Ecology IS a method of connecting past and future abiotic and biotic states to tell a story of the landscape. Distribution of plants is not random. This is my take on the dynamics of the naturalized tree community in Cowgary AB.
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Some general tree ecology information;
Shade tolerance is a very strong indicator of niche in trees, and shade tolerance is often inversely correlated with seed dispersal distance and size, and growth rate. Some exceptions include cherries (with larger seeds and aggressive growth in full sun) and spruce (with decent seed dispersal distance but high shade tolerance). Generally shade intolerant species will invade disturbed sites or need disturbance to remain competitive. Shade is also indicative of some amount of accumulated organic matter in the form of litter.
Around here, deciduous trees are often fast growing, shade intolerant, water loving, and require disturbance to remain competitive. Many deciduous trees can be cut to a stump and be better for it.
Growth rate is also linked to palatability, where unpalatable plants tend to grow more slowly as it is metabolically expensive to deter herbivores.
Steeper slopes will be better drained and you can see that water loving trees will be found at the foot of slopes.
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Northeast aspect- Mature Populus sp. dominate the community (possibly hybrid cottonwood) interspaced with meadows. In association with green ash, boxelder, American elm.
The Bow River valley in deep southern Alberta is typically Populus balsamifera dominated deciduous forest, mixed with grassland. There are allegedly 3 freely hybridizing cottonwoods in the greater region; P. balsamifera, P trichocarpa, P. deltoides. Allegedly only P. balsamifera is found in the Calgary area naturally, so I'm going to assume that is the main species I've been dealing with. The other "cottonwoods" tend to have more pyramidal, less irregular crown.
Calgary receives around 330 mm of rain a year- with the most precipitation June. In this climate, it is like a savannah, in that growing seasons are controlled by moisture availability, and on dry years, vegetation can be forced to go dormant in drier sites as water becomes scarce in late summer, long before frost. Trees turn yellow and lose leaves in October, frequent frosts start in late October. Conditions on upland sites can be too dry for trees, restricting them to north facing slopes and river valleys, or other areas where the water table is higher. Tree cover can be patchy and is typically deciduous. Historically, frequent low-intensity fires would keep fire adapted early successional trees competitive but in check relative to the dominant grassland.
Within the city limits of Calgary, on the south facing slopes, there is a gradual shift from scrubby grasslands on the most exposed upland sites to riparian forest in the lowest wettest zones. The dominant tree is Balsam Poplar, (Populus balsamifera) and the subdominant trees are Boxelder (Acer negundo) and Green Ash (Fraxinus pennsylvanica). There is a clear boundary just upslope of the floodplain and on South facing slopes where willow and boxelder become more dominant and adapt a larger tree-like growth habit - these trees can form a much denser forest type where they dominate as mid-successional trees, also in association with green ash.
On the north facing sites, the community is more Populus tremuloides, and Picea glauca, with Betula and salix as subdominant species.
Balsam Poplar
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Young balsam poplar on a rich site- showing the self-pruned barren trunks of adolescence - in an open canopy forest with a relatively dense understory.
Within the Bow valley of southern Alberta, the balsam poplar is often dominant in the sites that it can be found. It is the earliest successional and least shade tolerant riparian tree in the community. A community with balsam poplar as the only tree still is rich in plant species and habitat types. It tolerates suboptimal conditions such as drier south facing slopes by having little competition with other trees as a pioneer of disturbed areas. It produces an open canopy forest with a rich understory, and makes a patchwork of grasslands, scattered trees, meadows, open woodlands, and open forest. On exposed, rocky, or drier sites, young balsam poplar trees are spaced out and the understory is quite open compared to similarly aged forests on richer sites- where willow or other shrubs become virtually unpassable. As it grows, the poplar is self pruning due to it's extremely high metabolism - shaded vegetation is starved for light- a forest of mature trees is quite open even on richer sites with tall, straight, barren trunks. This tree’s belligerent refusal to grow in shade means it provides enough sunlight and space in the understory for the gradual invasion by green ash and boxelder, and supports a large variety of shrubs (including the introduced apple, cherry and mountain ash) and eventually, spruce.
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Balsam poplar is particularly dominant along riverbeds, where frequent disturbances from floods and subsidence occur - these events remove competition and provide opportunity. It can even reproduce from buried broken branches or fallen trees. These trees grow very fast and can form 20m canopies, (extremely exceptional trees can reach 30m) rivaled only by P. glauca in the area for maximum height.
Vegetative reproduction allows this species to invade grasslands by providing the energy and nutrients for young trees to grow above the dense shade and aggressive roots of grasses. , an adaptation perfect for areas that are frequently disturbed by subsidence and flooding. The poplar genus produces tiny fluffy seeds that can travel very long distances, where there is a minute chance of establishing a new population.
