Move over blue whale, Peru fossils indicate Perucetus colossus from 38-mn yrs ago was largest mammal

ScientiFix, our weekly feature, offers you a summary of the top global science stories of the week, with links to their sources.

An artist's rendition of Perucetus colossus, which is believed to have lived 38 million years ago | Credit: Alberto Gennari/Nature

New Delhi: Scientists have discovered fossils of an extinct whale species that may have been the largest mammal ever — the Perucetus colossus, believed to have lived on Earth more than 38 million years ago. 

In a study published in Nature on 2 August, scientists said that fossilised bones of the mammal — a basilosaurus whale, a genus of large, predatory, prehistoric archaeocete whale species that lived in the late Eocene epoch approximately 56 to 33 million years ago— showed that it had the highest skeletal mass ever recorded. 

The scientists who conducted the study are from Peru, Italy, Germany, France, Switzerland, The Netherlands, and Belgium.

The Perucetus colossus, whose name translates to ‘colossal Peruvian whale’ — so called because it was found in Ica desert in Peru — weighed up to 340 metric tons. The blue whale weighs 180-200 metric tons. 

Scientists previously associated an increase in body size in cetaceans — a family that includes whales, dolphins, and porpoises — with the transition from terrestrial to aquatic environments to help make them active swimmers in deep waters. 

But the newly discovered Perucetus colossus challenges this idea. This is primarily because scientists now believe that the ancient whale’s skeletal body mass and documented increase in its body size has helped it adapt and survive in shallow waters. Read more here 

AI screenings effective in detecting breast cancer             

Can Artificial Intelligence help make breast-cancer screening easier? Yes, a new trial has shown. 

Published in The Lancet Oncology this month, the randomised controlled trial saw 80,000 women from Sweden participate. Scientists in the study were from Lund University, Sweden.

The study was funded by the Swedish Cancer Society, Confederation of Regional Cancer Centres in Sweden and the Swedish governmental funding for clinical research (ALF).

Both AI and regular screenings were used in the study, which was primarily aimed at testing the safety of the former. Under the study, half the participants were assigned to AI and the other half went through regular screenings. The study then compared the AI screenings with regular mammograms that radiologists conduct.

The study found that AI screenings were as effective as regular screenings in detecting breast cancer. AI screenings, however, helped detect 244 cases of cancer as opposed to 203 in regular screenings. 

Both screenings also had similar false positive rates — 1.5 percent — and matching recall rates, that is how many women were asked to come back for further screening. 

The study concluded that AI helped reduce the work of radiologists by 44.3 percent. Read more. 

Thymus removal could cause cancer in adults, says new study

Removing the thymus — a small gland in the lymphatic system that’s located in the chest — leads to higher risk of cancer and mortality, a new study by researchers from Harvard University, USA, has shown. 

The thymus is an important part of the human immune system that makes white cells known as T-cells. These cells are essential in helping the immune system fight disease and infection. 

A study in The New England Journal of Medicine evaluated the impact of removing the thymus in adults. The study, published on 3 August, compared two groups — adult patients who had undergone thymectomy, or the removal of the gland, and those that had undergone a similar cardiothoracic surgery but did not have their thymus removed. 

The results showed that five years after surgery, the thymectomy group had higher all-cause mortality and a higher risk of cancer as compared to those who still had their thymus. 

Researchers also studied the measure of T-cell production and plasma cytokine levels — both important for immune response — in a small subgroup and found that removal of the gland results in lower production of new immune cells.  Read more. 

Archaeologists reconstruct 9,000-year-old necklace

A 9,000-year-old reconstructed necklace found in south Jordan’s Ba’ja has a story to tell, and it’s one about the social structures and burial rituals of the Neolithic period. 

The necklace, with its multi-layered beads, a double perforated stone pendant and a mother-of-pearl ring, was found partially broken and decomposed on the remains of a child. 

Researchers from the Sophia Antipolis-Université Côte d’Azur, the University of Stuttgart, the University of Berlin, and Cambridge University have now reconstructed the necklace. The research, published in the journal Plos One, shows that some of the necklace’s beads were made from exotic shells such as fossil amber — a material that has never before been associated with the Neolithic period.

The necklace, according to the study, was specifically made for the burial, and was likely seen as a connection between the living and the dead. It also indicated the high social status of the child. Read more 

Half the world could have mental health disorders by age 75

One in every two people could have mental health issues in their lifetime by age 75, a study conducted by researchers from the University of Queensland and Harvard Medical School has predicted.

The study uses data from the World Health Organization’s World Mental Health Survey from 29 countries between 2001 and 2022. The WHO survey uses a fully structured psychiatric diagnostic interview to assess the age of onset, lifetime prevalence, and morbid risk of mental disorders until age 75 for both male and female respondents.

In their study, researchers from the University of Queensland and Harvard Medical School  analysed the data of 1,56,331 respondents covering low-, middle-, and high-income countries and found that the lifetime prevalence of any mental disorder was around 29 percent in female respondents and 28.6 percent in male respondents. 

By age 75, about half of the population could expect to experience at least one of the mental disorders studied, the study said.

The most common mental disorders varied by gender, with alcohol use and major depressive disorder being more prevalent in male respondents and major depressive disorder and post-traumatic stress disorder (PTSD) being more common in women. Read more 

(Edited by Uttara Ramaswamy)