The Triumph of Seeds (14 page)

In my pea bed, the time had come to harvest. It was late summer, and the vines drooped in the heat, pods yellowed, peas ripe and dry within. Though Mendel often worked alone, he did have the help of various monastery novices, as well as a trained assistant. My staff consisted of one three-year-old, but Noah’s enthusiasm for any seed project made him an eager accomplice. We pulled up the vines, sat down on the shady porch, and started to separate peas from pods. Quick as a flash, Noah snatched up a handful and popped them into his mouth. Years before, I’d made the mistake of taking a dog with me on a mammal-trapping project, only to watch him pounce upon
and devour the start of a promising dataset. In this case I still got my data, because Noah spat the seeds right back out again. Unlike the sweet ones in Mama’s garden, these peas had been grown to maturity, and they were hard and dry, like raw lentils. He didn’t say anything, but gave me a disgusted look that recalled one of his earliest paragraphs, carefully phrased one morning after I served his breakfast: “Mama cook food. Papa cook poop.”

As we made our way through the pile of pods, I found myself impressed again by Mendel’s incredible patience, and the sheer size of his task in counting all those peas. Even though my harvest was small, reduced by an unexpected pest we’ll return to in
Chapter 8
, things had gotten a little monotonous by the time we scooped out the final pea. But that sameness was also fascinating—in fact, it was the whole point. My experiment replicated the first generation of Mendel’s work: crossing pure strains of two distinct varieties. I bred smooth, round Württemberg peas with an old American type called Bill Jump, whose seeds are distinctly wrinkled. If Mendel was right, then the dominant smooth genes should have completely swamped Bill Jump’s wrinklies. And now, after months of tending, here was exactly the expected result: a small jar of smooth, round peas, as if the Bill Jump genes had simply disappeared. I picked up a handful and let them run through my fingers, sensing what Mendel must have felt: the satisfaction of understanding a system well enough to predict it.

When something is known, it’s hard to imagine it as a mystery. But for decades after Mendel’s discoveries, no one else glimpsed the secrets of inheritance the way that he had. He lived out his life in Brünn, dying in obscurity while scientists around the world still struggled to understand how traits were passed from parents to offspring. As one frustrated botanist put it in 1899: “we need no more
general
ideas about evolution. We need
particular
knowledge of the
evolution of
particular
forms.” As if in answer to that wish, three researchers published “rediscoveries” of Mendelian inheritance the following year, and the field of modern genetics was born.
Independently, they each replicated aspects of Mendel’s work and came to similar conclusions. And independently, they all did so in the same way he had: by controlling pollination and examining the traits of seed plants: corn, poppies, wallflowers, evening primrose, and the smooth or wrinkled seeds of the common pea.

In nature, the consistent genetic mixing that goes on in seeds gives them great evolutionary potential. Where spore sex was haphazard and often self-induced, seeds combined the genes from two parents regularly and directly, using increasingly intricate flowering strategies. It’s a habit that helped seed plants diversify and dominate in nearly every terrestrial habitat, and it sped the development of all the other seed traits we’ll talk about in this book. For people, it allowed the breeding of crops as varied as string beans and starfruit, and it gave us one of our most profound insights into the process of evolution. But the genes in a seed would hardly be so useful without another characteristic that we tend to take for granted.

Breeding a generation of smooth peas brought me closer to Mendel, but I wanted to continue his elegant experiment for one more year, just to see that famous
three-to-one ratio in the same way that he had. If the Punnett Square could be trusted, then breeding this year’s crosses would produce a predictable number of double-recessive peas with the wrinkled appearance of a pure Bill Jump. I could only do this because I knew that a packet of dry peas would be just fine sitting on a shelf in the Raccoon Shack until President’s Day rolled around again. In fact, those seeds would last for two years, three years, or even longer—slumbering away in a peculiar state of suspended animation. Gardeners rely on it, plant breeders rely on it, and so does the ecology of everything from peas to rainforest trees to wildflowers in an alpine meadow. But exactly how a seed can lie dormant for years or even centuries before germinating is a fundamental mystery that scientists are only just beginning to understand.

Seeds Endure

Can you find another market like this?

Where, with your one rose

you can buy hundreds of rose gardens:

Where,

for one seed

you get a whole wilderness?

—Rumi,

“The Seed Market” (c. 1273)

CHAPTER SIX

Methuselah

Wheat in plenty was laid up, ample for the needs of the beleaguered for a long time, and wine and oil in abundance, as well, all sorts of pulses and dates heaped up together.

