Assessment Questions 5.1

The passage emphasizes the challenge of generalizing or making conclusions about a species with small sample sizes in paleoanthropology because, in most cases, the sample sizes for ancient, extinct forms of humanity are quite small. With very limited sample sizes, sometimes just one individual, it becomes difficult, if not impossible, to accurately generalize or say much about the variation within a species. The analogy is drawn with dogs, highlighting that characterizing dogs as a whole based on just one example, like a St. Bernard or a chihuahua, would not be accurate.

The fortunate circumstance mentioned in the passage is when paleoanthropologists find a large number of fossils together at the same site, all dating to the same time period. This circumstance allows for a more comprehensive study of variation within a species. Examples given include the First Family site of Australopithecus afarensis (13 individuals), Dmanisi (six individuals), Zhokoudian (about 40 individuals), and the Sima de los Huesos in Spain, where more than 6,500 bones and bone fragments belonging to 28 individuals of a single hominin species have been recovered.

The crania of the Sima de los Huesos hominins exhibit features such as a continuous, large brow ridge, a lower face that juts out (less than in an ape but more than in a modern human), and a large lower jaw as part of a massive masticatory complex for chewing. Fifteen of the crania have a mean cranial capacity of 1232 cc, about 85% of the modern human mean, within the range of modern human brain sizes but with a different configuration. The uncertainty about their formal classification is noted in the passage, with designations like Homo heidelbergensis and Homo neanderthalensis proposed, but most researchers recognizing them as a variety of premodern human beings, not representing Homo erectus but being close to modern humans.