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Australopithecus afarensis – just an extinct ape species?

 

Lucy AL 288-1, the most complete skeleton of the Australopithecus afarensis species, was found by Donald Johanson in the Afar region of Ethiopia in 1974.  For a fossilized australopithecine ape, this find might have received passing interest or fame that is except for the claims of Johanson and others that this species walked habitually on two legs.  “Ever since Darwin, bipedal walking has been considered the defining feature of the human lineage.”[1] So if it habitually walked bipedally, it could theoretically be evolutionists long sought after missing link between humans and apes. This idea has been promoted widely and is reflected, for example, in an article in the UK’s National History Museum website by Lisa Hendry which states:

 

“When this small-bodied, small-brained hominin was discovered, it proved that our early relatives habitually walked on two legs.” [2]

Whether Australopithecus afarensis could habitually walk upright like humans has been debatable from the beginning even among evolutionists. As more data has become available, the habitual walking upright proposition has been shown unlikely. So, what are the facts and what do they show?

(1)  Lucy’s Skeleton

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(2) Additional Specimens

 

Additional Australopithecus afarensis specimens have been found in other sites in Ethiopia, Kenya, and Tanzania. In all, about 400 specimens have been found consisting mostly of bone fragments and over 30 percent teeth. [8] All these specimens can fit on a picnic table.  It is important to note that it cannot be certain that all these specimens are from the same species.

Analysis of the specimens found at other sites indicates that the Australopithecus afarensis species were very ape-like as summarized below. 

·         They had small skulls housing brains “roughly 35 percent of the size of that of a modern human” [9] which is about the same size of a modern chimps.

·        Their organ of balance in the inner ear was decidedly ape-like. [10]

·         “[S]ulcal imprints reveal an ape-like brain organization and no features derived towards humans.” [11].

·        The position of the foramen magnum, the large opening at the base of the skull where the spine attaches, for the adult Australopithecus afarensis is like the chimp towards the back of the skull, whereas humans are more forward towards the center of the skull. [12]

·        Face sloped like a chimp today. [13] As the Australopithecus afarensis species grew to adulthood, their jaws became more pugnacious.[14]

·         Semicircular canals in ears were more like chimpanzees than humans. [15]

·        Their shoulders were nearly identical to living great apes. [16][17][18] Like an ape, its shoulder blade socket faces upward instead of to the side like a human. [19] [20]

·         Their arms were long like apes [21] and dangled down to their knees or lower. [22]

·         The wrists had locking mechanisms typical of knuckle-walkers.[23][24]

·         “[T]he fingers and toe bones of the species were curved and longer than the ones of the modern human” [25] and simitar to tree dwelling apes. [26][27] Like apes, they had opposable thumbs and toes for grasping.

·         Their rib cage was conical shaped like apes [28][29] whereas humans are barrel shaped.[30]

·         May have had approximately the same valgus angle as humans. [31]

·        Tali bones were “most like those of the tree-dwelling ape, the orangutan.” [32]

·         All its bones were ape-shaped and not exactly like the corresponding bones in the human body [33]

 

(3)  The Australopithecus afarensis walking habitually upright hypothesis

Arguments for this hypothesis center around the pelvis, femur, knee joint, and feet. 

Proponents claim that afarensis’ pelvis was human-like. However, there are significant differences such as the sharp outward flaring of the iliac blades of A. afarensis and the shape of the birth canal. [34] Their pelvis “lacked the refinements that enable humans to walk with a striding gait.” [35] “Lucy, like a modern ape, was not equipped for sustained, habitual, or efficient bipedal locomotion. An ape’s iliac blades are not oriented to allow its gluteal muscles to abduct (to pull its standing leg out to the side) so bipedal walking for an ape can only be an acrobatic maneuver. The ape tends to fall to the side when walking upright and may swing and sway to avoid falling over...” [36] 

A. afarensis’ femurs slanted toward their knees placing their legs near their center of gravity giving them more stability than chimps when they walked upright. But this slant is also present in some modern ape species, such as the spider monkey and orangutan, [37] which are not missing links, so neither does this condition support the idea for this species being a missing link between apes and humans. The A. afarensis overall knee structure “is compatible with a significant degree of arboreal locomotion.” [38]

