1. Evolutionary Biology
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The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa

  1. Paul HGM Dirks  Is a corresponding author
  2. Eric M Roberts
  3. Hannah Hilbert-Wolf
  4. Jan D Kramers
  5. John Hawks
  6. Anthony Dosseto
  7. Mathieu Duval
  8. Marina Elliott
  9. Mary Evans
  10. Rainer Grün
  11. John Hellstrom
  12. Andy IR Herries
  13. Renaud Joannes-Boyau
  14. Tebogo V Makhubela
  15. Christa J Placzek
  16. Jessie Robbins
  17. Carl Spandler
  18. Jelle Wiersma
  19. Jon Woodhead
  20. Lee R Berger
  1. James Cook University, Australia
  2. University of the Witwatersrand, South Africa
  3. University of Johannesburg, South Africa
  4. University of Wisconsin-Madison, United States
  5. University of Wollongong, Australia
  6. Environmental Futures Research Institute, Griffith University, Australia
  7. Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Spain
  8. The Australian National University, Australia
  9. The University of Melbourne, Australia
  10. La Trobe University, Australia
  11. Southern Cross University, Australia
Research Article
Cite this article as: eLife 2017;6:e24231 doi: 10.7554/eLife.24231
14 figures and 10 tables

Figures

Location of Rising Star Cave and the Dinaledi Chamber.

(a) Simplified geological map showing the position of the Rising Star Cave (in grey); (b) close-up map of the Dinaledi Chamber showing the distribution of the dating samples, including: U-Th flowstone samples (yellow dots, black text); ESR samples (purple dots, orange text); and OSL samples (red dots, blue text). Age estimates for the different samples are shown, with cross reference to Tables 1, 7 and 8.

https://doi.org/10.7554/eLife.24231.003
Geological face map and cross-sections through the sediment pile at different locations in the Dinaledi Chamber, illustrating the relationships between the flowstone groups and sedimentary units.

The positions of the section lines are shown in (a); a face map of the entry zone of the Dinaledi Chamber (looking NE) is shown in (b); geological cross-sections through the central part of the Dinaledi Chamber near the excavation pit are shown in (c) and (d).

https://doi.org/10.7554/eLife.24231.004
Field and close-up photographs of all flowstone samples collected for U-Th dating.

The flowstone groups (i.e., Flowstone Groups 1, 2 or 3), sample numbers, and ages (2σ uncertainty), as listed in Table 1, are shown below each sample. Ages reported here are from JCU, unless otherwise stated.

https://doi.org/10.7554/eLife.24231.005
Location of the three H. naledi tooth samples (samples 1767, 1788 and 1810) and one baboon (cf. Papio) tooth sample (sample 1841) used for combined U-series and ESR dating.

(a) Map of the Dinaledi Chamber showing the position of the excavation pit and the position of figures (b) and (c); (b) close-up of the SE corner of the excavation pit showing the sample site for sample 1810 and the 50 cm deep sondage from which sample 1841 was recovered; (c) the area to the W of the excavation pit from which samples 1767 and 1788 were collected.

https://doi.org/10.7554/eLife.24231.011
Samples of orange laminated mudstone of Unit 1 for OSL dating.

(a) sample OSL3 with an estimated MAM age of 231 ± 41 ka taken from sub-unit 1b; (b) sample OSL4 with an estimated MAM age of 241 ± 37 ka, taken from sub-unit 1b and covered by a flowstone sheet dated at 290 ± 6 ka (RS5); (c) sample OSL5 with an estimated MAM age of 353 ± 61 ka, taken from sub-unit 1a and covered by a flowstone sheet dated at 32.1 ± 0.4 ka (RS20). The scale bar in each of the photographs is 10 cm.

https://doi.org/10.7554/eLife.24231.012
Photographs of H. naledi teeth used for ESR dating.

(a) U.W.101–1767; (b) U.W.101–1788; (c) U.W.101–1810. The order of images for each panel is: buccal, distal, lingual, mesial, and occlusal views. The scale bar in each panel is 1 cm.

https://doi.org/10.7554/eLife.24231.013
Photographs of the baboon (cf. Papio) tooth (sample 1841), recovered from the sondage in the excavation pit, and used for ESR dating.

Views are: (a) buccal, (b) occlusal, (c) lingual, and (d) internal.

https://doi.org/10.7554/eLife.24231.014
Cartoon illustrating the sedimentary history resulting in the deposition and redistribution of sediment of Units 2 and 3, and Flowstone Groups 1 to 3 in the Dinaledi Chamber.