Although this tree is associated with wet areas, the most poorly drained conditions are still dominated by willow.
Whereas P. tremuloides is a fire adapted tree of cool climates and upland areas, P. balsamifera is a riparian species adapted to erosive disturbances - and probably soils poor in organic matter.
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Trembling Aspen
Trembling aspen on a northwest aspect- high above the river valley. The climate prevents them from attaining a large size. Here, aspen is excluded from the driest high point of the slope.
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P. tremuloides forms mostly monotypic forests of dwarf trees (often far less than 10m in height) on less exposed sites where there are less erosive forces than the deep river valley. Aspen is also a fast growing species intolerant of full shade, and it can invade grasslands with aggressive suckering so long as the site is not too exposed or dry. Most poplars form communities with few genetic individuals. It is rarely planted by urban planners, and reproduces very poorly by seed. This tree loves fire based disturbances, as its rootstock survives superficial burns, and can even require fires to remain competitive with white spruce. The relatively cooler soils mean the understory is more dense than in P. balsamifera dominated sites. The understory is characterized by cooler conditions where lush grasses and delicate herbs can stay green into the late summer.
It is susceptible to insect pests such as tent caterpillar and leaf miner.
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Boxelder
The water table rises further downslope (south aspect) where boxelder becomes larger and more common. Notice the lone boxelder (center left, midground) is at the base of a steeper slope where water will runoff less. This grassland is dried out in late summer.
Boxelder is probably the second most common tree on south facing slopes and within the river valley, found in association with balsam poplar, green ash, and willow, but rarely with aspen or spruce. This tree is dioecious and spreads by abundantly producing winged samsara- with moderate seed dispersal distance. It has intermediate shade tolerance and can invade shrub planters. Samsaras ripen late in the season so that they may blow around on top of snow during the long windy winter. This is a riparian tree that will tolerate dry conditions at the expense of size and longevity. Boxelder forms a globular shrubby growth habit when it gradually invades grassland, often sparsely spaced. It seems less successful along the larger river where sediment shifts and floods occur most often, and where organic matter is lower. It can form a dense forest along more stable tributaries. This tree is probably made more abundant by human influence.
Mortality of young saplings is quite high from rodent predation and dry late summer conditions.
Green Ash
South aspect- found in an open area surrounded by balsam poplar
Fraxinus pennsylvanica is the last tree to leaf in the last part of spring, long after it has flowered, also one of the last trees to drop its leaves in the fall. It produces samsaras as a primary reproductive method. This tree is sensitive to drought, though it does occasionally germinate within open grasslands. It is one of the more shade tolerant deciduous trees but rarely has complete dominance. Within a south facing slope community it will be found often upslope of mature P. balsimifera where some sort of small clearing has occurred. This microclimate will have shaded soil but access to full sunlight for a tree of even modest height.
This tree is quite common and found in association with balsam poplar and boxelder, or at the base of mature spruce (especially within suburbia), but rarely with aspen.
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Picea glauca
(photo from northern Alberta) Picea glauca is often within aspen forests and gradually becomes the dominant tree in the absence of disturbance. Aspen grows much larger (seen here) in cooler climates than in the Bow valley.
White spruce is the most common coniferous tree in the region, and the latest successional tree. Within city limits it mostly dominates the north facing slopes, and is more associated with trembling aspen than the balsam poplar community. The trees are slow growing and intolerant of disturbance, but their ability to gradually invade forests over time as shade tolerant saplings is their greatest strength. The tree is extremely hardy to cold and resistant to grazing. It prefers denser litter and often grows on the north side of large trees, but it seems to compete poorly with very dense shrubbery. This tree is rarely found in open sites. The Colorado blue spruce may be naturalized in the area as well.
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There are a variety of uncommon trees that can turn up in the area; introduced species and dubiously natives. Paper Birch and lodgepole pine are extremely uncommon members of this community. The most common introduced trees include Prunus padus and Caragena. American Elm occasionally escapes cultivation but reproduces quite slowly in natural sites. Introduced apple and mountain ash are often present at low density, tending to grow much smaller than their maximum size. Lilac can be occasionally found in the middle of grasslands, possibly from guerilla gardeners. It's possible or even likely that the relative abundance of green ash and boxelder benefit from anthropogenic influence.
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I'm new to ecological writing so I hope you learned something about the dynamics of trees in this region, or something applicable to your region. I'd love to hear insights on this type of study, or to be corrected about something. All the best.

