Premastication, the process of chewing a solid food with the intention of delivering it to another person to swallow, usually takes place from parent to child — or less commonly, from adult child to infirm parent. But almost never does the act take place from toddler to parent — except for one Chinese two-year-old, Gao Qianbo, who has been pre-chewing his mother’s food ever since she awoke from a coma in May.

Gao’s mother, Zhang Rongxiang, 42, got in a near fatal car accident in 2010, at a time when she was four months pregnant. Her husband, Gao Dejin, cared for her at home despite Zhang having slipped into a coma. She eventually delivered her baby boy on July 22, 2011 via Cesarean section, still comatose.

Zhang finally awoke from her coma in May of this year to the sound of her 2-year-old beside her. She remains in a vegetative state, and her son diligently attends to her, talks to her, and even pre-chews her food, Global Times reports.

The family survives mainly on government subsistence and support from friends and relatives.

As a practice, premastication may have evolutionary roots due to its ability to transfer crucial enzymes to infants that are unique to parental saliva, such as alpha-amylase, which aids in the digestion of starches fed to a baby. One 2009 study also found infants can benefit immunologically from premastication, developing resistance to asthma and other allergic responses.

Through cross-cultural studies, the team found the practice was grossly underestimated in prominence in non-Western countries. Roughly 63 percent of Chinese university students received premasticated food as infants, despite zero of eight ethnographic studies performed on the topic identifying it in their reports. The team concluded that pre-chewing a child’s food confers a host of health benefits, and that excluding it has posed consequences for the modern infant’s diet.

“Its abandonment,” the researchers wrote, “particularly in poor communities, has placed children at increased risk of inadequate nutrition and decreased ability to confront infections associated with the introduction of complementary foods.”