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Brief communication Bone remodeling rates in Pleistocene humans are not slower than the rates observed in modern populations A reexamination of Abbott et al. (1996)

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AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 141:315–318 (2010)
Brief Communication: Bone Remodeling Rates in
Pleistocene Humans are not Slower Than the Rates
Observed in Modern Populations: A Reexamination
of Abbott et al. (1996)
Margaret Streeter,1* Sam Stout,2 Erik Trinkaus,3 and David Burr4,5
1
Department
Department
3
Department
4
Department
5
Department
2
of
of
of
of
of
Anthropology, Boise State University, Boise, ID 83725
Anthropology, Ohio State University, Columbus, OH 043210
Anthropology, Washington University, St. Louis, MO 63130
Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202
Orthopedic Surgery, Indiana University School of Medicine, Indianapolis, IN 46202
KEY WORDS
bone histomorphometry; human; osteon
ABSTRACT
Bone histomorphometry has been applied
to the lower limb cortical bone of Pleistocene humans to
establish age at death and to determine bone remodeling
rates (Abbott et al.: Am J Phys Anthropol 226 (1996) 307–
313). Both of these procedures require the determination of
osteon density and mean osteon size. Previous analyses of
Middle and Late Pleistocene human lower limb bones have
produced bone remodeling rates that are slower than those
determined in a more recent archeological sample. Recalculation of the data reported in Abbott et al.: Am J Phys
Anthropol 226 (1996) 307–313) has revealed mathematical
errors in the remodeling rates reported for the Pleistocene
humans. The corrected remodeling rates for the Pleistocene
group are similar to the values obtained in the more recent
comparative sample. Am J Phys Anthropol 141:315–318,
2010. V 2009 Wiley-Liss, Inc.
It is generally held that Middle and Late Pleistocene
humans exhibit slower bone remodeling rates than modern populations. This interpretation is based primarily
on the comparison of the histomorphology of fossil and
modern human cortical bone samples (Thompson and
Trinkaus, 1981, Trinkaus and Thompson, 1987; Abbott
et al., 1996; Pfeiffer and Zehr, 1996). The most widely
cited study is Abbott et al. (1996), who undertook a comprehensive histomorphological analysis of ten lower limb
cortical bone samples representing both archaic and
early modern human Middle and Late Pleistocene fossils. In their study, several parameters of cortical bone
remodeling were determined histomorphometrically
using mean osteon area and the density (number per
unit area) of whole and fragmentary osteons. Abbott
et al. (1996) reported smaller osteons and slower bone
turnover rates in the Pleistocene humans compared to a
more recent late prehistoric, agricultural, sample from
Pecos Pueblo, New Mexico (Burr et al., 1990). They
interpreted their findings to mean that the greater bone
mass typical of the Pleistocene populations was the
result of the lower bone turnover. We have recently reexamined the data reported by Abbott et al. (1996), and
find some discrepancies in the calculations published.
Our purpose is to report the results of our reexamination
of the data collected for the Abbott et al. (1996) article
and to report the results of our reanalysis of the bone
remodeling rates in the Pleistocene humans compared
with the more recent Pecos Pueblo sample.
tested and verified by Stout and Paine (1994). The algorithm
employs the following histomorphometric parameters.
C
Bone Area (B.Ar)
The entire area of bone in the sample excluding the
marrow cavity (in mm2).
Mean Osteon Cross-Sectional Area (On.Ar)
The average area of bone (including Haversian canals)
contained within the cement lines of structurally complete secondary osteons (in mm2).
Mean Cross-Sectional Diameter (On.Dh)
The average diameter of complete secondary osteons
(in mm), determined from On.Ar using the formula
On:Dh ¼ ð4On:Ar=pÞ1=2
Intact Osteon Density (N.On)
The number of complete (unremodeled) Haversian systems (osteons/mm2)
*Correspondence to: Margaret Streeter, Department of Anthropology, Boise State University, 1910 University Drive, Boise, ID 83725.
E-mail: margaretstreeter@boisestate.edu
Received 26 October 2008; accepted 26 August 2009
MATERIALS AND METHODS
Bone remodeling rates are calculated using the algorithm
proposed by Wu et al. (1970) and Frost (1987a) and later
C 2009
V
WILEY-LISS, INC.
