A test of the karyotypic fissioning theory of primate evolution

Karyotypic fissioning theory has been put forward by a number of researchers as a possible driving force of mammalian evolution. Most recently, Giusto and Margulis (BioSystems, 13 (1981) 267–302) hypothesized that karyotypic fissioning best explains the evolution of Old World monkeys, apes, and humans. According to their hypothesis, hominoid karyotypes were derived from the monkey chromosome complement by just such such a fissioning event. That hypothesis is tested here by comparing the G-banded chromosomes of humans and great apes with eight species of Old World monkeys. Five submetacentric chromosomes between apes and monkeys have identical banding patterns and nine chromosomes share the same pericentric inversion. Such extensive karyological similarities are not in accodance with, or predicted by karyotypic fissioning. Apparently, karyotypic fissioning is an extremely uneconomical model of chromosomal evolution. The strong conservation of banding patterns sometimes involving the retention of identical chromosomes indicates that ancient linkages of genes have probably been maintained through many speciation events.     

Karyotypic fission theory and the evolution of old world monkeys and apes

The karyotypes of living catarrhines are correlated with the current concepts of their fossil record and systematic classification. A phylogeny, beginning at the base of the Oligocene, for those animals and their chromosome numbers is presented. Todd? (1970) theory of karyotypic fissioning is applied to this case — three fissioning events are hypothesized. A late Eocene event (the primary catarrhine fissioning) is hypothesized to underlie the diversification of the infraorder Catarrhini into its extant families, the second fissioning underlies the radiation of the Pongidae/Hominidae in the Miocene and the third accounts for the high chromosome numbers (54–72) and the Neogene (Miocene-Pliocene-Pleistocene) radiation of members of the genus Cercopithecus. Published catarrhine chromosome data, including that for “marked” chromosomes (those with a large achromatic region that is the site for ribosomal RNA genes) are tabulated and analysed. The ancestral X chromosome is always retained in the unfissioned metacentric state. The Pongidae/Hominidae have 15 pairs of mediocentric chromosomes that survived the second fissioning whereas the other chromosomes (besides the X) are thought to be fission-derived acrocentrics. Both the detailed karyology and the trend from low to high numbers is best interpreted to support Todd? concept of adaptive radiations correlated with karyotypic fissioning in ancestral populations.     

Reproductive biology of Dugesia sanchezi,a fresh-water planarian from Chile

Dugesia sanchezi reproduces in nature both sexually and by fission. Laboratory cultures have shown that fissioning is controlled by genetic factors. From sexual specimens randomly mated, 105 sexual and five fissiparous offspring were obtained. The former produced almost exclusively sexual descendents while the latter gave rise to fissiparous individuals, although successively many of them became sexual. These ex-fissiparous specimens show a high fertility and their offspring were almost all fissiparous, with the same characteristics displayed by the preceeding fissiparous generation. Some hypotheses are advanced in order to attempt a genetical interpretation of these results.     

Cosmic gourds: Cucurbit and Crescentia effigy pottery of coastal Ecuador

This paper treats the identification of modeled images of cucurbits —gourds and squash—in the ceramics of the Late Formative Era (or Chorrera culture) of coastal Ecuador (ca. 900 B.C. to 100 A.D.). These images provide good evidence for the sophisticated cultivation of cucurbits by the native peoples of the coast of South America from very early time periods in Ecuador. Their importance in the iconography of Late Formative cultures certainly demonstrates that the domestication of fruits with both hard and soft rinds must have been well established by the time ceramic production had begun. Depictions of combinations of animals with cucurbit-shaped bodies in the mortuary ceramics of the Late Formative period also demonstrate that cucurbits were an essential part of life (and death) on the coast of Ecuador.     

Feedback cue and switching characteristics

Asexual reproduction (fissioning) in planarians is controlled by group size; increased group size suppresses fissioning, isolation releases it. This effect is mediated through the brain; social stimulation from cohorts causes the brain to inhibit the segmental plexus fissioning system from initiating the events of fissioning. Experiments were conducted to elucidate (1) the stimulus cue conveying information regarding cohort number and (2) the switching characteristics of the control system. The results of these show that the social stimulus responsible for the effect involves neither vision nor discharge of pheromonal substances into the habitat; the sensory event apparently involves direct contact and chemoreceptive, as well as tactile, modalities. The switching characteristics (graduated response, long release time, short reinstatement time) found for the brain inhibitory system agree with those expected from the mathematical model derived for a simple neurohormonal control system in which it is postulated that social stimulation causes neurosecretory cells of the brain to release a fissioning inhibitory hormone (FIH) that inhibits the segmental plexus fissioning (SPF) system from initiating fissioning.     

