Table 1 Panda nut-cracking learning curves for the ‘number of nuts cracked per minute’ for Mbendjele foragers and Taï chimpanzees.

From: Learning curves and teaching when acquiring nut-cracking in humans and chimpanzees

Term*

Estimate

Lower CI

Upper CI

Min

Max

Intercept, c0

15.576

4.439

36.639

15.472

18.543

Agea, c1

21.454

9.092

48.030

21.375

24.782

Groupb, c2

−15.879

−37.048

−4.343

−18.786

−15.760

Group:agec, c3

−18.172

−44.756

−4.505

−21.463

−17.629

Sexd, c4

0.451

−0.636

4.793

0.283

0.706

Helpe, c5

0.006

−0.496

0.699

−0.053

0.087

Asymf, c6

1.348

0.873

1.886

1.289

1.413

Group:asymg, c7

0.632

−0.271

1.307

0.561

0.677

  1. Model results for absolute age and group (human or chimpanzee; indicated are the estimated coefficients, together with confidence limits and the minimum and maximum estimates derived from data dropping individuals one at a time).
  2. *The indexed coefficients (c0 to c7) refer to the coefficients as indicated in equation(1) and (2).
  3. az-transformed to a mean of zero and a standard deviation of one; mean (standard deviation) of the original predictor was 18.634 (14.722; years).
  4. bhumans = 0, chimpanzees = 1.
  5. cinteraction term informing about how much the effect of age in humans differed from that in chimpanzees.
  6. ddummy coded (females = 0, males = 1) and then centered to a mean of zero.
  7. ez-transformed to a mean of zero and a standard deviation of one; mean (standard deviation) of the original predictor was 0.061 (0.182; proportion sessions with help present).
  8. ffitted asymptotic performance of adult chimpanzees.
  9. ginteraction term informing about how much the asymptotic performance of humans differed from that of chimpanzees.
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