However, if a wasp enters a female fig, the flowers are too long for the eggs to be successfully placed; the wasp then spreads pollen but no next generation of fig wasps, and the female fig can produce unconsumed fruit and seeds for the next generation. If a synconium from this kind of fig is never pollinated at all, the fruit does not form at all, and the synconiums dry up and drop off the tree. In other words, to bear fruit and produce seeds for the next generation of trees, a fig tree flower must be both exposed to pollen and be left unpierced by a mother wasp. Therefore, all fruit of a regular fig tree have fig wasp embryos in them; whether the fruit is consumed by the wasp embryo or not determines whether the fruit survives to adulthood.
What is a Parthenocarpic Fig Tree?
But somewhere along the way, a mutation of the fig tree occurred that doesn't require pollination to bear fruit. In this case, no fig wasp needs to make its way into the synconium and you don't find any embryos in among the completed fruit. This kind of fig is called parthenocarpic, because it produces edible fruit without pollination. Since these trees are not fertile (even if you can produce fruit you can't produce a working seed without pollination), the only way a parthenocarpic fig tree can reproduce is with the assistance of another symbiote--a human being. It's not difficult to propagate parthenocarpic figs: all you have to do is cut a branch and root it. But that takes human intervention. And without human intervention, we would have no fig trees that bear fruit without wasp embryos today.
Human Intervention and the Fig
All plants and animals evolved originally irrespective of what humans wanted. The fig doesn't care if its fruit is tasty; neither does the wasp. But humans care, and when we are looking for figs and find a tree that produces good and tasty fruit, we pick that tree to propagate. In this way, humans subvert the natural selection processes, and instead create new forms of plants or animals: this we call domestication.
The archaeological evidence recovered from the early Neolithic sites of Gilgal, Netiv Haghdad, Jericho and Gesher in the Jordan Valley and from Mureybet in the Euphrates Valley are of parthenocarpic figs, figs undisturbed by wasp embryos, and therefore, figs which had to be propagated by human beings. On that basis, say the authors, incipient horticulture of fig trees by humans began in the greater Mediterranean region by at least 11,400 years ago.
Mordechai E. Kislev, Anat Hartmann, and Ofer Bar-Yosef. 2006. Early domesticated fig in the Jordan Valley. Science 312:1372-1374.
More Information on Fig Tree Domestication
- Are Figs the Earliest Domesticate?
- A Couple of Figgy Questions, in which a reader wants to know why is that fig covered in gold, and how did the Neolithic folks know to pick that particular fig tree to propagate?