The science of sex, love, attraction, and obsession

The symbol for love is the heart, but the brain may be more accurate.

  • How love makes us feel can only be defined on an individual basis, but what it does to the body, specifically the brain, is now less abstract thanks to science.
  • One of the problems with early-stage attraction, according to anthropologist Helen Fisher, is that it activates parts of the brain that are linked to drive, craving, obsession, and motivation, while other regions that deal with decision-making shut down.
  • Dr. Fisher, professor Ted Fischer, and psychiatrist Gail Saltz explain the different types of love, explore the neuroscience of love and attraction, and share tips for sustaining relationships that are healthy and mutually beneficial.

There never was a male fertility crisis

A new study suggests that reports of the impending infertility of the human male are greatly exaggerated.

  • A new review of a famous study on declining sperm counts finds several flaws.
  • The old report makes unfounded assumptions, has faulty data, and tends toward panic.
  • The new report does not rule out that sperm counts are going down, only that this could be quite normal.
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Sperm may play bigger role in pregnancy than we thought

The tiny swimmers appear to transmit signals that "persuade" the female body to have a baby.

Credit: MARCEL MOCHET via Getty Images

The following article was originally published on our sister site, Freethink.

New research suggests that sperm play a bigger role in pregnancy than previously believed, not only fertilizing the egg, but also "persuading" the female body to accept it.

Revisiting sex ed: Human reproduction typically starts with sperm traveling via seminal fluid to an egg and fertilizing it. That creates a zygote, which can then attach to the wall of the uterus and begin the process of developing into a baby.

Implantation isn't a given, though. The woman's immune system may reject the fertilized egg as something "foreign" and prevent her from becoming pregnant.

Persuasive swimmers: Past research has shown that seminal fluid contains proteins that dampen this immune response, encouraging the woman's body to accept the zygote and the pregnancy.

Now, researchers at the University of Adelaide have discovered that sperm send their own signals designed to persuade the woman's body.

"This overturns our current understanding of what sperm are capable of," project leader Sarah Robertson said in a press release. "They are not just carriers of genetic material, but also agents for convincing the female to invest reproductive resources with that male."

The study: For a new study, female mice were mated with males who produced sperm and males who'd been vasectomized (meaning they produced seminal fluid without sperm).

Based on changes in the expression of different genes in the females' uteruses, the researchers determined that the sperm-producing mice prompted a stronger immune tolerance in their mates than the vasectomized rodents.

By introducing male sperm to female cells in the lab, the researchers were able to confirm that the sperm was directly responsible for the changes.

Why it matters: Infertility is a common issue, affecting tens of millions of couples across the globe, and problems such as recurrent miscarriage, preeclampsia, and stillbirth have all been linked to the female immune response during reproduction.

Now that we know that sperm can affect that immune response, researchers may be able to identify new ways to treat infertility — potentially helping some couples conceive and give birth to healthy babies.

Freethink would love to hear from you! If you have a comment about this article or if you have a tip for a future Freethink story, please email us at tips@freethink.com.

7 most notorious and excessive Roman Emperors

These Roman Emperors were infamous for their debauchery and cruelty.

1876. Painted by Henryk Siemiradzki.
  • Roman Emperors were known for their excesses and violent behavior.
  • From Caligula to Elagabalus, the emperors exercised total power in the service of their often-strange desires.
  • Most of these emperors met violent ends themselves.

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Regret over a hookup doesn’t change our behavior

A study finds that sexual regret doesn't change how we behave in the future.

Credit: Niki Sanders/Unsplash
  • Researchers from the Norwegian University of Science and Technology investigate the degree to which regret regarding sexual encounters makes us modify our behavior.
  • Women more often have regrets about encounters that occurred, while men regret the ones that didn't.
  • According to the study, people keep doing what they've been doing and continue to have the same regrets.
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