Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=ghbi20 Historical Biology An International Journal of Paleobiology ISSN: 0891-2963 (Print) 1029-2381 (Online) Journal homepage: https://www.tandfonline.com/loi/ghbi20 Accuracy of environmental reconstruction based on a blind test of micromammal evidence from East Africa Denné Reed, Wendy Dirks, Laura McMaster & Terry Harrison To cite this article: Denné Reed, Wendy Dirks, Laura McMaster & Terry Harrison (2019) Accuracy of environmental reconstruction based on a blind test of micromammal evidence from East Africa, Historical Biology, 31:2, 243-252, DOI: 10.1080/08912963.2017.1360295 To link to this article: https://doi.org/10.1080/08912963.2017.1360295 Published online: 07 Aug 2017. Submit your article to this journal Article views: 54 View Crossmark data
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Full Terms & Conditions of access and use can be found athttps://www.tandfonline.com/action/journalInformation?journalCode=ghbi20
Historical BiologyAn International Journal of Paleobiology
Accuracy of environmental reconstruction basedon a blind test of micromammal evidence fromEast Africa
Denné Reed, Wendy Dirks, Laura McMaster & Terry Harrison
To cite this article: Denné Reed, Wendy Dirks, Laura McMaster & Terry Harrison (2019) Accuracyof environmental reconstruction based on a blind test of micromammal evidence from East Africa,Historical Biology, 31:2, 243-252, DOI: 10.1080/08912963.2017.1360295
To link to this article: https://doi.org/10.1080/08912963.2017.1360295
Accuracy of environmental reconstruction based on a blind test of micromammal evidence from East Africa
Denné Reeda , Wendy Dirksb, Laura McMasterc and Terry Harrisond
aDepartment of anthropology, University of texas at austin, austin, Usa; bDepartment of anthropology, Durham University, Durham, UK; coxford college of Emory University, atlanta, Usa; dDepartment of anthropology, center for the study of Human origins, New york University, New york, Ny, Usa
ABSTRACTPaleoenvironmental reconstructions based on mammalian faunas provide the contextual basis for understanding evolutionary events in many branches of paleobiology. This paper presents the first blind test of an environmental reconstruction using extant African small mammals. We collected 1216 specimens representing a minimum of 332 individuals from Ngofila 3, Tanzania, then conducted a blind analysis of the taxonomic and community composition. We found agreement between the observed habitat and the predicted habitat along eight aspects of the environment: (1) mean annual precipitation, (2) surface water availability, (3) soil type, (4) vegetation, (5) land use, (6) topography, (7) habitat heterogeneity, (8) temperature. Of these, the first six had high agreement between the observed and predicted descriptions, two (topography and habitat heterogeneity) had moderate agreement and the last, (temperature) was discussed in the observed habitat description but not addressed in the predicted description and could not be compared. The high level of agreement demonstrates that paleoenvironmental reconstruction can accurately portray a known habitat. In addition, we suggest factors that should be considered in a standard method of habitat description, which would improve comparability of results between different analyses.
Introduction
Mammalian fossils are a rich source of information about ter-restrial ecosystems and a key tool for reconstructing Neogene paleoenvironments, especially in the context of human evolu-tion in Africa (Vrba 1992; Kingston 2007; Fortelius et al. 2016). Paleoenvironmental studies of the African Neogene typically focus on either large or small mammals, reflecting the fact that mammal species’ body sizes in Africa are bimodal with many small (16–256 g) and large species (4–4000 kg) but fewer species of intermediate size (Kelt and Meyer 2009). Additionally, large and small mammals enter the fossil record through different taphonomic circumstances, (Behrensmeyer 1980) with one of the key differences being that small mammal assemblages often are accumulated by nocturnal predators, such as owls (Brain 1981; Andrews 1990).
Baseline work on modern owl-accumulated micromammal assemblages (OAMA) reveals that owls favor nocturnal prey (unsurprisingly) and are constrained to catching animals rang-ing in size from 2 to 500 g depending on the species of owl (Reed 2005). However, within these constraints they retain high taxonomic (Terry 2010a) and functional fidelity (Miller et al. 2014) to their source biological communities, where functional fidelity refers to the ecological roles represented in the community (e.g. ‘terrestrial herbivore’ or ‘arboreal insectivore’). Modern OAMAs also demonstrate sensitivity
to changes in vegetation, soil substrate, and moisture availa-bility across biogeographic and regional spatial scales (Reed 2007, 2011a). These qualities highlight the potential of small mammals as paleoenvironmental indicators. Several studies have employed OAMA to study diachronic change in fossil assemblages and associated habitats (Fernández-Jalvo et al. 1998; Avery 2001; Fernandez et al. 2007; Matthews et al. 2007) but there remain few baseline studies that evaluate how well an environment can be reconstructed from fossil faunal remains. Baseline studies (AKA actualistic research) help evaluate the various steps in the chain of inference between a living biolog-ical community and the fossil traces analysed to reconstruct that past community.
