Research ArticleANTHROPOLOGY

Evidence for precision grasping in Neandertal daily activities

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Science Advances  26 Sep 2018:
Vol. 4, no. 9, eaat2369
DOI: 10.1126/sciadv.aat2369
  • Fig. 1 PCA (nine entheses) without a priori group categorization.

    (A) PC1 versus PC2; (B) PC2 and PC3. The side figures in each plot demonstrate muscle entheses with high factor loadings (see Statistical analysis in Materials and Methods), describing the two opposite entheseal patterns of PC1 (A) and the entheseal pattern (that is, high values in both PC2 and PC3) separating Neandertals from all modern humans (B). FPL, flexor pollicis longus; ADM, abductor digiti minimi; FDM, flexor digiti minimi; ECU, extensor carpi ulnaris; EPB, extensor pollicis brevis; OP, opponens pollicis; FBP, flexor pollicis brevis; ABP, abductor pollicis; ADP, adductor pollicis; DI1, first dorsal interosseus.

  • Fig. 2 PCA (three thumb entheses) without a priori group categorization, PC1 versus PC2.

    The bottom figures describe the muscle entheses with high factor loadings on PC1 (see Statistical analysis in Materials and Methods).

  • Fig. 3 Two examples of precision grasping involving mainly the thumb and the index finger during the production and use of lithic flakes.

    Here, these hand movements are represented by high values on PC1 of the PCA using nine entheses (Fig. 1A).

  • Table 1 Two synergistic muscle groups reflected on the multivariate patterns among hand entheseal surfaces (21, 22).
    MusclesPrimary function (16)Insertion site
    analyzed (16, 21, 22)
    Muscles coordinated for precision grasping using the thumb and
    index finger (21, 5255)
    Abductor pollicisAbducts the thumbRadial base of the first
    proximal phalanx
    Adductor pollicisAdducts the thumbUlnar base of the first
    proximal phalanx
    First dorsal
    interosseus
    Abducts the second
    finger
    Radial base of the
    second proximal
    phalanx
    First palmar
    interosseus
    Draws the second finger
    toward the third
    finger
    Ulnar base of the
    second proximal
    phalanx
    Flexor pollicis brevisFlexes the first
    metacarpophalangeal
    joint
    Radial base of the first
    proximal phalanx
    Opponens pollicisAbducts, rotates, and
    flexes the thumb
    Radial diaphysis of
    the first metacarpal
    Muscles coordinated for producing sustained power grasping (21, 5355)
    Abductor digiti
    minimi
    Abducts the fifth fingerUlnar base of the fifth
    proximal phalanx
    Extensor carpi
    ulnaris
    Extends the wrist and
    adducts hand
    Ulnar base of the fifth
    metacarpal
    Extensor pollicis
    brevis
    Extends the thumbDorsal base of the first
    proximal phalanx
    Flexor digiti minimiFlexes the fifth fingerUlnar base of the fifth
    proximal phalanx
    Flexor pollicis
    longus
    Flexes the first distal
    phalanx
    Palmar diaphysis of the
    first distal phalanx
  • Table 2 Mean accuracy rates and posterior probability values of the two discriminant function analyses.
    DFAFirst (nine
    entheses
    data set)
    Second (three
    entheses
    data set)
    Accuracy (original/cross-validated)95.6%/93.3%95.6%/95.6%
    Predicted group/posterior probability values
    NeandertalsKebara 2Precision
    grip/>0.99
    Precision
    grip/>0.99
    La Ferrassie 1Precision
    grip/>0.99
    Precision
    grip/>0.99
    La Ferrassie 2Precision
    grip/>0.99
    Precision
    grip/>0.99
    Shanidar 3Precision
    grip/>0.98
    Shanidar 4Precision
    grip/>0.99
    Precision
    grip/0.99
    Tabun 1Precision
    grip/>0.99
    Early modern
    humans
    Abri Pataud 1Power grip/0.68
    Arene Candide
    2
    Precision
    grip/>0.98
    Precision
    grip/>0.99
    Dolni Vestonice
    14
    Precision
    grip/>0.99
    Nazlet Khater 2Power grip/0.98Power grip/0.89
    Ohalo 2Power grip/0.93Power grip/0.99
    Qafzeh 9Precision
    grip/>0.99
    Precision
    grip/>0.99

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/9/eaat2369/DC1

    Fig. S1. PCA using eight entheses from the same anatomical side of each fossil, either left (L) or right (R), and the right side of the reference specimens, PC1 versus PC2.

    Fig. S2. PCA using eight entheses from the same anatomical side of each fossil, either left (L) or right (R), and the right side of the reference specimens, PC2 versus PC3.

    Fig. S3. PCA using seven entheses from the same anatomical side of each fossil and the left side of the reference specimens, PC1 versus PC2.

    Table S1. Individual hand bone sets comprising the fossil samples.

    Table S2. Descriptive statistics for the size-adjusted entheseal surface area measurements of the fossil specimens.

    Table S3. Eigenvalues and factor loadings of the four PCAs on size-adjusted entheseal surface measurements.

    Table S4. Statistics of the two discriminant function analyses.

    References (5663)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. PCA using eight entheses from the same anatomical side of each fossil, either left (L) or right (R), and the right side of the reference specimens, PC1 versus PC2.
    • Fig. S2. PCA using eight entheses from the same anatomical side of each fossil, either left (L) or right (R), and the right side of the reference specimens, PC2 versus PC3.
    • Fig. S3. PCA using seven entheses from the same anatomical side of each fossil and the left side of the reference specimens, PC1 versus PC2.
    • Table S1. Individual hand bone sets comprising the fossil samples.
    • Table S2. Descriptive statistics for the size-adjusted entheseal surface area measurements of the fossil specimens.
    • Table S3. Eigenvalues and factor loadings of the four PCAs on size-adjusted entheseal surface measurements.
    • Table S4. Statistics of the two discriminant function analyses.
    • References (5663)

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