Using a non-intrusive method of examining the height of mummies, anthropologists have concluded that incest was rampant among the pharaohs of Egypt who believed they descended from the gods and sought to preserve the sacred bloodline by inbreeding.
The ethical considerations of preserving tissues on the 259 mummies saw Zurich evolutionary scientists turn to height which is believed to be a highly hereditable trait in looking for signs of incest among the commoners and royals.
The researchers looked at variation of body heights of royals and compared it with variations among commoners.
Pharaohs varied less in height than men of the common population clearly indicating inbreeding, with the royals often marrying siblings and cousins.
"It is actually one of the largest collections of body height of ancient Egyptians and spans all major periods of their history," Frank Rühli, director of the Institute of Evolutionary Medicine at the University of Zurich, told Discovery News.
Detailing their results in the American Journal of Physical Anthropology, Rühli and colleagues note the average height of kings was a steady 166 cm (5.44 feet), featuring much less variations compared to the general population. Queens and princesses averaged 156.7 cm (5.14 feet).
The study also confirmed the highly incestuous levels in the rulers of the 17th and 18th dynasty, with the 165 cm-tall King Amenhotep I scoring the highest on the incest scale.
"The study shows some evidence for consanguineous (incestuous) marriages in a reliable, non-invasive way," says Barry Bogin, professor of biological anthropology at Loughborough University, UK.
He achieved similar results in a study carried out in Guatemala on living boys and girls between five and 14 years old.
Earlier, DNA testing of King Tutankhamun's remains had shown that the pharaoh was the product of a marriage between siblings, resulting in bone diseases and many other infirmities.