Note that all hominin fossils are contained in sub-unit 3b, but that this sub-unit has been repeatedly reworked after its initial deposition. Fossil entry occurred during the initial stages of deposition of Unit 3 below the entry shaft and predated deposition of Flowstone 1c. H. naledi fossils may have continued to enter the Dinaledi Chamber as older parts of Unit 3 were eroded from below Flowstone 1c, and as remnants of all older units were reworked to be incorporated into Unit 3 sediments that accumulated along the floor of the Dinaledi Chamber.

https://doi.org/10.7554/eLife.24231.019
Photographs illustrating the sampling approaches taken by SCU-UoW and GU-ANU in obtaining the U-Th results presented in Tables 4 and 5.

(a) Comparison of sampling grids across the enamel-dentine boundary measured by SCU-UoW (red lines) vs. GU-ANU (blue circles). SCU-UoW (red lines) measured a series of parallel, shallow (<5 μm) pits along grid lines across the teeth and averaged U concentrations across each grid. GU-ANU (blue circles) measured the average composition of the tooth in single spots that were laser-bored along profiles across the teeth, and report results for each spot. (b, c) Locations of LA-ICP-MS spot analyses for teeth samples 1788 (b) and 1810 (c) conducted by GU-ANU. The detailed transects are shown in panels (d) to (h).

https://doi.org/10.7554/eLife.24231.020
Gamma dose rate reconstructions derived from analytical data of sediment samples collected around ESR samples 1767, 1788 and 1810 (closed circles and diamonds), combined with samples from a vertical profile in the excavation pit and sondage (open circles and diamonds).

The data show little variation in dose rate with depth (see text for explanation).

https://doi.org/10.7554/eLife.24231.021
ESR dose response curves (DRC’s) obtained for the samples 1767, 1788, 1810 and 1841.

To facilitate comparison, all DRC’s have been normalised to the intensity of the natural point (=1).

https://doi.org/10.7554/eLife.24231.023
Evolution of the Imax/Imin ratio vs the irradiation dose for the four tooth samples.

(see text for explanation).

https://doi.org/10.7554/eLife.24231.024
Samples and results of palaeomagnetic analyses forFlowstone 1a.

(a) Outcrop photo of hanging erosion remnant of Flowstone 1a from which the palaeomagnetic sample was taken. The three flowstone phases separated by detrital horizons are clearly visible, and their magnetic polarity has been marked (N = normal; R = reverse). The stratigraphic top is towards the top of the photo; (b) close-up of a hand sample taken for palaeomagnetic analysis from Flowstone 1a in the Dinaledi Chamber. The sample is layered and comprises three distinct phases (from base to top: A-C marked in yellow) separated by thin clastic horizons that mark disconformities indicated with red dashed lines. The larger-scale extent of the three phases can be seen in (a); (c) intensity spectra, Zijderveld plots, and stereo plots for samples from phases A to C taken from (b). Phases B and C show normal polarity and phase A shows reversed and intermediate polarity directions.

https://doi.org/10.7554/eLife.24231.025
Chronostratigraphic summary of radio-isotopic dating results, and interpretation of the depositional ranges of stratigraphic units, flowstones and H.

naledi fossils in the Dinaledi Chamber. Following the preferred US-ESR maximum age model and associated uncertainties for ESR samples 1788 and 1810, a maximum depositional age of 335 Ma was determined, while the minimum depositional age of 236 ka was constrained by Flowstone 1c (sample RS18), which covers H. naledi material in the entry zone.

https://doi.org/10.7554/eLife.24231.026

Tables

Table 1

Summary table of U-Th disequilibrium ages obtained for samples from the Dinaledi Chamber by James Cook University (JCU - 1) and the University of Melbourne (UoM - 2). The detailed analytical results are shown in Tables 2 and 3. Sample locations are shown in Figure 1b. The data are ranked by increasing age of the oldest flowstone horizon within the sample, based on the JCU ages. The grey shading highlights the different age groupings observed within the flowstones: 24–32 ka, ~50 ka, 88–105 ka, ~242 ka, ~290 ka and >440 ka. Ages are reported relative to 1950.