Some of these species are extremely rare and on the verge of extinction, especially where the forest has been disturbed. The reason for this pattern is that many species are highly specialized to fit a particular niche. Where that niche exists, that species may have a large population and constantly produce offspring that head off to colonize new areas. However, the colonizers almost always fail, because they cannot compete with the specialized species of other areas. Thus these colonizers are rare in the areas where they try to establish a foothold.
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What are the two main categories of ecosystems?

All types of ecosystems fall into one of two categories: terrestrial or aquatic. Terrestrial ecosystems are land-based, while aquatic are water-based. The major types of ecosystems are forests, grasslands, deserts, tundra, freshwater and marine.
Eastern redcedar invasion across Oklahoma results from decreases in fire frequency due to fire prevention programs and cultural changes. Urban sprawl and the red cedar problem is also a major threat to maintaining biodiversity across the state. It is critical that natural disturbances be incorporated into ecosystem management efforts to sustain system health. The habitat diversity was used both as a categorical and as a calculated continuous variable.

Sciencing_icons_ecosystems Ecosystems

Scientists are warning us about the high risk of losing more animals to human activities if conservation efforts are not done in earnest. The variability of life on Earth includes all forms of organism, terrestrial or marine, and other aquatic ecosystems and their ecological complexes. Not only that, but it also includes the diversity within each species itself. We will discover what biodiversity means, why is it important to humans, and we’re going to learn the different types of biodiversity and why each of them plays a vital role in our lives and world. The three types of biodiversity are Genetic Diversity, Species Diversity, Ecosystem Diversity.

What does an ecosystem need to be balanced and healthy?

Any balanced ecosystem consists of living as well as non-living organisms who interact with each other in an environment. The non-living features which are also called the abiotic features consist of sunlight, temperature, soil, precipitation, landscape, moisture and more.
Additionally, fringing corals occur along the coastlines of United Arab Emirates, Qatar, Saudi Arabia and Bahrain . Extremes in temperature, salinity and other physical factors in the Arabian Gulf restrict the growth and development of corals to patchy forms (Sheppard et al., 2010). However, despite these harsh environmental conditions, corals in the Arabian Gulf exhibit remarkable resilience and vitality. The Convention on Biological Diversity and UNDP offer a free course about how to communicate the value of biodiversity.

The Threat Of Invasive Species

Insight from such research can be invaluable for the conservation and the management of natural resources. Multiple anthropogenic stressors can lead to cumulative impacts on marine ecosystems (Crain et al., 2008). Coastlines of the Arabian Gulf are witnessing a rapid increase in the number and scale of coastal developments.

Five big questions for 2022 — BirdLife International

Five big questions for 2022.
Posted: Wed, 05 Jan 2022 10:52:59 GMT [source]
A region with numerous interactions among organisms likely has a large number of species and high species biodiversity. If a region has high species biodiversity, it has a lot of genetic variability in the organisms that make up the ecosystem. A second definition of ecosystem biodiversity refers to the number of ecological interactions among organisms in a certain area. This form of ecosystem biodiversity is a measure of the complexity of an ecosystem. A more diverse ecosystem has more ecological niches, more feeding relationships among organisms, more organisms that capture energy, and more species that recycle organic nutrients into inorganic forms.

Strengths And Weaknesses Of Community Ecology And Ecosystem Ecology

MPAs contribute significantly to both preservation and conservation of genetic characteristics, species, habitats and cultural diversity in coastal and marine environments. They can help in preventing or reducing the ongoing declines in marine biodiversity, habitats and fisheries productivity. MPAs can also improve ecosystem functions and services through maintaining ecological structure and processes that support economic and social uses of marine resources . Additionally, MPAs can contribute towards climate change adaptation by protecting ecosystem resilience and protecting essential ecosystem services (McLeod et al., 2009). The third type of biodiversity is ecological diversity, and this is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet. Progress achieved on the diversity–stability relationship has been particularly significant given the long, controversial history of this issue in ecology.

