Sri Lankan Prehistory Revealed

Book reviewed in this article:
The Prehistory of Sri Lanka: An Ecological Perspective . S. U. Deraniyagala. Memoir Volume 8, Parts 1 and 2. Sri Lanka: Department of Archaeological Survey, 1992. 813 pp.     

The Australian Twin Registry.

The Australian Twin Registry (ATR), established in the late 1970s, is a volunteer registry of over 30,000 pairs of Australian twins of all zygosity types and ages unselected for their health or medical history. The ATR does not undertake research itself but acts as facilitator, providing an important national and international resource for medical and scientific researchers across a broad range of disciplines. Its core functions are the maintenance of an up-to-date database containing basic contact details and baseline information, and the management of access to the resource in ways that enhance research capacity within Australia while protecting the rights of twins. The ATR has facilitated more than 200 studies using a variety of designs, including classic biometrical twin and twin family studies, co-twin control studies, intervention studies, longitudinal studies, and studies of issues relevant specifically to twins. These have yielded more than 300 peer-reviewed publications to date. Areas of major research include studies of behavior, musculoskeletal conditions, teeth and face patterns, cardiovascular risk factors, substance abuse, and risk factors for melanoma and breast cancer. Extensive longitudinal data are available for around 10,000 pairs. DNA samples have been obtained from more than 6000 twins. Considerable efforts are devoted to maintaining the commitment of registry members and recruitment. The ATR hopes to secure funding to expand its activities, including the systematic collection of DNA samples, so that it can continue to play a major role in the development of twin research and contribute to the annotation of the human genome.     

The Mid-Atlantic Twin Registry.

The Mid-Atlantic Twin Registry (MATR) is a population-based registry of twin pairs ascertained from birth records and school system records of Virginia, North Carolina, and South Carolina. The MATR was formed in 1997 with the merging of the Virginia and North Carolina Twin Registries, and it expanded to include South Carolina when access to twin birth records in that state was granted in 1998. Registered twins ("participants") number more than 51,000, with approximately 46,000 of these individuals representing complete pairs. Roughly two-thirds of MATR participants are over age 18, with a mean age of approximately 35 years. These participants have primarily been drawn from the more than 170,000 identical and fraternal twin pairs born in the three states between 1913 and 2000. Twins and their family members have participated in numerous research projects, ranging from general health surveys to studies on specific health topics such as cardiovascular disease; depression and anxiety; seizures; behavioral development; pregnancy complications; conduct disorder; drug use, abuse, and dependence; cleft lip/palate; obesity; and chronic fatigue syndrome. The MATR has established a privacy policy and strict standard operating procedures to protect the confidentiality of participant data. The MATR considers a limited number of qualified requests per year from investigators interested in recruiting MATR participants into their research studies.     

The Vietnam Era Twin Registry.

The Vietnam Era Twin (VET) Registry is composed of 7369 middle-aged male-male twin pairs both of whom served in the military during the time of the Vietnam conflict (1965-1975). The Registry is a United States Department of Veterans Affairs resource that was originally constructed from military records; the Registry has been in existence for more than 15 years. It is one of the largest national twin registries in the US and currently has subjects living in all 50 states. Initially formed to address questions about the long-term health effects of service in Vietnam the Registry has evolved into a resource for genetic epidemiologic studies of mental and physical health conditions. The management and administration of the VET Registry is described with particular attention given to the processes involved with database maintenance and study coordination. Several waves of mail and telephone surveys have collected a wealth of health-related information on Registry twins. More recent data collection efforts have focused on specific sets of twin pairs and conducted detailed clinical or laboratory testing. New Registry initiatives for the future include the construction of a web site and the development of a DNA repository.     

Volatile aroma constituents of Sri Lankan ginger

Two types of Sri Lankan ginger were examined (Sidda and Chinese varieties) and essential oils of both fresh and dried samples were prepared by standard procedures. Both varieties yielded relatively high percentages of oil (between 1.8 and 4.3%) and total aroma volatiles (ca 5 mg/g for dried samples). Analysis by GC and GC/MS showed terpenes to be the main aroma components (ca 99% for all samples). A number of the identified compounds have not previously been reported as ginger volatiles, including trans-β-ocimene, thujyl alcohol, terpinen-4-ol, myrtenal, guaiene, α-cubebene, δ-cadinene and farnesol. On drying, both varieties of Sri Lankan ginger showed considerable decrease in monoterpene content and very high increase in sesquiterpene concentration. Comparing the aroma volatiles of Sri Lankan dried ginger with those previously reported for dried ginger from some other countries, it was concluded that Sri Lankan ginger was as good as, if not superior to, other types. In particular, SriLankan dried ginger showed high levels of ar-curcumene together with reasonable levels of citral isomers and all other constituents previously claimed to be important to ginger aroma. Sri Lankan ginger would appear to be unusual in containing very low amounts of zingiberene but very high amounts of β-bisabolene.     

