Her labor begins, and she leans back on her bottom, pulling the first baby out of her body with her own hands and teeth. Within five minutes, another newborn arrives. Soon, her babies are squirming around her, squealing and desperate to suckle.
Although the mother rat has never given birth before this, she is now responsible for a dozen lives—so she hits the ground running, instinct as her compass, biology as her map. She has already stockpiled the materials for a warm nest. She uses what she can find. Strands of hair, dried grass, twigs, paper towels, furniture foam.
Her brain is closer to a human mother’s brain than that of a mouse or a dog. It has the same neurochemicals as a human’s. Her cortex is more like a person’s than it is different. She has a hippocampus, an amygdala, and the structure of her brain cells also resembles human cells, with their neurons and glia. During pregnancy, her neurological circuitry already started reprogramming itself. As a new mother, she will choose her babies over cocaine (even if she enjoyed cocaine before becoming pregnant). She is bolder than before. She will hunt during the day now, even though it is more dangerous—because her babies need her at night.
Prior to becoming a mother, she might have chased a cricket for food, “hither and thither, a haphazard pattern,” attracting predators, according to one study. Even after catching the cricket, it might have clumsily slipped from her grasp. But as a lactating mom, her method is “more direct and lethal.” She captures the cricket in 70 seconds—four times faster than non-mom rats—and does not let it go. She does not have time to waste. Her brain’s motor and sensory systems have sharpened.
Read more at The Atlantic.