Do bees have personalities?
Dog fertility on the decline
Exposure to harmful chemicals is making male dogs less fertile – and could well be the cause of a similar trend in humans, scientists believe. When researchers from Nottingham University analysed semen from stud dogs over a 26-year period, they found that motility – the ability of sperm to swim in a straight line – had fallen by around 35% overall, with the sharpest falls occurring between 1988 and 1998, when the average yearly decline was 2.5%. The fall-off, they believe, is caused by “contaminants” that have entered the food chain and ended up in the dogs’ bodies. When the researchers examined the dogs’ food, they found chemicals such as phthalates (used in food packaging) and PCBS (once commonly used in electrical goods); the same chemicals were also present in the dogs’ semen and testes. Given the close relationship between dogs and humans, the researchers think it likely that human males are similarly affected. “Dogs live in our homes, they sometimes eat the same food, they are exposed to the same environmental contaminants that we are,” said lead researcher Dr Richard Lea. Several studies have suggested that the quality of human sperm has been declining for some time, though scientists disagree over the scale of the problem.
Zika linked to joint condition
Scientists in Brazil have found “compelling” evidence that the Zika virus is linked to a rare joint condition affecting newborn babies. The team looked at seven cases of arthrogryposis – which results in abnormally curved joints – in infants born last autumn: six of the infants had also been diagnosed with microcephaly, a Zika-related condition that causes children to be born with abnormally small heads. Arthrogryposis is extremely rare, so it was unlikely to be a coincidence that seven cases had “suddenly” occurred during the Zika epidemic, said lead researcher Dr Vanessa van der Linden. The findings open up the possibility that Zika is linked to a spectrum of health problems, some of which might only emerge as children get older. “I think this is part of the move from describing microcephaly, which is just really a component of the congenital Zika syndrome, to starting to describe the whole spectrum of the Zika syndrome,” Laura Rodrigues, professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine, told The Guardian.
Individualist bees
Despite living, on average, only a month, bumblebees have surprisingly distinct personalities, according to researchers. A team at Queen Mary University of London tracked four bees over their entire lives by attaching tiny radar antennae to their bodies. “One bee was something of a lifelong vagabond, never settling down on a single patch of flowers,” said lead researcher Dr James Makinson. A second, by contrast, “was exceptionally diligent, quickly switching after only three flights from exploration of the surrounding environment to focusing exclusively on a single forage location”. The other two bees, meanwhile, combined exploration and single-location foraging throughout their lives. The scientists said they hoped their findings would help people appreciate the “poetry” of bees.
Being obese “ages your brain”
The brains of overweight people appear to age faster than those of their non-obese peers from middle age onwards, scientists have discovered. When researchers at the University of Cambridge studied the brain scans of 473 people aged between 20 and 87, they found that those who were overweight and in their late 30s or older had less “white matter” – which connects different brain areas and enables signalling between them – than those of the same age who were slim. In any individual, the volume of white matter increases during youth and then starts to decrease in middle age. However, this shrinkage appears to occur more rapidly in those who are overweight. “The overall message is that brains basically appear to be ten years older if you are overweight or obese,” said lead author Dr Lisa Ronan. While there was no evidence of any immediate effect on mental capacity, she added that the findings raised the possibility that obese people may be “more susceptible” to conditions such as dementia and Alzheimer’s later in life.