The extinction of silphium:
Damn Interesting » The Birth Control of Yesteryear: Unfortunately, modern science will probably never determine whether... [silphium] was an effective form of parenthood prevention.... By the end of the first century AD, following a fifty year decline in silphium numbers, the Roman historian Pliny the Elder recorded the plant's lamentable extinction.... The cause of the herb [silphium's] eradication is uncertain, however the most widely accepted theory is that over-harvesting coupled with livestock grazing caused the silphium population to decline beyond recovery. This trend may have started around 74 BCE when the region was absorbed into a Roman senatorial province. This change gave control of the laserwort crop to a long series of one-year-term governors who were largely motivated by short-term profits...
The consumer surplus from silphium was enormous:
Damn Interesting » The Birth Control of Yesteryear: Approximately 2,600 years ago--around 630 BCE--the Greek island of Thera was plagued by drought and overpopulation. According to legend, an assortment of settlers were selected to sail south to establish a colony in more hospitable climes. The men and women apprehensively put to sea, and the gaggle of enterprising Greeks eventually erected the city of Cyrene on Africa's northern tip. There, the settlers encountered a local herb which would ultimately bring them and their progeny fantastic wealth.
The prized plant became such a key pillar of the Cyrenean economy that its likeness was stamped upon many of the city's gold and silver coins. The images often depicted a regal-looking woman sitting in a chair, with one hand touching the herb and her other hand pointing at her genitals. The plant was known as silphium or laserwort, and its heart-shaped fruit brought the ancient world a highly sought-after freedom: the opportunity to enjoy sex with very little risk of pregnancy.
The silphium plants were giant fennels which grew wild along the dry hillsides of the Mediterranean coast. It didn't take long for the Greek settlers to discover its value as a food source, and the vegetable flesh came to be prized as a delicious garnish, while pleasant perfumes were coaxed from its yellow blossoms. Over time further uses for the wild fennel were found, such as the resin extracted from its stalks and roots which was used to treat cough, sore throat, fever, indigestion, snake bite, "warts in the seat," epilepsy, and a host of other disagreeable ailments. But of all of the plant's virtues, the silphium was certainly most prized for its pregnancy-preventing properties.
As word of the birth-control wonder-herb spread through ancient Europe, Africa, and Asia, a market for the versatile fennel developed rapidly. The seeds became widely used among the world's wealthier nations, including the citizens of ancient Greece, Rome, Egypt, and India. By some accounts the silphium seed was also a potent aphrodisiac, a property which considerably compounded its perceived value. The Roman bard Catullus famously alluded to its sexual properties in one of his love poems, where he declared that he and his lover would share as many kisses as there were grains of sand on Cyrene's silphium shores. More plainly, "We can make love so long as we have silphium."
Despite the efforts of the Cyreneans and their would-be competitors, the silphium industry stubbornly resisted expansion. Men worked long and hard to propagate the plant, but the notoriously cantankerous laserwort mocked all efforts at cultivation. It refused to sprout anywhere outside of its narrow swath of wild growth along the coast of the Mediterranean Sea. Though this limitation necessitated strict guidelines to prevent over-harvesting, the natural scarcity served to maintain the herb's high value. Occasional silphium smugglers penetrated the supply chain, but aside from these rare exceptions the royalty of Cyrene maintained a comfortable monopoly on civilization's contraceptives.
For centuries the north African city thrived on its laserwort bounty. The seeds of the fickle fennel came into such high demand that they were eventually worth their weight in silver. The Roman government went so far as to store a cache of the herb in the official treasury. Most of the primitive silver and gold coins from Cyrene were stamped with images of the silphium, some depicting just a single heart-shaped seed. It is thought by many historians that this ancient icon of unfettered lovemaking is the origin of today's ubiquitous "I love you" heart symbol.
Unlike many other medicines of its time, silphium was not thought of as a mere folk remedy; Scholars and doctors of the day openly praised the plant's effectiveness as a contraceptive. Ancient Rome's foremost gynecologist--a physician named Soranus--wrote that women should drink the silphium juice with water once a month since "it not only prevents conception but also destroys anything existing." Alternatively, a tuft of wool could be soaked in the juice and inserted into the vagina as a pessary. The herb's effectiveness and widespread use is evidenced by the observation that Rome's birth rate decreased during laserwort's heyday, despite increasing life expectancy, plentiful food, and relatively few wars or epidemics....
The extinction of silphium is now considered to be among humanity's earliest environmental blunders. If laserwort was indeed more effective than the alternatives, then the bygone birth control is certainly deserving of its glowing reputation...
I had never known why Cyrene was important enough to warrant a place in the list of "Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia, Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome." Writing in the fourth century C.E., Ammianus Marcellinus says that Cyrene is a deserted, ruined city.