Inspired by Indigenous Huichol art, the cover features a map of Mexico based on data that reflect the nation’s genetic diversity. In this week’s issue, Andrés Moreno-Estrada and his colleagues present the initial results of the Mexican Biobank project. To create the nationwide database, the team genotyped 6,057 individuals from across all 32 states of Mexico, making sure that representatives of the country’s Indigenous communities were included. The researchers used the data to perform genome-wide association studies for 22 complex traits and to evaluate how well polygenic scores predicted the risk of developing disease. In a separate paper, Jonathan Marchini and his co-workers reveal results from the Mexico City Prospective Study, which genotyped and sequenced 140,000 adults from two districts in Mexico City. Together, the papers uncover the genetic histories for the Mexican population and offer insight into the genetic risk of disease.

A significant gap exists in the understanding of how humans develop in the very early stages when a newly formed embryo is implanted in the wall of the uterus, largely because of the physical and ethical challenges that are presented by studying early human embryos. A collection of articles in this week’s issue examines possible ways to help address this problem. Three papers — by Jacob Hanna and colleagues, Berna Sozen and co-workers, and Magdalena Zernicka-Goetz and colleagues — present structures that mimic the development of human embryos after implantation in the uterus. The resulting complete model from Hanna and co-workers is pictured on the cover. Although there are differences between the structural morphology and composition of supporting cells and in each of the three models, all of them were assembled using just human stem cells in a dish, thereby avoiding the use of either egg or sperm in the generation of the structures. The research possibilities, challenges and ethical considerations for the work are examined in accompanying News & Views and Comment articles.

The cover shows a black microhylid frog (Melanobatrachus indicus), a rare species from the Western Ghats of India. In this week’s issue, Jennifer Luedtke and her colleagues present the results of a comprehensive re-evaluation of the conservation status of amphibians since 2004. Covering 8,011 species, the paper reveals that amphibians continue to be the most threatened class of vertebrates and that their status is deteriorating globally. The researchers drew their data from the second Global Amphibian Assessment, which was completed in June 2022. They find that around 41% of amphibian species are categorized as threatened, and note that the primary driver for the deteriorations in status has shifted from disease to climate change and habitat loss.

The cover shows a composite near-infrared image of Herbig-Haro 211, a striking interstellar jet emanating from a young star in the Perseus Molecular Cloud. Captured by Tom Ray and his colleagues using the James Webb Space Telescope, the image is analysed in this week’s issue. The protostar responsible for Herbig-Haro 211 is an analogue of the Sun when it was only a few tens of thousands of years old, and the image and accompanying spectroscopy offer insight into how the Solar System formed. The researchers found that, contrary to expectations, the jet is made up almost completely of molecules, rather than atoms and ions, and that these molecules explain the ‘green fuzzies’ seen in images of the jet taken by the Spitzer telescope in the early 2000s.