Multiple mechanisms for inbreeding avoidance used simultaneously in a wild ape

Mating with close kin can have considerable negative fitness consequences, which are expected to result in selective pressure for inbreeding avoidance mechanisms, such as dispersal, mate choice and post-copulatory biases. Captive studies have suggested that inbreeding avoidance through mate choice is far less widespread than expected and may be absent where other mechanisms already limit inbreeding. However, few studies have examined multiple mechanisms of inbreeding avoidance simultaneously, particularly in the wild. We use 13 years of detailed dispersal, copulation and paternity data from mountain gorillas to examine inbreeding avoidance. We find that partial dispersal of both sexes results in high kinship in multimale groups, but that copulations between close kin occur 40% less than expected. We find strong kin discrimination in mate choice, with significant avoidance of maternal kin but more limited avoidance of paternal kin. We find no evidence for post-copulatory inbreeding avoidance. Our analyses support familiarity-based mechanisms of kin identification and age-based avoidance that limits mating between fathers and daughters in their natal group. Our findings demonstrate that multiple complementary mechanisms for inbreeding avoidance can evolve in a single species and suggest that inbreeding avoidance through mate choice may enable more flexible dispersal systems to evolve.

Cumulative early-life adversity does not predict reduced adult longevity in wild gorillas

Extensive research across fields has repeatedly confirmed that early-life adversity (ELA) is a major selective force for many taxa, in part via its ties to adult health and longevity.1,2,3 Negative effects of ELA on adult outcomes have been documented in a wide range of species, from fish to birds to humans.4 We used 55 years of long-term data collected on 253 wild mountain gorillas to examine the effects of six putative sources of ELA on survival, both individually and cumulatively. Although cumulative ELA was associated with high mortality in early life, we found no evidence that it had detrimental consequences for survival later in life. Experiencing three or more forms of ELA was associated with greater longevity, with a 70% reduction in the risk of death across adulthood, driven specifically by greater longevity in males. Although this higher survival in later life is likely a consequence of sex-specific viability selection5 during early life due to the immediate mortality consequences of adverse experiences, patterns in our data also suggest that gorillas have significant resilience to ELA. Our findings demonstrate that the detrimental consequences of ELA on later life survival are not universal, and indeed largely absent in one of humans' closest living relatives. This raises important questions about the biological roots of sensitivity to early experiences and the protective mechanisms that contribute to resiliency in gorillas, which could be critical for understanding how best to encourage similar resiliency to early-life shocks in humans.

Rapid transmission of respiratory infections within but not between mountain gorilla groups

Minimizing disease transmission between humans and wild apes and controlling outbreaks in ape populations is vital to both ape conservation and human health, but information on the transmission of real infections in wild populations is rare. We analyzed respiratory outbreaks in a subpopulation of wild mountain gorillas (Gorilla beringei beringei) between 2004 and 2020. We investigated transmission within groups during 7 outbreaks using social networks based on contact and proximity, and transmission between groups during 15 outbreaks using inter-group encounters, transfers and home range overlap. Patterns of contact and proximity within groups were highly predictable based on gorillas' age and sex. Disease transmission within groups was rapid with a median estimated basic reproductive number (R0) of 4.18 (min = 1.74, max = 9.42), and transmission was not predicted by the social network. Between groups, encounters and transfers did not appear to have enabled disease transmission and the overlap of groups' ranges did not predict concurrent outbreaks. Our findings suggest that gorilla social structure, with many strong connections within groups and weak ties between groups, may enable rapid transmission within a group once an infection is present, but limit the transmission of infections between groups.

Social groups buffer maternal loss in mountain gorillas

Mothers are crucial for mammals’ survival before nutritional independence, but many social mammals reside with their mothers long after. In these species the social adversity caused by maternal loss later in life can dramatically reduce fitness. However, in some human populations these negative consequences can be overcome by care from other group members. We investigated the consequences of maternal loss in mountain gorillas and found no discernible fitness costs to maternal loss through survival, age at first birth, or survival of first offspring through infancy. Social network analysis revealed that relationships with other group members, particularly dominant males and those close in age, strengthened following maternal loss. In contrast to most social mammals, where maternal loss causes considerable social adversity, in mountain gorillas, as in certain human populations, this may be buffered by relationships within cohesive social groups, breaking the link between maternal loss, increased social adversity, and decreased fitness.

