Australia's recently established predators restore complexity to food webs simplified by extinction.

Since prehistory, humans have altered the composition of ecosystems by causing extinctions and introducing species. However, our understanding of how waves of species extinctions and introductions influence the structure and function of ecological networks through time remains piecemeal. Here, focusing on Australia, which has experienced many extinctions and introductions since the Late Pleistocene, we compared the functional trait composition of Late Pleistocene (130,00-115,000 years before present [ybp]), Holocene (11,700-3,000 ybp), and current Australian mammalian predator assemblages (≥70% vertebrate meat consumption; ≥1 kg adult body mass).

A 4.3-million-year-old Australopithecus anamensis mandible from Ileret, East Turkana, Kenya, and its paleoenvironmental context.

A hominin mandible, KNM-ER 63000, and associated vertebrate remains were recovered in 2011 from Area 40 in East Turkana, Kenya. Tephrostratigraphic and magnetostratigraphic analyses indicate that these fossils date to ∼4.3 Ma.

Dart and the Taung juvenile: making sense of a century-old record of hominin evolution in Africa.

The announcement in 1925 by Raymond Dart of the discovery of the Taung juvenile's skull in a quarry in sub-Saharan Africa is deservedly a classic publication in the history of palaeoanthropology. Dart's paper-which designated Taung as the type specimen of the early hominin species -provided the first fossil evidence supporting Charles Darwin's 1871 prediction that Africa was where the human lineage originated. The Taung juvenile's combination of ape and human characteristics eventually led to a paradigm shift in our understanding of human evolution.

Long-term biotic homogenization in the East African Rift System over the last 6 million years of hominin evolution.

Eastern Africa preserves the most complete record of human evolution anywhere in the world but we have little knowledge of how long-term biogeographic dynamics in the region influenced hominin diversity and distributions. Here, we use spatial beta diversity analyses of mammal fossil records from the East African Rift System to reveal long-term biotic homogenization (increasing compositional similarity of faunas) over the last 6 Myr. Late Miocene and Pliocene faunas (~6-3 million years ago (Ma)) were largely composed of endemic species, with the shift towards biotic homogenization after ~3 Ma being driven by the loss of endemic species across functional groups and a growing number of shared grazing species.

Environmental context shapes the relationship between grass consumption and body size in African herbivore communities.

Though herbivore grass dependence has been shown to increase with body size across herbivore species, it is unclear whether this relationship holds at the community level. Here we evaluate whether grass consumption scales positively with body size within African large mammalian herbivore communities and how this relationship varies with environmental context. We used stable carbon isotope and community occurrence data to investigate how grass dependence scales with body size within 23 savanna herbivore communities throughout eastern and central Africa.

Collapse of terrestrial mammal food webs since the Late Pleistocene.

Food webs influence ecosystem diversity and functioning. Contemporary defaunation has reduced food web complexity, but simplification caused by past defaunation is difficult to reconstruct given the sparse paleorecord of predator-prey interactions. We identified changes to terrestrial mammal food webs globally over the past ~130,000 years using extinct and extant mammal traits, geographic ranges, observed predator-prey interactions, and deep learning models.

Early Pleistocene large mammals from Maka'amitalu, Hadar, lower Awash Valley, Ethiopia.

The Early Pleistocene was a critical time period in the evolution of eastern African mammal faunas, but fossil assemblages sampling this interval are poorly known from Ethiopia's Afar Depression. Field work by the Hadar Research Project in the Busidima Formation exposures (~2.7-0.

No sustained increase in zooarchaeological evidence for carnivory after the appearance of .

The appearance of shortly after 2.0 Ma is widely considered a turning point in human dietary evolution, with increased consumption of animal tissues driving the evolution of larger brain and body size and a reorganization of the gut. An increase in the size and number of zooarchaeological assemblages after the appearance of is often offered as a central piece of archaeological evidence for increased carnivory in this species, but this characterization has yet to be subject to detailed scrutiny.

Rethinking the ecological drivers of hominin evolution.

A central goal of paleoanthropology is understanding the role of ecological change in hominin evolution. Over the past several decades researchers have expanded the hominin fossil record and assembled detailed late Cenozoic paleoclimatic, paleoenvironmental, and paleoecological archives. However, effective use of these data is precluded by the limitations of pattern-matching strategies for inferring causal relationships between ecological and evolutionary change.

