Palmar grasp reflex

How it works

Stroke the palm of a newborn, or press a finger into it, and the fingers curl and grip. The grip is not gentle. Pull the finger away and the baby holds on tighter¹. The same happens with the toes when the sole is pressed. That is the plantar grasp reflex².

The reflex runs through the spinal cord and the lower parts of the brain. The cortex, the thinking part of the brain, is not yet in charge of the hands. It is present before birth, is strongest at around one to two months of age, and fades away by five to six months¹. As the cortex matures it takes control of the hands and switches the reflex off. Grasping on purpose replaces it. The plantar version lasts longer and is usually gone by nine to twelve months².

In 1891 the doctor Louis Robinson tested the grip in dozens of newborns¹. Most could hang from a rod by their hands for at least 10 seconds, and some for much longer¹. Nobody should repeat this. It shows how strong the reflex is, not that it is safe.

The reflex is one of a family called primitive reflexes. Others include rooting, which turns the head toward a touch on the cheek, and the startle reflex, where a baby throws out its arms at a sudden drop or noise². Doctors check for them at newborn examinations. Their presence shows that the nervous system is working. Their disappearance on time shows that the brain is maturing².

Is it a problem?

In a baby, no. A grasp reflex that is missing at birth, is much weaker on one side, or is still strong after about six months is something a doctor will want to look at². In adults the reflex can return when the front of the brain is damaged, so doctors sometimes test the palm in older people².

History and culture

The reflex is sometimes called the Darwinian reflex, because it looks like a leftover from ancestors whose babies clung to their mother’s fur. Baby monkeys and apes do exactly this from birth¹. Whether the human reflex is truly a leftover, or simply a stage in learning to use the hands, is not settled.