Oxytocin
The positive and negative effects of the chemical known as the 'love hormone'
A
ADeep within the brain, the pituitary gland produces a hormone called oxytocin. Scientists' first clues about what this molecule does came not from people but from laboratory animals. In prairie voles — small rodents that pair up with a single partner for life — the hormone was found to cement the bond between mates, and in ewes it switched on the caring behaviour aimed at their newborn lambs. Human mothers, too, release it as they give birth, deepening the tie between parent and infant. Hardly any other chemical enjoys such a glowing reputation; 'the love hormone' is the nickname it has earned. A single inhalation, so the claim goes, leaves someone readier to trust, more generous and more willing to cooperate. That rosy picture, however, now needs correcting: a fresh round of research shows the hormone's influence shifting sharply from one individual and one setting to the next, and finds it can sour our dealings with others as easily as sweeten them.
B
BIt was in 2007 that oxytocin's part in human conduct came to light. Tobias Vasch and his team at the Rhineland Institute for Neuroscience in Cologne set volunteers a task in which they could hand over sums of money to an unseen partner whose honesty was not assured. Those given a puff of oxytocin from a nasal spray beforehand, the researchers found, parted with larger amounts than a group handed a harmless placebo. With that one experiment, the study of how the hormone shapes human dealings was born. 'For the best part of a decade it was a rather solitary line of work,' Vasch remembers. 'These days the field is crowded.' The investigations that followed reported that a dose left people more generous, sharper at recognising the feelings on other faces, and calmer in a disagreement. Such findings hardened the assumption that oxytocin reliably brought out the better side of our social selves.
C
CWithin a few years, though, clashing results began appearing. When volunteers in a study run by Dania Röslund of Fjordland University competed in a game, those who had breathed in the hormone took greater satisfaction in defeating their rivals — and felt a sharper sting of envy whenever a rival came out ahead. The hormone's effects, moreover, could pull in opposite directions according to the person receiving it. Priya Venkatesan of the Fenwick Medical School reported that oxytocin sharpened people's reading of others' emotions, but only among those who had been socially awkward to start with; in volunteers who were especially anxious, or easily wounded by rejection, it actually made them less willing to cooperate.
D
DA further finding was that who we are dealing with alters what the hormone does. Work by Lieve Maartens at the Lowlands Institute of Cognitive Science showed that a dose of oxytocin could make people less, not more, obliging when the person across from them was a total stranger. At much the same time, Joris Halbertsma of the Randstad Behavioural Institute uncovered a streak of favouritism in those given the hormone: Dutch men, for instance, grew quicker to pair pleasant words with home-grown names than with foreign-sounding ones. Oxytocin, Halbertsma argues, pushes us to look after our own circle and guard it against threats from beyond. Rather than spreading warmth indiscriminately, the hormone seems to deepen the loyalties and prejudices we already hold.
E
EHints of these complications had, in truth, been there from the outset. Venkatesan has lately shown that in close to half of the studies already published, the hormone made a difference only to particular people or under particular conditions. Such results were once brushed aside; today they steer research along fresh paths, and a subtler picture of what oxytocin does is emerging. For Venkatesan, the way forward is to pin down the hormone's single underlying job rather than keep listing its apparently limitless effects. Several explanations are on the table, and they need not rule one another out: perhaps the hormone dampens anxiety and fear, or perhaps it merely prompts us to reach out for company. Her own view is that oxytocin works like a spotlight trained on social signals — the small shift of posture, the flicker of the eyes, the falling note in a voice — leaving people keener observers of those around them. That would explain why it nudges us to meet another's gaze and helps us name what others feel. Yet for anyone thin-skinned, or inclined to read the worst into every signal, the same effect could make matters worse.
F
FThat the oxytocin story has grown more tangled should come as no surprise. Creatures as different as octopuses and sheep all carry the hormone, and its lineage reaches back some five hundred million years. 'This is an old and very plain molecule that evolution has repeatedly put to new uses,' notes Elena Marchetti of the Adriatic Neuroscience Centre. 'Because it acts on ancient structures such as the amygdala, its fingerprints end up on almost everything.' Venkatesan takes the same line. 'At bottom oxytocin is probably doing a few very basic things; but once you add our more sophisticated thinking and the tangle of real social life, those basic processes can surface in quite different ways from one person, and one situation, to the next.'
Kéo chỉnh
Question 1 - 4
Which section contains the following information?
A
B
C
D
E
F
1.
a reference to the extremely long span of evolutionary time behind the hormone
2.
an observation that evidence formerly overlooked is now shaping new lines of enquiry
3.
a statement that the hormone can harm our social dealings as much as improve them
4.
an account of how work on the hormone shifted from a neglected topic to a crowded one