Forbidden Archeology: The Hidden History of the Human Race

In humans, the teeth in the jaw are arrayed in a parabolic curve. In the Hadar jaws, such as AL 200, the teeth on either side of the jaw are set in straight, parallel rows, as in the apes, although the rearmost molars are sometimes slightly displaced (Johanson and Edey 1981, pp. 267–268). Both in apes and the Hadar fossils the palate is flat (Johanson and Edey 1981, p. 270). In humans it is arched.

TABLE 11.6

Evidence for Arboreality in Postcranial Anatomy of A. Afarensis

1. General anatomy of Lucy’s shoulder blade was characterized as “virtually identical to that of a great ape and had a probability of less than 0.001 of coming from the population represented by our modern human sample” (Susman et al. 1984, pp. 120–121).

2. Lucy’s shoulder blade has a shoulder joint which points upward (Oxnard 1984, p. 334-i; Stern and Susman 1983, p. 284). This would allow “use of the upper limb in elevated positions as would be common during climbing behavior” (Stern and Susman 1983, p. 284).

3. A. afarensis wrist bones are apelike. “Thus we may conclude that A. afarensis possessed large and mechanically advantageous wrist flexors, as might be useful in an arboreal setting” (Stern and Susman 1983, p. 282).

4. A. afarensis metacarpals (the bones in the palm region of the hand) “have large heads and bases relative to their parallel-sided and somewhat curved shafts—an overall pattern shared by chimpanzees.” This “might be interpreted as evidence of developed grasping capabilities to be used in suspensory behavior” (Stern and Susman 1983, pp. 282, 283).

5. The finger bones are even more curved than in chimpanzees and are morphologically chimpanzeelike (Stern and Susman 1983, pp. 282–284; Susman et al. 1984, p. 117; Marzke 1983, p. 198).

6. A. afarensis humerus (upper arm bone) has features that are “most likely related to some form of arboreal locomotion” (Oxnard 1984, p. 334-i; see also Senut 1981, p. 282).

7. One of the long bones in the forearm, the ulna, resembles that of the pygmy chimpanzee (Feldesman 1982b, p. 187).

8. Vertebrae show points of attachment for shoulder and back muscles “massive relative to their size in modern humans” (Cook et al. 1983, p. 86). These would be very useful for arboreal activity (Oxnard 1984, p. 334-i).

9. “Recently Schmid (1983) has reconstructed the A.L. 288-1 rib cage as being chimpanzee-like” (Susman et al. 1984, p. 131).

10. Blades of hip oriented as in chimpanzee (Stern and Susman 1983, p. 292). Features of afarensis hip therefore “enable proficient climbing” (Stern and Susman 1983, p. 290).

11. The thighbone of Lucy “probably comes from an individual with the ability to abduct the hip in the manner of pongids,” allowing for “movement in the trees” (Stern and Susman 1983, p. 296).

12. Knee joint is loose, as in gibbon. “The mobility and prehensility of the foot are greatly complemented” (Tardieu 1981, p. 76), making it good for climbing.

13. Lucy had valgus knee, as do humans. But “the orang-utan and the spider monkey . . . are extremely able arborealists that have similar valgus angles as humans” (Oxnard 1984, p. 334-ii; see also Prost 1980).

14. Lucy had “a relatively short hindlimb . . . comparable to that seen in apes of similar body size.” This “would clearly facilitate climbing” (Susman et al. 1984, pp. 115, 116).

15. Feet have long, curved toes and a mobile ankle joint, making them well suited for grasping limbs and climbing in trees (Susman et al. 1984, p. 125). Also, the big toe is divergent, as in the apes (Susman et al. 1984, pp. 137–138).

 

 

As in the apes, the canines of the Hadar jaws were conical. In humans, the inner surface of the canine is flattened. In order to accommodate the projecting lower canine of A. afarensis, the upper jaw has a noticeable gap between the incisor and the canine. Other australopithecines also have the same gap. This gap, called a diastema, is also present in apes but not in humans.

Departures from the ape condition were minor. In an ape, the first premolar has a single cusp. In humans, the first premolar has a prominent second cusp. In all of the Hadar specimens except Lucy, the first premolar has a slightly developed second cusp (Johanson and Edey 1981, p. 270).

All in all, the apelike condition of the Hadar jaws is so pronounced that even Johanson admitted: “If David Pilbeam were to find any of them in Miocene deposits without any associated long bones, he would surely say it was an ape” (Johanson and Edey 1981, p. 376).

11.9.7.2 Postcranial Anatomy