Your opinion it’s centralized, whereas in all aspects of crypto ecosystem diversity is paramount. How many universities and colleges, businesses, projects, professionals, etc., explain a topic or concepts in different ways and mechanics? What’s the point? Going to BNB only? — DExrpRuler💥💰 (@ElKioBaez2015) December 29, 2021

And with fewer herbivores, one can expect reduced populations of omnivores and carnivores. As every organism has a role to play in its ecosystem, the act of deforestation without replanting lost mature trees, can be catastrophic both locally and globally. Species diversity refers to the variety of species living in a particular area. By contrast, nosZ clade II showed the highest level of diversity in sandy sediments, intermediate levels in silty mud and Ruppia sediments and lowest levels in cyanobacterial mat sediments. The contrasting patterns of diversity for each nosZ clade indicate niche differentiation between the two clades, in accordance with previous studies in coastal sediments (Graves et al. In fact, communities of both clades I and II nosZ were significantly different between the four habitat types (Fig. Despite this, the importance of habitat diversity for maintaining diverse denitrifying communities in benthic environments is not well known. “The biggest challenge looking forward is to predict the combined effects of these environmental challenges to natural ecosystems and to society,” said J. Spatial skew in these can result in distorted model output that may not be apparent, even to those most expert in a given ecosystem type. Errors of commission are most likely for the dominant types, while errors of omission are most likely for rare types . In order to address these deficiencies, considerable new effort is needed to acquire reliable georeferenced data for all vegetation types we desire on our map legends. These data could come through increased sharing among researchers, coordinated and targeted field campaigns, and tapping the potential for acquisition through technology and citizen science. The strength of this approach is that it takes full advantage of local vegetation maps, available field reference samples, and global map surfaces–mostly satellite derived–to simultaneously generate plausible distributions of all map classes.

Product diversity takes AP to 5th spot in export value — Times of India

Product diversity takes AP to 5th spot in export value.
Posted: Mon, 03 Jan 2022 22:34:00 GMT [source]
In addition, the seasonal rise and fall of plant and invertebrate populations , which serve as food for other forms of life, also determine an area’s biodiversity. For numerous random draws of 1–19 species, we numerically determined mean equilibrial standing crop in the spatially heterogeneous habitat. Standing crop increased, variance in standing crop decreased, and concentrations of unconsumed resources decreased with increasing diversity (Fig. 2 C and D). Ecology has traditionally regarded biodiversity as an epiphenomenon driven by the abiotic environment and ecosystem functioning . Recent biodiversity and ecosystem functioning research has focused on the reverse effect of biodiversity on ecosystem functioning .
A study by a resource and environmental management researcher reveals that sunflower sea stars play a critical role in the resilience of B.C.’s kelp forests, which are among the most productive … That’s why species diversity is an important part of biodiversity; the more species that live and co-exist in one area, the more biodiverse that area is, therefore the more biodiverse the ecosystem is. Maintaining and sustaining biodiversity is thought to hold the average global temperature below 2 degrees Celsius. The less the planet warms, the less we have to worry about the impacts of climate change. Before we dive deeper into the differences in the three main types of biodiversity, it is crucial to explain why biodiversity is so important to all life, human life, and the planet.

Monoculture does not exist in a healthy ecosystem. Diversity and change are the foundations of life. If we are to create a healthy future, we must support these principles everywhere. — Greenman (@greenman) January 4, 2022

Sequencing was performed on a 454 FLX Genome Sequencer using Titanium FLX+ chemistry by Microsynth . The nucleotide sequences obtained in this study were submitted to the NCBI short read archive and are available under Bioproject accession number PRJNA398484. Leslie Gonzalez samples plant diversity at Coyote Ridge, Calif.; pollution threatens this site. Biologists David Hooper and Leslie Gonzalez measure plant diversity and productivity. “Several of us working on this study were surprised by the comparative strength of those effects.” Similarly, ecosystem ecology studies the fluxes of energy and materials at various spatial scales. What distinguishes the ecosystem ecological approach is its focus on the system as a whole, irrespective of the species that compose it. Ecological biodiversity is the diversity of ecosystems, natural communities, and habitats. In essence, it’s the variety of ways that species interact with each other and their environment.