https://doi.org/10.7554/eLife.24231.006
Sample IDFlowstone groupUnderlying unitAge1 (ka)1 (ka)Age2 (ka)2 (ka)
 RS19FS2sub-unit 3b24.70.224.530.43
 RS11FS3 (top to RS21)FS29.050.069.9460.063
 RS21FS2 (base to RS11)sub-unit 3b28.40.428.620.29
 RS10FS2sub-unit 3b (and bone)30.10.3
 RS20FS2sub-unit 1a (Facies 1a; OSL5)30.40.232.120.38
 RS6FS2sub-unit 1a, sub-unit 3b49.80.350.820.43
 RS15FS2 (blind duplicate of RS1)sub-unit 3b92.61.091.400.65
 RS1FS2 (blind duplicate of RS15)sub-unit 3b91.040.72
 RS8FS2 (below FS1a-e)sub-unit 3b95.01.096.290.69
 RS14FS2in drain, along dolostone wall100.11.296.200.36
 RS17FS2 (top to RS16)in drain, along dolostone wall102.60.898.61.4
 RS16FS2 (base to RS17)in drain, along dolostone wall104.01.999.11.4
 RS13FS2 (rim to RS18)sub-unit 3b88.460.67
 RS18FS1c (core to RS13)sub-unit 3b2425242.96.6
 RS5FS1sub-unit 1b (Facies 1b; OSL4)2906
 RS22FS1a (top to RS23)Unit 2equilibrium478+107/−41
 RS23FS1a (base to RS22)Unit 2equilibrium502+181/−53
 RS9n/a (surface outcrop)n/aequilibriumequilibrium
  1. 1James Cook University (JCU), Advanced Analytical Centre.

  2. 2University of Melbourne (UoM), paleochronology laboratory.

Table 2

U-Th data table for James Cook University. Uncertainties include: analytical error, decay constant uncertainty, and uncertainty on initial 230Th/232Th. Ages are reported relative to 1950 and assume an initial 230Th/232Th activity of 0.83 ± 0.5, and the equation given in Placzek et al. (2006). Decay constants for 234U and 230Th are from Cheng et al. (2013).

https://doi.org/10.7554/eLife.24231.007
Sample IDU (ppm)234U/238U230Th/238U232Th/238UAge (ka BP)2σ (ka)234U/238Uinitial
(activity)(activity)(corrected)(activity)
 RS112.3141.7720.0500.1440.0010.00010880.00000059.050.061.81840.0003
 RS190.6521.8550.0010.3870.0020.0021760.00000824.70.21.9890.001
 RS210.4211.9460.0010.4600.0040.0019200.00001528.40.42.1090.002
 RS100.8461.8850.0010.4660.0030.0007920.00000330.10.32.0530.001
 RS200.7951.8550.0010.4630.0030.0013630.00000530.40.22.0220.001
 RS60.5601.9660.0010.7470.0030.0009740.00000249.80.32.2630.002
 RS150.4001.9120.0011.1640.0080.004720.0000192.61.02.4840.007
 RS80.3281.8130.0031.1200.0080.003160.0000295.01.02.3730.007
 RS140.7341.6390.0951.0390.0080.002980.00002100.11.22.1750.008
 RS170.6801.6090.0011.0320.0050.0006790.000001102.60.82.1500.005
 RS160.9731.5830.0001.0240.0110.0004030.000006104.01.92.120.01
 RS180.1521.8480.0011.8560.0130.011750.0000524253.660.05
 RS50.0901.7280.0011.8180.0090.017320.0000529063.920.07
 RS230.3141.1870.0021.3150.0110.003460.00002>400
 RS220.3671.2090.0011.3220.0080.0001250.000001>400
 RS90.7371.0070.0021.0290.0040.0004620.000001>400
Table 3

U-Th data table for the University of Melbourne. Activity ratios are determined after Hellstrom (2003) and Drysdale et al. (2012). Ages are corrected for initial 230Th using Equation 1 of Hellstrom (2006), the decay constants of Cheng et al. (2013), and an initial 230Th/232Th activity of 1.5 ± 1.5. The initial 234U/238U ratios are calculated using corrected ages, which are reported relative to 1950.

https://doi.org/10.7554/eLife.24231.008
Sample IDU (ppm)234U/238U230Th/238U232Th/238UAge (ka BP)2σ (ka)234U/238Uinitial
(activity)(activity)(corrected)(activity)
 RS111.5181.8080.0030.15970.00090.00008750.00000049.9460.0631.8310.004
 RS190.5011.8840.0110.39160.00260.0043220.00001024.530.431.9470.011
 RS210.3611.9680.0110.46540.00300.00113420.000001928.620.292.0490.011
 RS200.6261.8780.0110.49250.00320.00238370.000004032.120.381.9610.011
 RS60.2762.0230.0040.78560.00210.004960.0001050.820.432.1810.004
 RS130.0762.0060.0041.18370.00470.0047860.00005888.460.672.2910.005
 RS150.3811.9340.0041.16610.00290.006390.0001291.370.652.2090.005
 RS140.6651.6260.0031.00100.00150.0012620.00001496.240.361.8220.003
 RS80.2571.8310.0041.13970.00340.0057460.00006096.290.692.0910.004
 RS170.5171.6370.0091.02480.00660.00239630.000003798.61.41.8410.010
 RS160.9051.5900.0100.99630.00670.00170990.000003799.11.41.7800.011
 RS180.1042.0010.0112.03200.01400.0205570.000041242.96.62.9870.027
 RS220.3241.2280.0071.30170.00830.00012010.0000008478+107/–41
 RS230.2061.2250.0071.30160.00930.0078180.000016502+181/–53
 RS90.8961.0100.0021.02040.00180.0009160.000012
Table 4

