Constraining the oxygen requirements for modern microbial eukaryote diversity.

Eukaryotes originated prior to the establishment of modern marine oxygen (O2) levels. According to the body fossil and lipid biomarker records, modern (crown) microbial eukaryote lineages began diversifying in the ocean no later than ~800 Ma. While it has long been predicted that increasing atmospheric O2 levels facilitated the early diversification of microbial eukaryotes, the O2 levels needed to permit this diversification remain unconstrained. Using time-resolved geochemical parameter and gene sequence information from a model marine oxygen minimum zone spanning a range of dissolved O2 levels and redox states, we show that microbial eukaryote taxonomic richness and phylogenetic diversity remain the same until O2 declines to around 2 to 3% of present atmospheric levels, below which these diversity metrics become significantly reduced. Our observations suggest that increasing O2 would have only directly promoted early crown-eukaryote diversity if atmospheric O2 was below 2 to 3% of modern levels when crown-eukaryotes originated and then later met or surpassed this range as crown-eukaryotes diversified. If atmospheric O2 was already consistently at or above 2 to 3% of modern levels by the time that crown-eukaryotes originated, then the subsequent diversification of modern microbial eukaryotes was not directly driven by atmospheric oxygenation.

Visual perception of emotion cues in dogs: a critical review of methodologies.

Comparative studies of human-dog cognition have grown exponentially since the 2000's, but the focus on how dogs look at us (as well as other dogs) as social partners is a more recent phenomenon despite its importance to human-dog interactions. Here, we briefly summarise the current state of research in visual perception of emotion cues in dogs and why this area is important; we then critically review its most commonly used methods, by discussing conceptual and methodological challenges and associated limitations in depth; finally, we suggest some possible solutions and recommend best practice for future research. Typically, most studies in this field have concentrated on facial emotional cues, with full body information rarely considered. There are many challenges in the way studies are conceptually designed (e.g., use of non-naturalistic stimuli) and the way researchers incorporate biases (e.g., anthropomorphism) into experimental designs, which may lead to problematic conclusions. However, technological and scientific advances offer the opportunity to gather much more valid, objective, and systematic data in this rapidly expanding field of study. Solving conceptual and methodological challenges in the field of emotion perception research in dogs will not only be beneficial in improving research in dog-human interactions, but also within the comparative psychology area, in which dogs are an important model species to study evolutionary processes.

How do children view and categorise human and dog facial expressions?

Children are often surrounded by other humans and companion animals (e.g., dogs, cats); and understanding facial expressions in all these social partners may be critical to successful social interactions. In an eye-tracking study, we examined how children (4-10 years old) view and label facial expressions in adult humans and dogs. We found that children looked more at dogs than humans, and more at negative than positive or neutral human expressions. Their viewing patterns (Proportion of Viewing Time, PVT) at individual facial regions were also modified by the viewed species and emotion, with the eyes not always being most viewed: this related to positive anticipation when viewing humans, whilst when viewing dogs, the mouth was viewed more or equally compared to the eyes for all emotions. We further found that children's labelling (Emotion Categorisation Accuracy, ECA) was better for the perceived valence than for emotion category, with positive human expressions easier than both positive and negative dog expressions. They performed poorly when asked to freely label facial expressions, but performed better for human than dog expressions. Finally, we found some effects of age, sex, and other factors (e.g., experience with dogs) on both PVT and ECA. Our study shows that children have a different gaze pattern and identification accuracy compared to adults, for viewing faces of human adults and dogs. We suggest that for recognising human (own-face-type) expressions, familiarity obtained through casual social interactions may be sufficient; but for recognising dog (other-face-type) expressions, explicit training may be required to develop competence. HIGHLIGHTS: We conducted an eye-tracking experiment to investigate how children view and categorise facial expressions in adult humans and dogs Children's viewing patterns were significantly dependent upon the facial region, species, and emotion viewed Children's categorisation also varied with the species and emotion viewed, with better performance for valence than emotion categories Own-face-types (adult humans) are easier than other-face-types (dogs) for children, and casual familiarity (e.g., through family dogs) to the latter is not enough to achieve perceptual competence.

