Con. = 0.121 Con. = 0.003 Roughness measuring Saragusti, I. †‡ , Sharon, I. ‡ , Smilansky, U. † and Karasik, A. † † Weizmann Institute of Science, Rehovot, Israel; ‡ The Institute of Archaeology, the Hebrew University, Jerusalem, Israel Correspondence: [email protected] The Handaxes - Handaxes first appear in the archaeological record around 1.6–1.7 million years ago, in East African sites, which are assigned to the Early Acheulian and the Developed Oldowan Techno-Complexes. This tool-type was gradually distributed over most of the Old World and remained an important part of hominids' toolkit till the end of the Lower Paleolithic. Roughness - the degree of roughness of handaxe contours is considered to be meaningful, since it is accepted that the roughness generally decreased over time. As such it may indicate chronological changes. Roughness – definition: In our study, the evaluation of roughness was confined to 2D projections of the handaxes (e.g. the plan-view contours). In two dimensions, roughness is a measure of directional changes in the object’s contour. Roughness is determined by the frequency and amplitude of the transitions between convex and concave sections along the contour (inﬂection points). Inflection points S1, S2 and S3, define a convex section (S1, S2) and a concave section (S2, S3). ds s k sign s k concavity ) ( 1 ) ( 2 1 The mathematical definition: the concavity is deﬁned as the sum of mismatch angles over all the concave sections of the contour: Roughness is a scale-dependent concept — a contour can be smooth on the visible scale, but very rough on the scale of mineral granularity. Thus, the first step in roughness analysis consists of an archaeologically-motivated assessment of the scale (or scales) of interest. The studied samples in chronological order, from the earliest to the latest (and sample sizes): ‘Ubediya (UB) (n=45) => Gesher Benot Ya’aqov (GBY) (n=96)=> Ma’ayan Barukh (MB) (n=50)=> Tabun bed 90 (T 90 ) (n=45) => Tabun Layer E (T ) Results: the mean concavity values of the studied handaxes The studied samples represent various stages throughout the Lower Paleolithic in Israel: - The concavity generally tend to decrease over time, i.e. handaxes generally become less rough. - These trends are seen only among the UB, GBY and MB samples, while the two Tabun samples, exhibiting higher values than could be expected, considering their assumed ages, deviate from these general trends. -It is suggested that the general decrease in the degree of roughness of handaxes represents developments in the technical and perhaps cognitive abilities of the early hominids. Thus, it may result from the introduction into use of the soft hammer, probably by the time of GBY, ca. 0.75 mya. -The observed increase in the degree of roughness towards the end of the period may represent changes Jerusalem ‘Ubeidi ya Tabun Cave Ma’ayan Barukh Gesher Benot Ya’aqov A relatively rough plan-view contour of a handaxe (left) and a relatively smooth one (right). (Left) Plan-view contours of a relatively rough handaxe (top) and a relatively smooth one (bottom). The original contours (blue) and the smoothed ones (magenta). (Right) The curvature of the contour as a function of the arc-length. Convex sections – above the zero-line; concave section – bellow the zero-line. The concavity values are given as a measure of the degree of roughness. k(s) : the curvature along the contour. s : arc-length. ca. 1.4 mya. ca. 300 kya. 0.000 0.040 0.080 0.120 UB GBY MB T 90 Te Time S 1 S 3 S 2

Con. = 0.121 Con. = 0.003 Roughness measuring Saragusti, I. †‡, Sharon, I. ‡, Smilansky, U. † and Karasik, A. † † Weizmann Institute of Science, Rehovot,

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Con. = 0.121

Con. = 0.003

Roughness measuring

Saragusti, I. †‡, Sharon, I.‡, Smilansky, U.† and Karasik, A.†

† Weizmann Institute of Science, Rehovot, Israel; ‡ The Institute of Archaeology, the Hebrew University, Jerusalem, Israel

Correspondence: [email protected]

The Handaxes - Handaxes first appear in the archaeological record around 1.6–1.7 million years ago, in East African sites, which are assigned to the Early Acheulian and the Developed Oldowan Techno-Complexes. This tool-type was gradually distributed over most of the Old World and remained an important part of hominids' toolkit till the end of the Lower Paleolithic.

Roughness - the degree of roughness of handaxe contours is considered to be meaningful, since it is accepted that the roughness generally decreased over time. As such it may indicate chronological changes.

Roughness – definition:In our study, the evaluation of roughness was confined to 2D projections of the handaxes (e.g. the plan-view contours).

In two dimensions, roughness is a measure of directional changes in the object’s contour.

Roughness is determined by the frequency and amplitude of the transitions between convex and concave sections along the contour (inflection points).

Inflection points S1, S2 and S3, define a convex section (S1, S2) and a concave section (S2, S3).

dssksignskconcavity )(1)(2

The mathematical definition: the concavity is defined as the sum of mismatch angles over all the concave sections of the contour:

Roughness is a scale-dependent concept — a contour can be smooth on the visible scale, but very rough on the scale of mineral granularity. Thus, the first step in roughness analysis consists of an archaeologically-motivated assessment of the scale (or scales) of interest.

The studied samples in chronological order, from the earliest to the latest (and sample sizes):

‘Ubediya (UB) (n=45) => Gesher Benot Ya’aqov (GBY) (n=96)=> Ma’ayan Barukh (MB) (n=50)=> Tabun bed 90 (T90) (n=45) => Tabun Layer E (Te) (n=79).

Results: the mean concavity values of the studied handaxes

The studied samples represent various stages throughout the Lower Paleolithic in Israel:

- The concavity generally tend to decrease over time, i.e. handaxes generally become less rough. - These trends are seen only among the UB, GBY and MB samples, while the two Tabun samples, exhibiting higher values than could be expected, considering their assumed ages, deviate from these general trends. -It is suggested that the general decrease in the degree of roughness of handaxes represents developments in the technical and perhaps cognitive abilities of the early hominids. Thus, it may result from the introduction into use of the soft hammer, probably by the time of GBY, ca. 0.75 mya. -The observed increase in the degree of roughness towards the end of the period may represent changes in social norms, and is consistent with other findings.

Jerusalem

‘UbeidiyaTabun Cave

Ma’ayan BarukhGesher Benot Ya’aqov

A relatively rough plan-view contour of a handaxe (left) and a relatively smooth one (right).

(Left) Plan-view contours of a relatively rough handaxe (top) and a relatively smooth one (bottom). The original contours (blue) and the smoothed ones (magenta).

(Right) The curvature of the contour as a function of the arc-length. Convex sections – above the zero-line; concave section – bellow the zero-line. The concavity values are given as a measure of the degree of roughness.

k(s) : the curvature along the contour.

s : arc-length.

ca. 1.4 mya. ca. 300 kya.

0.000

0.040

0.080

0.120UB

GBY

T90Te

Time