Do little dogs live longer than big dogs? Chen Hou says they do, and the reason lies in a complex relationship between energy usage and lifespan.

The S&T biological sciences researcher is using the principles of energy conservation and allometric scaling laws to measure aging on the basis of energy expenditure. His research shows that energy used during growth is key to understanding longevity.

Hou compares the birth mass of a greater Swiss mountain dog to that of a silky terrier as an example. A greater Swiss is born at only 1 percent of its final weight, but the terrier already weighs in at 8 percent of its final weight at birth. That means that the greater Swiss has to use more energy to grow to full adulthood, leaving relatively less energy for health maintenance and therefore a shorter lifespan than the terrier.

“If you were able to suppress or manipulate growth to maintain a smaller stature, the animal would live longer and have more energy for health maintenance — the way the body repairs itself,” says Hou. He says the energy needed for individuals with low birth weight to reach or exceed normal weight later in life can adversely impact adult health outcome and lifespan.