• FOOTPRINTS FOUND at Laetoli, Tanzania, in 1976 that date to 3.7 million years ago are among the most spectacular fossil discoveries because they record a moment in time when many different animals walked through wet volcanic ash leaving behind their tracks. Among these animals were several prehistoric humans who belonged to the species Australopithecus afarensis, a small brained, bipedal hominin that lived in East Africa from about 4 to 2.8 million years ago. Their footprints were preserved when the ash dried and hardened, and was covered by another layer of volcanic ash.

    The Laetoli Trackways offer a unique opportunity to explore how scientists study the behaviors of fossil organisms because the tracks, quite literally, record a snapshot of how Au. afarensis walked. The trackways also permit us to take measurements of both foot length and stride length of these individuals; however, other interesting information about this species, its height for example, is unknown.

  • Can we use the relationship between foot length and stride length versus height in living humans to estimate the stature of these fossil humans? If you look at the people around you, you'll note that there is a general relationship between foot length, stride length, and height: shorter people generally have shorter feet and take shorter strides, while taller people have longer feet and take long strides. This general relationship can be evaluated by measuring a large sample of people and, if the relationship (or correlation) is strong, it can be used to estimate or predict the height of Au. afarensis.

    Try it yourself. You can measure and evaluate the correlation between foot length and stride length versus body height, and then use these data to estimate the height of the Laetoli hominins.