By reconstructing the genomes of archaeological maize cobs and kernels, the study, by researchers at the University of York and the University of Copenhagen, revealed that 1,000-year-old maize from rockshelters in the Ozark region of Arkansas, US, shares a close genetic link with modern Northern Flint varieties.

These hardy varieties are cold-adapted and are the ancestors for commercially important maize grown around the world. Researchers say that understanding its origins and journey through different geographical regions could help find new ways of sustaining and improving crops today, as pressures on global food supply increases and crop health is challenged by climate change. 

Researchers showed that maize underwent selection as it was transported from the US Southwest across the Great Plains, particularly through a gene, known as waxy1. Genetic variants in the waxy1 gene affect the stickiness and chewiness of maize, traits that are still valued in some traditional cuisines today.

This suggests that farmers 1,000 years ago were not just engaged in planting and harvesting, but in selecting traits that could help in breeding and producing the best quality yield for food, not too dissimilar to farmers today.

Dr Nathan Wales, from the University of York’s Department of Archaeology, said: “We know that maize was domesticated in Mexico, but it has long been debated what route it took to regions of the US to become what it is today – one of the most globally important food crops.

“We now have a clearer idea of the journey it took from Mexico, and we better appreciate how regional varieties can become more globally significant than varieties grown near the domestication centre. It is valuable information for crop breeders because they can chart the evolution of the crop, reintroduce any lost genetic diversity or develop new varieties, which could be vital to helping food shortages in the future.”

Ancient maize genomes from the Ozark rockshelters indicated that maize entered eastern North America at least twice, tracing ancestry to both the upland US Southwest and southern Texas.

Dr Jazmín Ramos-Madrigal, from the Globe Institute at the University of Copenhagen in Denmark, said: “We also showed that maize could only be introduced into eastern North America once humans bred local varieties with the genetic tools to cope with the challenging environment of the region, which goes someway to demonstrating the skills and knowledge of farmers 1,000 years ago.”

The study is published in the journal Cell.

Galaxies in today’s Universe are diverse in morphologies and can be roughly divided into two categories: younger, disk-like spiral galaxies, like our own Milky Way, that are still forming new stars; and older, elliptical galaxies, which are dominated by a central bulge, no longer forming stars and mostly lacking gas. These spheroidal galaxies contain very old stars, yet how they formed has remained a mystery — until now.

The discovery of the birth sites of giant, elliptical galaxies — announced in a paper published today in Nature — come from analyzing data from the Atacama Large Millimeter/submillimeter Array (ALMA) on over 100 Submillimeter Bright Galaxies (SMGs) with redshifts dating to the “Cosmic noon” era, when the universe was between around 1.6 and 5.9 billion years old and many galaxies were actively forming stars. This study provides the first solid observational evidence that spheroids can form directly through intense star formation within the cores of highly luminous starburst galaxies in the early Universe, based on a new perspective from the submillimeter band. This breakthrough will significantly impact models of galaxy evolution and deepen our understanding of how galaxies form and evolve across the Universe.

In this study, researchers led by Chinese Academy of Sciences Purple Mountain Observatory Associate Researcher Qinghua Tan, and including Kavli IPMU Professor John Silverman, Project Researcher Boris Kalita, and graduate student Zhaoxuan Liu, used statistical analysis of the surface brightness distribution of dust emission in the submillimeter band, combined with a novel analysis technique. They found that the submillimeter emission in most of sample galaxies are very compact, with surface brightness profiles deviating significantly from those of exponential disks. This suggests that the submillimeter emission typically comes from structures that are already spheroid-like. Further evidence for this spheroidal shape comes from a detailed analysis of galaxies’ 3D geometry. Modeling based on the skewed-high axis-ratio distribution shows that the ratio of the shortest to the longest of their three axes is, on average, half and increases with spatial compactness. This indicates that most of these highly star-forming galaxies are intrinsically spherical rather than disk-shaped. Supported by numerical simulations, this discovery has shown us that the main mechanism behind the formation of these tri-dimensional galaxies (spheroids) is the simultaneous action of cold gas accretion and galaxy interactions. This process is thought to have been quite common in the early Universe, during the period when most spheroids were forming. It could redefine how we understand galaxy formation.

