Austroasiatic (AA) speakers constitute around 4% of the population of Thailand, while the majority (89.4%) speak Kra-Dai (KD) languages. Previous forensic and population genetic studies in various Thai populations have employed a limited number of short tandem repeats (STRs). This study aims to expand the investigation of the genetic makeup of AA populations in Thailand and their relationship to KD populations using a larger number of autosomal STRs with the VeriFiler™ Plus PCR Amplification Kit. We generated 593 new genotypes from AA-speaking groups and combined them with previously reported data from AA and KD groups. A total of 1,129 genotypes across 23 STR loci were used to construct the largest allelic frequency profile for Thai and Lao populations. However, several loci deviated from Hardy–Weinberg equilibrium, likely due to the reduced genetic diversity in some highland populations, which should be considered in forensic investigations. Beyond forensic applications, our findings reveal genetic differences between AA-speaking groups in Northern and Northeastern Thailand. The AA groups from Northeastern Thailand exhibit greater genetic homogeneity and diversity, likely due to population interactions. In contrast, reduced diversity and increased heterogeneity in AA groups from Northern Thailand are possibly driven by genetic drift and cultural and geographic isolation. In conclusion, we emphasize the usefulness of increasing the number of autosomal STRs in forensic and anthropological genetic studies. Additional Y-STR and X-STR data from various AA-speaking groups in Thailand would further enhance and strengthen forensic STR databases in the region.

Moklen [mkm] is a severely endangered Austronesian language spoken by a sea-based population along the Andaman coast in the southern part of Thailand. As an initial attempt to document this language, we propose a Thai-based orthography of Moklen that not only captures all the phonemic distinctions but also considers the social, political, and cultural contexts of Moklen communities. The proposal is based on fieldwork data collected intermittently in Bangsak, Phang Nga Province, Thailand, between 2017 and 2021. Based on Smalley’s (1959) criteria of adequacy, the proposed orthography adopts a subset of consonant and vowel symbols, as well as major orthographic rules of the Thai [tha] script. Notably, it includes a tone mark that captures a tonal distinction confirmed by this study. Moreover, it is flexible enough to allow indication of sociolinguistic variations reported in previous studies. While a formal evaluation of the proposed orthography is still needed, guidelines recommended by UNESCO are also adopted to assess several sociocultural determinants that may influence the usability and acceptance of the proposed orthography. The proposed orthography is a promising tool for the documentation of the language and has potential to contribute to efforts to preserve the cultural heritage of the Moklen community.

Moklen, a tonal Austronesian language spoken in Thailand, exhibits two tones with unbalanced distributions. We employed machine learning techniques for time-series classification to investigate its acoustic properties. Our analysis reveals that a synergy between pitch and vowel quality is crucial for tone distinction, as the model trained with these features achieved the highest accuracy.