Summary table of U-Th disequilibrium ages obtained for the three H. naledi teeth (samples 1767, 1788 and 1810) and the baboon tooth (sample 1841) from the Dinaledi Chamber obtained by SCU-UoW. No age calculations were carried out for U concentrations of ≤0.5 ppm or U/Th ≤250 (indicated in red and underlined). Mean values in this table only incorporate values from which meaningful ages could be calculated (indicated in black), however all values (i.e., red and black) were averaged to obtain the relevant mean values reported in Table 4. All uncertainties are given as 2σ.

https://doi.org/10.7554/eLife.24231.009
Sample1767U (ppm)U/Th230Th/238U234U/238UAge (ka)2s (ka)(234U/238U)i
1767-1 D7.226852.1670.0246.2590.00943.51.16.9490.026
1767-2 D7.759962.2610.0236.2820.01045.51.17.0090.030
1767-3 D8.031962.2250.8256.2760.012
1767-4 D8.559512.2090.0316.3010.00944.11.47.0070.030
1767-5* E3.6912382.2590.0316.1970.05546.21.86.9240.126
1767-6* E1.761082.2391.1336.1650.038
1767-7* E2.151092.3370.9476.2310.024
1767-8* E2.465182.2760.0216.2530.01946.11.16.9860.048
Mean:
1767 D7.848772.2120.0266.2810.00944.51.26.9880.029
1767 E3.088782.2680.0266.2250.03746.21.46.9550.087
Sample1788U (ppm)U/Th230Th/238U234U/238UAge (ka)2s (ka)(234U/238U)i
1788-1 D6.673902.9670.0266.4230.01161.41.57.4530.054
1788-2 D7.081763.3700.8336.4410.010
1788-3 D7.17603.2063.1266.3940.049
1788-4 D7.4513913.3130.0236.4450.01070.31.47.6450.056
1788-5 D5.5244233.2690.0236.3490.01070.41.47.5310.052
1788-6 D5.0740903.4160.0146.3780.01474.11.17.6340.054
1788-7 D5.3947293.3850.0206.4000.01472.91.47.6400.054
1788-8 D5.9332093.4270.0156.3930.01374.21.17.6540.054
1788-9 D5.2443293.4490.0146.4130.01474.51.07.6850.052
1788-10 D4.8931613.3900.0106.4030.01173.00.97.6450.052
1788-11 D4.825563.3940.0146.4160.01472.91.07.6590.052
1788-12 D5.4816063.3560.0176.3840.01472.31.17.6090.052
1788-13 D5.048383.3170.0256.4200.01470.71.57.6230.058
1788-14 D5.69933.2812.4266.4080.013
1788-15 D5.03723.3153.7316.4270.014
1788-16 E0.1331.78618.1493.8340.267
1788-17 E0.68250.7529.1496.2480.273
1788-18 E0.4160.80113.0536.2360.050
1788-19 E0.0831.78336.2314.3010.288
1788-20 E1.023062.9900.1175.5410.15475.19.36.6170.394
1788-21* E0.33502.04127.1355.7930.141
1788-22* E0.12301.51324.8015.9750.098
1788-23* E0.25341.36817.0715.9880.079
1788-24* E0.36901.23713.5556.1670.055
1788-25* E0.411071.0848.6726.2060.033
1788-26* E0.481021.30211.3336.3840.081
1788-27* E0.491650.6867.7336.3670.037
1788-28* E0.311671.6156.9755.6020.246
1788-29* E0.4462.31111.8985.5760.306
1788-30 E0.44620.9885.3106.0890.075
1788-31 E0.2981.06619.2566.1510.056
1788-32 E0.23950.99417.4516.3520.064
1788-33 E0.4161.10321.6516.3440.049
1788-34 E0.28511.34011.4506.3820.061