The influence of cultural factors on the demography and pattern of gene flow from the Makiritare to the Yanomama Indians

A single village of Yanomama Indians was found to have frequencies of Di^a of 0.06 and of Ap^a of 0.08, in contrast to 40 other villages whereDi^a was absent and Ap^a quite rare. The source of these genes was identified as a village of Makiritare Indians, but the two allele frequencies were approximately the same or even higher in the Yanomama than in the Makiritare village. Demographic, social and cultural parameters affecting marriage and reproduction in the two tribes explain this. Genealogical relationships and informants' accounts collected in the field, when viewed against the traditional marriage practices, reproductive advantages of headmen, and differential treatment of captured women, indicate that the mating and reproduction parameters inherent in tribal social organization of this kind constitute an essential part of the explanation of the genetic findings. It is argued that mating systems of this sort are such that the probability of a new gene introduced by a captive surviving in the recipient population is a function of the sex of the initial carrier. The implications for tribalization and potentially radical changes in allele frequencies are briefly explored by considering aspects of settlement pattern and population fissioning known to characterize the tribes in question. Finally, it is shown that genetic sampling from a single location can and does result in unrepresentative allele frequencies when this single sample is taken to characterize the tribe as a whole.     

Symbiosis, lateral function transfer and the (many) saplings of life

One of intuitions driving the acceptance of a neat structured tree of life is the assumption that organisms and the lineages they form have somewhat stable spatial and temporal boundaries. The phenomenon of symbiosis shows us that such ‘fixist’ assumptions does not correspond to how the natural world actually works. The implications of lateral gene transfer (LGT) have been discussed elsewhere; I wish to stress a related point. I will focus on lateral function transfer (LFT) and will argue, using examples of what many would call ‘superorganisms’, that the emergence of symbiotic individuals revives the importance of functional and adaptationist thinking in how we conceptualize the lineages of biological individuals. The consequence of the argument is that, if we really want to hold onto tree of life thinking, we had better accept that new saplings appear and disappear all the time.     

Abnormality in the fissioning control of a strain of asexual Dugesia dorotocephala found near Fort Collins,Colorado

Asexual Dugesia dorotocephala, collected from a new site several miles northwest of Fort Collins, Colorado, appeared similar, at the time of collection, to ones collected from other sites in the same general locale. However, these exhibited marked differences in the more crowded conditions of laboratory culture: abnormally long, 30–50 mm specimens, seemingly unable to fission, developed. Since previous studies of asexual D. dorotocephala had revealed an inhibitory effect of cohorts on fissioning (Best et al., 1969, 1974, 1975; Pigon et al., 1974), experiments were conducted with this new strain to ascertain the effect of population density (group size) on fissioning incidence. Results are described which show that this inhibitory effect of cohorts on fissioning is exaggerated in this new strain.     

Emergence in the central nervous system

“Emergence” is an idea that has received much attention in consciousness literature, but it is difficult to find characterizations of that concept which are both specific and useful. I will precisely define and characterize a type of epistemic (“weak”) emergence and show that it is a property of some neural circuits throughout the CNS, on micro-, meso- and macroscopic levels. I will argue that possession of this property can result in profoundly altered neural dynamics on multiple levels in cortex and other systems. I will first describe emergent neural entities (ENEs) abstractly. I will then show how ENEs function specifically and concretely, and demonstrate some implications of this type of emergence for the CNS.     

Life Without Pigs: Recent Subsistence Changes Among the Irakia Awa, Papua New Guinea

Beginning in the late 1980s, the Irakia Awa commenced changing their basic subsistence adaptation. This included altering gardening practices, changing basic food consumption patterns, and most importantly, eliminating the production of domestic pigs. These changes were undertaken as part of an effort to improve the life experience of local residents and usher in a new plan of village improvement. The plan promoted the disintensification of subsistence production and increased involvement in cash-earning and recreational pursuits, as well as Christianity. If successful, the promoters of the plan hope that the village will become a more attractive place to live, migrants living away will return home to help revitalize the community, and Irakia will flourish in the new cash-oriented modern economy.     