Marine sponges in the once and future ocean.

Animals originated under hypoxia-low-oxygen conditions that are currently expanding throughout the global ocean. How marine sponges respond to hypoxia is both relevant to reconstructing early animal evolution and for forecasting the fate of modern marine ecosystems. In a new effort, multiple sponge species from two different oceans were found to tolerate hypoxia in the lab, revealing a more general capacity for hypoxia tolerance across sponges with implications for both the deep past and near future of animal life.

Dogs can infer implicit information from human emotional expressions.

The ability to infer emotional states and their wider consequences requires the establishment of relationships between the emotional display and subsequent actions. These abilities, together with the use of emotional information from others in social decision making, are cognitively demanding and require inferential skills that extend beyond the immediate perception of the current behaviour of another individual. They may include predictions of the significance of the emotional states being expressed. These abilities were previously believed to be exclusive to primates. In this study, we presented adult domestic dogs with a social interaction between two unfamiliar people, which could be positive, negative or neutral. After passively witnessing the actors engaging silently with each other and with the environment, dogs were given the opportunity to approach a food resource that varied in accessibility. We found that the available emotional information was more relevant than the motivation of the actors (i.e. giving something or receiving something) in predicting the dogs' responses. Thus, dogs were able to access implicit information from the actors' emotional states and appropriately use the affective information to make context-dependent decisions. The findings demonstrate that a non-human animal can actively acquire information from emotional expressions, infer some form of emotional state and use this functionally to make decisions.

Epstein-Barr-virus-positive large B-cell lymphoma associated with breast implants: an analysis of eight patients suggesting a possible pathogenetic relationship.

Breast implant anaplastic large cell lymphoma (ALCL) is a T-cell neoplasm arising around textured breast implants that was recognized recently as a distinct entity by the World Health Organization. Rarely, other types of lymphoma have been reported in patients with breast implants, raising the possibility of a pathogenetic relationship between breast implants and other types of lymphoma. We report eight cases of Epstein-Barr virus (EBV)-positive large B-cell lymphoma associated with breast implants. One of these cases was invasive, and the other seven neoplasms were noninvasive and showed morphologic overlap with breast implant ALCL. All eight cases expressed B-cell markers, had a non-germinal center B-cell immunophenotype, and were EBV+ with a latency type III pattern of infection. We compared the noninvasive EBV+ large B-cell lymphoma cases with a cohort of breast implant ALCL cases matched for clinical and pathologic stage. The EBV+ large B-cell lymphoma cases more frequently showed a thicker capsule, and more often were associated with calcification and prominent lymphoid aggregates outside of the capsule. The EBV+ B-cell lymphoma cells were more often arranged within necrotic fibrinoid material in a layered pattern. We believe that this case series highlights many morphologic similarities between EBV+ large B-cell lymphoma and breast implant ALCL. The data presented suggest a pathogenetic role for breast implants (as well as EBV) in the pathogenesis of EBV+ large B-cell lymphoma. We also provide some histologic findings useful for distinguishing EBV+ large B-cell lymphoma from breast implant ALCL in this clinical setting.

Bodily emotional expressions are a primary source of information for dogs, but not for humans.

Dogs have remarkable abilities to synergise their behaviour with that of people, but how dogs read facial and bodily emotional cues in comparison to humans remains unclear. Both species share the same ecological niche, are highly social and expressive, making them an ideal comparative model for intra- and inter-species emotion perception. We compared eye-tracking data from unrestrained humans and dogs when viewing dynamic and naturalistic emotional expressions in humans and dogs. Dogs attended more to the body than the head of human and dog figures, unlike humans who focused more on the head of both species. Dogs and humans also showed a clear age effect that reduced head gaze. Our results indicate a species-specific evolutionary adaptation for emotion perception, which is only partly modified for heterospecific cues. These results have important implications for managing the risk associated with human-dog interactions, where expressive and perceptual differences are crucial.

Primate veterinarians' knowledge and attitudes regarding pain in macaques.

