Have you ever been sat on a flight with a crying baby in your vicinity, wondering more and more with each successive wail how much longer you can stand the sound? Or maybe you’ve been a parent, barely able to resist for a second before running to soothe your precious infant’s ear-piercing distress? Most of us have been there at some point in our lives. But what exactly is it about a baby’s cry that makes it so hard to ignore?
But why cry? As is the case with any primal vocalisation, crying evolved to have a specific impact on listeners. Plentiful research has shown these calls to specifically activate adults’ brain regions important for attention and empathy. This makes them highly effective at grabbing the attention of caregivers and orienting them to provide company, safety, food, or comfort.
While research is in its early stages, oxytocin – popularly termed the “love hormone” and central to the fostering of social bonds – seems to be at the neurochemical heart of this attention-grabbing behaviour. Infant distress results in reduced oxytocin and opioid levels, and evidence suggests that this then triggers and escalates crying. When a mother hears these cries, this in turn causes an increase in her oxytocin levels and encourages care-giving behaviour.
Smarter brains are blood-thirsty brains
August 30, 2016
A University of Adelaide-led project has overturned the theory that the evolution of human intelligence was simply related to the size of the brain—but rather linked more closely to the supply of blood to the brain.
The international collaboration between Australia and South Africa showed that the human brain evolved to become not only larger, but more energetically costly and blood thirsty than previously believed.
The research team calculated how blood flowing to the brain of human ancestors changed over time, using the size of two holes at the base of the skull that allow arteries to pass to the brain. The findings, published in the Royal Society Open Science journal, allowed the researchers to track the increase in human intelligence across evolutionary time.
“Brain size has increased about 350% over human evolution, but we found that blood flow to the brain increased an amazing 600%,” says project leader Professor Emeritus Roger Seymour, from the University of Adelaide. “We believe this is possibly related to the brain’s need to satisfy increasingly energetic connections between nerve cells that allowed the evolution of complex thinking and learning.
“To allow our brain to be so intelligent, it must be constantly fed oxygen and nutrients from the blood.