Settlement Hierarchies and Political Complexity in Nonmarket Societies: The Formative Period of the Valley of Mexico

Archaeologists have long recognized that increases in political centralization often coincide with the growth of regional settlement hierarchies. Here I develop a theoretical model which explicitly relates certain aspects of political complexity to variation in settlement size. This model applies specifically to hierarchical societies without well-developed market economies—societies which Service would classify as chiefdoms and (perhaps) simple states. Using settlement data from the Formative Period Valley of Mexico, I show how this model is useful in measuring (1) the number of levels in a regional hierarchy, (2) the degree of political centralization, and (3) the relative amount of surplus food mobilized to support the political establishment.     

Localization and identification of the receptors by electron micrographic and ablation studies

Asexual reproduction (fissioning) in the planarian Dugesia dorotocephala is socially controlled through a cephalic mechanism; isolation releases fissioning, grouping inhibits it; decapitation releases it even in grouped subjects. Experiments were performed to confirm previous indications that direct contact is involved in the sensing of cohorts; the partial release of fissioning in grouped planarians by introduction of a chemically inert lubricant (0.1% purified agar) into the habitat water further confirms the necessity of intimate contact between the sensors and bodily surfaces of the sensed cohorts. Further experiments, correlating electron microscopic observations with the release of fissioning by various selected surgical ablations, reveal the pertinent sensors to be clumps of neural cilia concentrated in the cephalic margins. Comparable structures occur in the chemoreceptors of catfish, lamprey, and honey bee as well as in the olfactory epithelium of mammals.     

Vacated niches,competitive release and the community ecology of pathogen eradication

A recurring theme in the epidemiological literature on disease eradication is that each pathogen occupies an ecological niche, and eradication of one pathogen leaves a vacant niche that favours the emergence of new pathogens to replace it. However, eminent figures have rejected this view unequivocally, stating that there is no basis to fear pathogen replacement and even that pathogen niches do not exist. After exploring the roots of this controversy, I propose resolutions to disputed issues by drawing on broader ecological theory, and advance a new consensus based on robust mechanistic principles. I argue that pathogen eradication (and cessation of vaccination) leads to a ‘vacated niche’, which could be re-invaded by the original pathogen if introduced. Consequences for other pathogens will vary, with the crucial mechanisms being competitive release, whereby the decline of one species allows its competitors to perform better, and evolutionary adaptation. Hence, eradication can cause a quantitative rise in the incidence of another infection, but whether this leads to emergence as an endemic pathogen depends on additional factors. I focus on the case study of human monkeypox and its rise following smallpox eradication, but also survey how these ideas apply to other pathogens and discuss implications for eradication policy.     

Effects of methoprene and juvenile hormone on larval ecdysis,emergence, and metamorphosis of the endoparasitic wasp, Apanteles congregatus

Topical application of juvenile hormone I and III or the hormone analogue methoprene to parasitized Manduca sexta larvae inhibited subsequent emergence of the endoparasitic wasp Apanteles congregatus. Methoprene treatment inhibited wasp emergence in a dose-dependent manner, causing either a delay or total inhibition of emergence. These results were interpreted as reflecting inhibitory effects of juvenile hormone on the second-larval ecdysis of the parasitoid that normally occurs during emergence from the host larva. Parasitoid ecdysis was disrupted even when methoprene was applied to host larvae a few hours prior to the normal expected time of emergence. A correlation between the number of emerging parasitoids and the timing of emergence was seen in methoprene-treated hosts, and few parasitoids emerged after day 9 of the host's fifth-instar. Our findings suggest that the suppression of emergence by juvenile hormone analogues noted in previous studies may be due to a similar inhibitory effect on parasitoid ecdysis. We also observed that parasitoids emerging from hosts treated with a low dose of methoprene (1 μg) later pupated normally but then formed nonviable pupal-adult intermediates. Thus use of this insect growth regulator must be undertaken carefully to prevent possible adverse effects on natural parasitoid populations.     

Qualitative Attribution,Phenomenal Experience and Being

I argue that the physiological, phenomenal and conceptual constitute a trichotomous hierarchy of emergent categories. I claim that each category employs a distinctive type of interactive mechanism that facilitates a meaningful kind of environmental discourse. I advocate, therefore, that each have a causal relation with the environment but that their specific class of mechanism qualifies distinctively the meaningfulness of that interaction and subsequent responses. Consequently, I argue that the causal chain of physical interaction feeds distinctive value-laden constructions that are ontologically distinct for each category. Within the limitations of the interactive mechanisms of each category, increasingly sophisticated forms tend to evolve. The increase in sophistication in each category inevitably leads to the emergence of the novel mechanism particular to the next in the hierarchy. In essence, there is an emergent hierarchy of evolving categories delineated by the nature of their mechanism of environmental engagement. I argue that biochemical mechanisms have a tendency to evolve meaningfully, specifically in a way that is both qualitatively relevant and responsive to environmental particulars. I explain that these mechanisms set in play an organisational imperative that leads to the emergence of the capacity to evaluate and prioritise qualitative biochemical assimilations which, inevitably, generates a subjectively individuated experience phenomenon. I then relate this to the novel characteristics of the human perspective.     

