Robert Llewellyn Robert Llewellyn Robert Llewellyn (born 10 March 1956 in Northampton, Northamptonshire) is a British actor, comedian and writer. He plays the mechanoid Kryten in the TV sci-fi sitcom "Red Dwarf" and formerly presented the TV engineering gameshow "Scrapheap Challenge". He also presents a YouTube series, "Fully Charged". Llewellyn's first foray into the world of show business started out as a hobby, organising a few amateur cabaret evenings in a riverside warehouse overlooking Tower Bridge in London. The shows were a great success and he eventually helped form an alternative comedy theatre group called the Joeys. Within six months he had
Challenge hypothesis However, during periods of heightened male aggression, testosterone levels increase further to a maximum physiological level. This additional boost in testosterone appears to facilitate male-male aggression, particularly during territory formation and mate guarding, and is also characterized by a lack of paternal care. The challenge hypothesis has come to explain patterns of testosterone production as predictive of aggression across more than 60 species. The challenge hypothesis presents a three-level model at which testosterone may be present in circulation. The first level (Level A) represents the baseline level of testosterone during the non-breeding season. Level A is presumed to maintain feedback