DOI 10.1002/ajpa.21192
Published online 19 November 2009 in Wiley InterScience
(www.interscience.wiley.com).
316
M. STREETER ET AL.
TABLE 1. Histomorphometric parameters calculated using OPD as reported in Tables 1, 4, and 5 of Abott et al. (1996)
Name
Archaics
Shanidar 2
Shanidar 3
Shanidar 4
Shanidar 5
Shanidar 6
Tabun 1
Broken Hill
Early modern
Skhul 3
Skhul 6
Skhul 7
Agea (yr)
On.Arb (mm2)
OPD (mm2)
AOC (mm2)
On.Bc (mm2)
Ac.Fd (#/mm2/yr)
BFR (%/yr)
25
45
37.5
42.5
27.5
22.5
–
0.038
0.018
0.030
0.024
0.023
0.030
0.036
11.46
24.29
10.34
13.5
10.05
9.29
13.9
11.92
25.26
10.44
13.65
10.05
9.38
15.01
38.4
34.6
25.4
27.3
18.5
22.9
43.5
0.93
0.78
0.42
0.46
0.67
0.63
–
3.57
1.38
1.25
1.12
1.54
1.89
–
–
30
35
0.016
0.039
0.023
8.02
5.7
13.6
8.02
5.70
13.75
11.3
20.5
25.1
–
.33
.61
–
1.30
1.39
See text for explanation of acronyms.
a
Mean of age range.
b
Converted from lm2 for this study.
c
Formula used was On.B 5 (On.Ar 3 On.N).
d
Calculated by subtracting 12.5 yr from median age.
Fragmentary Osteon Density (N.On.Fg)
2
The number of fragmentary osteons/mm . Fragmentary osteons are those osteon segments with a cement
line but no Haversian canal.
Osteon Population Density (OPD)
2
The total number of intact and fragmentary osteons/mm
OPD ¼ N:On þ N:On:Fg=mm2
Accumulated Osteon Creations (AOC)
The total number of osteon creations (both visible and
removed osteons and fragments) corresponding to a
given OPD. AOC is expressed in #/mm2
AOC ¼ bðOPDÞ
Continuous remodeling eventually reaches an asymptote of OPD at which each newly created osteon
removes evidence of previous osteon creations. The
number of missing osteons, those that have been remodeled out, increases exponentially as the asymptote
is reached. The algorithm proposed by Frost (1987a)
uses a scaling operator, b, which when multiplied by
the OPD, gives an estimation of AOC. b is defined by
the equation
b ¼ ð1 ax Þ1
where a is an OPD normalized to its predicted asymptote a 5 (OPD)(OPD asymptote1). The exponent x is
equal to 3.5 as suggested by Frost (1987b). The formula
for the OPD asymptote of a given specimen is
OPD asymptote ¼ kððOn:DhÞ2 Þ1
To calculate the OPD asymptote, the value of the
osteon fragment packing factor, k, is needed. The value
of k accounts for the fact that a unit (1 mm2) of bone can
contain more intact osteons and osteon fragments than
theoretically predicted, as a result of overlap. The value
American Journal of Physical Anthropology
of k is specific for each bone and is determined by the
formula
k ¼ ðOPD asymptoteÞ ðOn:DhÞ2
The k value for the tibia has not been established, but
because of gross morphological similarities between the
femur and tibia, the femoral value of 1.38 was used for
both bones in Abbott et al. (1996).
Mean Activation Frequency (Ac.f)
The mean number of osteons created annually expressed
in #/mm2/yr. The annual osteon bone formation rate is
equal to the mean osteon area multiplied by all of the
osteons previously created (AOC), divided by the number
of years over which these osteon creations accumulated.
Cortical drift (movement of the bone cortex through
space as a result of change in shape and size of bone during growth) causes a significant proportion of the original
bone that was present at birth to be removed before skeletal maturity. Because of this, the actual age of the bone is
younger than its chronological age. It is necessary, therefore, to average the formation rate over the age of the bone
(mean tissue age) rather than the chronological age. The
age of adult compacta has not been established for human
bones other than the sixth rib (Wu et al., 1970). Failure to
account for the difference in the age of observed compacta
would result in the calculation of erroneous values for activation frequency. Wu et al. (1970) have suggested that the
effective birth of adult compacta for most cortical bone is
within ca. 3 years of the 12.5 years reported for the rib.
