out of Africa theory suggests that the cradle of all humanity was Africa. Homo sapiens evolved exclusively and recently on that continent. At some point in prehistory, our ancestors migrated from Africa to Eurasia and replaced other subspecies of the genus Homo, such as Neanderthals. This is the dominant theory among scientists, and current evidence seems to support it best — though, say that in some circles and be prepared for a late-night debate that goes well past last call.

    The multi-regional theory suggests that humans evolved in parallel across various regions. According to this model, the hominins Homo erectus left Africa to settle across Eurasia and (maybe) Australia. These disparate populations eventually evolved into modern humans thanks to a helping dollop of gene flow.

    Of course, there are the broad strokes of very nuanced models, and we're leaving a lot of discussion out. There is, for example, a debate as to whether African Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies, Homo ergaster.

    Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a single migration out of Africa or at least two major waves of migration followed by a lot of interbreeding.

    Did we head east or south of Eden?

    Not all anthropologists agree with Begun and his team's conclusions. As noted by New Scientist, it is possible that the Nikiti ape is not related to hominins at all. It may have evolved similar features independently, developing teeth to eat similar foods or chew in a similar manner as early hominins.

    Ultimately, Nikiti ape alone doesn't offer enough evidence to upend the out of Africa model, which is supported by a more robust fossil record and DNA evidence. But additional evidence may be uncovered to lend further credence to Begun's hypothesis or lead us to yet unconsidered ideas about humanity's evolution.

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