The part of that inferential chain addressed here is whether a paleoenvironmental analysis of a modern OAMA yields a result that matches the present and observable environment, specifically we examine the efficacy of paleoenvironmental analysis based on micromammal remains through a blind test. Two of the authors (WD & TH) collected a micromam-mal assemblage from a site in Africa, another (DR) analysed the assemblage without any knowledge about its origin other than it was an extant owl-accumulated assemblage from Africa. Blind tests are common in related domains such as archaeology (Odell and Odell-Vereecken 1980; Blumenschine et al. 1996; Hardy and Garufi 1998; Proffitt and de la Torre
level and rodents have higher diversity of genera than other groups, such as shrews. Specimens were prepared and iden-tified following the methods outlined in (Reed 2011b). The resulting bone assemblage comprised 1216 identifiable jaws and isolated teeth, representing a minimum of 332 individuals from eight genera (Figure 3). MNI values were tabulated by counting the maximum value of each individual dental ele-ment. No attempt was made to refine MNI values based on age, wear stage or sex.
All statistical analyses were conducted in the R statistical pro-gramming language (R Core Team 2016) using MNI values to represent taxonomic frequencies. Non-metric Multidimensional Scaling (NMDS) was based on a Jaccard distance matrix and con-ducted in R using the metaMDS function in the vegan package (Oksanen et al. 2016).
Results
The results of the blind test were written by DR as a narrative describing the habitat as predicted by the rodent fauna, hereafter referred to as the predicted environment. A description of the observed environment where the specimens were collected was written by WD and TH. The results of the faunal analysis are presented first, followed by the verbatim narrative summary of the predicted environment based on the analysis of the rodent fauna. A verbatim account of the observed environment is given, followed by a comparison of the predicted and observed environ-mental narratives.
Blind analysis of the rodent assemblage
The collection is conspicuous for having low taxonomic rich-ness and high dominance by a single taxon, Mastomys, lead-ing to low taxonomic diversity. Table 1 compares Ng3 against 12 OAMAs from various habitats in the Serengeti ecosystem (SR) (Reed 2011a) and one sample from Amboseli (AM). The Ng3 assemblage has the largest sample size but lowest value for Fisher’s alpha diversity index, which is less sensitive than other measures to differences in sample size (Magurran 1988; Hayek and Buzas 1997). Ng3 has also the third lowest value for richness, and the second lowest value for Shannon diver-sity (H) and effective number of species (Jost 2006). Thus, despite having the largest sample size, Ng3 has low diversity and high dominance by a single species. These are character-istics of drier, and more sparsely vegetated habitats as shown in Table 1.
An ordination of the blind assemblage in comparison with modern assemblages from Serengeti and Amboseli (Figure 4) indicates greatest similarity to the Amboseli assemblage.
Habitat descriptions
The verbatim predicted and observed environmental descrip-tions are provided in Box 1 and Box 2 respectively. These narratives were generated independently and without prior consultation, yet they contain nearly identical types of infor-mation about the habitat, which we have organised into eight
2014), stratigraphy (Liu 2003), comparative anatomy (Meindl et al. 1985), but seldom if ever applied to paleoenvironmen-tal reconstruction. Blind testing is the optimal mechanism for establishing that a paleoenvironmental analysis of an OAMA works as expected, but implementation is difficult because separate teams are required to collect and analyse the data.
The results of our blind test show that an indicator species approach to analysing rodent communities can accurately recover the local environment in the area 1 km around where the sample was collected. We compare a description of the envi-ronment derived from the analysis of the mammalian fauna (the predicted environment) against a description of the environment from ground truthing the area at the time the faunal assemblage was collected (the observed environment).
The predicted and observed descriptions were written with-out coordination between the authors, yet they exhibit a high degree of overlap regarding which aspects of the environment are reported. This overlap suggests that there is a common set of salient characteristics or aspects useful for describing paleoenvi-ronments. To date there are no standards for how paleoenviron-mental reconstructions are conveyed, and the similarity in the descriptions generated for our project suggests that a standard could be developed and that this would be helpful for comparing results between different studies.
