Platypus odder than thought
At first dismissed as a prank, and later cited as proof that God has a sense of humour, the duck-billed platypus has finally given up its evolutionary secrets. The creature has become the latest to have its genetic code sequenced, revealing it to be a bizarre mix of mammal, bird and reptile, with very complex sexuality.
While humans have two sex chromosomes, the X and Y, the platypus has 10, with five of each kind. An international team of scientists extracted DNA from a female platypus, named Glennie, reading all 2,2-billion pairs of her genetic “letters”. The fact that the animal has five X and five Y chromosomes is “the weirdest thing about a very weird animal”, said Ewan Birney, a co-author on the paper, based at the European Bioinformatics Institute, near Cambridge, England. “In theory it means there are 25 possible sexes, though in practice that doesn’t happen.”
The leggier the better
Leggy women and gangly men are less likely to develop Alzheimer’s, according to a study that suggests a healthy upbringing protects against the degenerative disease. Researchers took limb measurements of 2 798 men and women with an average age of 72 and monitored them for five years.
At the end of the study 480 had developed Alzheimer’s or other types of dementia. The study showed that women with longer legs had a much lower risk of dementia, with every extra inch of leg reducing their risk by 16%. Women with the shortest arms were 50% more likely to develop the disease than those with the longest arms. The study, which appears in the journal Neurology, revealed that only arm length was linked to men’s risk of Alzheimer’s, with every extra inch lowering their risk by 6%.
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