• The effects of changes in habitat diversity on ecosystem functioning remain unexplored.
• These areas are harboring sensitive ecosystems such as mangroves, and intertidal mudflats.
• A major progress would be the emergence of a genuine evolutionary ecosystem ecology that connects aggregate properties at the ecosystem level and evolution of species traits at the individual level .
• J. R. Pasari, T. Levi, E. S. Zavaleta, D. Tilman, Several scales of biodiversity affect ecosystem multifunctionality.
• Some scientists estimate that half of all species on Earth will be wiped out within the next century.

A species would have inherent value if it had some worth apart from its usefulness, for example simply because it exists on the planet. It is extremely difficult to attach a monetary amount to inherent values. Historically, examples of the value of biodiversity are anthropocentric instrumental examples of value. The ecosystem engineering and niche construction concepts further seek to capture biological feedbacks on the abiotic environment . All of these threats have put a serious strain on the diversity of species on Earth. According to the International Union for Conservation of Nature , globally about one third of all known species are threatened with extinction.
From: https://envirprotect.blogspot.com/2022/01/what-is-another-word-for-ecosystem.html

• Article
• Open Access
• Published: 09 August 2021

Early Pleistocene faunivorous hominins were not kleptoparasitic, and this impacted the evolution of human anatomy and socio-ecology

https://www.nature.com/articles/s41598-021-94783-4#Sec6

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Averaged relative distribution of cut marks in the experimental assemblages (baseline combined sample) replicating primary and secondary access to carcasses (upper) and in the FLK Zinj, DS and PTK archaeological data sets (lower). Colored vertical bands show bone portions where cut marks in “secondary access” experiments are non-existent in the experimental data set, and which would indicate access to fully fleshed carcasses. Notice how cut mark on the DS and PTK stylopodial fragments cluster preferential in these bone portions, suggesting bulk defleshing. Notice also how cut mark patterning in zeugopods are more ambiguous than in stylopods. Three areas of cut mark clustering are documented in the arcghaeological samples conforming to the primary access experiments: (A–C) A indicates patterning in cut mark clustering on the proximal half of humeri and distal femora. (B) indicates patterning on the proximal half of femora. (C) Shows that the cut marks pattern documented in the three archaeological samples is virtually identical to the primary access experiments, with clustering on the proximal epiphysis and metadiaphysis and almost no cut marks on the mid-shaft. The position of the tibia is different to the other long bones because it was programmed (scanned) in Ikhnos the opposite way. The X axis show the longitudinal dimensions of the complete series of the four long bones placed sequentially.

