He was in bad health, having lost most of his teeth and suffering from bone resorption in the mandible and advanced arthritis.

Boule's reconstruction of La Chapelle-aux-Saints 1, published during 1911–1913, depicted Neanderthals with a thrust-forward skull, a spine without curvature, bent hips and knees and a divergent big toe.

Straus and Cave attributed Boule's errors to the severe osteoarthritis in the La Chapelle-aux-Saints Neanderthal, although physical anthropologist Erik Trinkaus has suggested that Boule's errors were primarily related to the fragmentary nature of the remains.

All of the mandibular molars were absent and consequently, some researchers suggested that the 'Old Man' would have needed someone to process his food for him.

Later studies have shown that La Chapelle-aux-Saints 1 did have a number of incisors, canines and premolars in place and therefore would have been able to chew his own food, although perhaps with some difficulty.