Left-handedness common in Ice Age
The fraction of left-handed people today is about the same as it was during the Ice Age, according to data from prehistoric handprints. They were found in caves painted during the Upper Palaeolithic period, between 30,000 and 10,000 years ago. Left-handedness may have conferred prehistoric man advantages, such as in combat, say the researchers … They suggest that because left-handedness is relatively rare it provides certain advantages over those who are right-handed, such as in solo and group fighting.
Oh no, not again! Why do people have to assume that every biological curiosity must have selective advantage? Yes, there probably is an advantage in being left-handed when it comes to fighting (and playing tennis)—because your opponents won't be so used to south-paw adversaries—but, if there was any real advantage in left-handedness, there would be more left-handers. I much prefer the 'explanation' that whether you are right-handed or left-handed is an outcome of some other selected genetic trait (most probably something affecting the the brain), but is itself irrelevant in terms of selective advantage. Who knows, perhaps the phenomenon of handedness only exists at all because there isn't sufficient selective pressure for ambidextrousness. I mean, if walruses exhibit handedness (or, more accurately, flipperedness), why shouldn't humans?