Hominid (Australopithecus afarensis)

*Australopithecus afarensis* is one of the longest-lived and best-known early human species—paleoanthropologists have uncovered remains from more than 300 individuals! Found between 3.85 and 2.95 million years ago in Eastern Africa (Ethiopia, Kenya, Tanzania), this species survived for more than 900,000 years, which is over four times as long as our own species has been around.  It is best known from the sites of Hadar, Ethiopia (‘Lucy’, AL 288-1 and the 'First Family', AL 333); Dikika, Ethiopia (Dikika ‘child’ skeleton); and Laetoli (fossils of this species plus the oldest documented bipedal footprint trails).

Similar to chimpanzees, *Au. afarensis* children grew rapidly after birth and reached adulthood earlier than modern humans. This meant *Au. afarensis* had a shorter period of growing up than modern humans have today, leaving them less time for parental guidance and socialization during childhood.

*Au. afarensis* had both ape and human characteristics: members of this species had apelike face proportions (a flat nose, a strongly projecting lower jaw) and braincase (with a small brain, usually less than 500 cubic centimeters -- about 1/3 the size of a modern human brain), and long, strong arms with curved fingers adapted for climbing trees. They also had small canine teeth like all other early humans, and a body that stood on two legs and regularly walked upright. Their adaptations for living both in the trees and on the ground helped them survive for almost a million years as climate and environments changed.

## Biographical information

### Place of birth

East Africa, Earth, Sol system, Space Sector 2814

### Place of death

East Africa, Earth, Sol system, Space Sector 2814

## Physical description

### Height

Males: average 4 ft 11 in (151 cm); Females: average 3 ft 5 in (105 cm)

### Weight

Males: average 92 lbs (42 kg) ; Females: average 64 lbs (29 kg)

## History of Discovery:

The species was formally named in 1978 following a wave of fossil discoveries at Hadar, Ethiopia, and Laetoli, Tanzania.  Subsequently, fossils found as early as the 1930s have been incorporated into this taxon.

## How They Survived:

*Au. afarensis* had mainly a plant-based diet, including leaves, fruit, seeds, roots, nuts, and insects… and probably the occasional small vertebrates, like lizards.

How do we know what *Au. afarensis* ate?

Paleoanthropologists can tell what *Au. afarensis* ate from looking at the remains of their teeth. Dental microwear studies indicate they ate soft, sugar-rich fruits, but their tooth size and shape suggest that they could have also eaten hard, brittle foods too – probably as ‘fallback’ foods during seasons when fruits were not available.

## Evolutionary Tree Information:

This species may be a direct descendant of *Au. anamensis* and may be ancestral to later species of *Paranthropus,* *Australopithecus*, and *Homo*.

## Questions:

We don’t know everything about our early ancestors—but we keep learning more! Paleoanthropologists are constantly in the field, excavating new areas, using groundbreaking technology, and continually filling in some of the gaps about our understanding of human evolution.

Below are some of the still unanswered questions about *Au. afarensis* that may be answered with future discoveries*:*

1. A fossil similar to *Au. afarensis* and dating to 3.5 million years ago has been found in Chad—did this species extend so far into central Africa?
2. We know *Au. afarensis* were capable of walking upright on two legs, but they would have walked differently than modern humans do today; so, what did their bipedal locomotion look like?
3. Did *Au. afarensis* usually walk upright like modern humans, or did they spend more time climbing trees like other living African apes?
4. The species *Au. afarensis* existed through a period of environmental fluctuation yet showed no adaptations to the changing environment—why? Was it because they were able to migrate to where their usual food sources were located? Or were their food sources somehow unaffected?
5. *Au. afarensis* shows strong sexual dimorphism in that the body sizes between males and females are quite different; however, sexual dimorphism in other primates is usually characterized by size differences in bodies *and* teeth. Fossil evidence shows that male *Au. afarensis* individuals had canine teeth comparable in size to those of females. Did male dominance in *Au. afarensis* individuals not include the need to bear large canine teeth, as it does in many other male primates?
6. The teeth and jaw of *Au. afarensis* are robust enough to chew hard foods, but dental microwear studies show *Au. afarensis* individuals ate soft foods like plants and fruit instead. While most scientists think that *Au. afarensis* ate hard, brittle foods during tough times when vegetation was not easily found, further microwear studies show that eating hard foods did not coincide with dry seasons of little vegetation. So how do properties of *Au. afarensis* teeth relate to their diet?

## References:

**First paper**:

* Johanson,  D.C., White, T.D., Coppens, Y. 1978. A new species of the genus *Australopithecus* (Primates: Hominidae) from the Pliocene of Eastern Africa. Kirtlandia 28, 2-14.

**Other recommended readings**:

* Alemseged, Z., Spoor, F., Kimbel, W.H., Bobe, R., Geraads, D., Reed, D., Wynn, J.G., 2006. A juvenile early hominin skeleton from Dikika, Ethiopia. Nature 443, 296-30.
* Johanson, D.C., Edey, M.E., 1981. Lucy: The Beginnings of Humankind. St Albans, Granada.
* Kimbel, W.H., Delezene, L.K., 2009. "Lucy" redux: A review of research on *Australopithecus afarensis*. Yearbook of Physical Anthropology 52, 2-48.
* Schmid, P., 2004. Functional interpretation of the Laetoli footprints. In: Meldrum, D.J., Hilton, C.E. (Eds) From Biped to Strider: The Emergence of Modern Human Walking, Running, and Resource Transport. Kluwer Academic/Plenum, New York, pp 50-52.