It is hard to box against a southpaw, as Apollo Creed found out when he fought Rocky Balboa in the first of an interminable series of movies. While "Rocky" is fiction, the strategic advantage of being left-handed in a fight is very real, simply because most right-handed people have little experience of fighting left-handers, but not vice versa.

The orthodox view of human handedness is that it is connected to the bilateral specialisation of the brain that has concentrated language-processing functions on the left side of that organ. Because, long ago in the evolutionary past, an ancestor of humans underwent a contortion that twisted its head around 180°relative to its body, the left side of the brain controls the fight side of the body, and vice versa. In humans, the left brain is usually dominant. And on average, left-handers are smaller and lighter than right-handers. That should put them at an evolutionary disadvantage. Sporting advantage notwithstanding, therefore, the existence of left-handedness poses a problem for biologists. But Charlotte Faurie thinks he knows the answer.

As any schoolboy could tell you, winning fights enhances your status. If, in prehistory, this translated into increased reproductive success, it might have been enough to maintain a certain proportion of left-handers in the population, by balancing the costs of being left-handed with the advantages gained in fighting. If that is tree, then there will be a higher proportion of left-handers in societies with higher levels of violence, since the advantages of being left-handed will be enhanced in such societies. Dr. Faurie set out to test this hypothesis. Fighting in modem societies often involves the use of technology, notably firms, that is unlikely to give any advantage to left-handers. So Dr. Faurie decided to confine his investigation to the proportion of left-handers and the level of violence in traditional societies.

By trawling the literature, checking with police departments, and even going out into the field and asking people, Dr. Faurie found that the proportion of left-handers in a traditional society is, indeed, correlated with its homicide rate. One of the highest proportions of left-handers, for example, was found among the Yanomamo of South America. Raiding and warfare are central to Yanomamo culture. The murder rate is 4 per 1,000 inhabitants per year. And, according to Dr. Faufie, 22.6% of Yanomamo are left-handed. In contrast, Dioula-speaking people of Burkina Faso in West Africa are virtual pacifists. There are only 0.013 murders per 1,000 inhabitants among them and only 3.4% of the population is left-handed.

While there is no suggestion that left-handed people are more violent than the right-handed, it looks as though they are more successfully violent. Perhaps that helps to explain the double meaning of the word "sinister".

The example of "Apollo Creed" is mentioned to show that

A．right-handers are put at a psychological disadvantage.

B．right-handers do not excel at boxing.

C．left-handers enjoy advantage in some sports.

D．left-handers are often involved in fighting.