The Great Plague, the Black Plague, the Black Death – call it what you will, it was the greatest scourge the Medieval World had ever seen. It arrived in Sicily on disease-riddled ships in 1347, and swept through European cities and countries wiping out one-third to one-half of the entire population, killing 20 million people in its wake.

People’s rapid demise coupled with the mystery of contagion added to the horror. While it was observed that being in contact with infected people, their clothing or houses was a factor in catching the disease, the idea of contagion was incomprehensible at that time. Physicians were more likely to blame the position of the planets. Meanwhile, the young, old, and every age in between died in droves, so quickly that pits became massive gravesites. Rarely did anyone survive, but some did.
Did the plague discriminate or was everyone susceptible? Sharon DeWitte, a bioarchaeologist, is trying to discover just that. She spends her summers in London studying the bones of Black Death victims. She’s recorded metadata on each of the 2000 skeletons she’s studied so far, looking for clues.
People of the Middle Ages were a few inches shorter in stature than people today, i.e. the average male was 5’ 7” (170 cm) and female 5’ 2” (157.5 cm). Did their stunted stature mean there was less to eat? It is possible due to the Little Ice Age; after a long warming stretch, temperatures began to cool rapidly around 1300 and continued to drop until the late 1700s. During those previous long years of warming, plants and farming flourished in more places and so did the people, increasing the population. When temperatures cooled, many places that had once sustained growth were now unable to, and hence masses of people had less and less to eat. While it may seem obvious that the aristocrats were immune because they had money for food, it doesn’t necessarily follow that there was food to be had.
Professor DeWitte’s research shows that those who suffered malnutrition earlier in their lives were more susceptible to the Black Death. And while it is true that aristocrats also fell victim, her conclusion is that the poor died in greater numbers, and this mainly due to lack of nutrition earlier in their lives.

For more info: http://www.newsobserver.com/2014/06/22/3943477/black-deaths-silver-lining.html