Ghost of long-extinct ancestor lives on in people today

Protein sequences extracted from ancient *Homo erectus* teeth found in China reveal molecular variants that reappear in Denisovans and in present-day humans. This finding suggests that genetic material from *H. erectus*, a species that went extinct long ago, may have been passed forward through interbreeding and survives in the genomes of living people. The work extends paleoproteomics — the recovery of ancient proteins rather than DNA — deeper into human evolutionary history than previously achieved, offering a way to study lineages too old for DNA preservation. The results imply that the Denisovans themselves may have carried *H. erectus* ancestry, serving as an intermediate link through which those ancient variants reached modern populations.

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Genetic variability of SARS-CoV-2 in wastewater and associations with community transmission

Tracking viral genetic diversity in sewage offers a richer picture of disease spread than simple virus concentration measurements. Researchers analyzed 12,290 SARS-CoV-2 wastewater sequences to examine whether nucleotide variation and variant counts could serve as indicators of community COVID-19 transmission. They found a strong correlation between weekly genetic diversity metrics and weekly new infection rates. Notably, diversity outperformed viral concentration as a transmission indicator, likely because concentration measurements are more susceptible to noise from wastewater variability. Consistency across multiple diversity measures strengthens confidence in the approach. The findings suggest that incorporating genetic diversity into wastewater surveillance programs could substantially improve their ability to track disease dynamics in communities.

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From wastewater analysis to public health action

Wastewater surveillance has proven valuable for tracking infectious disease spread, but most programs focus on detecting whether a pathogen is present rather than characterizing its genetic diversity. This perspective argues that systematically sequencing viral genomes from wastewater could substantially strengthen public health responses. By capturing the full range of variants circulating in a community — including strains missed by clinical testing — wastewater genomic data could provide earlier warning of emerging variants, guide vaccine updates, and inform targeted interventions. The approach complements individual-level clinical surveillance, particularly in settings where testing access is limited. Realizing this potential requires investment in sequencing infrastructure, standardized protocols, and analytical frameworks capable of resolving mixed viral populations from environmental samples. The authors contend that expanding wastewater analysis from simple detection to comprehensive genetic characterization represents a meaningful opportunity to improve how public health systems anticipate and respond to viral disease outbreaks.

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