1788-35 E0.3541.28621.0886.3210.062
1788-36 E0.41151.21612.8966.3720.041
1788-37 E0.3611.10617.0596.3130.073
1788-38 E0.542792.8100.2376.3000.06458.912.27.2620.270
Mean:
1788 D5.5927933.3350.0186.4020.01371.51.27.6160.054
1788 E0.782932.9000.1775.9200.10967.010.86.9360.332
Sample1810U (ppm)U/Th230Th/238U234U/238UAge (ka)2s (ka)(234U/238U)i
1810-1 D7.073483.2310.0215.8140.01777.91.67.0030.056
1810-2 D8.294113.1120.0305.8630.01073.42.16.9860.062
1810-3 D8.889793.1060.0275.9290.01072.11.87.0460.060
1810-4 D9.198333.0490.0445.9930.01169.42.67.0790.066
1810-5 D9.175082.9370.0475.9900.00766.22.87.0200.066
1810-6 D9.12553.1436.9195.9810.012
1810-7 D7.954323.0990.0185.9770.01371.11.37.0890.054
1810-8 D8.844892.9860.0746.0350.060674.17.0880.084
1810-9 D9.39159053.1220.0135.8700.00673.61.16.9990.052
1810-10 D9.7878393.1650.0175.8730.01174.81.37.0240.054
1810-11 D9.0372423.1740.0305.8880.01574.82.07.0430.058
1810-12 D9.5396263.1570.0195.8890.00974.31.47.0360.054
1810-13 D10.19102403.0940.0185.9040.00872.21.37.0160.052
1810-14 D10.64144633.1550.0305.9580.01073.11.97.0990.058
1810-15 E0.0051−0.384146.0361.9650.186
1810-16 E0.0022−1.06048.1681.0140.108
1810-17 E0.00415.40317.5732.3570.194
1810-18 E0.24553.1959.1094.0540.062
1810-19 E0.544264.0090.1865.0540.109130.821.86.8720.466
1810-20 E0.853283.6250.1194.2870.137146.822.75.9840.524
1810-21 E0.41485.0094.4744.4940.186
1810-22 E0.1577.6908.2254.3490.351
1810-23 E0.0329.9121.8435.1530.599
1810-24 E0.0100.661166.0561.8770.144
1810-25 E0.0227.4089.3864.9640.557
1810-26* E0.7333.7624.1004.7350.100
1810-27* E0.1435.2714.5104.2550.112
1810-28* E0.1853.5418.0794.5620.081
1810-29* E0.2593.5117.0954.5620.058
1810-30* E0.2134.0275.2914.0730.149
1810-31* E0.0913.87539.1364.0290.072
1810-32* E0.0522.4699.0994.1870.072
1810-33* E0.0612.60224.1694.4260.141
1810-34* E0.9120103.1310.0684.5610.032105.27.05.7980.128
1810-35 E1.0134.29115.5144.0850.025
1810-36 E0.04996.2978.8904.0600.242
1810-37 E0.145285.7533.9324.3850.234
1810-38 E0.02555.68728.4904.2110.437
1810-39 E0.01174.20331.0484.4740.314
1810-40 E2.0915863.9930.0494.9930.037132.56.26.8140.146
Mean:
1810 D9.0753323.1070.0305.9220.014572.31.97.0400.060
1810 E1.1010883.6900.1054.7240.0788128.814.46.5950.316
Sample1841U (ppm)U/Th230Th/238U234U/238UAge (ka)2s (ka)(234U/238U)i
1841-1 E2.51784.4153.2525.8510.035
1841-2 E1.96514.2687.6315.8420.044
1841-3 E2.372184.3190.0415.8710.021115.53.57.7580.090
1841-4 E1.883504.2610.0465.8910.016112.63.67.7300.082
1841-5 E2.52144.3780.0455.8460.032118.74.37.7840.124
1841-6 E2.5124.4282.7445.8810.044
1841-7 E2.4634.4841.7445.9460.044
1841-8 E2.14474.4992.4675.9620.037
Mean:
1841 E2.252614.3190.0445.8690.023115.63.87.7570.099
Table 5

