Irene Esteban
I conducted my graduate studies in archaeobotany at the University of Barcelona under the direction of Prof. Rosa M. Albert. As a result, I received my PhD in December 2016. I use an archaeobotanic discipline, phytoliths, to study plant remains from the archaeological record in order to study the exploitation of vegetal resources by past populations and past environmental conditions. For my thesis work, I developed a modern phytolith reference collection on plants and soils from the world’s most diverse and endemic extra-tropical floral, the Greater Cape Floristic Region, located in South Africa. This material was later used as proxy for the reconstruction of past human plant gathering strategies and for the reconstruction of the past vegetation and climate conditions at Pinnacle Point, on the south coast of South Africa. Currently, I am a postdoctoral fellow at the Evolutionary Studies Institute (University of the Witwatersrand, South Africa). My postdoc research focuses on correlating human strategies of exploitation of plant resources and landscape adaptation with climate and environmental conditions during the Pleistocene in southern Africa.
Supervisors: Rosa M Albert and Dan Cabanes
Supervisors: Rosa M Albert and Dan Cabanes
less
InterestsView All (10)
Uploads
Papers by Irene Esteban
The non-anthropogenic soils are acidic, show a wide range of clay contents and different degrees of human activity according to their available phosphorus content. Soil-forming processes are related to fine fraction mobility and alternating redox conditions. Contrarily, the soils of the raised fields show a distinct pattern of redoximorphic features from ridge to channel. Moreover, ridges tend to be less acidic and have lower aluminium saturation than channels. Nevertheless, they have neither artifacts nor charcoal, and their colour and P content is similar to those of surrounding soils.
The raised fields appear to have been built to improve the drainage conditions. Chemical soil fertility was not the main issue and they were used for cultivation including maize. The set of characteristics encountered (differences in pH, and drainage status at a microscale) should be used to improve the classification of these anthropogenic soils.
past human use of plants and palaeoenvironment in Middle
Paleolithic sites, little is known on this aspect in the welldocumented
central region of Mediterranean Iberia. This paper
presents the first phytolith and mineralogical study conducted at
Abrigo de la Quebrada (Chelva, Valencia). Forty-one samples
were analyzed through phytoliths and Fourier transform infrared
spectroscopy (FTIR) from different areas, stratigraphic
levels, and archeological contexts (hearth, hearth-related, and
non-hearth-related sediments) of the shelter. The results obtained
point towards a different pattern of preservation in the site
depending firstly on the stratigraphy and secondly on the area
where the samples were collected. Postdepositional processes
that may have chemically affected phytolith preservation are
discussed. Grasses are the main plant component identified in
all the samples while woody plants are scarce. The abundance
of grasses in the non-hearth-related sediments might be related,
at least partially, to the dispersion of ashes from hearths, as
indicated by the FTIR results. The results are indicative of an
occupation of the site during the spring-autumn season. At this
time, the area would be dominated by a semi-open environment
with supramediterranean vegetation.
The climate is semi-arid and the landscape is defined by platforms and flat-bottomed valleys. Four profiles were
described from both slope and valley-floor terraces and sampled for analyses. A buried Ahb horizon appears at
various depths between 40 and 180 cm,with thicknesses ranging from35 to 160 cm, probably due to earthworks
since this depends on the position of the profile within the terrace.Many of these buried soils would correspond
to Phaeozems: they are identified by an Ahb having lowvalues and chromas (usually 4 or less), a structure due to
faunal activity (100% of the structural forms related to fauna either in the form of empty or infilled channels, vermic qualifier), and an organic matter content that is 1.7–3.3%, which is higher but not significantly different than the SOM content of the present day topsoils. P (Olsen) is 1–6 ppm.
The present soils are non-saline and highly calcareous (N40%), they showsome calcium carbonate redistribution
in the formof pseudomycelia, and biogenic calcite. Charcoal is present in some of these buried horizons, together with small ceramic fragments. These buried horizons have several common micromorphological features: a spongy, highly porous structure due to high faunal activity, frequent silt cappings, charcoal fragments, and biogenic carbonates (queras). In some cases the biogenic calcite has undergone dissolution and reprecipitated as micrite. Pollen assemblages of the buried horizons reveal a large forest cover mainly of oaks and pines, which is also corroborated by the occurrence of Quercus phytoliths; but the presence of pollen of some deciduous crops (such as cereals, Vitis vinifera and Olea europaea.) at the top of the sequences points to a Upper Holocene origin of these soils. The results from the charcoal study support the presence of perennial Quercus and pines as well as shrubs in the period when the terraces were built.
