The annual pilgrimage to Mecca, the Islamic hajj, began in the seventh century as a local custom that then became an international meeting that facilitated the transfer of everything from Islamist ideas and political movements (the Idrisis of Libya) to luxury goods (ivory) plants (rubber to Southeast Asia, rice to Europe), and diseases (meningococci, skin infections, infectious diarrheal and blood-borne diseases, and respiratory tract infections, including perhaps the brand-new MERS-CoV).
Other Islamic injunctions also have unintended, negative health implications. The imperative for modesty has led some Muslim women to wear full head and body coverings (niqabs and burqas) which cause Vitamin D deficiency, discourage exercise, and are implicated in a host of medical problems, including rashes, respiratory disease, rickets, osteomalacia, and multiple sclerosis.
The daytime fast during Ramadan often leads observant Muslims to exercise less and to "tend to overeat upon breaking their fast, and usually the meal involves heavy, fatty foods that are high in calories," notes the head of the Emirates Diabetes Society. One survey in Jidda, Saudi Arabia, found 60 percent of respondents reporting excessive weight gain after Ramadan.
A preference for first-cousin marriages, which harks back to pre-Islamic tribal practices (to keep wealth in the family and to benefit from daughters' fertility) over approximately fifty generations has led to widespread inbreeding with negative consequences, including about twice the incidence rate of such genetic disorders as thalassemia, sickle cell anemia, spinal muscular atrophy, diabetes, deafness, muteness, and autism.
With regard to women, injunctions about mahram protection by male relatives, and a vastly lower social and legal status combined to create such inadvertent patterns as physical seclusion, obsession with virginity, honor killings, female genital mutilation, and (Saudi-style) gender apartheid. Polygamy creates permanent anxiety in wives.
Although orphans enjoy an honored status in Islamic law (kafala), that honor is tied to a tribal structure incompatible with modern society, resulting in Muslim orphans today persistently discriminated against, even by Muslims in the West.
Islam's scriptures have provided the base from which many other patterns evolved, including: the establishment of dynasties through conquest, not by internal overthrow; recurrent problems with dynastic succession; power leading to wealth, not the reverse; the near absence of municipal governments; inadequate regulation of cities; laws arising from ad hoc decisions, not formal legislation, reliance on hawalas for money transfers, and the practice of
Inadvertent patterns, sometimes called Islamicate, change over time, with some (slave soldiers) becoming defunct and others (polio) starting only recently. These patterns remain as powerful today as in premodern times and are key to understanding Islam and Muslim life.