The racialised and classed constitution of English village life

This article explores ethnographically the ‘village’ as a stage for the enactment and reproduction of a racialised set of white middle-class social and moral values. To do this I draw upon interview material with middle-class whites who live in a suburban ‘village’ on the border of rural Leicestershire and urban Leicester in England. I explore the way in which my co-conversationalists reflexively and imaginatively defend their area's ‘village’ identity through a discourse that ‘others’ its wealthy Asian residents. Although these raced others have achieved economic parity with the more affluent wealthy white middle-class residents, they are imagined to lack the ‘proper’ middle-class values of respectability and decorum, which are associated with the traditional white rhythms of English village life.     

Models for lineal effects in rhesus group fissions

Gene distributions in daughter groups produced by three rhesus monkey group fissions are analyzed. Data employed are for the Tf, 6PGD, and CA II electrophoretic marker systems in the fissions producing new daughter groups F and M, F and O, and J and N in the Cayo Santiago rhesus colony. Wide variations in FST values were observed among the different markers in the various fissions. Overall, the observed FST values exceeded predictions of simple random fissioning models. However, on average, observations on electrophoretic markers fitted well with predicted values from lineal fissioning models. One of these lineal fissioning models, a simulation, incorporated the propagation of alleles in the matrilines of the fissioning groups. The second, an algebraic expression, utilized group sizes and average kinship values as parameters.     

No intracolonial nepotism during colony fissioning in honey bees

Most species of social insects have singly mated queens, but in some species each queen mates with numerous males to create a colony whose workers belong to multiple patrilines. This colony genetic structure creates a potential for intracolonial nepotism. One context with great potential for such nepotism arises in species, like honey bees, whose colonies reproduce by fissioning. During fissioning, workers might nepotistically choose between serving a young (sister) queen or the old (mother) queen, preferring the former if she is a full-sister but the latter if the young queen is only a half-sister. We examined three honeybee colonies that swarmed, and performed paternity analyses on the young (immature) queens and samples of workers who either stayed with the young queens in the nest or left with the mother queen in the swarm. For each colony, we checked whether patrilines represented by immature queens had higher proportions of staying workers than patrilines not represented by immature queens. We found no evidence of this. The absence of intracolonial nepotism during colony fissioning could be because the workers cannot discriminate between full-sister and half-sister queens when they are immature, or because the costs of behaving nepotistically outweigh the benefits.     

The Demography of Colony Fission from 1878–1970 Among the Hutterites of North America

Periodic colony fision has been characteristic ofHutterite society for more than 100 years. From 1878–1970 fission occurred an average of every 14–15 years when colonies attained a size of 166 persons. Emigrating groups were comprised of35%–55% of the mother colony's population. Between founding and fission, daughter populations grew at an average rate of 4.3% per year. Over time, fissioning size and length of fission cycles decreased, but the size of new daughter colonies and rate of population growth remained constant through 1960. Demographic analysis suggested that the model of fission followed by the Hutterites has not always focused on even division of the mother colony into two equal-sized groups, but rather that they have had a fairly constant conceptual model of the size that new colonies should be. As fissioning size decreased over time the proportionate size of new colonies increased, maintaining the absolute size nearly constant since 1900. These findings suggest a number of questions for further investigation.     

Eating money: Narratives of equality on customary land in the context of natural resource extraction in the Solomon Islands

Why do Solomon Islands’ villagers continue to engage with large scale logging projects by foreign companies when they have decades of experience of the disadvantages of such deals? This paper explores village level narratives of equality surrounding a logging dispute in a village on Kolombangara Island in the Western Province of the Solomon Islands. Drawing on empirical evidence I seek to understand firstly, why villagers continue to engage with logging companies, and secondly, why seemingly viable and financially attractive alternative forestry projects may not be taken up. Additionally, I examine legal recognition of a local conservation Non‐Government organisation as an environmental ‘stakeholder’, with an accepted interest in customary land as distinct from the categorisation of ‘landowners’. I conclude that village communities may continue to engage with foreign logging companies, despite their clear knowledge of the disadvantages of such projects, partly as a means of maintaining some measure of social equality in the village.