Most mammals depend entirely upon their mothers when they are born. In these species, losing a mother at a young age has dramatic consequences for survival. In cases where orphaned individuals do reach adulthood, they often suffer negative effects, like reduced reproductive success or lower social status. But this is not the case for humans. If a child loses their mother, relatives, friends and the wider community can take over. This does not tend to happen in nature. Even our closest relatives, chimpanzees, are much less likely to survive if their mothers die before they reach adolescence.

Although orphan survival is not the norm for mammals, humans may not be entirely unique. Mountain gorillas also live in stable family groups, usually with a dominant male and one or more females who care for their offspring for between 8 and 15 years. It is possible that gorillas may also be able to provide community support to orphans, which could buffer the costs of losing a mother, just as it does in humans.

To answer this question, Morrison et al. examined 53 years of data collected by the Dian Fossey Gorilla Fund to assess the effects of maternal loss in mountain gorillas. The analysis examined survival, reproduction and changes in social relationships. This revealed that, like humans, young gorillas that lose their mothers are not at a greater risk of dying. There is also no clear long-term effect on their ability to reproduce. In fact, gorillas who lost their mothers ended up with stronger social relationships, especially with the dominant male of the group and young gorillas around the same age. It seems that gorilla social groups, like human families, provide support to young group members that lose their mothers.

These findings suggest that the human ability to care for others in times of need may not be unique. It is possible that the tendency to care for orphaned young has its origins in our evolutionary past. Understanding this in more depth could provide clues into the social mechanisms that help to overcome early life adversity, and have a positive impact on future health and survival.

Comparing measures of social complexity: larger mountain gorilla groups do not have a greater diversity of relationships

Social complexity reflects the intricate patterns of social interactions in societies. Understanding social complexity is fundamental for studying the evolution of diverse social systems and the cognitive innovations used to cope with the demands of social life. Social complexity has been predominantly quantified by social unit size, but newer measures of social complexity reflect the diversity of relationships. However, the association between these two sets of measures remains unclear. We used 12 years of data on 13 gorilla groups to investigate how measures of social complexity relate to each other. We found that group size was a poor proxy for relationship diversity and that the social complexity individuals experienced within the same group varied greatly. Our findings demonstrate two fundamental takeaways: first, that the number of relationships and the diversity of those relationships represent separate components of social complexity, both of which should be accounted for; and second, that social complexity measured at the group level may not represent the social complexity experienced by individuals in those groups. These findings suggest that comprehensive studies of social complexity, particularly those relating to the social demands faced by individuals, may require fine-scale social data to allow accurate comparisons across populations and species.

Hierarchical social modularity in gorillas

Modern human societies show hierarchical social modularity (HSM) in which lower-order social units like nuclear families are nested inside increasingly larger units. It has been argued that this HSM evolved independently and after the chimpanzee–human split due to greater recognition of, and bonding between, dispersed kin. We used network modularity analysis and hierarchical clustering to quantify community structure within two western lowland gorilla populations. In both communities, we detected two hierarchically nested tiers of social structure which have not been previously quantified. Both tiers map closely to human social tiers. Genetic data from one population suggested that, as in humans, social unit membership was kin structured. The sizes of gorilla social units also showed the kind of consistent scaling ratio between social tiers observed in humans, baboons, toothed whales, and elephants. These results indicate that the hierarchical social organization observed in humans may have evolved far earlier than previously asserted and may not be a product of the social brain evolution unique to the hominin lineage.

Fatigue in primary care

Fatigue is a common problem in primary care that may represent a reaction to life problems or be a component of a disease state. A careful history, physical examination, and a few directed laboratory tests can usually allow the physician to differentiate between fatigue caused by depression, situational stress, or physical causes such as postviral or drug-induced fatigue, endocrine disorders, sleep disorders, infectious diseases, autoimmune disorders, or neurologic disease. Uncommonly, patients may have otherwise unexplained fatigue lasting 6 months or more that fulfills the criteria of chronic fatigue syndrome. A range of diagnostic skills coupled with a therapeutic physician-patient relationship will usually be successful in treating women with symptoms of fatigue.

