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Toppling a widespread assumption that a "lactation" hormone only cues animals to produce food for their babies, Cornell researchers have shown the hormone also prompts zebra finches to be good parents.
Lowering the hormone prolactin in zebra finches reduces the time and attention both males and females spend taking care of their chicks, the study found. The research was published Jan. 3 in Hormones and Behavior.
Work - Notion - Prolactin - Lactation - Hormone
"This work changes the notion that prolactin is just a lactation hormone. It's a hormone that has a more basic function of feeding in general," said lead author Kristina Smiley, Ph.D. '17.
Smiley, now a postdoctoral researcher at University of Otago, New Zealand, co-wrote the paper while at Cornell with Elizabeth Adkins-Regan, professor of psychology and of neurobiology and behavior.
Work - Sheds - Role - Prolactin - Time
The work sheds light on how the role of prolactin has evolved over time to include lactation, Smiley said.
It has long been thought in the field that prolactin not only prompts mammals to produce milk, but also cues birds to take care of their young. That's because previous studies had shown prolactin cues a few specialized birds and fish to produce regurgitated "crop" milk and milky secretions to feed their offspring.
Studies - Birds - Food - Source
But no studies had shown how prolactin works in birds that do not produce food from an internal source.
This research confirms that the hormone does prompt parents to feed their offspring – even in a species that does not internally produce food for its young, Smiley said.
Implications - Understanding - Hormone - Animals - One
And that has implications for our understanding of how prolactin evolved from a hormone that prompts animals to feed their offspring into one that makes an animal produce the food themselves, Smiley said.
"Since birds and fish are older evolutionarily than mammals, prolactin's larger role beyond just feeding offspring tells us prolactin has evolved to become more specialized for lactation behaviors in mammals,"...
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