The available information about present day similar soils indicates that the formation of these horizons took place
under a moister, milder climate in the past, compared with the present one in the study area.
Talks by Irene Esteban
Using phytoliths -siliceous microremains that reproduce the cellular tissue of plants- we try to reconstruct the vegetation of these two sites, to better understand the influence of the environment in human evolution. Our research includes the description and phytolith study of modern analogous landscapes which are later compared to the archaeological results. Fourier Transformed Infrared Spectroscopy (FT-IR) is used to determine the mineralogical components of sediments to understand the preservation conditions of the identified remains.
The results obtained to date at Olduvai Gorge have allowed reconstructing the vegetation of FLK and HWKEE areas, where the remains of Parantropus boisei and Homo habilis were recovered. Vegetation studies at Mossel Bay, have finalized at PP13B, showing the use of dicotyledonous leaf plants during low occupation moments. PP5/6 studies are still in process.
The non-anthropogenic soils are acidic, show a wide range of clay contents and different degrees of human activity according to their available phosphorus content. Soil-forming processes are related to fine fraction mobility and alternating redox conditions. Contrarily, the soils of the raised fields show a distinct pattern of redoximorphic features from ridge to channel. Moreover, ridges tend to be less acidic and have lower aluminium saturation than channels. Nevertheless, they have neither artifacts nor charcoal, and their colour and P content is similar to those of surrounding soils.
The raised fields appear to have been built to improve the drainage conditions. Chemical soil fertility was not the main issue and they were used for cultivation including maize. The set of characteristics encountered (differences in pH, and drainage status at a microscale) should be used to improve the classification of these anthropogenic soils.
past human use of plants and palaeoenvironment in Middle
Paleolithic sites, little is known on this aspect in the welldocumented
central region of Mediterranean Iberia. This paper
presents the first phytolith and mineralogical study conducted at
Abrigo de la Quebrada (Chelva, Valencia). Forty-one samples
were analyzed through phytoliths and Fourier transform infrared
spectroscopy (FTIR) from different areas, stratigraphic
levels, and archeological contexts (hearth, hearth-related, and
non-hearth-related sediments) of the shelter. The results obtained
point towards a different pattern of preservation in the site
depending firstly on the stratigraphy and secondly on the area
where the samples were collected. Postdepositional processes
that may have chemically affected phytolith preservation are
discussed. Grasses are the main plant component identified in
all the samples while woody plants are scarce. The abundance
of grasses in the non-hearth-related sediments might be related,
at least partially, to the dispersion of ashes from hearths, as
indicated by the FTIR results. The results are indicative of an
occupation of the site during the spring-autumn season. At this
time, the area would be dominated by a semi-open environment
with supramediterranean vegetation.
The climate is semi-arid and the landscape is defined by platforms and flat-bottomed valleys. Four profiles were
described from both slope and valley-floor terraces and sampled for analyses. A buried Ahb horizon appears at
various depths between 40 and 180 cm,with thicknesses ranging from35 to 160 cm, probably due to earthworks
since this depends on the position of the profile within the terrace.Many of these buried soils would correspond
to Phaeozems: they are identified by an Ahb having lowvalues and chromas (usually 4 or less), a structure due to
faunal activity (100% of the structural forms related to fauna either in the form of empty or infilled channels, vermic qualifier), and an organic matter content that is 1.7–3.3%, which is higher but not significantly different than the SOM content of the present day topsoils. P (Olsen) is 1–6 ppm.
The present soils are non-saline and highly calcareous (N40%), they showsome calcium carbonate redistribution
in the formof pseudomycelia, and biogenic calcite. Charcoal is present in some of these buried horizons, together with small ceramic fragments. These buried horizons have several common micromorphological features: a spongy, highly porous structure due to high faunal activity, frequent silt cappings, charcoal fragments, and biogenic carbonates (queras). In some cases the biogenic calcite has undergone dissolution and reprecipitated as micrite. Pollen assemblages of the buried horizons reveal a large forest cover mainly of oaks and pines, which is also corroborated by the occurrence of Quercus phytoliths; but the presence of pollen of some deciduous crops (such as cereals, Vitis vinifera and Olea europaea.) at the top of the sequences points to a Upper Holocene origin of these soils. The results from the charcoal study support the presence of perennial Quercus and pines as well as shrubs in the period when the terraces were built.
The available information about present day similar soils indicates that the formation of these horizons took place
under a moister, milder climate in the past, compared with the present one in the study area.
Using phytoliths -siliceous microremains that reproduce the cellular tissue of plants- we try to reconstruct the vegetation of these two sites, to better understand the influence of the environment in human evolution. Our research includes the description and phytolith study of modern analogous landscapes which are later compared to the archaeological results. Fourier Transformed Infrared Spectroscopy (FT-IR) is used to determine the mineralogical components of sediments to understand the preservation conditions of the identified remains.