BACKGROUND: Assessment of pain in macaques is challenging. The aims of this study were (1) to investigate current knowledge and attitudes of primate veterinarians concerning acute pain in macaques; (2) to synthesise current knowledge and opinion to facilitate pain assessment. A primary question of interest was whether more confident individuals differ in their knowledge and attitudes from less-confident individuals. METHODS: An online survey was conducted amongst primate veterinarians serving both laboratories and zoos/sanctuaries. The questionnaire consisted of demographic information, attitudes towards pain, pain rating and analgesics, pain recognition and confidence in recognising pain and sources of information used. RESULTS AND CONCLUSIONS: There was generally good use of analgesia by respondents. More confident individuals reported that they recognise pain both behaviourally and in facial expressions, rated all pain signs more highly and used more analgesics. Specialist support networks aimed at increasing veterinarian confidence in macaque pain assessment could be beneficial.

Perception of dynamic facial expressions of emotion between dogs and humans.

Facial expressions are a core component of the emotional response of social mammals. In contrast to Darwin's original proposition, expressive facial cues of emotion appear to have evolved to be species-specific. Faces trigger an automatic perceptual process, and so, inter-specific emotion perception is potentially a challenge; since observers should not try to "read" heterospecific facial expressions in the same way that they do conspecific ones. Using dynamic spontaneous facial expression stimuli, we report the first inter-species eye-tracking study on fully unrestrained participants and without pre-experiment training to maintain attention to stimuli, to compare how two different species living in the same ecological niche, humans and dogs, perceive each other's facial expressions of emotion. Humans and dogs showed different gaze distributions when viewing the same facial expressions of either humans or dogs. Humans modulated their gaze depending on the area of interest (AOI) being examined, emotion, and species observed, but dogs modulated their gaze depending on AOI only. We also analysed if the gaze distribution was random across AOIs in both species: in humans, eye movements were not correlated with the diagnostic facial movements occurring in the emotional expression, and in dogs, there was only a partial relationship. This suggests that the scanning of facial expressions is a relatively automatic process. Thus, to read other species' facial emotions successfully, individuals must overcome these automatic perceptual processes and employ learning strategies to appreciate the inter-species emotional repertoire.

Therapeutic plasma exchange in neurological disorders: Experience from a tertiary neuroscience centre.

Therapeutic plasma exchange (TPE) involves the extracorporeal separation of plasma from the cellular components of blood with replacement fluid, such as human albumin or fresh frozen plasma. A number of studies across the world revealed that more than one third of TPE procedures were performed for neurological disorders. Myasthenia gravis (MG), Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) were the most frequently cited indications for TPE, followed by multiple sclerosis (MS). However, treatments of these conditions have evolved over the years and it is likely that this has impacted on clinical practice. Here we present our experience of using TPE to treat neurological disorders. We reviewed the medical records of all 63 patients who received 349 procedures over 70 therapeutic cycles between 2012 and 2015 in a tertiary neurology centre. In total only 2 patients with GBS and MG were treated with TPE. The commonest indication was voltage gated potassium channel (VGKC) complex antibody associated disorders followed by CIDP and MS. There were 11 patients with limbic encephalitis. Nine of them had antibodies against VGKC complex and two had N-methyl-D-aspartate (NMDA) receptor antibodies. Sixty four percent of patients with limbic encephalitis and overall 78% of patients responded to TPE. The complication rate associated with this procedure was 8.6 per 100 therapeutic cycle. There was no treatment related mortality. We observed a change in indications of TPE compared to historical studies. It was less frequently used to treated GBS and MG. It was found to be safe and effective.

Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters.

A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (<10 nmol⋅L(-1)) is therefore essential for understanding and modeling nitrogen loss in OMZs. We determined rates of ammonium and nitrite oxidation in the seasonal OMZ off Concepcion, Chile at manipulated O2 levels between 5 nmol⋅L(-1) and 20 µmol⋅L(-1) Rates of both processes were detectable in the low nanomolar range (5-33 nmol⋅L(-1) O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L(-1) O2 for ammonium oxidation and 778 ± 168 nmol⋅L(-1) O2 for nitrite oxidation assuming one-component Michaelis-Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis-Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss.