—Flavius Josephus, describing the storehouses of Masada,

History of the Jewish Wars
(c.
AD
75)

T
he Roman general Flavius Silva arrived at the base of Masada Fortress in the winter of
AD
72–73. History tells us he had a full legion of soldiers at his command, as well as thousands of slaves and camp followers. History does not preserve what he was thinking at that moment, but anyone who has ever seen Masada Fortress knows it must have been some version of, “Oh, shit.”

Perched atop a 1,000-foot (320-meter) rock spire and surrounded by sheer cliffs, the stronghold boasted fortified casemate walls, watchtowers, and a well-stocked armory. It commanded sweeping views in every direction, and one of the only approaches was a steep, winding trail known ominously as “the snake path.” What’s more, the people defending Masada belonged to a particularly fierce group of Jewish rebels called the Sicarii, named for the wicked daggers they used to assassinate their enemies. General Silva must also have realized that while he and his army would be forced to camp in the harsh, rocky desert that surrounded the fortress, the rebels had their choice of villas and palaces styled to the tastes of Masada’s original builder, Herod the Great.

F
IGURE
6.1.  This 1858 painting by Edward Lear,
Masada (or Sebbeh) on the Dead Sea
, shows the formidable approach to Masada Fortress. The ancient ramp erected by its Roman attackers is clearly visible as a ridge ascending from the right. W
IKIMEDIA
C
OMMONS
.

The Romans settled in for a long siege. Silva had orders to crush the Sicarii, the last holdouts of a widespread Jewish uprising known as the Great Revolt. Over the course of several months, his engineers erected an embankment that is still clearly visible, rising like a massive wave of earth up the western side of the mountain. When it was finished, Silva’s soldiers marched to the top, breached the wall with a battering ram, and took the fortress by storm. At the time, this victory gave General Silva a major career boost. He served as governor of Judaea for eight years and later returned to Rome as consul, a position second only to the emperor. In retrospect, however, the Siege of Masada did quite a lot more for the cause of Jewish nationalism, for coin collectors, and for our understanding of dormancy in seeds.

When Silva’s legionaries entered Masada, they expected to find dagger-wielding warriors, but were met instead with an eerie silence. Rather than surrender or risk capture, nearly 1,000 Sicarii men, women, and children had committed mass suicide. The story of their resistance and sacrifice has become a near-mythic symbol of
endurance to the Jewish people. In the run-up to statehood, future leaders of Israel embraced Masada as an allegory for national unity and resolve. For decades young Israeli scouts and soldiers have hiked the snake path as a rite of passage, and Masada now ranks among the most popular tourist attractions in the country. If Silva returned today, he could take a cable car to the top, and he would find the phrase “Masada Shall Not Fall Again” emblazoned on everything from t-shirts to coffee mugs.

For coin collectors and seed experts, the defenders of Masada are remembered less for what they did than for what they left behind. Not wanting the Romans to recover anything of value, the last Sicarii moved their possessions and food supplies into a central warehouse and then
set the building ablaze. As the wooden beams and rafters burned, the stone walls collapsed inward, forming a heap that would lie undisturbed for nearly 2,000 years. Archaeologists picking through the rubble in the 1960s unearthed a trove of ancient shekels that settled several nagging questions about
Jewish numismatics. Not surprisingly, many of the coins featured the graceful curving leaves of the Judaean date palm, a tree whose fruit was both a local staple and a highly profitable export. Emperor Augustus was said to favor them, and vast date-palm orchards lined the Jordan River from the Sea of Galilee south to the shores of the Dead Sea. Digging deeper, the excavation team soon encountered provisions: salt, grain, olive oil, wine, pomegranates, and a generous supply of the dates themselves, so beautifully preserved that scraps of fruit still clung to the seeds.

While it makes perfect sense for the Sicarii to have stocked up on their country’s most famous crop, finding dates at Masada was still a major event. Though mentioned in the Bible and the Koran, and praised for their sweetness by everyone from Theophrastus to Pliny the Elder, the particular date variety grown in Judaea had long since disappeared—a victim of changing
climate and settlement patterns. Now, for the first time in centuries, people could see and hold the fruit that was once considered King Herod’s main source of revenue. What happened next, however, was even more remarkable. Four decades after museum workers had cleaned, labeled, and cataloged the Masada dates, someone decided to plant one.

F
IGURE
6.2.  Date (
Phoenix dactylifera
). Cultivated since ancient times for their sweet fruits, date palms also hold the record for longevity in seeds. A date seed recovered from the ruins of Masada Fortress germinated after lying dormant for nearly 2,000 years. I
LLUSTRATION
© 2014
BY
S
UZANNE
O
LIVE
.