Materials and methods
As part of the 1994 Wembere-Manonga Paleontological Expedition in East Africa two authors (WD & TH) supervised the collection of a micromammal bone assemblage from an owl roost at the site of Ngofila 3 (Ng3, located at 3° 54.75′S, 33° 49.34′E), a steep southwest facing promontory, 12 m high, overlooking the Manonga Valley. The site is located about 5.7 km east of Ngofila Village, and 5 km north of the Manonga River (Figure 1).
Owl pellets and associated skeletal material were recovered from a narrow ledge, about 2.5 m from the summit of the prom-ontory (Figure 2). A ledge along the cliff face had a number of cavities one of which was inhabited by a Spotted Eagle Owl (Bubo africanus) nest containing two chicks. On an initial visit, the identity of the adult owl was confirmed visually. On a subsequent visit, no owls were present, and all the regurgitated pellet mate-rial was collected, including intact pellets as well as osteological material from disintegrated pellets. The intact pellets have been preserved and are not part of the analysis, which was done on the osteological material alone.
The edge of the cliff also has large trees for adult birds to roost in and maintain vigilance close to the nest site. The steepness of the cliff effectively prevents humans and livestock from disturb-ing the nesting site, but it should be noted that the eagle owls at Ng3 shared the cliffs with spotted hyaena (Crocuta crocuta) and porcupines (Hystrix cristata) that use the natural cavities as dens.
Taxonomic identifications were made on cranial and den-to-gnathic elements of rodent specimens. The analysis focused on rodents because they can be reliably identified at the generic
244
Figure 1. site map showing location of the Ngofila 3 (Ng3) roost in the Manonga Valley, tanzania. (source: Harrison and Mbago 1997).
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Figure 2. Photograph of the cliff face containing the Ng3 owl roost at the time that pellets were collected.Note: the roost is located in a cavity, in the sandstone outcrop near the top of the cliff.
Figure 3. abundances (Minimum Number of individuals) of rodent genera from Ng3.Note: Dento-gnathic specimens of lemniscomys and arvicanthis cannot be distinguished reliably and are grouped together as lemn/arvi.
D. REED ET AL.246
make comparable assertions about the first seven categories. The observed narrative includes assertions about temperature, whereas no assertions about temperature are made in the pre-dicted analysis.
aspects: (1) precipitation, (2) surface water availability, (3) soil characteristics, (4) vegetation, (5) land use, (6) topog-raphy, (7) habitat heterogeneity, (8) temperature. Of these eight categories, the predicted and observed descriptions both
Table 1. comparison of species richness and diversity across sites. collection size for each site is given as minimum number of individuals, MNi. taxonomic richness, r, is the number of rodent genera in each collection. the effective number of taxa (ENt) is an intuitive measure of diversity taking into account the evenness of the assemblage. H is the shannon diversity index. the sites are ordered by values of Fisher’s alpha, which is the diversity metric least influenced by sample size.
Figure 4. Non-metric multidimensional scaling (NMDs) ordination of micromammal assemblages based on faunal composition.Note: sr = serengeti, aM = amboseli, Ng = Ngofila. Ng3 appears in the lower left quadrant alongside the amboseli roost and both are distinct from the serengeti roosts. sites situated to the left on axis 1 are drier and share a higher proportion of gerbils.
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Predicted: ‘Moderate to low, less than 800 mm per annum and likely less than 600’.
Observed: ‘The average annual precipitation is 600–800 mm, but rainfall is unreliable’.
Comparison of the analytical results
The habitat descriptions each make clear assertions about the environmental and climatic conditions at the site. The following analysis itemises the assertions in both narratives and groups them into the eight categories described earlier, based on the topic of the assertion. For each category we evaluate the level of agreement between the two descriptions as high, moderate or low. Of the eight categories (Table 2), five show high agreement, two show moderate agreement, and one, temperature is men-tioned only in the observed account and cannot be compared.
(1) Precipitation – high agreement
Table 2. summary of results from the comparison of the ‘predicted’ and ‘observed’ habitat descriptions.
tree canopy type and density: sparse canopy, less than 20% and probably less than 10%.