Poly-4-Hydroxybutyrate (P4HB) Scaffold Internal Support: Preliminary Experience with Direct Implant Opposition During Complex Breast Revisions.

BACKGROUND: The GalaFLEX scaffold is a mesh composed of resorbable poly-4-hydroxybutyrate (P4HB) monofilament fibers that aids in providing immediate internal soft tissue support, similar to that offered by an underwire bra, after breast reduction, lift, or augmentation. OBJECTIVES: Our goal was to explore the possibility of using GalaFLEX as an internal support to prevent future sagging, predominantly in the lower pole of the breast. This preliminary study investigated GalaFLEX as a direct alternative to implants in a variety of complex revisional breast cases. Our intention was to establish a safety and efficacy profile in an effort to promote further investigation. METHODS: A retrospective case series of 5 patients over 2 years were evaluated. Inclusion criteria were capsular contracture with concerns over soft tissue coverage and future ptosis, along with complicated muscle coverage deficits secondary to plane switching. RESULTS: A retrospective review of photographs taken at the most recent follow-up consistently showed retention of implant position and soft implants. Additionally, patients presented with a mean ± SD Baker Grade Contraction score of 2.8 ± 0.9189 preoperatively compared with a score of 1 ± 0 postoperatively. CONCLUSIONS: This preliminary study shows the initial safety of GalaFLEX but indicates the need for a multicenter, exhaustive study. Its versatility for complex revisional cases combined with acceptable aesthetic outcomes makes GalaFLEX an invaluable tool for plastic surgeons to consider.

Sociability modifies dogs' sensitivity to biological motion of different social relevance.

Preferential attention to living creatures is believed to be an intrinsic capacity of the visual system of several species, with perception of biological motion often studied and, in humans, it correlates with social cognitive performance. Although domestic dogs are exceptionally attentive to human social cues, it is unknown whether their sociability is associated with sensitivity to conspecific and heterospecific biological motion cues of different social relevance. We recorded video clips of point-light displays depicting a human or dog walking in either frontal or lateral view. In a preferential looking paradigm, dogs spontaneously viewed 16 paired point-light displays showing combinations of normal/inverted (control condition), human/dog and frontal/lateral views. Overall, dogs looked significantly longer at frontal human point-light display versus the inverted control, probably due to its clearer social/biological relevance. Dogs' sociability, assessed through owner-completed questionnaires, further revealed that low-sociability dogs preferred the lateral point-light display view, whereas high-sociability dogs preferred the frontal view. Clearly, dogs can recognize biological motion, but their preference is influenced by their sociability and the stimulus salience, implying biological motion perception may reflect aspects of dogs' social cognition.

Is a local sample internationally representative? Reproducibility of four cognitive tests in family dogs across testing sites and breeds.

A fundamental precept of the scientific method is reproducibility of methods and results, and there is growing concern over the failure to reproduce significant results. Family dogs have become a favoured species in comparative cognition research, but they may be subject to cognitive differences arising from genetic (breeding lines) or cultural differences (e.g. preferred training methods). Such variation is of concern as it affects the validity and generalisability of experimental results. Despite its importance, this problem has not been specifically addressed to date. Therefore, we aimed to test the influence of three factors on reproducibility: testing site (proximal environment), breed and sex (phenotype). The same experimenter tested cognitive performance by more than 200 dogs in four experiments. Additionally, dogs' performance was tested in an obedience task administered by the owner. Breed of dog and testing site were found to influence the level of performance only mildly, and only in a means-end experiment and the obedience task. Our findings demonstrate that by applying the same test protocols on sufficiently large samples, the reported phenomena in these cognitive tests can be reproduced, but slight differences in performance levels can occur between different samples. Accordingly, we recommend the utilisation of well-described protocols supported by video examples of the whole experimental procedure. Findings should focus on the main outcome variables of the experiments, rather than speculating about the general importance of small or secondary performance outcomes which are more susceptible to random or local noise.

Warfarin genotyping with hybridization-induced aggregation on a poly(ethylene terephthalate) microdevice.