Summary table of U-Th disequilibrium ages obtained for two H. naledi teeth (samples 1788 and 1810) from the Dinaledi Chamber obtained by GU-ANU. No age calculations were carried out for U concentrations of ≤0.5 ppm or U/Th ≤250 (indicated in red and underlined). Negative U/Th values are due to the Th background being higher than the measured values. Mean values in this table only incorporate values from which meaningful ages could be calculated (indicated in black). All uncertainties are given as 2σ. CS = Closed System; Diff = diffusion (i.e., calculated ages are based on the assumption of continuous diffusion after Sambridge et al. (2012).

https://doi.org/10.7554/eLife.24231.010
Sample 1810aU (ppm)U/Th230Th/238U234U/238UAge – CS (ka)2σ (ka)Age – Diff (ka)2σ (ka)(234U/238U)i*
 1 E0.03−273.71131.25084.43020.8881n/a
 2 E0.02−193.16480.93904.20830.4703n/a
 3 E0.04−333.02571.05315.12200.4988n/a
 4 E0.05−353.63521.38974.92240.4912n/a
 5 E0.19−2583.45040.19654.81060.1376n/a
 6 D6.07−29723.29090.06665.98010.055977.22.387.32.77.190.11
 7 D6.10−53543.26180.08245.97680.031276.32.686.23.37.170.08
 8 D6.39114363.31690.08005.98270.051477.92.688.33.37.210.11
 9 D6.4761933.33180.08995.94700.087379.03.289.73.87.180.17
 10 D6.65−50553.49850.10486.04620.040382.53.494.44.57.370.11
 11 D6.9551493.54650.09106.05310.040683.83.096.34.07.400.11
 12 D7.1532443.52380.09976.05010.042383.23.395.44.37.390.11
Mean:
1–5 E0.07 ± 0.063.43210.30034.79620.1504112.015.7137.125.5
6–12 D6.54 ± 0.313.40180.07496.00700.042880.12.591.13.27.270.11
Sample 1810bU (ppm)U/Th230Th/238U234U/238UAge – CS (ka)2σ (ka)Age – Diff (ka)2σ (ka)(234U/238U)i*
 1 E0.01176.844214.04350.02285.5626n/a
 2 E0.0039.233016.2333−2.28384.6085n/a
 3 E0.00–216.168827.6564−0.10337.6336n/a
 4 E0.00–314.9980967.0421−0.7695259.2590n/a
 5 E0.02−1827.1338296.11363.625048.0742n/a
 6 E0.86−24934.51760.17864.65880.0795189.116.7381.3137.97.240.44
 7 E0.98−6034.87970.14164.87370.0681201.414.00.00.07.840.40
 8 D4.49204233.57780.06705.93270.077387.12.7100.83.17.310.15
 9 D5.35−101283.30460.06595.91420.067778.72.489.22.87.140.13
 10 D5.67−41973.40770.07775.94800.045981.32.692.83.37.230.10
Mean:
1–5 E0.01 ± 0.018.7750204.69881.654793.9630n/a-----
6–7 E0.92 ± 0.124.71010.14654.77300.0602195.713.8471.0269.47.540.42
8–10 D5.17 ± 0.703.42140.07905.93190.052382.12.793.73.67.230.13
Sample 1788aU (ppm)U/Th230th/238U234U/238UAge – CS (ka)2σ (ka)Age – Diff (ka)2σ (ka)(234U/238U)i*
 1E0.0348772.10953.30583.57401.6107n/a
 2E0.01−213.78455.52711.35252.7713n/a
 3E0.00–110.503027.8940−2.490910.1171n/a
 4E0.00–19.0249113.8912−0.712032.3636n/a
 5E0.00–26.679566.27500.776918.7506n/a
 6E0.01–63.02310.98442.19040.4875n/a
 7E0.24−1052.81390.20766.37910.1624n/a
 8E0.24−2041.64951.58116.01230.2961n/a
 9E0.195792.40754.26206.33411.3187n/a
 10E0.481893.17172.28626.10060.1341n/a
 11E1.34138333.87920.28646.35210.102488.59.2102.912.67.870.32
 12E2.577554.17700.06096.32750.097298.63.0117.73.18.040.19
Mean:
1–6 E0.01 ± 0.013.51884.45312.34717.1463n/a---
7–10 E0.29 ± 0.132.64840.24696.18240.097856.26.561.07.7
11–12 E1.96 ± 1.234.07460.09416.33610.048295.13.2112.34.77.960.26
Sample 1788bU (ppm)U/Th230Th/238U234U/238UAge – CS (ka)2σ (ka)Age – Diff (ka)2σ (ka)(234U/238U)i*
 1E0.0242.39451.87743.50401.4368n/a
 2E0.02141.96561.32993.30990.9022n/a
 3E0.01–82.81562.10342.53590.8082n/a
 4E0.021602.102458.18543.23427.4009n/a
 5E0.03−312.38591.40844.12851.5222n/a
 6E0.03−202.895111.29114.10463.9747n/a
 7E0.02−102.84863.53834.93622.3343n/a
 8E0.03−182.83251.61135.70520.7139n/a
Mean:
1–8 E0.02 ± 0.012.55976.76184.13081.2209n/a
Sample 1788cU (ppm)U/Th230th/238U234U/238UAge – CS (ka)2σ (ka)Age – Diff (ka)2σ (ka)(234U/238U)i*
 1D5.44215783.92810.07076.42600.074088.62.6103.03.17.970.15
 2D5.391550373.89080.05656.44160.052487.22.0101.02.47.960.11
 3D4.9517083.89010.08286.40850.079287.83.0102.03.67.930.16
 4D3.8716533.80330.08596.37860.106885.83.399.03.67.850.20
 5D4.2511683.95690.08006.40510.095790.03.1105.03.67.970.19
 6D5.1214933.94330.05796.49510.096187.82.5102.02.58.040.17
 7D5.3426593.80200.05816.47130.058184.02.096.72.47.940.11
 8D5.0610933.99480.06726.44790.063090.32.4105.53.08.030.13
 9D4.7810184.04810.07186.44680.058692.02.5108.03.38.060.13
 10D5.228173.90110.05826.51870.081386.12.399.62.48.040.15
 11D5.254253.88720.08506.44150.062487.12.8101.03.67.960.14
 12D5.463453.95610.05846.46580.073388.82.3103.32.58.030.14
Mean:
1–12 D5.01 ± 0.283.91750.07966.44790.046187.92.6102.03.67.980.06
Table 6

