Eastern African environmental variation and its role in the evolution and cultural change of Homo over the last 1 million years

Lupien, R.; Russell, James M.; Subramanian, Avinash; Kinyanjui, Rahab; Beverly, Emily J.; Uno, Kevin T.; Menocal, Peter de; Dommain, René; Potts, Richard

doi:10.1016/j.jhevol.2021.103028

Cited by 33 publications

(18 citation statements)

References 123 publications

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“…Thus, we hypothesize that the higher interglacial atmospheric CO 2 concentrations after the transition phase may have decreased the influence of the SE trade winds on coastal hydroclimate change, and therefore indirectly reduced the influence of obliquity forcing. The increase in the amplitude of the high-pass filtered record of the ln (K/Al) record after the transition phase (∼400-300 ka) suggests that the hydroclimate system shifted to a phase of higher millennial-scale variability (Figure 6d and Figure S5 in Supporting Information S1), a behavior that has previously been recognized in tropical proxy records from eastern Africa (Lupien et al, 2021;Owen et al, 2018). This rise in millennial-scale variability, particularly during the latest ∼200 kyr, is supported by the observation of millennial-scale precipitation anomalies in northeastern and eastern Brazil during Heinrich Stadials (HS) of the last glacial period (∼last 120 kyr, Campos et al, 2019;Kanner et al, 2012; (Schulz & Mudelsee, 2002).…”

Section: A Transition (During ∼400-300 Ka) To Millennial-scale Variab...mentioning

confidence: 58%

Obliquity Influence on Low‐Latitude Coastal Precipitation in Eastern Brazil During the Past ∼850 kyr

Hou

Bahr

Chiessi

et al. 2022

Paleoceanog and Paleoclimatol

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Paleoclimate records from tropical South America typically show precession‐paced variability in rainfall, caused by insolation‐driven changes in the South American Monsoon System, however this mechanism may not be responsible for hydroclimate change outside of the core monsoon domain, such as in the coastal zone of tropical eastern Brazil. Our findings are based on a ∼850 kyr‐long multiproxy record from a marine sediment core collected from the eastern Brazilian margin that represents the longest continuous record of South American hydroclimate to date. Utilizing the ln (K/Al) chemical weathering proxy from the core, we determine that past hydroclimate change in the coastal zone was primarily modulated by obliquity forcing. We demonstrate that high obliquity is associated with an increase in the boreal summer interhemispheric insolation contrast which decreases the zonality of the southern trade winds and reduces moisture advection to the coastal zone. Based on the long‐term coherence between the ln (K/Al) record and benthic δ13C records from the Atlantic during Marine Isotope Stages 16–13, we infer that an increase in the strength of the overturning circulation, caused by Northern Hemisphere high‐latitude forcing, may have produced surface cooling in the western tropical South Atlantic which led to reduced moisture advection to the coastal zone. We suggest that this mechanism may have also caused the amplification in millennial‐scale variability in the coastal hydroclimate system, which began after the decoupling of the coastal hydroclimate system from obliquity forcing.

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Section: A Transition (During ∼400-300 Ka) To Millennial-scale Variab...mentioning

confidence: 58%

Obliquity Influence on Low‐Latitude Coastal Precipitation in Eastern Brazil During the Past ∼850 kyr

Hou

Bahr

Chiessi

et al. 2022

Paleoceanog and Paleoclimatol

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“…However, the lack of stratigraphically secure archaeological records proximate to the core site limits the potential to make strong links between dispersals and climate change. Elsewhere, at Olorgesailie highresolution core data is associated with Acheulean and MSA deposits just 24km away from the drill site, allowing for the identi cation of a period of increased variability coinciding with the origin of the MSA [20,21]. This is supported by the pollen records at nearby Lake Magadi where the general trend of increased aridi cation for this period is also reported [22].…”

Section: Introductionmentioning

confidence: 70%

A Spatiotemporally Explicit Paleoenvironmental Framework for the Middle Stone Age of Eastern Africa