The St. Thomas' UK Adult Twin Registry.

The Registry consists of nearly 10,000 monozygous and dizygous adult caucasian twins aged 18-80 from all over the UK and was started in 1993. This is a volunteer sample recruited by successive media campaigns without selecting for particular diseases or traits. All twins receive a series of disease questionnaires. In addition over half the twins have been assessed in detail clinically for several hundred phenotypes related to common diseases or intermediate traits. The focus has been primarily on cardiovascular, metabolic, musculoskeletal, dermatological, and opthalmological diseases. Over 3000 DZ twins have had a genome wide scan performed as well as many candidate genes allowing both linkage and association studies. The registry has led to many successful innovative research projects, particularly in common diseases previously thought to be predominantly environmental and helped positionally clone some novel genes for common diseases.     

The Swedish Twin Registry in the third millennium.

Since the Swedish Twin Registry was first established in the late 1950s to study the importance of smoking and alcohol consumption on cancer and cardiovascular diseases, it has been expanded and updated on several occasions. The focus has similarly broadened to most common complex diseases. The content of the database is described, ongoing projects based on the registry are summarized, and we review some of the principal findings on aging, cancer and cardiovascular disease that have come from the registry. Ongoing efforts and future plans for the STR are discussed. Among others, we plan blood collection and genotyping to study the genetic bases of complex diseases, a first contact ever with the cohorts born after 1958, and in-depth studies of selected diseases, such as Parkinson's disease and chronic fatigue syndrome.     

Challenges in recruiting older twins for the Sri Lankan twin registry.

The National Twin Registry of Sri Lanka was established in 1997 as a volunteer register. To extend it to a population-based register, we examined the effectiveness of tracing older twins by inspecting birth records and recruiting them by postal invitation and in-person contact. Birth records at a divisional secretariat reported from 2 maternity hospitals between the years of 1954-1970 were scrutinised to identify a random sample of twins. These hospitals had the highest twin delivery rates for the whole country. We identified 620 twins and a questionnaire was mailed to them. Research assistants visited a cohort of non-respondents (71) in the postal survey. These 620 twins were identified after perusing 20700 birth records. The twinning rate was estimated at 29.95 ([620/20700] x 1000) twins per 1000 registered births (CI 27.63-32.27). In the postal survey, 37 (12%) responded and 62 letters were returned (20%). Both twins were still alive in 20 pairs, one was still alive in 15 pairs, and both twins were dead in 2 pairs. During field visits, 42 (59.2%) addresses were located. Information was available on 16 twin pairs. Both twins were alive in 8 pairs, one each in 4 pairs, and both were dead in 4 pairs and at least one twin was traced in 10 pairs (14%). Both the postal and the field survey gave a low yield. This finding is different from tracing younger twins born between 1985-1997 by using the same methods. Migration, urbanization and development in the country might have affected tracing older twins from the birth record addresses, which were decades old.     

Species associations in a heterogeneous Sri Lankan dipterocarp forest

We used point pattern analysis to examine the spatial distribution of 46 common tree species (diameter at breast height >10 cm) in a fully mapped 500x500-m tropical forest plot in Sinharaja, Sri Lanka. We aimed to disentangle the effect of species interactions (second-order effects) and environment (first-order effects) on the species' spatial distributions. To characterize first-order associations (segregation, overlap), we developed a classification scheme based on Ripley's K and nearest-neighbor statistics. We subsequently used heterogeneous Poisson null models, accounting for possible environmental heterogeneity, to reveal significant uni- and bivariate second-order interactions (regularity, aggregation and repulsion, attraction). First-order effects were strong; overall, 53% of all species pairs occupied largely disjoint areas (segregation), 40% showed partial overlap, and 6% overlapped. Only 5% of all species pairs showed significant second-order effects, but about half of the species showed significant intraspecific effects. Significant plant-plant interactions occurred mostly within 2-4 m and disappeared within 15-20 m of the focal plant. While lack of significant species interactions suggests support for the unified neutral theory, species' observed spatial segregation does not support the assumptions of the neutral theory. The strong observed tendency of species to segregate may have supplementary effects on other processes promoting species coexistence.     