Discussion

The results of the present study show that by the early Pleistocene, hominins were already inserted in the carnivore guild. Their regular access to fleshed carcasses invalidates hypotheses positing the kleptoparasitic role of these ancestors. Like any other predator, hominins would have exploited available opportunities of carcasses found at other carnivore kills51; however, we argue that such strategies constituted a minor element in their carcass-acquisition behaviors. Carcasses obtained from felid kills would have registered typical taphonomic signatures (i.e., bone modifications) resulting from prior felid carcass consumption. In the past several years, with an already extensive archaeological record, such traces have been actively sought and only one unambiguous evidence of felid-hominin interaction has been found, at the DS site precisely (under review). Likewise, the first application of DL computer vision methods to the determination of agency in carnivore bone modification in a fossil assemblage showed that, with the aforementioned exception aside, all tooth pits from the DS archaeofaunal assemblage were caused by hyenas (under review). This eliminates the possibility of felids being the primary providers of carcasses for hominins and reinforces the results of the present study showing that the butchery pattern documented is typical of processing of complete (i.e., fully fleshed) carcasses. Carnivore intervention seems mostly restricted to post-depositional damage by durophagous fissipeds. This means that both small and medium-sized animals of up to 350 kg of weight at the two sites analyzed provided large surpluses of flesh for hominin groups.
These results underscore the role of meat in the early Pleistocene hominin diet and in their socio-reproductive behavior. Primary access to the animals present in these sites (also attested by the presence of eventration cut marks on rib fragments) would have required collective participation of, at least, several individuals, under a behavioral framework that implied intentional cooperation and expectation of resource sharing. Meat-eating would have increased diet quality, thus releasing Homo dentition from the selective pressure of copying with high strains caused by wide-range vegetarian omnivory. These changes in dentition could also be explained as selection for their use in preprocessing of meat52,53. The reduction in tooth size documented for the first time in this phase of human evolution seems to coincide with an increase of the neurocranium, perhaps being coevolving factors. This supports the impact of this dietary change in the morphing of basal metabolic energy allocation and the evolution of the human brain10,13,18,54. In addition, it is precisely at this time that we have evidence also of a major skeletal modification in some early Homo, with the emergence of H. erectus55,56. The modern human bauplan (long body, shortened forelimb and expansion of the hindlimb, with barrel-shaped thorax) emerges also at about this time. This probably is a reflection of the anatomical impact that the dietary change towards carnivory produced8. If hominins were predators, this would have required substantial behavioral changes resulting in major anatomical modifications compared to the previous Pliocene and the pene-contemporaneous early Pleistocene hominin stocks.
The presence of a nuchal ligament in H. erectus is suggestive of the stabilization of the head to the trunk, probably to counter the shock wave effect of the heel strike of the foot during running57,58. The fact that other cursor mammal runners have nuchal ligaments suggests that H. erectus was also a runner. The co-occurrence of a nuchal ligament with the earliest evidence of long legs in a larger body size (which, although also selected for by walking, are essential for running) supports the interpretation that this hominin taxon engaged in endurance running. Additional evidence for the stability needed during running comes from the long Achilles tendon, the podal plantar arch, the short forefoot and, especially, the enlarged semicircular canals of the ear57,58. An expanded gluteus maximus, which stabilizes the trunk, as inferred from the larger sacroiliac trough in H. erectus, would also have been essential for the proper biomechanical adaptation to running57,58. Bramble and Lieberman (2004) showed that the decoupling of head and shoulder muscles, would also have enabled the efficient swinging of the arms while keeping the head fixed and stable during running. Chimpanzees have their heads and shoulders connected by three muscles, which have been modified in modern humans. Only one of these muscles (the trapezius) still connects the shoulder and head in humans. Two independent tubular structures (a long neck and a long waist) also enhanced the trunk rotation during arm swinging to counter the angular momentum caused by the spinal rotation triggered by leg swinging. The first hominin in which all these features, which are clearly fundamental for running, are documented is H. erectus. If running was positively selected for the acquisition of animal food, then meat-eating and the evolution of human anatomy were interdependent co-evolving factors.
The predatory role of these hominins could also have left an anatomical imprint in the evolution of their arms. Humans are the most endowed primates to store and release energy at the shoulder needed for efficient throwing. No other primate can do so with as much control and with as much speed, strength and accuracy59. Although the capability of H. erectus to use their arms efficiently during throwing was questioned by their inferred narrow shoulders, low humeral torsion and anterior position of the scapula60,61, it has been shown that H. erectus claviculo-humeral ratio falls within the range of variation of modern humans59. In addition, no evidence exists in adult H. erectus specimens that the low humeral torsion is maintained ontogenetically as documented in the subadult KNMWT15000 individual. Roach and Richmond (2015) have also demonstrated that there is no relationship between clavicle length (i.e., shoulder width) and throwing performance. Biomechanical studies show that fast and strong throwing in modern humans is enabled by three factors: tall and mobile waists, humeral torsion and the laterally-oriented gleno-humeral joint62. H. erectus is the first hominin in which these three factors can be anatomically documented. However, the humeral torsion of this taxon is lower than modern humans and it is not known how this could have impacted this hominin´s skills at throwing. If the anatomical indications are correct in pointing at the throwing biomechanical efficiency in H. erectus, the subsequent inference is that such skill was probably selected for hunting. The evolutionary co-occurrence of these anatomical shifts and the taphonomic evidence in the archaeological record associated with this taxon that hominins were consuming meat provides compelling support to the interpretation that behavior and anatomy co-evolved through positive selection of predation and meat-consumption.