Summary table of model parameters used in ESR dating separated by sample number and laboratory. See text for detailed discussion.

https://doi.org/10.7554/eLife.24231.015
Sample:1767178818101841
Laboratory:SCUSCUCenieh-guSCUCenieh-guSCU
Enamel:
De (Gy)194 ± 4231 ± 8159 ± 10296 ± 14232 ± 301676 ± 127
U (ppm)2.52 ± 0.530.38 ± 0.170.07 ± 0.070.32 ± 0.120.16 ± 0.162.28 ± 0.48
234U/238U6.21 ± 0.035.95 ± 0.326.258 ± 0.3494.04 ± 0.184.773 ± 0.0605.87 ± 0.03
230Th/234U0.37 ± 0.050.55 ± 0.520.598 ± 0.0380.92 ± 0.050.950 ± 0.0340.785 ± 0.038
Alpha efficiency*0.13 ± 0.020.13 ± 0.020.13 ± 0.020.13 ± 0.020.13 ± 0.020.13 ± 0.02
Initial thickness (μm)1027 ± 2101049 ± 2771486 ± 2481150 ± 2501527 ± 257650 ± 145
Water (%)000000
Dentine:
U (ppm)7.88 ± 0.665.76 ± 0.864.71 ± 0.279.08 ± 0.445.81 ± 0.37
234U/238U6.28 ± 0.096.40 ± 0.036.448 ± 0.0465.93 ± 0.035.969 ± 0.035
230Th/234U0.35 ± 0.110.62 ± 0.020.608 ± 0.0120.52 ± 0.090.572 ± 0.010
Water (%)10 ± 510 ± 510 ± 510 ± 510 ± 5
Sediment:
U (ppm)3.0 ± 0.32.9 ± 0.12.9 ± 0.13.2 ± 0.33.2 ± 0.30.64 ± 0.06
Th (ppm)7.9 ± 0.48.3 ± 0.68.3 ± 0.68.6 ± 0.48.6 ± 0.44.72 ± 0.47
K (%)1.17 ± 0.141.21 ± 0.141.21 ± 0.141.23 ± 0.141.23 ± 0.141.47 ± 0.15
Water (%)25 ± 1025 ± 1025 ± 1025 ± 1025 ± 1025 ± 10
Depth below ground surface (cm)0225555
Gamma Dose rate (μGy a−1)
25 ± 10% Water, 80% Rn degassing
25 ± 10% Water, no Rn degassing
534 ± 69
724 ± 116
534 ± 69
724 ± 116
534 ± 69
724 ± 116
534 ± 69
724 ± 116
534 ± 69
724 ± 116
534 ± 69
724 ± 116
Cosmic dose rate (μGy a−1)15 ± 115 ± 115 ± 115 ± 115 ± 115 ± 1
  1. A relative error of ± 10% was assumed.

Table 7

Summary of ESR dating results (2σ uncertainties) for two end-member scenarios: (i) complete burial of the samples, 80% Rn loss in the sediment and post Th-230 equilibrium in dental tissue (i.e., maximum age scenario); (ii) complete burial of the samples and post-Rn equilibrium in sediment (i.e., minimum age scenario). See text for detailed discussion.