This research was made possible thanks to the A3COSMOS and A3GOODSS archival projects, which enabled researchers to gather a large number of galaxies observed with a high enough signal-to-noise ratio for detailed analysis. Future exploration of the wealth of ALMA observations accumulated over the years, along with new submillimeter and millimeter observations with higher resolution and sensitivity, will allow us to systematically study the cold gas in galaxies. This will offer unprecedented insight into the distribution and kinematics of the raw materials fueling star formation. With the powerful capabilities of Euclid, the James Webb Space Telescope (JWST), and the China Space Station Telescope (CSST) to map the stellar components of galaxies, we will gain a more complete picture of early galaxy formation. Together, these insights will deepen our understanding of how the Universe as a whole has evolved over time.

A multinational team led by Josef Penninger (MedUni Vienna, IMBA — Institute of Molecular Biotechnology, Vienna, University of British Columbia, Canada, Helmholtz Centre for Infection Research, Germany) observed that the intestinal villi reorganise during pregnancy and breastfeeding and significantly enlarge, doubling their surface area. The studies were carried out in genetically modified mice and intestinal organoids from mice and humans — self-organised three-dimensional tissues derived from stem cells in the intestine. Mechanistically, the researchers identified the RANK receptor/RANK ligand (RANK/RANKL) system as the key to the villous enlargement of the small intestine during reproduction, which is regulated by sex and lactation hormones. When mice were engineered to lack the RANK/RANKL system in the intestine, the villous expansion during pregnancy and breastfeeding was significantly impaired.

Fundamental importance for evolution

For decades, researchers have studied the RANK/RANKL system as a key facilitator of essential, evolutionarily conserved processes. The Penninger group has already identified key functions of the RANK/RANKL system in bone turnover, in the biology of the mammary gland, in breast cancer, and in immune tolerance in pregnancy, contributing to the development of drugs against bone loss used by millions of people and clinical trials for breast cancer prevention and cancer immunotherapies are underway. The researchers now discovered that these intestinal changes, which appear to be completely reversible when nursing is stopped, are important for proper feeding and nourishment of the babies. “Our study shows that the impairment of this intestinal expansion by the lack of the RANK/RANKL system during pregnancy changes the milk of the nursing mothers. This results in lower weights of the babies and transgenerational long-term metabolic consequences,” states the lead author Masahiro Onji. “Mothers need to eat for themselves and their babies. These new studies provide for the first time a molecular and structural explanation of how and why the intestine changes to adapt to enhanced nutrient demand of mothers, which is probably the case in all pregnant and nursing mammals,” adds study leader Josef Penninger.

How mothers adapt to the demands of pregnancy and breastfeeding remains a central question of evolution and human health. During this phase, female hormones influence multiple organs to control and change their structure and functions, which is crucial for the health of the mother and the development of the offspring. It was known that pregnant women have enhanced nutrient demands. However, this fundamental aspect has not been well studied until now: “By identifying the RANK/RANKL system as the driving force behind intestinal adaptation during pregnancy and lactation, our study contributes to a deeper understanding of biological processes that are of fundamental importance for evolution and human health,” says Josef Penninger, summarising the impact of the findings.

This massive expansion is controlled by sex and pregnancy hormones, which change the stem cells in the gut via the RANK/RANKL system and then give the intestinal cell a survival signal to grow much larger. This growth then leads to a near doubling of the intestinal surface area, which also increases the molecular machinery for the uptake of sugar, protein, and fat, and even leads to a profound architectural change in the intestinal villi, which probably slows down the flow of food, again maximising the uptake of nutrients. Josef Penninger: “Our team has discovered an amazing new way how mother’s bodies change to keep babies healthy. Hardly anybody knew about this, apart from a few old studies that have largely been forgotten. We have also found that this system, via stem cells, can directly affect tumours in the intestine; maybe we can learn from pregnant and nursing mothers to reversibly rewire this system to develop new treatments and a better understanding of intestinal cancer or gut regeneration.”

The study was a close collaboration between the Medical University of Vienna, the Institute of Molecular Biotechnology of the Austrian Academy of Sciences in Vienna, the Life Sciences Institute in Vancouver, the Helmholtz Centre for Infection Research, Braunschweig, the Hubrecht Institute, Utrecht, and the Kiel University. Researchers from the University of Tokyo and the University of Cambridge also participated.