Ac:f ¼ AOC=ðage 12:5 yearsÞ
Bone Formation Rate (BFR)
The annual rate of bone formation in %/yr
BFR ¼ Ac:f ðOn:ArÞ3100
Net Remodeling Rate (BRh)
The total amount of remodeling that occurred over the
lifetime of the individual expressed in mm2/mm2. If a
317
REMODELING RATES IN PLEISTOCENE HUMANS
TABLE 2. Individual values and group means recalculated in this analysis (using N.On derived from the Abbott et al. formula for
On.B) for comparison with group means as reported in Table 6 of Abbott et al. (1996)
N.On (mm2)
Name
Archaics
Shanidar 2
Shanidar 3
Shanidar 4
Shanidar 5
Shanidar 6
Tabun 1
Broken Hill
Group mean
Early modern
Skhul 3
Skhul 6
Skhul 7
Group mean
Ac.F (#/mm2/yr)
Abbott
Present
3.57
10.1
19.2
8.5
11.4
8.0
7.6
12.1
11.0
3.37
7.1
5.3
10.9
7.8
BFR (%/yr)
Abbott
Present
0.10
0.42
0.44
0.23
0.27
0.29
0.34
–
0.33
0.09
–
0.18
0.32
0.25
Abbott
Present
0.24
1.06
0.85
0.69
0.65
0.70
1.02
–
0.92
0.27
–
0.68
0.71
0.70
See text for explanation of acronyms.
TABLE 3. Comparison of group mean values for the Pleistocene humans and the Pecos Pueblo sample as reported in Table 6 by
Abbott et al. (1996) with the recalculated values from N.On (derived from their formula for On.B)
N.On (#/mm2)
Ac.F (#/mm2/yr)
BFR (%/yr)
Abbott
Present
Abbott
Present
Abbott
Present
3.57
3.37
7.26
6.21
11.0
7.8
0.10
0.09
0.22
0.20
0.33
0.25
0.24
0.27
0.78
0.82
0.92
0.70
Archaic group mean
Early modern group mean
Pecos males group mean
Pecos females group mean
See text for explanation of acronyms.
reasonably accurate age at death is not available, the
net osteonal remodeling can be estimated as follows
BRh ¼ AOC ðOn:ArÞ
RESULTS
Table 1 provides the histomorphometric values
reported for the Pleistocene humans in Tables 1, 4, and
5 of Abbott et al. (1996). The bone remodeling rates
listed in these tables were calculated using OPD (whole
and fragmentary osteon density). However, for comparison of bone remodeling parameters with the more recent
Pecos Pueblo sample only the total number of whole secondary osteon could be used because fragmentary osteon
counts were not included in the original analysis of the
Pecos Pueblo sample (Burr et al., 1990). Histological
remodeling parameters calculated using OPD are not
available for a recent femoral sample of known age. Furthermore, in the comparison of bone parameters between
the Pleistocene humans and Pecos Pueblo, only group
mean values were reported (Table 6, Abbott et al., 1996).
The histomorphological values for the Pecos Pueblo sample were taken from the Abbott et al. article and were
not recalculated for this article. The osteon counts
reported in Table 6 of Abbott et al. are labeled as OPD
but a footnote indicated that the values listed are intact
osteon counts only. Whole osteon numbers (N.On) for the
Middle (3.57/mm2) and Late (3.37/mm2) Pleistocene
groups given in Table 6 of Abbott et al. (1996) are lower
than would be expected based on the group means
derived from OPD (13.26/mm2 Middle Pleistocene
humans) and (9.11/mm2 Late Pleistocene humans) given
in Table 4 of Abbott et al. (1996). Individual values for
N.On for each of the Pleistocene humans can be derived
indirectly from the formula for percent osteonal bone
[On.B 5 (On.Ar 3 N.On)/(100)] given in Table 2 of
Abbott et al. (1996). For example, N.On for the Shanidar
3 femur can be determined using the values given for
percent osteonal bone (On.B, 34.63%), and mean osteon
size (On.Ar, 0.018 mm2) in Table 3 of Abbott et al. (1996)
as follows.