Intrataxonomic trends in herbivore enamel δC are decoupled from ecosystem woody cover.

Analysis of enamel stable carbon isotopes (δC) of fossil herbivores is an important tool for making inferences about Plio-Pleistocene vegetation structure in Africa and the environmental context of hominin evolution. Many palaeoecological studies implicitly or explicitly assume that individual variation in C-C plant consumption among fossil herbivores directly reflects the abundance of C (trees, shrubs) or C (low-altitude tropical grasses) vegetation. However, a strong link between δC of herbivores and ecosystem vegetation structure has not been rigorously established.

Functional traits of the world's late Quaternary large-bodied avian and mammalian herbivores.

Prehistoric and recent extinctions of large-bodied terrestrial herbivores had significant and lasting impacts on Earth's ecosystems due to the loss of their distinct trait combinations. The world's surviving large-bodied avian and mammalian herbivores remain among the most threatened taxa. As such, a greater understanding of the ecological impacts of large herbivore losses is increasingly important.

Evaluation of chromosomal insertion loci in the Pseudomonas putida KT2440 genome for predictable biosystems design.

The development of strains for industrial production of fuels and chemicals will require the integration of heterologous genes and pathways into the chromosome. Finding the most appropriate integration site to maximize strain performance is an essential part of the strain design process. We characterized seven chromosomal loci in KT2440 for integration of a fluorescent protein expression construct.

Trophic rewilding presents regionally specific opportunities for mitigating climate change.

Large-bodied mammalian herbivores can influence processes that exacerbate or mitigate climate change. Herbivore impacts are, in turn, influenced by predators that place top-down forcing on prey species within a given body size range. Here, we explore how the functional composition of terrestrial large-herbivore and -carnivore guilds varies between three mammal distribution scenarios: Present-Natural, Current-Day and Extant-Native Trophic (ENT) Rewilding.

Geographically divergent evolutionary and ecological legacies shape mammal biodiversity in the global tropics and subtropics.

Studies of the factors governing global patterns of biodiversity are key to predicting community responses to ongoing and future abiotic and biotic changes. Although most research has focused on present-day climate, a growing body of evidence indicates that modern ecological communities may be significantly shaped by paleoclimatic change and past anthropogenic factors. However, the generality of this pattern is unknown, as global analyses are lacking.

Statistical estimates of hominin origination and extinction dates: A case study examining the Australopithecus anamensis-afarensis lineage.

Reliable estimates of when hominin taxa originated and went extinct are central to addressing many paleoanthropological questions, including those relating to macroevolutionary patterns. The timing of hominin temporal ranges can be used to test chronological predictions generated from phylogenetic hypotheses. For example, hypotheses of phyletic ancestor-descendant relationships, based on morphological data, predict no temporal range overlap between the two taxa.

Early hominins evolved within non-analog ecosystems.

Present-day African ecosystems serve as referential models for conceptualizing the environmental context of early hominin evolution, but the degree to which modern ecosystems are representative of those in the past is unclear. A growing body of evidence from eastern Africa's rich and well-dated late Cenozoic fossil record documents communities of large-bodied mammalian herbivores with ecological structures differing dramatically from those of the present day, implying that modern communities may not be suitable analogs for the ancient ecosystems of hominin evolution. To determine when and why the ecological structure of eastern Africa's herbivore faunas came to resemble those of the present, here we analyze functional trait changes in a comprehensive dataset of 305 modern and fossil herbivore communities spanning the last ∼7 Myr.

Plio-Pleistocene decline of African megaherbivores: No evidence for ancient hominin impacts.

It has long been proposed that pre-modern hominin impacts drove extinctions and shaped the evolutionary history of Africa's exceptionally diverse large mammal communities, but this hypothesis has yet to be rigorously tested. We analyzed eastern African herbivore communities spanning the past 7 million years-encompassing the entirety of hominin evolutionary history-to test the hypothesis that top-down impacts of tool-bearing, meat-eating hominins contributed to the demise of megaherbivores prior to the emergence of We document a steady, long-term decline of megaherbivores beginning ~4.6 million years ago, long before the appearance of hominin species capable of exerting top-down control of large mammal communities and predating evidence for hominin interactions with megaherbivore prey.