Precipitation: Moderate to low, less than 800 mm per annum and likely less than 600 mm.
substrate: soft soils suitable for burrowing, not rocky.
surface water: little to none in the immediate vicinity (ca 500 m)
Elevation: No clear elevation indicators, but low vegetation heterogeneity and lack of rocky substrate point to lowland or plateau rather than an area with high slope or dissected terrain.
a grassland, or dwarf shrubland dominated environment with a relatively soft substrate suitable for burrowing rodents. tree canopy cover less than 20% and probably less than 10%. Mean annual precipitation less than 800 mm and probably less than 600 mm. a disturbed environment in conjunction with human habitation and probably cultivation nearby. low spatial variability in habitat. little or no surface water in the immediate vicinity.
the basis for this interpretation is as follows. Mastomys is the dominant taxon and its preferred habitat is disturbed habitats, cultivated fields and areas with human presence. the second most dominant taxon is Gerbillus, an open habitat, arid adapted taxon. the third most dominant taxon is Steatomys, a burrowing rodent often found in conjunction with Gerbillus in open habitats with soil substrates suitable for burrowing. there are no arboreal specialists. there are no moist habitat or semi aquatic specialists. the species richness and all measures of species diversity are low, suggesting low habitat heterogeneity and consistent with low precipitation. areas with higher than 600 mm mean annual precipitation often have significant woody vegetation. the gerbilinae to Murinae ratio is 0.344 which is not high, and would normally indicate a mixed habitat with some tree cover. However in this case the ratio is heavily influenced by Mastomys rather than a diversity of murines and this suggests a more open, xeric habitat with the murine component coming from nearby human occupation. Mastomys is known to have pulses of population explosions and the assemblage may reflect one such pulse and therefore mask the more general community composition.
Box 2. Verbatim description of the observed environment based on ground truthing at the time the assemblage was collected.
During the rainy season, the Manonga river flows eastwards across the Manonga Valley, and drains into lake Kitangiri, but during much of the year it is com-pletely dry. the central part of the Manonga Valley, where Ngofila 3 is located, is 10–20 km wide, and bordered to the north and south by low cliffs and slopes, no more than 25 m high. Few people live in the Valley itself. Villages and fields are primarily located on the tops of the cliffs, where the soils are better suited for farming and where the stronger breezes provide relief from the heat and flies.
the general area has low relief, with a relatively flat or gently undulating topography, ranging in elevation from 1060–1120 m. calcareous soils, especially mbu-ga clays (i.e. black cotton soils), are widespread. the average annual precipitation is 600–800 mm, but rainfall is unreliable. From June to November, during the single dry season, ephemeral streams and rivers are completely dry, but subsurface water is generally available in the Manonga river in shallow pools excavated and maintained by local people and wildlife. During the course of fieldwork in the Manonga Valley from 1990 to 1996, no rainfall was recorded during May to august. However, during the 2006 field season (July–august) heavy rain was recorded on several days. Mean ambient temperatures range between 21 and 25 °c, but there is considerable daily and seasonal variation (Harrison and Mbago 1997).
in the central region of the Manonga Valley, the vegetation varies according to soil type and topography. the tops of cliffs, hills and ridges have rich calcareous soils that typically support open woodland vegetation, with trees up to 10m in height, dominated by Vachellia (formerly Acacia, principally V. tortilis and V. mellifera), Balanites, Albizia, Grewia and Combretum. today, cultivated fields dominate the tops of cliffs. tall trees are largely restricted to the edges of cliffs and to relictual woodland patches in areas less accessible to humans. the slopes of the cliffs are covered with relatively thin layers of mbuga clay overlying deep, friable calcareous soils derived from erosion of the underlying Mio-Pliocene lake sediments. these are usually highly eroded and dissected badlands with sparse tree (up to 3 m in height), bush and grass cover. the dominant trees and shrubs in this community are Acacia drepanolobium, Commiphora, Balanites and euphorbias. the floor of the Manonga Valley is extensively covered by mbuga clay, sometimes exceeding 3 m in thickness. these areas are very sparsely vege-tated, with grasses and scattered Acacia drepanolobium, or occasionally dense thickets of thorn scrub, but mostly consisting of bare soils and deeply dissected badlands. closer to the Manonga river, where the mbuga clays become thinner and access to water is more reliable, dense stands of trees and shrubs line the water course to form patches of dense woodland. although population density is relatively low in the Manonga Valley (about 25–30/km2), recent population growth has led to overgrazing by livestock and poor agricultural management, as well as clearance of woodlands for firewood, construction of houses, and cul-tivation. this has resulted in extensive soil erosion and badlands formation. the general vegetation in the central Manonga Valley can best be described as open thorn scrub and subdesertic grasslands, with patches of open woodland and thicket on more elevated areas, and riverine woodland along major watercourses. the ecology has been impacted on by a moderate degree of anthropogenic disturbance. the region is relatively hot and arid, with low precipitation and no permanent bodies of water during the dry season.