A Sri Lankan child with 49,XXXXY syndrome

Pentasomy 49,XXXXY is a rare sex chromosome disorder usually presenting with ambigous genitalia, facial dysmorphism, mental retardation and a combination of cardiac, skeletal and other malformations. The incidence of the condition is estimated to be 1 in 85,000 male births. Previously, this condition was identified as a Klinefelter variant. The condition is suspected in a patient, by a combination of characteristic clinical findings, and the diagnosis is confirmed by chromosome culture and karyotyping. In the case we report here, the main presentation of ambiguous genitalia led to a suspicion of a sex chromosome aneuploidy which was subsequently confirmed by chromosomal analysis.     

The Danish Twin Registry: 127 birth cohorts of twins.

The Danish Twin Registry is the oldest national twin register in the world, initiated in 1954 by ascertainment of twins born from 1870 to 1910. During a number of studies birth cohorts have been added to the register, and by the recent addition of birth cohorts from 1931 to 1952 the Registry now comprizes 127 birth cohorts of twins from 1870 to 1996, with a total of more than 65,000 twin pairs included. In all cohorts the ascertainment has been population-based and independent of the traits studied, although different procedures of ascertainment have been employed. In the oldest cohorts only twin pairs with both twins surviving to age 6 have been included while from 1931 all ascertained twins are included. The completeness of the ascertainment after adjustment for infant mortality is high, with approximately 90% ascertained up to 1968, and complete ascertainment of all liveborn twin pairs since 1968. The Danish Twin Registry is used as a source for large studies on genetic influence on aging and age-related health problems, normal variation in clinical parameters associated with the metabolic syndrome and cardiovascular diseases, and clinical studies of specific diseases. The combination of survey data with data obtained by linkage to national health related registers enables follow-up studies both of the general twin population and of twins from clinical studies.     

The Minnesota Twin Registry: current status and future directions.

The Minnesota Twin Registry is a birth-record-based twin registry. Begun in 1983, it includes data for 4307 surviving intact pairs born in Minnesota between 1936 and 1955. In addition, the Registry includes 901 twin pairs born in Minnesota from 1904 to 1934, as well as 391 male pairs born in Minnesota from 1961 to 1964. The research focus is primarily on human individual differences assessed by self-report. Questionnaires completed by the participants include measures of personality, occupational interests, demographics, and leisure-time activities. We outline major contributions that have resulted from Registry research, as well as current and future research directions.     

Toxigenic Aspergillus flavus and aflatoxins in Sri Lankan medicinal plant material

The fungal flora of 6 Asian medicinal plants, Aerva lanata (Linn.) Juss. Alyssicarpus vaginalis D.C., Tribulus terrestris Linn. Adhatoda vasica Nees., Centella asciatica (L.) Urb., Cardiospermum halicacabum Linn. was determined. After surface disinfection Aspergillus spp. were most frequently observed. Aspergillus flavus, isolated from Alyssicarpus vaginalis and Aerva lanata produced aflatoxins in culture. Aflatoxin B₁ was also detected in a sample of Aerra lanata at a level of 0.5 g/g. Plant material destined for medicinal use should be stored carefully prior to its use to prevent growth of naturally occurring toxigenic mold fungi.     

Phylogenetic diversity of Sri Lankan freshwater crabs and its implications for conservation

As part of a Global Biodiversity Hotspot, the conservation of Sri Lanka's endemic biodiversity warrants special attention. With 51 species (50 of them endemic) occurring in the island, the biodiversity of freshwater crabs is unusually high for such a small area (65 600 km²). Freshwater crabs have successfully colonized most moist habitats and all climatic and elevational zones in Sri Lanka. We assessed the biodiversity of these crabs in relation to the different elevational zones (lowland, upland and highland) based on both species richness and phylogenetic diversity. Three different lineages appear to have radiated simultaneously, each within a specific elevational zone, with little interchange thereafter. The lowland and upland zones show a higher species richness than the highland zone while – unexpectedly – phylogenetic diversity is highest in the lowland zone, illustrating the importance of considering both these measures in conservation planning. The diversity indices for the species in the various IUCN Red List categories in each of the three zones suggest that risk of extinction may be related to elevational zone. Our results also show that overall more than 50% of Sri Lanka's freshwater crab species (including several as yet undescribed ones), or approximately 72 million years of evolutionary history, are threatened with extinction.     

Catching the pulse: money and circulation in a Sri Lankan marketplace

This article traces the movement, management, and generation of money in a Sri Lankan wholesale vegetable market, pulling into focus certain local economic and moral logics. What traders do with cash is revealing. I argue that how traders use money – the way it is handled, risked, spent, and lent – exhibits skill, implies hierarchy, and cultivates social connections. Exploring idioms of economic activity such as ‘catching the pulse’ and ‘rolling the money’, the article examines relations between different kinds of trader. Moving money through businesses permits participation in the complex communication network of the market. This is central to existing in the social world of the trader. I argue that following money notes – rather than commodities – as they travel around the marketplace and between the hands of transactors renders ethnographically observable the formations of personhood and long‐term relations that take place in the market.     

