THE kings and queens of England may have murdered their closest kin to secure
the throne, but they still stayed true to a basic rule of evolutionary
biology.
The history of Britain between the 14th and 16th centuries is full of epic
tales of jealousy, intrigue and murder. To ensure their right to the throne
remained unchallenged, members of the royal family frequently murdered their
closest relatives. Both Henry IV and Henry VIII killed five cousins each.
John McCullough, an evolutionary biologist at Cambridge University, and his
colleagues at Indiana State University felt sure the lure of the ultimate prize
would force British monarchs to break free from the shackles of their own
selfish genes. 鈥淚t was kill or be killed,鈥� he says.
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But to their surprise, the researchers found that despite the high death
toll, the kings and queens of England all obeyed a golden theory of biology
known as Hamilton鈥檚 rule. According to the theory, people or animals can pass on
their genes by helping their relatives. That means they should be more willing
to help brothers or sisters, who share half their genes on average, than more
distant relatives who share less.
But relatives also have a nasty habit of competing with you for resources, be
they chicks squabbling over food, or heirs fighting for the throne. And this is
where the flip side of Hamilton鈥檚 rule comes in. If you kill two brothers, say,
you鈥檝e essentially wiped out your genetic identity rather than preserving it for
future generations, says McCullough. 鈥淭hen you have really damaged yourself in
an evolutionary sense. So you can eliminate relatives but only up to a certain
濒别惫别濒.鈥�
But it turns out no king or queen, from Edward III who succeeded to the
throne in 1327 to Elizabeth I who died in 1603, killed enough relatives to wipe
out the equivalent of their own genetic inheritance
(see Graphic). Edward IV,
who reigned in the late 15th century, was the worst offender, executing his
brother, George, Duke of Clarence, and five cousins, including Henry VI and
Edward, Prince of Wales. Yet even Edward IV鈥檚 victims shared only two-thirds of
his genes in total.
鈥淚 was astounded. We thought that at least two or three would violate
[Hamilton鈥檚 rule] because some very close relatives were killed,鈥� says
McCullough. 鈥淭hey had no theory of genetics at the time so they were simply
operating under their own set of rules,鈥� he says. 鈥淎s it turns out, it is in
accord with scientific expectations.鈥�
