Complutense University of Madrid

Global biodiversity is threatened by human impact, which has already led to the extinction of hundreds of species. However, the known tree of life continues to expand with the discovery of numerous clades (groups of organisms that share a common ancestor and all its descendants), according to a international study pubished in PNAS. According to their estimates, made between 2015 and 2020, more than 700 new genera, more than 20 new families, and more than three new orders are described each year, all based on newly discovered species. According to the authors, many new clades remain undiscovered, and describing them before they become extinct should be a priority for research and conservation.

When Neanderthals and modern humans had offspring together, little Neanderthal DNA from the X chromosome entered the human gene pool. A study published in the journal Science traced ancient gene flow and found a relative excess of 62% modern human ancestry on Neanderthal X chromosomes. This suggests that the couples who had children were mostly Neanderthal men and modern human women, although the authors cannot rule out the possibility that demographic processes played a significant role.

On social network X (formerly Twitter), when users select the ‘for you’ option, the algorithm tends to steer them towards more conservative political options, according to research conducted with nearly 5,000 participants in the United States in 2023. The authors randomly assigned users to either an algorithmic or chronological feed for seven weeks. The switch from chronological to algorithmic feed increased engagement and shifted political opinion towards more conservative positions, especially on political priorities, perceptions of criminal investigations into Donald Trump, and opinions on the war in Ukraine. Conversely, switching from the algorithmic feed to the chronological feed had no comparable effects. ‘Initial exposure to X's algorithm has persistent effects on users' current political attitudes,’ say the authors of the study, published in Nature.

A team in China has studied the ability of a test to detect the human papillomavirus (HPV)—responsible for the vast majority of cervical cancers—in menstrual blood from more than 3,000 women. The results indicate that the test is comparable to current screening performed in medical offices. According to the researchers, “Using menstrual blood for HPV testing is practical and non-invasive, allowing women to collect samples at home and thus potentially offering a practical way to expand access to screening.” The study is published in The BMJ. 

A study published in Nature suggests that a brain network that controls the execution of actions (SCAN), which was described in 2023, plays an important role in Parkinson's disease. Focusing treatments—such as transcranial stimulation—on the SCAN rather than other brain regions associated with movement could improve their effectiveness, according to the research.

A higher body mass index (BMI) correlates—regardless of age at menarche—with a lower risk of breast cancer, according to a meta-analysis based on genetic data from more than 56,000 women. The study, published in Science Advances, seeks to clarify previous seemingly contradictory findings: more body fat (measured by BMI) before puberty could have a protective effect against breast cancer; however, a higher BMI is also linked to earlier menarche, which is associated with an increased risk of developing this disease. The authors indicate that the prepubertal stage is a ‘critical window’ in which adiposity has the greatest influence on future breast cancer risk.

People with colour vision deficiency and bladder cancer have lower survival rates than patients with the same cancer who have not been diagnosed with this visual condition, according to an analysis of medical records between 2004 and 2025 comparing a group of 135 people with both diagnoses and another group of 135 with bladder cancer without visual impairment. In a study published in Nature Health, the authors suggest that this difference could be due to these patients not detecting the presence of blood in their urine, which delays the seeking of medical care and cancer diagnosis.

One in five people in Spain suffers from unwanted loneliness, but what exactly is it? What consequences can it have and who suffers from it most? Is it appropriate and realistic to talk about an epidemic of loneliness? What are the causes and possible solutions? What role do social networks play? We answer these and other questions about a central problem in our societies.

Restrictions on mobility and activity imposed during the covid-19 pandemic had an impact on the beaks of a species of bird, specifically the dark-eyed junco, which lived in urban areas of Los Angeles (USA). This is shown in a study published in the journal PNAS, which reveals how birds born during these lockdowns had beaks similar to their counterparts in the wild. With the return of human activity, the beak returned to its pre-pandemic shape. The authors argue that this change was mainly due to an adaptation to the food available, as the birds no longer had access to human food waste. 

A research team led by the British Museum presents evidence in the journal Nature that humans were making fire – deliberately and not just taking advantage of natural fires – 400,000 years ago in Barnham (United Kingdom). The remains analysed, including burnt sediments, heat-damaged flint axes and pieces of pyrite, are much older than those recorded to date, which dated the deliberate use of fire to around 50,000 years ago in northern France.