In 1976, Mary Leaky stumbled on a 27-meter track with about 70 footprints at Laetoli, Tanzania. [39] These footprints “are indistinguishable from the prints of modern humans who walk habitually barefoot.” [40] They were found in a hardened volcanic ash sediment layer that also contained Australopithecus afarensis fossils. [41] Since the theoretical evolutionary timeline places no humans until millions of years later, these footprints were assumed to have been made by A. afarensis, the only candidate available. So, by circular reasoning it is claimed by one anthropologist that these Laetoli footprints provide “irrefutable evidence that A. afarensis walked bipedal.” [42] The fossil evidence does not support this conclusion. For A. afarensis to have made these footprints, their big toe needed to line up with the other toes like humans. But “using multivariate analysis, the anatomist Dr. Charles Oxnard has shown that” A. afarensis’ “big toe actually sticks out as in chimpanzees.” [43] Also, A. afarensis toes are longer than modern humans and curved [44] [45] which are two other characteristics that should to some degree distinguish their footprints from modern humans. The Laetoli footprints could not therefore have been made by A. afarensis and among the australopithecines, A. afarensisis “[t]he only possible upright walker.” [46]

Metatarsal bones bridge between the heel bones and the toe bones.  An isolated human looking fossilized metatarsal bone AL 333-160 was found in the Hadar formation where Lucy was found. [47] By the same circular reasoning as used by some evolutionists in assigning the above Laetoli footprints, this bone was assigned to A. afarensis and then used as supposed proof that they walked habitually upright like humans.  Yet aside from evolutionary assumptions this metatarsal would logically be assigned to a human.

(4)  The Australopithecus afarensis did not walk habitually upright hypothesis

 

Considerable evidence points away from them being habitual bipedal walkers in the above summary.  Often cited by critics of A. afarensis’ habitual bipedal walking are its organ of balance, foramen magnum, sloped face, pugnacious jaws, locking mechanism for knuckle walking, and chimp-like feet.

 

In Dikika, Ethiopia, a skeleton was found of an A. afarensis infant.  “[I]mages of the inner ear of the specimen show it to have semicircular canals more like those of chimpanzees than modern humans. The fluid-filled semicircular canals are crucial in maintaining balance.” [48] As chimpanzees are knuckle-walkers that occasionally walk terrestrially bipedally, it is likely that A. afarensis’ are not obligate bipedal walkers either.

The foramen magnum (FM) is the location where the spinal cord enters the skull. In humans, the FM is located underneath the skull near the center balancing it over the body’s center mass. This stabilizes the head for bipedal walking and allows it to rotate from side to side in a horizontal plane to view the surroundings. A. afarensis’ foramen magnum is also underneath but further back than humans and has an angle suitable for walking on all fours. “The angle of the opening remains clearly in the “ape” category.” [49]

Humans have a relatively flat face with a nose that protrudes between the eyes. This arrangement allows humans to see the ground immediately in front of them which greatly aids in walking and running.  An A. afarensis walking bipedal with its head vertical could not view the ground immediately ahead because its forward sloping face and pugnacious jaws would restrict its view.  Instead, it would need to walk hunched over. 

There is little to distinguish the shoulder, arm, and hand configuration of A. afarensis from modern chimps and gorillas which are agile at climbing trees and knuckle walking. They all have shoulder blades directed upward, long arms that can extend below their knees, long curved fingers for climbing and manipulating fruit, and wrists with locking mechanisms required for knuckle walking. “This form of hand-walking posture allows these tree climbers to use their hands for terrestrial locomotion while retaining long fingers for gripping and climbing.” [50] Some evolutionists have speculated that A. afarensis’ wrist locking mechanism is vestigial (left over and not used) however there is no evidence to support this.

