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The plagues of Egypt are among the most impressive of God’s wonders recorded in the Old Testament. They showcase His incredible power and are what finally pushes Pharaoh to allow the Israelites to leave Egypt and slavery behind. They are also among the events of the Bible that seem to be beyond any sort of rational explanation besides that of divine intervention. That said, science has taken a stab at explaining everything it can in the Bible. So, what does it have to say about the plagues of Egypt?

Nile as Blood

The first plague was that the Nile turned red as blood. The water became noxious to drink and killed all the fish. There are two main explanations for this event. The first is that there was high rainfall that pushed large amounts of red clay from the Ethiopian highlands into the river. This would have choked the fish and caused them to die and also given the river a reddish color. The decaying fish then made the Nile stink and turned it to poison for both people and the fish remaining in the river. The second explanation is that the river turned red due to a sudden overabundance of algae. This could have been caused by a variety of different organisms, but the most likely suspect would be Oscillatoria rubescens, a freshwater algae related to the organism that causes the infamous “Red Tide” in oceans. This algae bloom thrives in slow moving waters that are high in nutrients, but it is poisonous. It also stains water red when it dies.
The slowing of the Nile’s usually swift current could have been caused by rising water levels due to increasing temperatures in Egypt. They might also have come from a sudden abundance of clay in the water. Either way, a slower current could have allowed the algae to bloom and set off the domino effect that created the plagues of Egypt.

Frogs

The second plague was the plague of frogs. Assuming that the Nile was choked by either clay or toxic algae blooms, it makes sense that the frogs would scramble to get away from the water. As such, they swarmed out of the poisoned Nile and took to shore where they would run into people. They might well have found their way into homes as they sought shelter from predators. The frogs could have truly entered Egypt in extraordinary numbers, or their numbers could have been overestimated by shocked and horrified Egyptians. In the case of the latter, one only needs to think about how many people find a single spider, cockroach or mouse in their house and assume they have an infestation. If it is the former, the death of fish that normally ate frogs or frogspawn could have allowed the frog population to explode. Then, there were more frogs to invade Egypt when the Nile became too toxic for the frogs to continue living in its waters. 

Bugs

The third plague is said to be a plague of “keenim,” a Hebrew word with no good English equivalent. It could mean anything from lice to fleas to gnats and flies. Regardless, the insect population likely boomed when the frogs began to die off.
After all, frogs can only live for so long outside of water. With the Nile poisoned, they had nowhere to go. As they died off, the insect populations they normally kept under control exploded as there was a sudden dearth of predators but an increase in food in the form of frog corpses. The bugs, whatever they were, likely carried the bacteria that would later become the plagues that took the forms of diseases.

Wild Animals

The fourth plague is another that is identified using an ambiguous Hebrew word, “arov.” The word roughly translates to “mixture,” but the plague has over the centuries been identified as being one of some sort of wild animals. This could mean Egypt was suddenly inundated with invasive canines such as the African Painted Dog; an uptick in attacks by native animals such as the golden jackal Ethiopian wolf or lion; a sudden swelling of smaller creatures such as scorpions and snakes or even massive swarms of flies. What precisely caused these attacks would depend on what animals the plague was referring to. Flies, for example, would have been attracted to the vast numbers of rotting frogs and fish. Invasive species could have been pushed out of their normal range by the poisoned Nile or, in the case of disasters upriver, a lack of food. Local predators would likely have been searching for water as the Nile had become toxic which would have put them in conflict with humans. 

Diseased Livestock

The fifth plague, the plague of diseased and dying livestock, was likely caused by the bugs that came as part of the third or fourth plagues.
The disease is theorized to have been rinderpest, an infectious and lethal viral disease that has decimated populations of cattle throughout African history, malaria, bluetongue, African horse sickness or even the Bubonic plague. It could also have been caused by livestock drinking water contaminated with toxic water from the Nile or feed that had gone bad from either the water or the insects. It also might have simply been dehydration brought on by a lack of clean water. As for why the diseases did not strike Israelite livestock, this could simply be because they were kept separate from Egyptian livestock or kept farther from water sources. They simply had fewer opportunities to catch diseases from the infected livestock. 