Telephone medical care of patients with HIV/AIDS

It has been reported that primary care physicians make 27% of their patient contacts by telephone. With the knowledge that more than 90% of the population has access to a telephone, it is reasonable to propose that the telephone might be employed in a more structured and organized manner for improved, cost-effective medical care. In the current study, two diverse practices (multiphysician and university-affiliated HIV/AIDS clinic, private practice specializing in HIV/AIDS care), both of which used the telephone as having a central role in patient management, were critically observed and reported through three case reports. The results indicate that personnel other than the primary physician provider, such as the triage nurse, may handle a large percentage of calls and successfully manage numerous psychologic and health care issues for the patient, referring, when necessary, appropriate medical inquiries to the physician. It is recommended that physicians take the time to construct sound protocols for clinic personnel to manage patient inquiries by telephone.

Chronic fatigue syndrome. Helping patients cope with this enigmatic illness

Chronic fatigue syndrome is a recurring, debilitating illness complicated by the fact that its diagnosis is largely based on subjective complaints and the absence of reproducibly reliable tests. There is no known "cure" for this illness; however, in general, the prognosis for patients is good. Some physicians accept the existence of chronic fatigue syndrome, while others are convinced that it exists only in the minds of its "victims." The majority of physicians, however, are skeptical but open-minded and wish to help their chronically fatigued patients. As more information comes to light, it is likely that modern medicine will have to rethink its views on this elusive illness. In the interim, patients with chronic fatigue syndrome need the support and reassurance of their physicians to help them cope with their symptoms and resume normal, productive lives.

Bacteremia in young urban women admitted with pyelonephritis

The objective of this study was to determine the rate of bacteremia in young women admitted to the hospital with presumed pyelonephritis and compare it with other published rates. The study design was a retrospective, structured chart review and a review of published reports of bacteremic pyelonephritis. An urban county teaching hospital provided the setting for the study. The patients were nonpregnant women (n = 98) 44 years of age or younger who were without bladder dysfunction and who had not been admitted to an intensive care unit. Further criteria for participation included discharge with the diagnosis of acute pyelonephritis. Blood cultures were ordered for 69 women; the results of 64 were noted in the chart. Twenty-three women (35.9% of those cultured; 23.4% of all patients) were diagnosed with bacteremia. In patients for whom blood culture results were obtained, trends developed between those patients with bacteremia and those with complicated pyelonephritis, defined as a known or newly discovered genitourinary abnormality or a risk factor (P = 0.044), those who were black (P = .044), those with higher pulses on admission (P = .050), those with more white blood cells per high-powered field after urinalysis (P = 0.007), and those whose fever lasted longer (P = 0.033). Blood culture results were positive in two patients whose urine cultures were negative. This comparatively high bacteremia rate supports routine ordering of blood cultures for urban women suspected of having pyelonephritis.

Appropriate and inappropriate prescribing of narcotics for ambulatory HIV-positive patients

OBJECTIVE

To assess the appropriateness of narcotic-prescribing practices in an ambulatory clinic for patients infected with HIV.

DESIGN, SETTING, AND PATIENTS

The medical records of 220 (190 HIV-positive) patients, seen in a clinic primarily designed for the long-term follow-up of ambulatory HIV-infected patients and located in an inner-city, public teaching hospital, were retrospectively reviewed to determine the prevalence and appropriateness of prescribing Drug Enforcement Administration schedule 2 narcotics. Appropriateness was based on published guidelines for the use of narcotics in the treatment of cancer patients.

