Tag Archives: Evolution

Oxytocin, A Conspiracy Story

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Conspiracy theories maintain that a small group of people can not only change the world, but that they can do so in such a way that virtually everyone is unaware of their role in shaping history. These theories are criticized, in part, because they assume that too few people can get away with too much.

conspiracy-theory-alertNeuroscience commentators have adopted conspiracy-like theories about the molecule oxytocin. These theories hold that evolution has found a way to make this molecule solely responsible for complex psychological phenomena like altruism, happiness, love, morality, or trust. Can a single molecule really get away with so much?

As is often the case, the science is more complicated than its commentary. A hormone that acts as a neuropeptide in the mammalian brain (Landgraff & Neuman, 2004), oxytocin plays many roles in reproduction and other social behaviors for many species, including ours (Gimpl & Fahrenholz, 2001; MacDonald & MacDonald, 2010).

Simplistic accounts of oxytocin’s function are Procrustean beds that suffer from four serious problems.

Problem 1: What Exactly Does Oxytocin Do?

Terms like altruism, happiness, love, morality, and trust are not synonyms (e.g., love is a feeling whereas morality refers to beliefs about right and wrong). This means that either oxytocin is the molecule behind only one of these concepts, or it plays a role in something that is present in all of them (e.g., the feeling of attachment).

In either case, neuroscience commentators should not rush to label oxytocin as the molecule of [insert complex psychological phenomenon] with such confidence.

Problem 2: Inconsistent Findings about Oxytocin

The positive effects of oxytocin in experiments are not always consistent. In fact, most studies only find evidence of these effects in some people under some circumstances (Bartz, Zaki, Bolger, & Ochsner, 2011). For example, oxytocin does not increase participants’ trust of individuals who appear untrustworthy (Mikolajczak et al., 2010).

Some studies find that oxytocin has negative effects (Bartz et al., 2011), like defection (Declerck, Boone, & Kiyonari, 2010), envy (Shamay-Tsoory et al., 2009), and in-group favoritism, the preferential treatment of the groups to which we belong (De Dreu, 2012).

Problem 3: Oxytocin Does Not Work Alone

Oxytocin is part of a complex brain chemistry. This molecule regulates social behavior and cognition alongside the neuropeptide vasopressin (Donaldson & Young, 2008; Carter, Grippo, Pournajafi-Nazarloo, Ruscio, & Porges, 2008). For example, individual differences in a vasopressin receptor correlate with variability in altruism displays (Knafo et al., 2007).

In fact, vasopressin and oxytocin have many similarities. They share a receptor family (Peter et al., 1995) and work in the same neural pathway (Ebstein et al., 2009). They were likely created by the duplication of the same ancestral gene (Gimpl & Fahrenholz, 2001) and the same gene may regulate their levels (Ebstein, Knafo, Mankuta, Chew, & Lai, 2012).

Problem 4: Negative Consequences of Oxytocin Hype

Science writer Ed Yong has argued that commentary that oversells our understanding of oxytocin can lead to its misuse by a misinformed public. The alleged prosocial effects of this molecule have led parents to give oxytocin to their autistic children (Yong, 2012a, 2012b). This is troubling because the side effects of oxytocin are not fully understood yet.

Takeaways

  • Neuroscience commentators claim incorrectly that oxytocin is the molecule behind complex psychological phenomena like altruism, happiness, love, morality, or trust
  • These simplistic accounts suffer from four serious problems
    1. Inconsistency with each other
    2. Dismissal of conflicting scientific findings
    3. Oversimplification of brain chemistry
    4. Dangerous consequences from a misinformed public

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The Brain Is Not That Hard

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Promiscuous Teleology

From childhood, we show a proclivity for promiscuous teleology, readily ascribing function and purpose to the objects around us (Kelemen, 1999). We view an apple primarily as nourishment; an apple tree as a source of apples first and foremost. We are wont to believe that most every thing, natural or artificial, is there for a special reason; designed with a larger goal in mind.

This teleological bias is often present in neuroscience commentary. The finding that a brain region shows more neural activity when people (often adults) do X than when they do Y is taken as evidence that our brain is “hard-wired,” or evolved, for the purpose of doing X. Using this logic, neuroscience commentators claim that psychological phenomena ranging from altruism to racism are built in to our neural hardware from birth.

Evolution versus Experience

The brain is by no means a blank slate at birth, of course; it is the product of evolution (Creely & Khaitovich, 2006). But genes are not destiny; the experiences that we have and the environments that we navigate shape how our brains function in critical ways. For example, the brains of blind humans repurpose cortical regions typically involved in vision for other senses, like audition and touch (Pascual-Leone, Amedi, Fregni, & Merabet, 2005).

Superman_Batman_by_Clayton_HenryConsequently, the finding that a brain region shows more neural activity when people do X than when they do Y need not mean that this brain region evolved to do X; there may be no “hard-wiring” at work. Our brains can tell Batman and Superman apart, but it does not follow that we evolved an ability to identify super heroes. What we experience (e.g., comic books and action movies) has an important influence in how our brains function. This neuroplasticity helps us adapt successfully to an environment that changes constantly (van Praag, Kempermann, & Gage, 2000).

Hard Wires Require Hard Evidence

Neuroscience commentators who rush to evolutionary interpretations of neuroscience studies are often making a Procrustean bed. They reach conclusions that say more about their promiscuous teleology than about what can reasonably be induced from the data at hand. It is difficult to show that an element of our psychology is the product of evolution.

For example, to show conclusively that laughter is “hard-wired” in the brain would require a deprivation experiment: does a person raised in isolation laugh spontaneously? Barring such an unethical study, it would require converging evidence from scientific experiments that examine development (do infants laugh before they hear laughter?), culture (do people in all cultures laugh?), and genetics (can we identify genes that, when expressed, allow us to laugh?) (Nota bene: See here for an interesting discussion on the evolution of laughter.)

Takeaways

  • Neuroscience commentators often interpret data from neuroscience studies as evidence that different psychological phenomena are “hard-wired” in the brain
  • Such evolutionary explanations rarely follow from the results provided by these studies
  • Claims about the evolutionary status of a psychological phenomenon are difficult to make because they require converging evidence from different scientific disciplines

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