The results obtained to date at Olduvai Gorge have allowed reconstructing the vegetation of FLK and HWKEE areas, where the remains of Parantropus boisei and Homo habilis were recovered. Vegetation studies at Mossel Bay, have finalized at PP13B, showing the use of dicotyledonous leaf plants during low occupation moments. PP5/6 studies are still in process.
"
"
Session: A15d The educational activities of archeology and socialization of knowledge
El Grupo de Estudios Paleoecológicos y Geoarqueológicos (GEPEG, Universitat de Barcelona) tiene como objetivo el estudio de fitolitos y del análisis mineralógico de los sedimentos con el fin de comprender los diversos modos de explotación de los recursos vegetales por las poblaciones humanas del pasado, así como de la reconstrucción del clima y la vegetación del pasado, teniendo en cuenta los procesos postdeposicionales que pudieron afectar los fitolitos en el momento de su deposición en suelos y sedimentos. Este póster pretende dar a conocer las líneas de investigación de las que forman parte nuestros proyectos de tesis doctoral y máster que se enmarcan dentro de las líneas generales de investigación del GEPEG: reconstrucción del paleoambiente durante la evolución de los primeros Homo; la explotación de los recursos vegetales y el uso del fuego por los primeros humanos modernos y por poblaciones neandertales en la Península Ibérica, así como el desarrollo de las primeras sociedades de agricultores y ganaderos.
Using the available data, which comprise phytoliths, macro-plant remains, charcoal, and techniques such as FTIR, we a empt to gain a deeper understanding of environmental in uence on human evolution and the mode of acquisition of plant resources by early human populations for di erent purposes, including diet. This ongoing research focuses on two key chronological periods in human evolution: i) hominin populations during the Plio-Pleistocene in eastern Africa, with Olduvai Gorge as a study site; ii) emergence of early Homo sapiens during the Middle Stone Age period in South Africa, based on the studies conducted at Pinnacle Point archaeological complex.
Phytoliths provide a record of past vegetation and can therefore be used in the reconstruction of palaeoenvironmental conditions. In archaeological contexts, they can also be used to infer what humans were collecting and eating. Reconstruction of the palaeovegetation is based on the comparative study of modern analogous landscapes; this includes a detailed description of the vegetation, and compilation of a modern reference collection of plants and soils which are analysed for phytoliths. Results are later compared to archaeological and palaeoanthropological samples.
The phytolith record at Olduvai Gorge, together with other related studies on plants, bones and sediments, have depicted a more humid landscape than initially thought for Bed I and Bed II which represent the times in which Homo habilis and Paranthropus boisei were present in the area. For these time periods, phytoliths identify a range of plants usually related to fresh water sources, including grasses, sedges, and a signi cant number of palm species. Many of these would provide important edible resources during the rainy season.
At Mossel Bay, our research in caves PP13B and 5/6 has documented the presence of dicotyledonous-leaf phytoliths related to some of the hearths. The use of these leaves as fuel, food or other purposes is still an open question. Current study on modern vegetation and food resources available to those modern H. sapiens will try to shed more light on this issue.
South Africa has one of the oldest and richest records of human coastal occupation. This research project focuses on South Africa's East Coast where very narrow continental shelf has limited coastline movements during glacial periods. This prevented large coastline movements and created stable coastal ecosystems. In one these places, known as Pondoland, rare records of coastal occupation and resource use during the Last Glacial Maximum (ca. 26,000-19,000 years ago) have already been recovered by the P5 Project. These records provide a unique opportunity to study hunter-gatherers living in stable coastal contexts over long time periods and compare evidence of their behaviors to hunter-gatherer groups living inland. The project synergizes researchers from numerous international universities and disciplines to answer complex questions about the evolution of human behavior in a unique and persistent environment along Pondoland's coastline. Detailed archaeological, zooarchaeological, and paleoenvironmental information from excavations at two coastal archaeological sites will be collected as well as datasets from systematic landscape studies and ethnographic observations of modern plant foods and coastal foraging. The research will generate new evidence to test questions about coastal ecological variability across glacial and interglacial periods and how these changes impacted hunter-gatherer food-choice patterns, social networks, settlement patterns, and technology. Situating these data within the broader southern African paleolandscape will bring renewed focus on hunter-gatherer's use of coastal and inland resources across glacial and interglacial cycles and it will provide a more nuanced understanding of human evolution and social complexity across broad bio-geographical contexts. The project's interdisciplinary