Caral: an ancient South American city
Huge earth and rock mounds rise out of the desert of the Supe Valley near the coast of Peru in South America. These immense mounds appear simply to be part of the geographical landscape in this arid region squeezed between the Pacific Ocean and the Andes mountains. But looks deceive. These are actually human-made pyramids. Strong evidence indicates they are the remains of a city known as Caral that flourished nearly 5,000 years ago. If true, it would be the oldest known urban center in the Americas and among the most ancient in the world.
Research undertaken by Peruvian archaeologist Ruth Shady suggests that the 150-acre complex of pyramids, plazas and residential buildings was a thriving metropolis when Egypt's great pyramids were still being built. Though discovered in 1905, for years Caral attracted little attention, largely because archaeologists believed the structures were fairly recent. But the monumental scale of the pyramids had long interested Shady, who began excavations at the site in 1996, about 22 kilometers from the coast and 190 kilometers north of Peru's capital city of Lima.
Shady and her crew searched for broken remains of the pots and containers that most such sites contain. Not finding any only made her more excited: it meant Caral could be what archaeologists term pre-ceramic, that is, existing before the advent in the area of pot-firing techniques. Shady's team undertook the task of excavating Piramide Mayor, the largest of the pyramids. After carefully clearing away many hundreds of years' worth of rubble and sand, they identified staircases, walls covered with remnants of colored plaster, and brickwork. In the foundations, they found the remains of grass-like reeds woven into bags. The original workers, she surmised, must have filled these bags with stones from a nearby quarry and laid them atop one another inside retaining walls, gradually giving rise to the pyramid's immense structure. Shady had samples of the reeds subjected to radiocarbon dating and found that the reeds were 4,600 years old. This evidence indicated that Caral was, in fact, more than 1,000 years older than what had previously been thought to be the oldest urban center in the Americas.
What amazed archaeologists was not just the age, but the complexity and scope of Caral. Piramide Mayor alone covers an area nearly the size of four football fields and is 18 meters tall. A nine-meter-wide staircase rises from a circular plaza at the foot of the pyramid, passing over three terraced levels until it reaches the top. Thousands of manual laborers would have been needed to build such a project, not counting the many architects, craftsmen, and managers. Shady's team found the remains of a large amphitheater, containing almost 70 musical instruments made of bird and deer bones. Clearly, music played an important role in Caral's society. Around the perimeter of Caral are a series of smaller mounds and various buildings. These indicate a hierarchy of living arrangements: large, well-kept rooms atop pyramids for the elite, ground-level quarters for craftsmen, and shabbier outlying dwellings for workers.
But why had Caral been built in the first place? Her excavations convinced Shady that Caral once served as a trade center for the region, which extends from the rainforests of the Amazon to the high forests of the Andes. Shady found evidence of a rich trading environment, including seeds of the cocoa bush and necklaces of shells, neither of which was native to the immediate Caral area. This environment gave rise to people who did not take part in the production of food, allowing them to become priests and planners, builders and designers. Thus occupational specialization, elemental to an urban society, emerged.
But what sustained such a trading center and drew travelers to it? Was it food? Shady and her team found the bones of small edible fish, which must have come from the Pacific coast to the west, in the excavations. But they also found evidence of squash, sweet potatoes and beans having been grown locally. Shady theorized that Caral's early farmers diverted the area's rivers into canals, which still cross the Supe Valley today, to irrigate their fields. But because she found no traces of maize, which can be traded or stored and used in times of crop failure, she concluded that Caral's trade leverage was not based on stockpiling food supplies.
It was evidence of another crop in the excavations that gave Shady the best clue to Caral's success. In nearly every excavated building, her team discovered evidence of cotton—seeds, fibers and textiles. Her theory fell into place when a large fishing net made of those fibers, unearthed in an unrelated dig on Peru's coast, turned out to be as old as Caral. 'The farmers of Caral grew the cotton that the fishermen needed to make their nets,' Shady speculates. 'And the fishermen gave them shellfish and dried fish in exchange for these nets.' In essence, the people of Caral enabled fishermen to work with larger and more effective nets, which made the resources of the sea more readily available, and the fishermen probably used dried squash grown by the Caral people as flotation devices for their nets.