MEASUREMENTS AND MAIN RESULTS

The prevalence of narcotic use among the HIV-positive patients was 15%. Narcotics were prescribed for 38% of the patients who died, 33% of those with AIDS [Centers for Disease Control and Prevention (CDC) clinical class C], 4% of those with AIDS-related complex (ARC) (CDC clinical class B), and 5% of asymptomatic HIV-positive patients (CDC clinical class A). None of the HIV-negative patients seen in the clinic received narcotics. Narcotics were more likely to be prescribed for patients with AIDS than for patients with ARC (p < 0.001) or for HIV-positive patients (p < 0.001). For the three CDC clinical classes, there was no significant difference among the proportions of patients receiving narcotics inappropriately (p = 0.108). Among the risk groups, intravenous drug abusers were more likely to be prescribed narcotics inappropriately than were men who were homosexual (p < 0.001) or individuals who were heterosexual (p = 0.013); transfusion recipients were also more likely to be prescribed narcotics inappropriately than were homosexual men (p = 0.026) or heterosexual men or women (p = 0.032). Narcotics were more likely to be prescribed for patients with disseminated histoplasmosis (p = 0.022), Pneumocystis carinii pneumonia (p = 0.001), candidal esophagitis (p = 0.020), Kaposi's sarcoma (p < 0.001), or wasted appearance (p = 0.043). Inappropriate prescriptions were more likely to be given to patients with dementia (p = 0.005) or wasted appearance (p = 0.019).

CONCLUSIONS

Physicians tend to prescribe narcotics inappropriately to patients known to have previously abused drugs and to those who appear wasted or have dementia. Physicians have a duty to prescribe narcotics appropriately as guided by recognized medical indications and the patients' views concerning their current medical needs.

Telephone medicine in a southern university private practice

Routine, office-hour, patient-directed telephone calls to a general and multi-specialty-university, private-practice clinic were surveyed. The calls were short, averaging 1 to 2 minutes. Two-thirds of the calls concerned medications, and 13% were for new medical problems. Patients called with a variety of chronic conditions and less commonly for new problems. Medications such as antihypertensives, antibiotics, and diuretics were prescribed and refilled. The role of telephone medicine in providing access in some managed-care settings is yet to be studied.

Description of a nurse practitioner inpatient service in a public teaching hospital

A new nurse practitioner service at a public teaching hospital received patients from internal medicine teaching services. To determine the characteristics of the patients, the ratings by the residents, and the professional team costs, the authors performed a case-series study of the first 248 patients. Transferred patients had conditions that necessitated long hospitalizations, most frequently cerebrovascular accident, dementia, and pneumonia. Housestaff rated the service positively. Estimated professional costs were similar to teaching service costs after 15 months. The nurse practitioner inpatient service effectively cared for internal medicine patients with long lengths of stay and received favorable housestaff ratings.

Histoplasmosis as a cause of pleural effusion in the acquired immunodeficiency syndrome

Disseminated histoplasmosis is an increasingly important opportunistic infection in patients with the acquired immunodeficiency syndrome (AIDS). We report the first case of histoplasmosis as a cause of pleural effusion in a patient with AIDS. Recognition of the typical intracellular yeast on a Wright-Giemsa stained smear of the pleural fluid cells allowed prompt initiation of amphotericin B.

Melioidosis: a reminder

Recrudescent pulmonary melioidosis developed in two patients 12 and 16 years after their last travels to an endemic area. In one, a clinically silent prostatic abscess may have been the focus; and in both, the diagnosis was difficult to make even when the laboratory was notified of the possibility of infection with Pseudomonas pseudomallei. Recrudescent melioidosis should be considered in febrile patients who have been in endemic areas regardless of the interval from last exposure to the development of disease.

Oral amoxycillin, an alternative treatment for neurosyphilis

A serum amoxycillin concentration of 0.11 g/l was established as being treponemicidal in a rabbit model with orchitis. Seventeen patients treated with amoxycillin 2 g by mouth three times a day plus 500 mg probenecid twice a day attained treponemicidal CSF amoxycillin concentrations. Thus amoxycillin by mouth offers an effective alternative method for treating patients with neurosyphilis.

Manipulation of stimulus onset delay in reading: evidence for parallel programming of saccades

On-line eye movement recording of 12 subjects who read short stories on a cathode ray tube enabled a test of direct control and preprogramming models of eye movements in reading. Contingent upon eye position, a mask was displayed in place of the letters in central vision after each saccade, delaying the onset of the stimulus in each eye fixation. The duration of the delay was manipulated in fixed or randomized blocks. Although the length of the delay strongly affected the duration of the fixations, there was no difference due to the conditions of delay manipulation, indicating that fixation duration is under direct control. However, not all fixations were lengthened by the period of the delay. Some ended while the mask was still present, suggesting they had been preprogrammed. But these "anticipation" eye movements could not have been completely determined before the fixation was processed because their fixation durations and saccade lengths were affected by the spatial extent of the mask, which varied randomly. Neither preprogramming nor existing serial direct control models of eye guidance can adequately account for these data. Instead, a model with direct control and parallel programming of saccades is proposed to explain the data and eye movements in reading in general.