This dependence on meat could also have triggered important changes in early hominin physiology by adapting to a regular consumption of animal protein and fat. There is evidence that modern human physiology, which makes our species highly dependent on regular intake of cobalamine, may also have its origins in the early Pleistocene63. Choline, an essential nutrient that plays a crucial role in gene expression (through methylation of its oxidized form, S-adenosylmethionine) and in brain and liver function is also most abundant in meat and animal products, with very few plants containing any substantial amount of it64,65. Humans are also more dependent on this essential nutrient than other primates and failure to meet minimum doses leads to serious pathological conditions. Genomic analysis of the trypanosomic Taenia (tapeworm) indicates that human-host infection could have started by 1.7 Ma66,67, further suggesting that by that time hominins were facultative carnivores. Pathogens (viruses, bacteria, prions) associated with meat consumption limit other primates’ carnivory and suggest that humans evolved meat-specific genes that allowed a more effective buffer against pathogens and meat-related pathologies (e.g., hypercholesterolemia, vascular diseases)68,69, as well as hosting a different microbiome more apt for digesting animal fat and protein70,71,72.
The adoption of carnivory for early Homo is also relevant from an ecological perspective. Most modern African carnivores can be qualified as anything but occasional kleptoparasites, with the exception of vultures and brown hyenas. The latter survive in moderate to low competitive ecosystems and complement their diet with hunting of small animals and wide-range foraging for insects and plants. Even more kleptoparasitic organisms do not base the bulk of their food acquisition on this strategy, since it is risky and frequently incurs in additional costs compared to self-foraging73. Evolutionary Stable Strategy modeling shows that kleptoparasitism is an inefficient strategy unless used as a complement74. Opportunistic strategies are ecologically very valuable, because they reflect intensity in resource competition, high competitor biomass and limited herbivore biomass75. The higher the degree of trophic competition, the more frequent kleptoparasitic behaviors are and this impacts on predator group size and, indirectly, on prey size75,76. Predators affected by opportunistic competitors may buffer this behavior by expanding group size, switching to larger prey and being more successful at defending kills75. This shows that kleptoparasitism behaviors are only successful short-term, but cannot be a stable way of acquiring resources74; especially in African savannas, where carnivore diversity and high degree of trophic dynamic competition renders it adaptive for only a small number of specialists, such as vultures or brown hyenas. Hominins would have lacked the ability to monitor savanna habitats for miles from the air and their locomotion adaptation (priming endurance over speed) would have prevented them from being efficient scavengers like brown hyenas, which may tread for more than 30–40 km in each foraging bout77. Thus, the carnivoran impact of hominins on savanna ecosystems must be interpreted on different grounds.
Given that all the taphonomic evidence from early Pleistocene anthropogenic sites suggest that hominins may have successfully hunted small and medium-sized animals, their ecological impact affected first and foremost the predatory guild. Analytical studies of carnivore functional and evenness richness across the Pliocene and Pleistocene in East Africa show that there has been a loss of functional richness > 99% from the Pliocene until today78. Climatic and environmental information does not correlate with carnivore extinctions, especially after 2 Ma78. A thorough analysis of the past four million years shows, in contrasts, that there is a strong correlation between carnivore richness decrease and hominin brain expansion, suggesting that an increase in cognitive skills may have enabled hominins to overtake ecological niches occupied by other carnivore taxa during Quaternary79. This supports that “anthropogenic influence on biodiversity started millions of years earlier than currently assumed”79. If meat-eating allowed for a high-quality diet impacting on higher hominin demographics, hominin expanding densities across landscapes could have pressured several competing carnivores and could have placed the latter at selective disadvantage. Such a demographic increase is also supported by much bigger sizes of Acheulian sites after 1.7 Ma and the conspicuous evidence of megafaunal exploitation (not necessarily through hunting) after this date by hominins, probably suggesting bigger group sizes36,38,39, given the ecological correlation between carcass size exploitation and number of carnivore commensals80,81,82,83,84. Body-size ecology (including total carnivore mass and pack size) determines targeting specific prey sizes in mammalian predators80,81,82,83,84. The increase of hominin body size and anatomical robustness across the early and middle Pleistocene indicates a selection of physical strength, probably either reflecting predatory strategies that required force or an exaptation in this direction.
