A couple of experiments by Dario Maestripieri, a University of Chicago biologist, offer insight into how early mothering affects our brain's chemical responses later in life -- as well as how we develop the urge to mother.
Since the 1990s, Maestripieri has worked with rhesus macaque monkeys. Socially, the rhesus aren't so much like humans. They're non-monogamous; females live in matrilineal groups, sharing food and casually lending a hand with each others' babies. Males hang out with each other, fighting for dominance; they occasionally stop by the females to copulate or steal food. But if you look at the attachment between mother and baby, Maestripieri thinks they're a perfect model: Rhesus females have one baby at a time, and they invest years in their care, just like humans do.

Observing the rhesus colony at the Yerkes Primate Center in Atlanta, Maestripieri noticed that the rhesus' mothering styles were as varied as humans'. Even before they became mothers, some females just loved to touch and hold babies, but some were about as maternal as Paris Hilton. When they had babies of their own, some of them doted, and some were downright abusive. So, he began a systematic look at how the rhesus' hormones changed with time and experience.

Maestripieri compared the mothers' estrogen, progesterone, and prolactin levels and tracked them over time, but found no differences. He tried manipulating their endogenous opioids, the beta-endorphins that get us naturally high. Nothing. Next, he looked at the role of early experiences. Right after birth, he switched around some newborn monkeys, giving the babies of good mothers to bad mothers, and letting the good mothers raise the babies of abusive females. The children of aggressive mothers tended to be aggressive themselves -- even though they were raised by sweet mothers. The same held true for sociability; the babies of irritable, unfriendly mothers tended to react to others the same way, even though they grew up in a cordial clan. This showed that an individual's tendency to be sweet or mean may be inherited.

But when Maestripieri looked at the brain chemicals of baby monkeys, he found that the kind of mothering they got did matter -- a lot. Some of the babies who were regularly rejected by their mothers -- being pushed away when they tried to climb into her arms, for example -- had up to 20 percent less serotonin, a neurotransmitter that's a mood elevator. Low levels of serotonin are associated with depression, anxiety, and impulsive aggression in monkeys and humans. The more rejection a baby experienced, the less serotonin it produced, and these low levels continued into adulthood. Some of these low-serotonin monkeys went on to become bad mothers themselves.

While serotonin isn't a direct part the oxytocin/attachment system, the two brain chemicals are closely related. Serotonin stimulates the release of both oxytocin and vasopressin. Therefore, it's a good bet that monkeys and humans with low levels of serotonin don't experience as strong an oxytocin response. They may not bond as deeply; they may not be able to bond at all.

About half of the abused monkey babies, however, went on to become relatively good mothers. And they didn't have lowered serotonin levels. It's possible that they inherited more resilience to stress and more oxytocin-rich parasympathetic nervous systems from their loving mommas. This is reassuring to all of us who didn't get the kind of mothering we wish we had. We can overcome both nature and nurture to raise children who are even more secure and more loving than we are.

If, like me, you're fascinated about how nature and nurture made us the way we are -- and why we do or don't turn out like our parents, it's well worth searching out his research. Here are the studies I've covered:

Maestripieri, Dario. 2003. Similarities in Affiliation and Aggression Between Cross-Fostered Rhesus Macaque Females and Their Biological Mothers. Developmental Psychobiology 43(4):321-327.

Maestripieri, Dario. 2005. Early experience affects the intergenerational transmission of infant abuse in rhesus monkeys. Proceedings of the National Academy of Sciences 102:9726–9729.

In response to a recent comment, I took a new look at the database of clinical trials that are recruiting subjects for oxytocin studies, available at ClinicalTrials.gov. I see that Daniel Feifel of the University of California San Diego is recruiting subjects for two studies to test oxytocin on symptoms of schizophrenia.

And it looks like Evdokia Anagnostou of Eric Hollander's Mt. Sinai team is recruiting for a couple of studies of adults with ASD, although it's hard to tell if the database is current.

Meanwhile, the National Institutes of Mental Health is recruiting for a study of people without psychiatric diagnoses on "Identifying the Role of Oxytocin and Vasopressin in the Functioning of Neurocognitive Systems Involved in Mood Disorders."

We can expect more and more of these as #1 scientists strive to learn more and more about the neurochemical basis of emotion and #2 pharm companies look for new classes of drugs they can sell.

 Oxytocin is the new party drug in India, according to this story from the Times of India.

I've seen previous news stories about police seizing illegal oxytocin or counterfeit versions, and wondered if this was a mistranslation and they meant oxycontin, the pain reliever. And evidently farmers often inject cows with oxytocin to increase milk production, an effect noted by Kristen Uvnas Moberg, the Swedish researcher who was the first to understand this hormone/neurochemical's powerful effects on our moods and ability to bond.

The Times explains that kids inject the oxytocin.

According to a pharmacy expert, the drug induces a numb state of mind. "After a period of intense activity and enjoyment where the addicts are numb to pain, effect of the drug wears off and the users drop, literally. It leaves the addicts’ nervous system in a mess and the users need time to recover," he said.

I dunno about this numb state of mind. They may, rather, feel very calm and connected to each other, similar to the way people who take ecstasy at raves say they feel. (It's been shown that this drug causes a release of oxytocin in the brain of mice.) Oxytocin certainly does reduce sensitivity to pain, and the "mess" side effects have been seen in people who take ecstasy frequently.

The authorities may be overstating the negative effects, as they sometimes do. Nevertheless, I do NOT advocate using oxytocin recreationally. First, because it acts in so many ways to regulate the body, messing with the natural system could have unforeseen and not pretty consequences. Second, it's dangerous to inject anything into your body if you don't have sterile equipment and know what you're doing -- especially if you can't be sure of what you're injecting.

The Mike & Juliet Show was mostly an attack on Liquid Trust. The manufacturer refuses to say how much oxytocin is in the product, but it won't get into your body - or anyone else's -- if you spray it on your clothes or even skin.

There are plenty of ways to experience a natural oxytocin release without buying anything. In my book (The Chemistry of Connection, April 2009) I explain the oxytocin response, why we don't all have a healthy one, and talk about ways of building it up.

But all of us do have a hypothalamus and all of us do release oxytocin; without it, we'd die. To get the social benefits, try one or more of the following. If you can, set aside at least 15 minutes to do this and nothing else:

• Cuddle
• Sing in a choir
• Hold a baby
• Stroke a dog or cat
• Perform a generous act
• Pray
• Make love
• Have an orgasm (alone or with someone else)

I'm very excited to be a guest on the Morning Show with Mike and Julie on Fox this Thursday. And, while I'll talk about my own experience taking oxytocin, I'll also talk about the research and my book.

The producers hope to find someone who's taken oxytocin on their own, just to see how it feels, solve a social problem or something. If that's you, and you're prepared to show up in New York by Thursday 8 AM (they'll pay travel) email

michelle dot niger at mikeandjuliet dot com right away!