Warfarin, a commonly prescribed oral anticoagulant, is burdened by a narrow therapeutic index and high inter-individual variability in response, making it the second leading cause of drug-related emergency room visits. Since genetic factors contribute significantly to warfarin sensitivity, a genotype-guided dosing strategy may reduce the occurrence of adverse events. While numerous methods have been demonstrated for warfarin genotyping, the specifications of most assays with respect to turnaround time and cost are not ideal for routine testing. Here, we present a unique method for warfarin genotyping based on multiplex PCR coupled with Hybridization-induced Aggregation (HIA), a bead-based technique for sequence-specific detection. A multiplex allele-specific PCR reaction was used to generate products corresponding to 3 genetic variants associated with warfarin sensitivity [CYP2C9 *2, CYP2C9 *3, and VKORC1 (1173C>T)] and an internal control product. The products were detected simultaneously on a poly(ethylene terephthalate) (PeT) microdevice using HIA, which provided genotyping results in approximately 15 minutes following PCR. The genotyping results of 23 patient DNA samples using this approach were in 100% concordance with the results of a validated test (WARFGENO test, ARUP laboratories). Additionally, the PCR reaction was successfully transferred to a PeT chip, which provided accurate genotyping results from patient DNA samples in under an hour. This work demonstrates a simple, rapid, and affordable approach to warfarin genotyping based on multiplex allele-specific PCR coupled with HIA detection. By demonstrating both chemistries on PeT microdevices, we show the potential for integration on a single device for sample-to-answer genotyping.

A survey of the impact of owning a service dog on quality of life for individuals with physical and hearing disability: a pilot study.

BACKGROUND: Quality of life refers to a person's experienced standard of health, comfort and happiness and is typically measured using subjective self-report scales. Despite increasing scientific interest in the value of dogs to human health and the growing demand for trained service dogs, to date no research has reported how service dogs may affect client perceptions of quality of life. METHOD: We compared quality of life scores on the 16 item Flanagan quality of life scale from individuals who owned a trained service dog with those who were eligible to receive a dog, but did not yet have one (waiting list control). Data were analysed separately from two groups; those with a service dog trained for individuals with physical disabilities (with physical service dog: n = 72; waiting for a service dog: n = 24; recruited from Dogs for Good database) and those with a hearing service dog (with hearing service dog = 111; waiting for a service dog = 30; recruited from Hearing Dogs for Deaf People database). RESULTS: When controlling for age and gender individuals scored higher on total quality of life scores if they owned a service dog or a hearing service dog, but this was only statistically significant for those with a service dog. Both groups (physical service dog and hearing service dog) scored significantly higher on items relating to health, working, learning and independence if they owned a service dog, in comparison to those on the waiting list. Those with a physical service dog also scored significantly higher on items relating to recreational activities (including items relating to reading/listening to music, socialising, creative expression), and those involving social interactions (including items relating to participating in organisations, socialising, relationship with relatives). Additionally, those with a physical service dog scored higher on understanding yourself and material comforts than those on the waiting list control. In contrast, those with a hearing service dog appeared to receive fewer benefits on items relating to social activities. CONCLUSIONS: Owning a service dog can bring significant specific and potentially general benefits to the quality of life of individuals with physical disabilities and hearing impairments. These benefits may have considerable implications for individuals with disabilities, society and the economy by promoting independence, learning and working abilities.

The use of imepitoin (Pexion™) on fear and anxiety related problems in dogs - a case series.