Timbrell

Grove

Manica

et al. 2021

Preprint

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Eastern Africa has played a prominent role in debates about human evolution and dispersal due to the presence of rich archaeological, palaeoanthropological and palaeoenvironmental records. However, substantial disconnects occur between the spatial and temporal resolutions of these data that complicate their integration. Here, we apply high-resolution climatic simulations of two key parameters, mean annual temperature and precipitation, and a biome model, to produce a highly refined characterisation of the environments inhabited during the eastern African Middle Stone Age. Occupations are typically found in sub-humid climates and landscapes dominated by or including tropical xerophytic shrubland. Marked expansions from these core landscapes include movement into hotter, low-altitude landscapes in Marine Isotope Stage 5 and cooler, high-altitude landscapes in Marine Isotope Stage 3, with the recurrent inhabitation of ecotones between open and forested habitats. Through our use of high-resolution climate models, we demonstrate a significant independent relationship between past precipitation and patterns of Middle Stone Age stone tool use overlooked by previous studies. Engagement with these models not only enables spatiotemporally explicit examination of climatic variability across Middle Stone Age assemblages in eastern Africa but enables clearer characterisation of the habitats early human populations were adapted to, and how they changed through time.

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“…This perspective is supported by others (Oliveras & Malhi, 2016;Touboul et al, 2018): Forested and grassy systems may oscillate back and forth in space and time in response to varying fire and browsing pressures and in response to climate change and changing atmospheric CO 2 . Indeed, we have seen this trend in both mainland Africa over the past million years (e.g., Anhuf et al, 2006;Cerling et al, 2011;Ivory et al, 2017;Lupien et al, 2021) and in Madagascar over the past 150 + K years (Gasse & Van Campo, 2001). These studies were able to track the effects of changes in landscape vegetation cover with changes in climate and fire regimes, but the concomitant role of herbivory has proven more challenging to show.…”

Section: Grassy Biomesmentioning

confidence: 89%

The grassy ecosystems of Madagascar in context: Ecology, evolution, and conservation

Silander,

Bond,

Ratsirarson

2023

Plants People Planet

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Societal Impact StatementMadagascar is famous for its unique forests and their fauna. Most of the island is covered by flammable grassy ecosystems long considered to be of human origin and threatening the remaining forests. Yet new studies show that many plants and animals of the grassy systems are unique to Madagascar and restricted to these open habitats. Open grassy ecosystems have markedly different management requirements from forests and bring different contributions to society. We argue that the grassy ecosystems can benefit Madagascar if understood and managed wisely using expanded knowledge bases that also include collaboration with locals.SummaryUntil recently, nearly all research and interests in Madagascar focused on forested habitats. To help place Madagascar's grassy ecosystems in context, we provide a summary of the origin, development, and evolution of open tropical, C4 grassy ecosystems elsewhere, especially those from Africa; we summarize similarities and differences with the distribution of C3 and C4 grasses in the Malagasy landscape, their plant traits, and inferences on the evolutionary legacy of grasses. We also discuss the animal communities that use and have coevolved in these grassy systems; to help resolve controversies over the pre‐settlement extent of grassy ecosystems, we suggest a variety of complementary geochemical, palaeobotanical, and molecular genetic tools that have been effectively used elsewhere to untangle forest/grassy ecosystem mosaics and the ecological and evolutionary processes that influence them. Many of these tools can and should be employed in Madagascar to fully understand the spatio‐temporal dynamics of open, grassy, and closed forest systems across the island; as regards conservation, we discuss the ecosystem services provided by grassy systems, which are too often ignored in general, not only as a biome, vis‐à‐vis forests, but also for their global importance as a carbon sink and role they play in water management and providing goods to local villagers. We conclude by outlining the necessary research to better manage open ecosystems across Madagascar without threatening endangered forest ecosystems.

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Eastern African environmental variation and its role in the evolution and cultural change of Homo over the last 1 million years

Cited by 33 publications

References 123 publications

Obliquity Influence on Low‐Latitude Coastal Precipitation in Eastern Brazil During the Past ∼850 kyr

Obliquity Influence on Low‐Latitude Coastal Precipitation in Eastern Brazil During the Past ∼850 kyr

A Spatiotemporally Explicit Paleoenvironmental Framework for the Middle Stone Age of Eastern Africa

The grassy ecosystems of Madagascar in context: Ecology, evolution, and conservation

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