Without the hair, they searched for just 18-19 seconds. With vellus hair, the bedbugs took between 22 and 26 seconds to find a good place. They had to intervene quicker if the arms were shaved. They waited until the bug started to extend its bloodsucking snout before plucking it off. While the volunteers looked away, Dean and Siva-Jothy placed a bedbug within the rectangles. The duo recruited 29 student volunteers and drew a rectangle of Vaseline on both their forearms, after first shaving one of them. Some have suggested that they have no role at all.īut Isabelle Dean and Michael Siva-Jothy from the University of Sheffield have an intriguing possible answer: they think that the vellus hairs help us to spot parasites. They look like the results of a half-hearted evolutionary stab at becoming hairless. But very few of them have offered answers to an equally mysterious question: why have we kept our vellus coat? The fine hairs aren’t very good at preserving body heat, and they don’t make us more or less sexually attractive. Many scientists have speculated about why we humans have lost a thick coat of body hair. We are coated with a layer of short, fine hair, known technically as vellus hair and colloquially as peach fuzz. We actually have the same density of body hair as other apes of our size, but ours is largely fine and colourless rather than thick and dark. It might seem like a deserved nickname after all, we lack the lush coats of body hair that chimps, bonobos and gorillas have in abundance. We humans are often known as “ naked apes”.
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