How plants fight back
A Recent research has shown that plants are more aware of their environment and more active in their responses than was ever previously imagined. Simon Gilroy, a professor of botany at the University of Wisconsin-Madison in the USA, has spent much of his career trying to understand how plants work. Now, Gilroy and one of his post-doctoral researchers, Masatsugu Toyota, have produced a series of videos that shows how plants responded when they subjected them to wounds, including scissor cuts and caterpillar bites.
B Gilroy and Toyota discovered that when one part of a plant is attacked or damaged, a wave of calcium spreads throughout the rest of the plant. The calcium alerts the plant to danger and the need to deploy defence tactics. The team were able to see this by utilising a naturally occurring fluorescent-green protein which binds to the calcium, making its path visible.
While scientists already knew that plants reacted to danger via an electrical charge that moves across the plant, they didn't know exactly how it happened. Gilroy and Toyota suspected it had something to do with calcium and were able to confirm their suspicions. They were also able to reveal how glutamate—an abundant neurotransmitter in animals—triggers this wave of calcium.
C The find was fortuitous given that Gilroy hadn't intended to study wounding at all. His real passion is understanding how plants sense gravity and seem to know which way is up—something that's proving extremely hard to work out. It was during the early stages of an experiment into gravity that Toyota came across the wounding response.
'We work very intensely on the calcium signal, because it's a ubiquitous signal. Biology uses it absolutely everywhere,' explains Gilroy. 'It makes your heart beat, it makes your muscles contract. Plants use it for a lot of their signalling machinery. We had some hints that the gravity-sensing system is based around the calcium signal, and so we were developing the technology to image calcium cells in real time.' It was during this process that Gilroy and Toyota realised they'd captured something never usually visible to humans.
D The team found that the calcium travels at one millimetre per second, fast enough to spread to other leaves in just a couple of minutes. From the data collected up to now, it appears that how far the calcium travels depends on the extent of the wound, or, as Gilroy puts it, 'The more you hurt it, the louder it screams.'
That 'scream' can result in a range of responses. 'Plants are masters of chemistry,' says Gilroy. 'We deal with the world by running away from it; plants deal with the world by growing in response to it, or by making a tonne of stuff.' That 'tonne of stuff' could be chemicals that poison a hungry insect, or that make the plant unattractive, tough or unpalatable. Some plants even make proteins that block the ability of a caterpillar's gut to digest the plant material. This is dinner that fights back.
E The next step for Gilroy and his team is to delve deeper into the signalling response on a cellular level, dissecting the genes and proteins responsible. In contrast to our understanding of human nerve cells, Gilroy admits that the equivalent responses in plants are still barely understood. He is also going to widen the scope of the study and look at other signals that plants send out—signals regarding temperature and changes in light and touch.
Gilroy explains that there may be a wider use for the research, albeit a long way in the future. Once scientists have managed to identify the specific genes that make the signalling process work and can understand what happens when you switch those genes on and off, it's not hard to think about the potential. 'You can imagine that we should be able to take a crop plant and switch on its defences on-call,' says Gilroy. 'We're nowhere near that point yet, but once we get there—say you're in a field and you predict there's going to be an outbreak of some pest—you could go in and pre-defend all of the plants in the field, but you do it on-call so the plants aren't wasting their resources defending themselves the whole time.'
F For now, though, Gilroy is happy to simply increase understanding of plants. He is energetic in his insistence that they are not the inactive and unreceptive organisms that people generally believe them to be. For that reason, he's as enthusiastic about the way the videos bring the response process to life as he is about the future potential of the research. 'When you look at a plant, just because it doesn't do what we do, and it doesn't move, that doesn't mean it isn't doing anything. They're hugely dynamic organisms,' he says.
Rewards for scientific achievement
While the Nobel Prizes are over 115 years old, rewards for scientific achievement have been around much longer. As early as the 17th century, at the very origins of modern experimental science, promoters of science realized the need for some system of recognition and reward that would provide incentive for advances in the field.