Manipulation of stimulus onset delay in reading: evidence for parallel programming of saccades

On-line eye movement recording of 12 subjects who read short stories on a cathode ray tube enabled a test of direct control and preprogramming models of eye movements in reading. Contingent upon eye position, a mask was displayed in place of the letters in central vision after each saccade, delaying the onset of the stimulus in each eye fixation. The duration of the delay was manipulated in fixed or randomized blocks. Although the length of the delay strongly affected the duration of the fixations, there was no difference due to the conditions of delay manipulation, indicating that fixation duration is under direct control. However, not all fixations were lengthened by the period of the delay. Some ended while the mask was still present, suggesting they had been preprogrammed. But these "anticipation" eye movements could not have been completely determined before the fixation was processed because their fixation durations and saccade lengths were affected by the spatial extent of the mask, which varied randomly. Neither preprogramming nor existing serial direct control models of eye guidance can adequately account for these data. Instead, a model with direct control and parallel programming of saccades is proposed to explain the data and eye movements in reading in general.

Masking of foveal and parafoveal vision during eye fixations in reading

A window or visual mask as moved across text in synchrony with the reader's eye movements. The size of the window or mask was varied so that either information in foveal or parafoveal vision was masked on each fixation. In another experiment, the onset of the mask was delayed for a certain amount of time following the end of the saccade. The results of the experiments point out the relative importance of foveal and parafoveal vision for reading and further indicate that most of the visual information necessary for reading can be acquired during the first 50 msec that information is available during an eye fixation.

Masking of foveal and parafoveal vision during eye fixations in reading

A window or visual mask as moved across text in synchrony with the reader's eye movements. The size of the window or mask was varied so that either information in foveal or parafoveal vision was masked on each fixation. In another experiment, the onset of the mask was delayed for a certain amount of time following the end of the saccade. The results of the experiments point out the relative importance of foveal and parafoveal vision for reading and further indicate that most of the visual information necessary for reading can be acquired during the first 50 msec that information is available during an eye fixation.

Spinal cord abscess caused by Listeria monocytogenes

Listeria monocytogenes organisms were isolated from an intramedullary abscess in the cervical part of the spinal cord of an afebrile, previously healthy man who was occupationally exposed to farm animals. Acute neurologic abnormalities developed after a lumbar puncture, and cord widening was shown by myelography. Surgical decompression and antibiotic treatment for four weeks resulted in apparent bacteriologic cure with moderate neurologic sequelae.

Asymptomatic glomerulonephritis after nonstreptococcal upper respiratory infections

Two hundred forty previously healthy military personnel with nonstreptococcal upper respiratory infections were prospectively studied to define the incidence and clinicopathologic characteristics of possible virus-associated glomerulonephritis. Nine patients without preceding streptococcal infection had erythrocyte casts on urinalysis and glomerulonephritis on biopsy. Of these nine, four had a reduction in total hemolytic complement and five had serologic evidence of infection with adenovirus, influenza A, or influenza B. Initial renal biopsy showed either focal or diffuse mesangial proliferation in all nine, with mesangial C3 deposits in six specimens. Repeat biopsy in three showed histologic improvement or loss of immunofluorescent staining, or both. Sequential creatinine clearances were reduced to 74 to 90 mL/min.1.73 m2 in five patients for the duration of follow-up. We conclude that nonstreptococcal upper respiratory infection is frequently associated with glomerulonephritis and that abnormal glomerular structure and decreased creatinine clearances may persist for at least 2 to 8 months.

Herpes simplex virus type I from a patient with radiculoneuropathy

Herpes simplex virus type I was isolated from the CSF of a patient with atypical lumbosacral pain. The features of this case are unusual and important in light of the current understanding of herpes-simplex-virus-associated neurologic disease.