Daily briefing: COVID’s origins — what we do and don’t know

Nature

by Flora Graham

February 26, 2026

AI-Generated Deep Dive Summary

The origins of SARS-CoV-2 remain a mystery, with most peer-reviewed evidence pointing to an animal source but failing to determine the exact timing or location of the virus's spillover into humans. This uncertainty underscores the need for further research to understand how and when the virus transitioned from animals to humans, which is critical for preventing future pandemics. Horses are unique among animals in their ability to produce two sounds simultaneously—whinnies that combine a low-frequency vocal fold vibration with a high-pitched whistle created by airflow through laryngeal cartilage. This complex vocalization allows horses to communicate intricate messages, making them one of only a few species, including certain birds and humans, capable of such multilayered sounds. The rise of artificial intelligence is reshaping the job market in science, particularly for roles like research programmers. While AI tools are streamlining tasks and reducing demand for certain jobs, early-career researchers may face challenges as these stepping stones to career advancement become obsolete. This shift could lead to short-term gains in efficiency but risks long-term declines in scientific progress by limiting opportunities for young scientists. Denmark's approach to addressing the "motherhood penalty"—the significant income loss women experience after becoming mothers—stands out. The country's generous childcare and parental-leave policies offset 80% of this financial burden, offering a model for other nations seeking to support working parents and reduce gender inequalities. Japan has taken a bold step in approving innovative stem-cell therapies for treating Parkinson’s disease and severe heart failure, despite their limited clinical trial data. While these treatments show promise, experts caution that commercialization may be premature given the need for larger-scale safety and efficacy studies. This move highlights both the potential of regenerative medicine and the risks associated with rapid regulatory decisions. Archaeological findings from a ninth-century BCE site in Serbia reveal evidence of gender-based violence on an unprecedented scale, with mass graves containing women and children who were targeted in attacks. These discoveries provide rare insights into early Iron Age power dynamics and shifting gender relations during periods of population movement and displacement. China is doubling down on Alzheimer’s research amid its aging population, which could see 66 million people living with dementia by 2050. The country is investing in new

Verticals

scienceresearch

Originally published on Nature on 2/26/2026