Before the prize, it was the gift that dominated in science. Precursors to modern scientists—the early astronomers, philosophers, physicians, alchemists and engineers—offered wonderful discoveries, inventions and works of literature or art as gifts to powerful patrons, often royalty. Many scientists prefaced their publications with extravagant letters of dedication; they might, or they might not, be rewarded with a gift in return. Eventually, different kinds of incentives, including prizes and awards, as well as new, salaried academic positions, became more common and the favor of particular wealthy patrons diminished in importance. But at the height of the Renaissance, early scientists relied on gifts from powerful princes to compensate and advertise their efforts.
With courtiers all vying for a patron's attention, scientific gifts had to be presented with drama and flair. The astronomer Galileo Galilei (1564–1642) presented his newly discovered moons of Jupiter to the Medici dukes of Italy as a 'gift' that was literally out of this world. In return, the Medici family 'ennobled' Galileo with the title and position of court philosopher and mathematician. If a gift succeeded, the gift-giver might, like Galileo in this case, be fortunate enough to receive a gift in return. Gift-givers could not, however, predict what form a patron's gift would take, and they might find themselves burdened with offers they couldn't refuse. Tycho Brahe (1546–1601), the great Danish Renaissance astronomer, received everything from exotic animals to chemical secrets in return for his discoveries.
By the early-17th century, scientific promoters realized that gift-giving was ill-suited to encouraging experimental science. Experimentation required many individuals to collect data in many places across long periods of time. Gifts emphasized competitive individualism at a time when scientific collaboration and the often humdrum work of empirical observation were paramount.
While it was accepted that some competitive rivalry helped to inspire and advance science, scientific reformers believed that too much led to the ostentation that too often plagued courtly gift-giving. Most of all, reformers feared an individual would not tackle a problem that couldn't be finished and presented to a patron in his or her lifetime—or even if they did, their findings might die with them.
For these reasons, promoters of experimental science saw the reform of rewards as integral to radical changes in the pace and scale of scientific discovery. For example, Sir Francis Bacon (1561–1626), lord chancellor of England and an influential booster of experimental science, emphasized the importance even of 'approximations' or unfinished attempts at reaching a particular goal. Instead of dissipating their efforts attempting to appease patrons, many researchers, he hoped, could be stimulated to work toward the same ends via a well-publicized research wish list. Bacon coined the term 'desiderata', still used by researchers today to denote widespread research goals. He also suggested many ingenious ways to advance discovery by stimulating the human hunger for fame; a row of statues celebrating famous inventors of the past, for example, could be paired with a row of empty plinths upon which researchers might imagine their own busts one day resting.
Bacon's techniques inspired one of his chief admirers, the reformer Samuel Hartlib (circa 1600–1662), to collect many schemes for reforming the system of recognition. One proposed that rewards should go not only 'to such as exactly hit the marke, but even to those that probably misse it', because their errors would stimulate others and make 'active braines to beate about for New Inventions'. Hartlib planned a centralized office systematizing rewards for those who 'expect Rewards for Services done to the King or State, and know not where to pitch and what to desire'.
Collaborative scientific societies, beginning in the mid-17th century, distanced rewards from the whims and demands of individual patrons. The periodicals that many new scientific societies started publishing offered a new medium that allowed authors to tackle ambitious research problems that might not individually produce a complete publication pleasing to a dedicatee. The societies saw their periodicals as a means to entice discovery by offering credit. Today's Leopoldina, the German national scientific society, founded its publication in 1670. According to its bylaws, those who might not otherwise publish their findings could see them 'exhibited to the world … with the praiseworthy mention of their name'—an important step on the way to standardizing scientific citation.
States might also offer rewards for solutions to problems, most famously in the case of the prize offered by the British government in 1714 for figuring out how to determine longitude at sea. Some in the 17th century likened this long-sought discovery to the philosopher's stone. The idea of using a prize to highlight a specific problem is alive and well today. In fact, some contemporary scientific prizes, such as the Simons Foundation's 'Cracking the Glass Problem', set forth specific questions that still need to be resolved.
The shift from gift-giving to prize-giving completely transformed the rules of engagement in scientific discovery. Of course, the need for monetary support hasn't gone away. Obtaining financial support can still be a sizable part of what it takes to get science done today. Succeeding in grant competitions might seem mystifying, and winning a career-changing Nobel might come as a bolt out of the blue. But researchers can take comfort that they no longer have to present their innovations on bended knee as wondrous gifts that will appeal to the whims of individual patrons.