An epidemiologist and a medical researcher travel from Egypt to Canada and across America in search of a scientific explanation of the Ten Plagues which, the Bible tells us, devastated Egypt some 4,000 years ago.
00.30 — 07.30
Introduction to the Bible story of the Ten Plagues of Egypt, and the two scientists — John S Marr and Curtis Malloy — who think they have come close to solving the mystery. The papyrus in a Dutch museum, created 1,000 years later, which describes events which parallel the Ten Plagues.
07.30 — 13.15
The first plague: the Nile turns red and the fish die. Marr and Curtis’s theory that the cause could be algal blooms. A similar event in a US river in 1997 provides support for the idea — the cause here is a species of algae, a particular dinoflagellate that secretes neurotoxins which make water toxic and which cause blood to leak from dying fish. Algal blooms are triggered by changes in weather conditions — and this could equally well have happened in ancient Egypt as in modern-day America.
13.15 — 17.15
The second plague: the plague of frogs. Marr and Malloy speculate that the first plague created the conditions for the second. The description of the ‘frogs’ fits that of the common toad, a species that has very large clutches of eggs.
17.15 — 20.15
The third plague: the plague of lice. Identifying the lice is problematic, since there was no precise classification system for animals and plants until 1,000 years after the time of the Ten Plagues. At the time there were about a hundred species that could have been called ‘lice’, and the descriptions were of a species that, unusually, attacked both humans and animals. Marr and Malloy put the problem to one side for now.
20.15 — 24.15
The fourth plague: the plague of flies. Marr and Malloy speculate that this must have something to do with the death of the frogs from the second plague. There are five possible flies; elimination of the ones that don’t fit the evidence leaves a single candidate: the stable fly, which lays around 500 eggs at a time.
24.15 — 31.45
The fifth plague: the epidemic of sickness in livestock. Marr and Malloy visit Plum Island Agricultural Research Station, an island deliberately infected with tropical diseases. Again, they eliminate the diseases that don’t fit. Current work on African horse sickness provides the clue they are seeking. It doesn’t affect ruminants, but there is a similar disease which does. Both diseases are carried by midges, which might well have been the cause of the third plague.
31.45 — 34.15
The sixth plague: boils and blains. The outbreak of ulcers which affected humans and animals alike. The description fits a disease known as glanders which is spread by stable flies.
34.15 — 35.15
The seventh plague: the plague of hail. Modern equivalents: hailstorms in the Middle East.
35.15 — 36.15
The eighth plague: the plague of locusts. No mystery here; the same thing happens today.
36.15 — 37.15
The ninth plague: the plague of darkness. Again, no mystery; sandstorms are common in the region.
37.15 — 47.00
The tenth plague: the death of the firstborn. No previous explanations fitted the description in Exodus. Malloy thought it must be the culmination of the sequence of events which involved the previous nine plagues. Evidence from modern epidemics provided the vital clue: mycotoxins carried by the spores of moulds which grow in dark damp conditions. Marr and Malloy conclude that droppings from the locusts of the eighth plague contaminated grain which was stored in damp cellars during the ninth plague. Mycotoxins cause disease in animals and humans. It is the firstborn who die, because the eldest sons are sent to get the grain, and they get bigger rations; and it’s the elder, more dominant animals that are fed first. Because there was no evidence of the cause, this plague truly seemed like an act of God.
47.00 — end
Summing up: the importance of drawing on evidence from a variety of disciplines. Relevance to the present day: diseases are still with us, and there is an ever-present potential for plagues.