Table 1 Comparative brain and body size of Australopithecus and Homo based on the most complete specimens in each group.

See Box 1 for a discussion of how body and brain size ranges may change based on the size of more fragmentary remains in each assemblage. The 1470 and 1813 groups in particular are skewed to larger and smaller sizes, respectively, by considering only their more complete members. Individual data points included in these species’ means can be found in table S2. Sources for endocranial capacity data are as follows: A. sediba (6); A. africanus (127); A. afarensis (128); Homo, as indicated in table S2 of this paper. The apparent difference in cranial capacity between the 1470 and 1813 groups is due to the fact that only a single large cranium, KNM-ER 1470, contributes to the capacity for that group. Dental measurement definitions and most data are from (41); A. afarensis, from (129); A. sediba, as above; newer Homo data not in 41 follow (5, 32, 130). I1, upper incisor 1; I1, lower incisor 1. Body mass estimates from orbital dimensions are from (131, 132). The values presented are the range of individual predicted values; the mean of individual predicted values rounded to whole values; and the total range of the 95% confidence intervals for all individual values. The Kappelman values are predicted from orbital area. The Aiello and Wood values are predicted from orbital height dimensions and hominoid predictive equations. The apparent difference in body mass between 1470 and 1813 groups is because only a single large cranium, KNM-ER 1470, contributes to the body mass estimate for that group. Postcranial body mass estimates follow (24) and table S2 of this paper. The East Africa unattributed non-erectus Homo group includes H. habilis. CV, coefficient of variation; CI, confidence interval; dash entries, not applicable or no fossils or data available.

South
Africa
A. sediba
South
Africa
A. africanus
East
Africa
A. afarensis
East
Africa
1470
group
East
Africa
1813
group
East
Africa
unattributed
non-erectus
Homo
East
Africa
All
non-erectus
Homo
South
Africa
H. aff.
erectus
East Africa/
Georgia early
H. erectus
Brain Size (cm3)
Range420385–571400–550750*510–660*630–680510–750546–1067 (with Dmanisi)
690–1067 (East Africa)
Mean459478586650629787 (with Dmanisi)
863 (East Africa)
CV15.915.710.55.412.220.2 (with Dmanisi)
15.9 (East Africa)
Dental Size
I1 labio-lingual (mm)
Range6.96.5–8.77.1–9.78.07.2–8.27.2–8.27.6–9.4 (with Dmanisi)
8.2–9.4 (East Africa)
Mean8.08.47.77.88.4 (with Dmanisi)
8.8 (East Africa)
CV12.58.56.55.610.9 (with Dmanisi)
9.6 (East Africa)
I1 labio-lingual (mm)
Range5.9–6.96.9–7.75.46.6–75.4–76.0–6.9 (East Africa)
Mean6.57.46.86.36.45 (East Africa)
CV8.144.213.19.9 (East Africa)
I2 labio-lingual (mm)
Range5.16.4–7.26.6–8.26.1–7.35.8–8.25.8–8.26.9–8.5 (with Dmanisi)
8.1–8.5 (East Africa)
Mean6.97.56.77.27.17.8 (with Dmanisi)
8.3 (East Africa)
CV4.97.512.715.213.810.6 (with Dmanisi)
3.4 (East Africa)
I2 labio-lingual (mm)
Range6.9–8.26.7–8.86.67.4–7.66.6–7.67.0–8.3 (with Dmanisi)
7.0–8.3 (East Africa)
Mean7.78.07.57.27.4 (with Dmanisi)
7.4 (East Africa)
CV8.69.61.97.38.2 (with Dmanisi)
10.1 (East Africa)
M1 area (mm2)
Range15481620–203018501560–17902010–20901560–20901490–1770 (with Dmanisi)
1490–1770 (East Africa)
Mean17951687205017981630 (with Dmanisi)
1630 (East Africa)
CV8.55.62.810.17.8 (with Dmanisi)
12.1 (East Africa)
M1 area (mm2)
Range1310–14501470–20701460– 183515001410–19501410–19501330–1780 (with Dmanisi)
1330–1790 (East Africa)
Mean138017311683163016311533 (with Dmanisi)
1534 (East Africa)
CV7.211.911.714.213.211.3 (with Dmanisi)
13 (East Africa)
M2 area (mm2)
Range17671960–270020161640–18901940–25701640–25701500–1860 (with Dmanisi)
1500–1860 (East Africa)
Mean22181797217719331622 (with Dmanisi)
1640 (East Africa)
CV11.75.615.813.18.7 (with Dmanisi)
11.8 (East Africa)
M2 area (mm2)
Range1720–18581790–21001680–18401650–27301650–27301380–1990 (with Dmanisi)
1490–1770 (East Africa)
Mean178919451760212820431573 (with Dmanisi)
1660 (East Africa)
CV5.511.36.416.215.814.1 (with Dmanisi)
13.7 (East Africa)
Body Size
Body mass from orbits (kg)
Predicted value range
Kappelman
Aiello

27–28
22–29
46
51
30–35
31–36

30–46
31–51

57–59 (East Africa)
58–65 (East Africa)
Mean of predicted
Kappelman
Aiello and Wood

27
25


32
34

37
39

58 (East Africa)
61 (East Africa)
CI range
Kappelman
Aiello and Wood

19–40
19–36

34–70
43–63
21–50
22–42

21–70
22–63

40–86 (East Africa)
48–82 (East Africa)
Body mass from postcrania (kg)
Range32–3623–4527–5031–5731–5730–5840–68 (with Dmanisi)
40–68 (East Africa)
Mean33344044444752 (with Dmanisi)
55 (East Africa)
CV918.720.23131.53219.3(with Dmanisi)
18.8 (East Africa)
Femur length (mm)
Range276–434281–382396–401315–401429–485 (East Africa)
Mean355346315398398450.5 (East Africa)
CV16.31135.8 (East Africa)

*Listed ranges for brain and body size reflect only a limited number of fossils with sufficient preservation for estimates but do not reflect the size diversity in the groups as known from fragmentary remains. Thus, because the small face KNM-ER 62000 is about 80% the size of KNM-ER 1470, we conservatively estimate that the lower range of brain size for this group may be as little as 560 cm3; and, because the largest capacity of the 1813 group (from OH 13) is from an individual with a palate just 85% the size of the large OH 65, the upper value in that group may be around 775 cm3.