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‘[The floor of the Manonga Valley is] very sparsely vegetated, with grasses and scattered Acacia drepanolobium, or occasionally dense thickets of thorn scrub, but mostly consisting of bare soils and deeply dissected badlands’.
‘The general vegetation in the central Manonga Valley can best be described as open thorn scrub and subdesertic grasslands, with patches of open woodland and thicket on more elevated areas, and riverine woodland along major watercourses’.
The analysis predicts an area with grasslands or low shrub and a very sparse tree canopy. This matches closely the description for the area within a kilometre of the roost. The NG3 fauna does not detect the denser woodland stands near the Manonga River, located five kilometres to the south.
(5) Land Use – high agreementPredicted: ‘A disturbed environment in conjunction with human habitation and probably cultivation nearby’.
Observed: ‘The ecology has been impacted on by a moderate degree of anthropogenic disturbance’.
The land use category shows high agreement between the pre-dicted and observed descriptions of the environment. A satellite image of the area today shows extensive cultivation in the area within a kilometre of the roost location.
(6) Topography – moderate agreementPredicted: ‘No clear elevation indicators … lowland or plateau rather than an area with high slope or dissected terrain’.
Observed: ‘The central part of the Manonga Valley where Ngofila 3 is located … is bordered … by low cliffs and slopes, no more than 25 m high’.
‘The general area has low relief, with a relatively flat or gently undu-lating topography, ranging in elevation from 1060–1120 m’.
The area around Ng3 comprises plateaus broken by dissect-ing drainages and badlands leading down to the Manonga River valley. The Ng3 roost site is situated near 12–25 m high cliffs
There is nearly identical agreement about the mean annual precipitation at Ng3.
(2) Surface Water – high agreementPredicted: ‘Little or no surface water in the immediate vicinity (ca 500 m)’.
Observed: ‘During the rainy season the Manonga River flows … into Lake Kitangiri, but during much of the year it is completely dry’.
The analysis predicts no surface water in the immediate area around the roost and this agrees with the onsite observations that indicate the nearest surface water is 5 km south of Ng3 and only available during the raining season. This is confirmed by analysis of present-day satellite imagery (Figure 5).
(3) Soils – high agreementPredicted: ‘Soft soils suitable for burrowing, not rocky’.
Observed: ‘Calcareous soils, especially mbuga clays (i.e. black cot-ton soils), are widespread. The slopes of the cliffs are covered with relatively thin layers of mbuga clay overlying deep, friable calcare-ous soils derived from erosion of the underlying Mio-Pliocene lake sediments’.
The analysis agrees with the onsite assessment that the soils in the regions are friable and suitable for burrowing rather than rocky.
(4) Vegetation - high agreementPredicted: ‘Grassland, dwarf shrubland’, ‘Sparse canopy, less than 20% and probably less than 10%’
Observed: ‘Today, cultivated fields dominate the tops of cliff. Tall trees are largely restricted to the edges of cliffs and to relictual woodland patches in areas less accessible to humans’.
‘[The cliffs] are usually highly eroded and dissected badlands with sparse tree (up to 3 m in height), bush and grass cover. The dom-inant trees and shrubs in this community are Acacia drepanolo-bium, Commiphora, Balanites and euphorbias’.
Figure 5. High-resolution satellite image of the area around Ng3.Note: the inner dashed circle is centered on Ng3 (red dot) with a radius of 1 km. the outer solid circle shows a distance of 5 km.
HISTORICAL BIOLOGY 249
(8) Temperature – N/APredicted: N/A
Observed: ‘Mean ambient temperatures range between 21 and 25 °C, but there is considerable daily and seasonal variation’.
‘The region is relatively hot and arid, with low precipitation and no permanent bodies of water during the dry season’.
The analysis makes no assertions about temperature. This is the only category of observation not shared by both narratives.
An independent evaluation of the area surrounding Ng3 is provided by modern high resolution satellite imagery shown in Figure 5. The imagery indicates that much of the area around Ng3 is currently used for cultivation, and it confirms that the Ng3 roost is 5 km north of the main channel of the Manonga River where, presently there is denser vegetation (Figure 6).
Discussion
This experiment set out to address was whether a blind anal-ysis of an OAMA could produce results that match the actual habitat. The results indicate that for precipitation, surface water availability, soils, vegetation, and land use the predicted habitat from the micromammal analysis matched the observed habitat. For vegetation and land use it also matches assessments based on modern satellite imagery.