BACKGROUND: Fear and anxiety based problems are common in dogs. Alongside behaviour modification programmes, a range of psychopharmacological agents may be recommended to treat such problems, but few are licensed for use in dogs and the onset of action of some can be delayed. The low affinity partial benzodiazepine receptor agonist imepitoin (Pexion™, Boehringer Ingelheim) is licensed for treating canine epilepsy, has a fast onset of action in dogs and has demonstrated anxiolytic properties in rodent models. This case series reports on the use of imepitoin in a group of dogs identified as having fear/anxiety based problems. Twenty dogs were enrolled into the study, attended a behaviour consultation and underwent routine laboratory evaluation. Nineteen dogs proceeded to be treated with imepitoin orally twice daily (starting dose approximately 10 mg/kg, with alterations as required to a maximum 30 mg/kg) alongside a patient-specific behaviour modification plan for a period of 11-19 weeks. Progress was monitored via owner report through daily diary entries and telephone follow-up every two weeks. A Positive and Negative Activation Scale (PANAS) of temperament was also completed by owners during baseline and at the end of the study. RESULTS: The primary outcome measure was average weekly global scores (AWG) from the owner diaries. Average weekly reaction scores (AWR) for each type of eliciting context was used as a secondary outcome. Seventeen dogs completed the trial. Treatment with imepitoin alongside a behaviour modification programme resulted in owner reported improvement with reduced AWG and reduced AWR for anxiety across a range of social and non-social eliciting contexts including noise sensitivities. Significant improvement was apparent within the first week of treatment, and further improvements seen at the 11 week review point. There was a significant reduction in negative activation (PANAS) with 76.5% of owners opting to continue imepitoin at their own expense after completion of the study. CONCLUSIONS: This study provides initial evidence indicating the potential value of imepitoin (Pexion™) alongside appropriate behaviour modification for the rapid alleviation of signs of fear and anxiety in dogs. Further research with a larger subject population and a placebo control would be useful to confirm the apparent efficacy reported here.

The influence of dog ownership on objective measures of free-living physical activity and sedentary behaviour in community-dwelling older adults: a longitudinal case-controlled study.

BACKGROUND: There is some evidence to suggest that dog ownership may improve physical activity (PA) among older adults, but to date, studies examining this, have either depended on self-report or incomplete datasets due to the type of activity monitor used to record physical activity. Additionally, the effect of dog ownership on sedentary behaviour (SB) has not been explored. The aim of the current study was to address these issues by using activPAL monitors to evaluate the influence of dog ownership on health enhancing PA and SB in a longitudinal study of independently-mobile, community-dwelling older adults. METHODS: Study participants (43 pairs of dog owners and non-dog owners, matched on a range of demographic variables) wore an activPAL monitor continuously for three, one-week data collection periods over the course of a year. Participants also reported information about their own and their dog demographics, caring responsibilities, and completed a diary of wake times. Diary data was used to isolate waking times, and outcome measures of time spent walking, time spent walking at a moderate cadence (>100 steps/min), time spent standing, time spent sitting, number of sitting events (continuous periods of sitting), and the number of and of time spent sitting in prolonged events (>30 min). For each measure, a linear mixed effects model with dog ownership as a fixed effect, and a random effects structure of measurement point nested in participant nested in pair was used to assess the effect of dog ownership. RESULTS: Owning a dog indicated a large, potentially health improving, average effect of 22 min additional time spent walking, 95%CI (12, 34), and 2760 additional steps per day, 95%CI (1667, 3991), with this additional walking undertaken at a moderate intensity cadence. Dog owners had significantly fewer sitting events. However, there were no significant differences between the groups for either the total time spent sitting, or the number or duration of prolonged sedentary events. CONCLUSIONS: The scale of the influence of dog ownership on PA found in this study, indicates that future research regarding PA in older adults should assess and report dog ownership and/or dog walking status.

Oxygen requirements of the earliest animals.

A rise in the oxygen content of the atmosphere and oceans is one of the most popular explanations for the relatively late and abrupt appearance of animal life on Earth. In this scenario, Earth's surface environment failed to meet the high oxygen requirements of animals up until the middle to late Neoproterozoic Era (850-542 million years ago), when oxygen concentrations sufficiently rose to permit the existence of animal life for the first time. Although multiple lines of geochemical evidence support an oxygenation of the Ediacaran oceans (635-542 million years ago), roughly corresponding with the first appearance of metazoans in the fossil record, the oxygen requirements of basal animals remain unclear. Here we show that modern demosponges, serving as analogs for early animals, can survive under low-oxygen conditions of 0.5-4.0% present atmospheric levels. Because the last common ancestor of metazoans likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content of the atmosphere and oceans. Instead, other ecological and developmental processes are needed to adequately explain the origin and earliest evolution of animal life on Earth.