Boils

The explanation for the sixth plague, that of festering boils and sores, is rather self-explanatory. The Egyptian people were by this time living with contaminated water sources, dying or diseased livestock, rotting fish and frogs absolutely everywhere, limited food supplies as the livestock and crops died off and an overabundance of disease carrying insects. The transfer of diseases from livestock to humans was almost inevitable, and the few who escaped that fate would still have had to contend with the wide variety of diseases carried by the flies, mosquitoes and other insects swarming Egypt. Some people have argued, however, that the diseases were more extreme than most people imagine. With so many people now living with unsanitary conditions, the “boils” could have actually been smallpox sores or even the black lumps caused by the Bubonic Plague.
In fact, mummies from around the time that the Exodus is believed to have occurred have been discovered with smallpox scars. 

Flaming Hail

The seventh plague of fire, hail or flaming hail is one that seems like it would be the most difficult to explain with science. After all, fire does not often fall from the sky. When the Santorini volcano in the Aegean Sea erupted, however, there might have been. The ash would have mixed with natural storms to create massive balls of hail. The ash would also have turned any lightning a vivid red, making it appear that the sky was on fire. The presence of ash in the atmosphere would also have increased the amount of lightning in the storms. Volcanic ash is known to create electricity when it rubs against itself hence the phenomenon of “dirty lightning” in volcanic eruptions. The flaming hail could also have been still-hot pumice that was flung from the volcano. Pumice has been found in excavations of Egyptian ruins despite there not being a volcano anywhere in Egypt. The stone is light, airy and usually white or off-white. It also floats, so it could have been mistaken for hail. That said, it is cooled lava that is still searing hot when it is hurled out of the volcano by the eruption.

Locusts

The eighth plague was the plague of locusts in numbers greater than anyone had ever seen. There are two main explanations for this sudden surge in numbers. The first is that there were more locusts because more locusts than ever had been born. Locusts lay their eggs in the ground. After the incredible amount of hail dropped by the seventh plague, the conditions would have been ideal for locusts to form. Given the death of all the frogs from the second plague, there would also have been fewer predators than usual to consume the hungry locusts. Those locusts would also have been able to do more damage given that there were fewer healthy crops. The already damaged crops would also mean that there would not need to be as many locusts as usual to consume everything that was green.

The second explanation for the swarm of locusts is that they were pushed out of their usual habitats by natural disasters. This could have been trouble upriver on the Nile that pushed the locusts into Egypt where there was still at least some small amount of food, or the volcanic eruption that caused the hail in the seventh plague could have dropped ash on the locusts’ usual habitats and driven them toward Egypt. 

Darkness

There are several possible explanations for the ninth plague, the plague of darkness. One of the most popular is that the darkness was caused by the expanding ash cloud of the Santorini volcano blocking out the sun as can occur in massive eruptions. This would explain why the darkness was said to last for three days. It took that long for the ash cloud to disperse. Other explanations include easterly winds blowing dust storms across Egypt from neighboring Libya or even a simple solar eclipse. The eclipse, however, would not have lasted for days as is described in the Bible. 

Death of the Firstborn

The death of the firstborn was the final and tenth plague of Egypt. This appears to be the most miraculous of the plagues, and there is certainly not a bacterium that can differentiate between first and second born children. As such, the explanation for this plague may be cultural rather than natural. Firstborn children, especially firstborn sons, were arguably the most important members of the family. They would inherit the most and carry on the family line. As such, when times were harsh, firstborn children were taken care of first and anything leftover was giving to their siblings. Some scholars believe that firstborn children were given more to eat during the plagues of Egypt in an attempt to keep them healthy. The food stores, however, had been contaminated by mold, insect droppings, volcanic ash, algae from the Nile or a combination of such. This meant that as the firstborn ate more, they consumed more toxins. As such, they died when their siblings survived. 

Science attempts to find an explanation for everything with varying degrees of success. People may or may not accept scientific explanations for the plagues of Egypt. Some may feel that the explanations are not convincing while others might object to what they see as an attempt to dismiss God’s miracles. Even if the scientific explanations for the various plagues were exactly what happened, that does not make the plagues less miraculous. All it means is that the miracle was in nature’s timing.