On one hand these results are expected. Previous studies have calibrated analysis results against modern data. For example,
where the plateau breaks. Below the roost the topography slopes gently down to the Manonga River. The analysis points to a rel-atively low relief area but also states there are not strong eleva-tion indicators, and indeed the general topography is plateau or gently sloping terrain with some small cliff faces at the edge of the plateau. On this point there seems to be moderate, but not perfect agreement.
Observed: ‘In the central region of the Manonga Valley, the vegeta-tion varies according to soil type and topography’.
Habitat heterogeneity refers to the degree of spatial varia-bility in land cover. The two propositions differ, possibly due to differences in spatial extent of the description. The analysis asserts low heterogeneity in the immediate proximity of the roost as owls usually hunt within 1 km of their roosting site. The observed description covers an area ranging about 4–5 km down to the river and over to Ngofila Village. Over this larger area there are differences in vegetation according to soil type and topography ranging from sparse grassland to open-wood-land. There is a moderate degree of heterogeneity in the area immediately surrounding the roost, with treed grasslands topping the plateau, grading into sparse grassland less than 500–1000 m down the slope. The analysis doesn’t register this subtle difference.
Figure 6. a view of the Manonga Valley in the vicinity of Ngofila.Note: Note the trees on top of the cliffs in the distance associated with human habitation and cultivation, the scrub thicket on the slope in the foreground, and the sparse vegetation covering the valley floor.
D. REED ET AL.25 0
The land use category reflects anthropogenic modifications to the environment which alter species community compositions. It is an important element in the analysis of modern community composition because anthropogenic change is so prevalent. It may also be a relevant factor in prehistoric paleoenvironmental analysis following the development of fire, and plant domesti-cation. In the case of Ng3, nearby cultivation has a pronounced impact on the community composition by providing culti-vated fields where semi-commensal species such as Mastomys dominate.
Conclusions
We conducted the first blind test of an environmental reconstruc-tion and it demonstrates that a micromammal indicator species approach can accurately capture details of an environment such as precipitation, surface water availability, dominant vegetation, soil substrate, and to a lesser extent topography and habitat het-erogeneity. These results suggest that future blind testing would be productive, but such tests will require coordinated efforts from multiple research teams, and a standardised protocol for charac-terising terrestrial environments. A standardised protocol would have wide application in paleoenvironmental analysis and should be developed with reference to modern ecosystem modeling and at scales relevant to human evolution.
AcknowledgementsWe gratefully acknowledge the support of the Tanzanian government for permission to conduct the fieldwork, as well as the many undergraduate students who assisted in the collection and preparations of the material.
Disclosure statementNo potential conflict of interest was reported by the authors.
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Our results indicate that recovering key aspects of the habitat from micromammals is feasible, even when conducted blind, but the reliability of this result and scope of applicability requires more extensive testing across a broader range of modern habitats and deploying different analytical approaches.
The analysis also indicates that some aspects of the habitat (e.g. topography and habitat heterogeneity) are better predicted than others. Aspects such as mean annual precipitation, surface water availability, vegetation structure and soil types, directly influence adaptations in small mammal species and are detected in the analysis. Topography and habitat heterogeneity reflect var-iability in the environment than a central tendency of an area and interpreting characteristics of the environment relies more on aspects of the community as a whole (such as its ecological diversity) rather than indicator adaptations in specific species. The extra level of inference needed to interpret aspects such as topography and habitat heterogeneity may reduce the effective-ness of these proxies.
A broader question that arises from this experiment is the issue of how we report or summarise an environment. Ultimately, our aim is to understand paleoenvironments sufficiently to pro-vide context for human evolution and adaptation, or more gen-erally to understand the environmental context for any group of organisms in the fossil record. From this perspective we need to understand the environment on human scale and scope, and with specific reference to environmental affordances relevant to humans. This perspective guides much of the reasoning behind why certain characteristics of the environment are salient to pale-oanthropology while other are not. It also provides an explana-tion for why there is strong consilience between the predicted and observed environmental descriptions with regard to what type of information is reported, even absent any prior agreement about what should be included. The eight aspects of the envi-ronment outlined in this paper provide a valuable descriptive set for an African environment relevant to understanding human ecology and adaptation. The absence of temperature from the predicted habitat description is a shortcoming, but also a reflec-tion of the fact that there are no strong temperature indicators known for African rodents. This aspect should be investigated further.
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