Human hydrographical changes interact with propagule predation behaviour in Sri Lankan mangrove forests

For mangroves with almost no tidal influence and a subsequent mosaic vegetation structure we describe the relation between propagule predators and both vegetation structure and environmental factors on a vegetation assemblage or ‘forest patch’ level. We then report the interaction between natural propagule predation and human influence. In different forest patches dominated by Avicennia officinalis, Excoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata or R. mucronata or in open or mixed areas identified from aerial photographs, the predation on propagules of A. officinalis, B. gymnorrhiza, R. apiculata and R. mucronata was monitored in a total of 24 experimental plots (3 per forest patch). Relationships to environmental factors (topography, water level, rainfall and season) on the level of predation were investigated. The highest predation intensity by crabs was on A. officinalis propagules, and in E. agallocha forest patches. Predation by crabs, snails, insects and mammals was observed, and the significant differences in predation intensity across species and across forest patches were explained directly by propagule predator identity and abundance, and by the interaction between rainfall, water level and microtopography. We illustrated how hydrography changes alter the behaviour of propagule predators and play a role in the shaping of vegetation structure by reconstructing the lagoon water level of a site over a period of 50 years based on rainfall data. This time frame covered both a condition without and with human impacts, and past and present propagule predation settings were confronted with the simulated hydrology. The importance of spatial and temporal microhabitat variations in opening multiple successional pathways in vegetation dynamics is illustrated, and is highly relevant for ecosystems with unpredictable or short-lived (< 20 years) patchy vegetation structures and microhabitats.     

Effect of parboiling and bran removal on aflatoxin levels in Sri Lankan rice

Commercial parboiling of rice in Sri Lanka and many south Asian countries provides ideal conditions for the occurrence of aflatoxins because the rice is steeped (allowing fermentation) thus providing ideal conditions for growth of toxigenic Aspergillus species. However the traditional cottage method of parboiling rice, which does not involve steeping, appears to reduce Aspergillus growth even after long storage periods. Preferential infection of parboiled rice by Aspergillus flavus was observed. Aflatoxin contents in inoculated rice produced by commercial parboiling (AFB₁ 60–92 mg/kg) were significantly higher than that in inoculated cottage processed rice (AFB₁ 12–29 g/kg). The steeping (precooking/ soaking) process in commercial parboiling appears to increase the susceptibility of rice grains to fungal infection. Aflatoxin content in grains increased considerably with the increase in duration of soaking. However, the addition of 10 ppm calcium hypochlorite (bleach) to soaking water appreciably reduced A. flavus contamination and subsequent aflatoxin content in parboiled rice. No significant reduction in aflatoxin levels were observed after bran removal of contaminated rice.     

Blood genetic markers in Sri Lankan populations--reappraisal of the legend of Prince Vijaya

Serum protein (haptoglobin types; transferrin and group-specific component subtypes); haemoglobin and red cell enzymes (acid phosphatase, esterase D, glyoxalase I, 6-phosphogluconate dehydrogenase, adenylate kinase, and phosphoglucomutase (locus 1) (subtypes) were studied in the Sinhalese, Tamils, and Muslims of Sri Lanka. The allelic frequencies of all the polymorphic systems were similar in these populations without any significant differences. A close look at the present results and earlier investigations on 13 polymorphic loci controlled by 37 alleles did not reveal any genetic characteristics in the present-day Sinhalese population that are distinct from those in the Tamils of Sri Lanka. As such, genetic evidence linking the legendary origin of the Sinhalese population to East India (Prince Vijaya) is lacking.     

Relationships of desire for no more children and socioeconomic and demographic factors in Sri Lankan women.

Data from the 1982 Sri Lanka Contraceptive Prevalence Survey are used to identify women who wish to stop childbearing; they differ in socioeconomic status from their counterparts who want more children. Educated women are more likely to be motivated to cease childbearing than non-educated women; Christian or Sinhalese/Buddhist women are more willing to stop childbearing than Moor/Muslim or Tamil/Hindu women. The relationships between sex composition of existing children and women's fertility desires indicate that although moderate son preference exists it does not affect their contraceptive behaviour. Among those who want no more children, 15% are at risk of unwanted pregnancy because they do not practise contraception. Again better education and being Christian or Sinhalese/Buddhist reduced the risk of unwanted pregnancy. Women whose husbands disapproved of contraception had over four times higher risk of unwanted pregnancy than women whose husbands approved.