On:B ¼ ðOn:ArÞðN:onÞð100Þ
34:63% ¼ ð0:018 mm2 ÞðN:onÞ=100
ð100Þ34:63% ¼ ð0:018 mm2 ÞðN:onÞ=100ð100Þ
0:3463 ¼ ð0:018 mm2 ÞðN:OnÞ
0:3463=0:018 ¼ ð0:018 mm2 =0:018ÞðN:OnÞ
0:3463=0:018 ¼ N:On
19:2=mm2 ¼ N:On
The mean N.On for the two fossil groups (Middle and
the Late Pleistocene humans) determined by this method
are 11.0/mm2 and 7.8/mm2, respectively (Table 2). Recalculation of bone remodeling rates using the revised
N.On values for the Pleistocene fossils also produces valAmerican Journal of Physical Anthropology
318
M. STREETER ET AL.
ues that are greater than the values originally reported
in Table 6 of Abbott et al. (1996). The revised values
for bone remodeling in the Pleistocene humans are
equal to or greater than the remodeling rates determined for the comparison sample from Pecos Pueblo
(Table 3).
CONCLUSIONS
A recalculation of the cortical bone histomorphometry
of Pleistocene humans reported in the Abbott et al.’s
article (1996) finds that, contrary to the original report,
the fossil human bones exhibit bone remodeling rates
that are similar to those determined for the modern comparative sample from Pecos Pueblo. However, the Pecos
Pueblo samples, although recent relative to the Pleistocene samples, date to the 15th and 16th Centuries and
may not be representative of bone remodeling activity
typical of modern human populations. The Pecos people
were primarily dependent on maize agriculture, which
has been shown to lead to nutritional stress (Goodman
et al., 1984) and linked with changes in remodeling
(Martin and Armelagos, 1979). Comparison of histological data with the Pecos Pueblo sample is also complicated because only intact osteons numbers were counted
for Pecos (Burr et al., 1990). A true picture of remodeling
activity requires the inclusion of fragmentary osteons
(Wu et al., 1970). A more accurate comparison of bone
remodeling rates between Pleistocene and modern
humans will require a comparison between lower limb
bones from a more recent skeletal sample that includes
osteon fragments.
American Journal of Physical Anthropology
LITERATURE CITED
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in later Pleistocene fossil hominids. Am J Phys Anthropol
99:585–601.
Burr DB, Ruff CB, Thompson DD. 1990. Patterns of skeletal histological change through time: comparison of an archaic Native American population with modern population. Anat Rec 226:307–313.
Frost HM. 1987a. Secondary osteon population densities: an
algorithm for estimating the missing osteons. Yrbk Phys
Anthropol 30:239–254.
Frost HM. 1987b. Bone ‘‘mass’’ and the ‘‘mechanostat’’: a proposal. Anat Rec 219:1–9.
Goodman AH, Lallo J, Armelagos G, Rose JC. 1984. Health
changes at Dickson Mounds, Illinois (AD 950–1300). In:
Cohen MN, Armelagos GJ, editors. Paleopathology at the origins of agriculture. Orlando: Academic Press. p 271–301.
Martin DL, Armelagos GJ. 1985. Skeletal remodeling and mineralization as indicators of health: an example from prehistoric Sudanese Nubia. J Hum Evol 14:527–537.
Pfeiffer S, Zehr MK. 1996. A morphological and histological study of
the human humerus from Border Cave. J Hum Evol 31:49–59.
Stout SD, Paine RR. 1994. Bone remodeling rates: a test of an
algorithm for estimating missing osteons (Brief communication). Am J Phys Anthropol 93:123–129.
Thompson DD, Trinkaus E. 1981. Age determination for the
Shanidar 3 Neandertal. Science 212:575–577.
Trinkaus E, Thompson DD. 1987. Femoral diaphyseal histomorphometric age determinations for the Shanidar 3, 4, 5, and 6 Neandertals and Neandertal longevity. Am J Phys Anthropol 72:123–129.
Wu K, Schubeck KE, Frost HM, Villanueva AR. 1970. Haversian bone formation rates determined by a new method in a
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