This cycle repeated during the 30,000 years that fossils were accumulating at Rancho La Brea. The remains of only one human have ever been found at Rancho La Brea. Seventeen bones, including the skull and pelvis, were recovered from Pit 10 in 1914, along with a few artifacts and the partial skeleton of a domestic dog. Evidence indicates the woman was the victim of violent blow to the head. Scattered artifacts of human origin have also been found.
Evidence indicates that four plant associations occurred in the region.
Coastal sage scrub broken with groves of pines and cypress grew in the immediate vicinity of the asphalt seeps. Chaparral, with some pine and juniper scattered within, covered the slopes of the local mountains. Stream courses crossing the plain supported a riparian association that included sycamore, walnut and numerous herbs. Most of the types of plants that live here today were present here in the late Pleistocene. This indicates that rainfall was strongly seasonal, with most precipitation occurring in the late fall, winter and early spring, whereas the summer months were relatively dry.