THEIR leaves clothed Adam and Eve; their roots were used by the Maasai people’s god to shuttle the first cattle from heaven to Earth; and according to an Indonesian story, two gods carved the first couple from their wood. The presence of fig trees in numerous origin myths is down to more than coincidence. They have shaped our world since long before the dawn of humanity, and have fed us and our imaginations for millennia. Now, as the world warms and forests fall, these extraordinary trees could help us to restore life to deforested landscapes.
It’s all because fig trees cut a curious deal with tiny wasps back when dinosaurs still roamed. Thanks to this, they sustain far more biodiversity than other trees. Today, there are more than 750 species of Ficus, each of which relies on its own wasp species to pollinate its flowers. In turn, the wasps can only breed inside the figs of their partner tree. Genetic studies suggest that this remarkable codependency is at least 80 million years old.
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It begins with a tiny female fig wasp. Barely 2 millimetres long, she crawls out of a hole in the fig she was born inside, and takes flight for the first time carrying pollen and hundreds of fertilised eggs. She seeks a fig on another tree of the same species. The nearest one could be tens of kilometres away, yet the insect has less than 48 hours to complete her mission.
Fortunately, fig trees are great communicators. As their figs hit the right age to receive pollen, they pump a cocktail of chemicals into the air. This whiff of perfume is what our female fig wasp seeks. She lands on the tree’s hard green fruit and forces herself through a tiny orifice that leads to its hollow centre. The squeeze wrenches her antennae and wings from her body. No matter – this is a one-way journey.
Inside are hundreds of flowers, packed together. As the female wasp moves, she scatters them with pollen from her birth fig, ensuring that they will produce seeds. She also injects as many as she can reach with her eggs, just one per flower. If she’s fast, she can lay more than 200 before finally dying of exhaustion.
“Figs feed more bird and mammal species than any other fruit”
Weeks pass and the offspring are ready to emerge. The males are first. They are virtually blind and wingless but have strong jaws. During their short adult lives, they crawl around inside the fig, chew holes in the plant tissue encasing the females and fertilise as many as possible before dying. Soon after, the females will take flight and the cycle repeats.
What of the figs? After the wasps depart, their entire biology becomes geared towards attracting far bigger animals than fig wasps. The figs swell, blush and are pumped with sugar. Birds, bats, monkeys and other animals will come to feed on them, depending on the species of Ficus. Later, when the animals defecate, they will disperse tiny fig seeds far and wide, each with the potential to grow into a new tree.
A side effect of depending on short-lived wasp pollinators is that ripe figs are found year round across the tropics. They sustain wild animals when other fruit are scarce, feeding at least 1270 bird and mammal species, far more than any other fruit. This makes them ecological linchpins: without them, many rainforest animals would struggle or starve, with knock-on effects for the thousands of other plants whose seeds they disperse.
And now there are signs that planting fig trees could help us address deforestation, biodiversity loss and climate change in countries as diverse as Australia, Costa Rica, Indonesia, Rwanda, South Africa and Thailand.
In Thailand, biologist Steve Elliott has been planting several Ficus species in the degraded forest of Doi Suthep-Pui National Park. “Figs are a magnet for seed dispersal,” he says. “Wildlife comes flooding in.” They grow fast and their thick leaves cast a dense shadow that prevents weedy grasses from taking hold. Within three years of planting, several of the Ficus species were producing figs, attracting monkeys, civets and barking deer. Within six years, the number of bird species in the area rose from 30 to 87. Within eight years, more than 70 other tree species had recolonised the experimental plots.
In Costa Rica, researchers have been lopping 4-metre-long branches from fig trees and planting them as “instant trees” that sprout fresh roots and branches. The aim is to regenerate the rainforest faster than is possible by planting seedlings. Early results show that the trees survive well and can produce figs in under a year.
Stronger than stone
Back in Thailand, Elliott noticed fig seeds germinating in cracks in walls and pavements of Chiang Mai University. The cracks got wider as the roots expanded. If figs could do that to concrete, he wondered, could they do it to rock?
His team is now testing whether fig trees can help turn former opencast mines into rainforest by using their roots to split the bare rock into smaller pieces, letting air and water in so soil can develop. “If anything can break it open it’s going to be figs,” he says.
To encourage seeds to germinate under such harsh conditions, Elliott’s team have developed a hydrating gel into which seeds are added. They are also experimenting to see if packets of this seed-filled gel can be delivered to steep, remote locations by drones.
This and similar research shows that Ficus species can kick-start the regrowth of rich forests whose trees and soils lock away carbon and so limit global warming. Their figs sustain hundreds of animal species, their roots stabilise soil, limiting landslides and erosion. Modern science is learning a lesson that was among the first our species grasped: fig trees are our friends, and good things come to those who protect them.
One significant fig
Humans and fig trees have a long shared history: fossilised fig wood was found alongside Ardipithecus ramidus, a hominid from 4.6 million years ago; when the first modern humans emerged in Africa about 200,000 years ago, the continent had more than 100 fig species; and when their descendants migrated out of Africa, they found new kinds of fig trees offering similar gifts. These days, far-flung cultures – from the Maya in Central America to the Kikuyu in Kenya – have taboos against cutting fig trees down.
These trees may also have helped our nomadic ancestors settle into villages. In 2004, archaeologists led by Mordechai Kislev of Israel’s Bar-Ilan University excavated the remains of an 11,400-year-old building in the lower Jordan valley – one of the first ever built. Inside, they found partially fossilised figs along with acorns, wild barley and oats.
The figs were from sterile trees that could have only spread if people were intentionally planting branches in the soil. For Kislev, this is a sign that the Jordan valley settlers were already domesticating fig trees during the early days of agriculture.
Even if he is wrong, others have found evidence of fig cultivation dating back to 5000 years ago. It was only a matter of time before farmed figs were fuelling the bodies that built the great civilisations of the Sumerians, Egyptians, Greeks and Babylonians.
This article appeared in print under the headline “Figs on a roll”
