Tooth growth is essential to health and survival. In humans the growth rate can be inferred from the width of perikymata growth intervals. We hypothesized that in ancient times teeth grew faster than in modern humans. We measured the intervals between perikymata ridges on the surfaces of teeth and in thin sections of molars (which we used as standards) in ancient, prehistoric and modern humans. We compared statistically the results from ancient and modern specimens and assessed the impact of dietary factors and sociality on tooth growth. We found that ancient teeth grew faster than modern teeth (wider intervals) because of environmental, nutritional and life style influences. This apparently conferred evolutionary advantages for human survival. Our results gleaned from combining measurements of sections of teeth with modeling of web-available images suggest that life styles of modern humans have lead to smaller teeth.