https://doi.org/10.7554/eLife.24231.016
Sample:1767178818101841
Laboratory:SCUSCUCenieh-guSCUCenieh-guSCU
 Scenario 1: 25 ± 10% Water, complete burial and 80% 222Rn degassing (maximum age scenario)
internal dose rate (μGy a−1)1142 ± 515190 ± 12947 ± 47323 ± 175176 ± 1761411 ± 596
alpha (μGy a−1)*008 ± 208 ± 20
beta dose rate, dentine (μGy a−1)73 ± 3391 ± 6264 ± 1675 ± 4151 ± 14
beta dose rate, sediment (μGy a−1)101 ± 24105 ± 3186 ± 1795 ± 2486 ± 18358 ± 74
gamma and cosmic (μGy a−1)549 ± 69549 ± 69549 ± 69549 ± 69549 ± 69549 ± 69
total dose rate (μGy a−1)1865 ± 521935 ± 162754 ± 871042 ± 194870 ± 1902318 ± 606
p enamel−0.030.49−0.02−0.70−0.770.91
p dentine0.080.13−0.061.020.54
Age (ka)104 ± 29247 ± 42211 ± 28284 ± 51267 ± 68723 ± 181
Combined SCU/CENIEH-GU age (ka)229 + 60/–46276 + 59/–77
Average age for 1788 & 1810 (ka)253 + 82/–70
 Scenario 2: 25 ± 10% Water, complete burial and no 222Rn degassing (minimum age scenario)
internal dose rate (μGy a−1)1277 ± 552216 ± 16551 ± 51335 ± 193184 ± 1841520 ± 630
alpha (μGy a−1)*008 ± 208 ± 20
beta dose rate, dentine (μGy a−1)82 ± 35102 ± 7869 ± 1887 ± 5059 ± 16--
beta dose rate, sediment (μGy a−1)132 ± 26134 ± 33111 ± 19126 ± 26112 ± 19380 ± 81
gamma and cosmic (μGy a−1)739 ± 116739 ± 116739 ± 116739 ± 116739 ± 116739 ± 116
total dose rate (μGy a−1)2230 ± 5861191 ± 219978 ± 1291287 ± 2321102 ± 2192639 ± 647
p enamel−0.310.06−0.37−0.83−0.910.67
p dentine−0.22−0.22−0.400.540.10
Age (ka)87 ± 22194 ± 34163 ± 24230 ± 40210 ± 50635 ± 148
Combined SCU/CENIEH-GU age (ka)179 + 49/–40220 + 50/–60
Average age for 1788 & 1810 (ka)200 + 70/–61
  1. *using alpha attenuation values of Grün (1987).

  2. considered as negligible given the low radioelement concentrations in the sediment and the high total dose rate value.

  3. for 1841, the beta dose rate on both sides of the enamel layer is derived from the sediment.

Table 8

Summary of OSL results obtained by the University of the Witwatersrand for samples of Unit 1 from the Dinaledi Chamber (samples OSL3, 4 and 5). The ages were calculated using effective U concentration values (taking disequilibrium into account; see text for details). CAM = Central Age Model; MAM = Minimum Age Model.

https://doi.org/10.7554/eLife.24231.017
Sample IDH2O (%)Th (ppm)U (ppm) pre-RnU (ppm) post-RnK (%)Total dr (Gy/ka)Total de (Gy) CAMTotal de (Gy) MAMCAM
Age (ka)
CAM
MAM age (ka)MAM 2σOver dispersion
(%)
OSL318.9 ± 53.71 ± 1.600.75 ± 0.1770.193 ± 0.0440.45 ± 0.120.760.07428.5968.92176.427.75601032314163
OSL425.8 ± 53.38 ± 1.600.485 ± 0.1770.097 ± 0.0440.47 ± 0.120.700.06379.8943.58168.020.7546792413755
OSL522.7 ± 55.11 ± 1.600.692 ± 0.1770.138 ± 0.0440.56 ± 0.120.900.07759.54102.33315.6748.688491323536168
Table 9

Final mean palaeomagnetic data for all subsamples analysed from each phase of Flowstone 1a as shown in Figure 13. MAD = mean maximum angular deviation for individual samples; K = precision/sample dispersal parameter; Plat = palaeolatitude).

https://doi.org/10.7554/eLife.24231.018
Flowstone 1aDeclination (O)Inclination (O)MADKPlat.Polarity
 Phase C15.5−39.7370.875.4N
 Phase B26−28.17.4156.263.3N
 Phase A156.415.95.730.2−60.0R
Table 10

ESR fitting results obtained by SCU and CENIEH-GU. Both laboratories employed a Single Saturating Exponential (SSE) fitting function. Dmax was selected in accordance with Duval and Grün (2016) to avoid DE overestimation. SCU results in brackets show DE values that were obtained by SCU using the CENIEH-GU procedure (see text for details).

https://doi.org/10.7554/eLife.24231.022
SCUCenieh-gu
SampleDE (Gy)Dmax (Gy)Dmax/DEDE (Gy)Dmax (Gy)Dmax/DE
1767194 ± 4 (193 ± 6)12647
1788232 ± 8 (232 ± 22)12045159 ± 11164910
1810296 ± 14 (281 ± 34)27359232 ± 2916497
18411676 ± 127 (1648 ± 500)35262

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