Although it has recently been argued that no evidence exist for the anthropogenic impact in African Pleistocene mammal faunas85, the arguments against it are affected by similar anecdotal assumptions as some arguments in favor of such an impact. The focus on megaherbivores and their higher representation in the past, for example, is biasing and needs to be properly justified. Megaherbivores´ ecological niches are preferentially situated in certain alluvial habitats, which favor their preservation because of the fast sedimentation processes operating in such environments. Most Plio-Pleistocene paleontological and archaeological localities represent portions of alluvial habitats. The greater representation of megaherbivores in the past has certainly been impacted by this and might as well be just a taphonomic artefact affecting our perception of megafaunal paleoecological diversity and biomass. Climatic–based interpretations overlook the bias introduced by taphonomy as much as arguments using taxa richness for ecological transitions. Faith et al.85 correctly argument that carnivoran richness and extinction rates can alternatively be reflecting sampling intensity (i.e., number of sites per period). They also counter-argument that grassland expansion could be responsible of such extinctions. However, it has been shown that it is sampling biases (i.e., number of sites and fossiliferous localities per period and collection intensity) that can account for specific taxic diversity and not climatic forcing, especially for the 1.9 Ma period86. No climatic explanation currently can be used to account for mammal evolution without taphonomic calibration86. Without this, true climatic evolutionary signals cannot be supported. In their own explanation, Faith et al.85 detect a decreasing carnivore taxonomic diversity “trend” after 1.9 Ma (and, especially after 1.5 Ma), which they interpret as ecological, while it is also related to the decrease of sampling intensity, given the smaller number of localities and their areal sizes at the end of early Pleistocene in Africa.
Faith et al.85 also reject for the sake of their arguments that hominin might be targeting meat-consumption in the Pliocene and early Pleistocene and claim that the early archaeological record merely documents bone marrow exploitation and hominin kleptoparasitic behaviors, against all taphonomic evidence currently available1,2. These authors additionally assume (without support) that small-carnivore extinction should precede large carnivore extinction if hominins were a competitive factor. This assumption is also not ecologically justified and also goes against the zooarchaeological evidence showing that starting 2.6 Ma, hominins were targeting medium-sized taxa preferentially, which affects large carnivores far more than small ones. An argument in favor of hominin impact can be found in Faith et al.´s own data, which clearly show an abrupt decline of large carnivore taxa at 1.8 Ma, precisely the age in which our analysis documents strong carnivoran adaptations by hominins consuming prey that is typical of larger carnivores. In addition, it is the megapredators that show a higher degree of specialization on meat, whereas mesopredators tend to be more generalists87, rendering the former more susceptible to be affected by competition.
By focusing on all taxa, including viverrids and mustelids, Faith et al. are also missing the point that it is the large carnivore trends that are most important for assessing the impact of hominins on the predatory guild. Additionally, Faith et al. put some faith in the intrinsic association of large carnivores and megaherbivores, when there is a strong record of similarly-sized carnivores and their preferential adaptation to the consumption of medium-sized (100–400 kg) prey, and even smaller animals88. No evidence exist that could be used to support taxon-wide association of predator–prey dependence between Homotherium or Pachycrocruta and megaherbivores. In most of the geographic record of Homotherium, for example, the taphonomic evidence of its involvement with megaherbivores is rather limited. It should be emphasized that in Africa, these large carnivores disappeared way before their potential megafaunal prey did.
FLK Zinj, DS and PTK are probably the best preserved of the early Pleistocene anthropogenic sites in Africa spanning the first million years of the archaeological record. They occur as stratigraphically discrete horizontal concentrations of hominin-processed faunal remains. The Kanjera site (Kenya) has also been used as an example of possibly predatory carnivory by early hominins4; however, the nature of this deposit presents more potential time-averaging problems that may have impacted on its integrity and resolution. Its structure as a thicker deposit indicates much more time for a potential diversity of biotic and abiotic agents to have intervened and create a palimpsest from which disentangling the hominin part is challenging. As a matter of fact, the reported frequency of anthropogenic BSM is marginal and substantially lower than those reported in experiments and archaeological assemblages where the agency in the accumulation of the assemblage is solely or mostly hominin. It would be interesting to apply the same methods described here to this assemblage.
The virtually identical patterning in the relative distribution of cut mark clustering on long bones at the three archaeological sites analyzed here (Fig. 3) indicates that: (a) such patterning has a behavioral non-stochastic nature, and b) it clearly indicates a better match with experiments reproducing primary butchery of complete carcasses. The main differences seem to be related to less secondary limb dismembering occurring at the archaeological assemblages. This may have interesting implications on the interpretation of the social behavior of carcass consumption by early hominins, which also seems to have been spatially more restricted than observed among modern human foragers. The relevance of the patterning discovered at the three sites cannot be overemphasized. These are the only taphonomically-supported fully anthropogenic sites in the African early Pleistocene prior to 1.5 Ma1,2. It means that if further behavioral variation existed, that must be uncovered with new sites. It also means that the pattern unveiled shows a socio-structural behavior in the adaptation of those early humans. The evidence of primary access and bulk defleshing by hominins at these three sites precedes similar evidence also documented at some sites after 1.5 Ma2. Some archaeofaunal assemblages from Olduvai (BK), Peninj (ST4) (Tanzania), and Swartkrans (member 3) (South Africa) have yielded an abundance of taphonomic data indicating that hominins regularly enjoyed early access to prime portions of ungulate carcasses90,91,92.