“[M]orphometric analysis of australopithecine tali, bones vital to locomotion, indicated a gulf between modern man, the habilines, the australopithecines and modern African apes.” [51]

“Neither Lucy nor any other australopithecine is ... intermediate between humans and African apes. Nor are they similar enough to humans to be any sort of ancestor of ours.” [52]

Conclusion

Although Australopithecus afarensis could probably walk short distances on two feet as the chimpanzee and gorilla do today, there is no evidence that it walked habitually bipedal. Furthermore, there is no reason to assume based on the bone and Laetoli footprint fossils found that it is intermediate between apes and humans. It was unquestionably a unique ape species that went extinct.

 

Photo:

(a)  Pierre Fidenci, CC BY-SA 2.5, via Wikimedia Commons (b)

(b)  120, CC BY-SA 3.0, via Wikimedia Commons, Lucy skeleton (AL 288-1) Australopithecus afarensis, cast from Museum national d'histoire naturelle, Paris

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[1] Raicten, D. et. al, Laetoli Footprints Preserve Earliest Direct Evidence of Human-Like Bipedal Biomechanics, Internet

[2] Hendry, L., Australopithecus afarensis, Lucy’s species, Natural History Museum, UK, Internet

[3] Lucy: Did She Walk Like Us? Answers in Genesis, Internet

[4] Morris, J., Was Lucy An Ape-man? Institute for Creation Research, November 1, 1989, Internet

[5] Ibid.

[6] Mehlert, A. W., Australopithecus afarensis and Homo habilis – pre-human ancestors? Journal of Creation 10(2):219-240, August 1996, Internet

[7] Ibid.

[8] “Lucy” the Australopithecus Afarensis: Evidence for Evolution or Extinct Ape? Answers tv, Answers in Genesis

[9] Australopithecus, New World Encyclopedia, Internet

[10] Mehlert

[11] Gunz, P. et. al, Australopithecus afarensis endocasts suggest ape-like brain organization and prolonged brain growth, Science Advances, Research Article, Internet

[12] Mehlert

[13] “Lucy” the Australopithecus Afarensis: Evidence for Evolution or Extinct Ape?

[14] Mehlert

[15] Wood, B, A precious little bundle, Nature, volume 443, pages 278-279, September 20, 2006, Internet

[16] Dorey, F., Australopithecus Afarensis, Australian Museum, Internet

[17] Lucy: Did She Walk Like Us? Answers in Genesis, Internet

[18] ‘Lucy isn’t the ‘Missing Link’! Creation 12(3):32, June 1990, Internet

[19] Dorey

[20] Mehlert

[21] Wieland, C., ‘Lucy walked upright!’ (or did she?), Creation.com – Creation Ministries, February 17, 2011, Internet

[22] Mehlert

[23] Wieland

[24] Lucy: Did She Walk Like Us?

[25]The Genus Australopithecus, Anthropology, Columbia University, Internet

[26] Lucy: Did She Walk Like Us?

[27] Plaisted, D., Problems with Lucy and Skull 1470, A Creation Perspective, University of North Carolina, Chapel Hill, Internet

[28] Dorey

[29] Mehlert

[30] Ibid.

[31] Ibid.

[32] Ibid.

[33] Thomas, B., More Evidence Lucy Was Just an Ape, Institute for Creation Research, July 11, 2018, Internet

[34] Mehlert

[35] Dorey

[36] Menton, D. and Mitchell, E., Lucy, the Knuckle-Walking “Abomination”? Answers in Genesis, October 24, 2012, Internet

[37] Mehlert

[38] Plaisted

[39] Laetoli Footprint Trails, Smithsonian, Internet

[40] Wieland

[41] Laetoli Footprint Trails

[42] The Genus Australopithecus

[43] Catchpoole, D., New evidence: Lucy was a knuckle-walker, Creation. com, Creation Ministries, May 5, 2000

[44] Plaisted

[45] The Genus Australopithecus

[46] Plaisted

[47] Thomas, B., Human Foot Bone Misidentified as Lucy’s, Institute for Creation Research, February 18, 2011, Internet

[48] Wood

[49] Menton

[50] Knuckle Walking, Wikipedia

[51] Mehlert

[52] ‘Lucy isn’t the ‘Missing Link’!

 

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