All of us may be unique but Raimundo Avelino is unique in a way few others in the world are – if the concept of being uniquely unique is not too much of a pleonasm. He is an elderly man who lives in the northwest of Brazil. He is also the last known native, fluent speaker of the Kiaxana language (Mosley, 2010). His death means the death of this language in human history and culture. We often have a fascination with the last of something: Hotel Terminus, The Last of the Mohicans, the last man standing, the last star fighter, Star Trek the Last Generation. The pianist Horowitz advertised himself as ‘the last romantic.’ Orwell’s 1984 was originally called The Last Man in Europe, and Mary Shelley wrote a novel actually called The Last Man.
The Ginkgo biloba is unique in that it is the last known surviving species of a once more abundant phylum called Ginkgophyta. Darwin himself coined the term ‘living fossil’ to describe such species. Some scientists now think the term should be abandoned as it has the wrong connotations. It implies that such species have stopped evolving, when in fact their evolutionary history may be quite dynamic (Gomez, 2013; and Mao, 2012).
The fossil record of ginkgos dates back to the early Permian (Koch, 2008). There are Jurassic fossils from the Asiatic part of Russia – though way back then this would have been part of the Laurasian supercontinent. They may have been very diverse and widespread during the Cretaceous with at least 16 genera; though fossils have limited geographic coverage, and it is difficult for taxonomists to distinguish species from just fossil leaves. During the Paleocene this diversity seems reduced. Gingkoes disappear from the fossil record in North America about 7 million years ago and from Europe 2.5 million years ago. No fossils are known from the Pleistocene. The last surviving population of Ginkgos was in the Dalou Mountains of China (Tang, 2012).
This plant is now more widespread thanks to human cultivation over the last 300 years. According to recent evidence they are most closely related to the cycads in the plant kingdom (Wu, 2013). Gingkoes are vascular plants (they have leaves that function as a plumbing system). The leaf veins look unique as they branch into 2 smaller veins; hence the name ‘biloba.’ Like other trees they produce wood by division of cambian cells – they have the same familiar division of sapwood (living tissue) which dies and becomes heartwood. A ginkgo tree is either male or female. The males produce pollen cones. The females produce stalks with ovules on the end that develop into seeds after pollination. Unlike flowering plants these ovules are exposed rather than being protected by the tissue we commonly call fruit. And unlike flowering plants the sperm are motile.
Now wind pollinated, there is evidence of insect pollination from the past (Penalvar, 2012). Cretaceous amber deposits in Spain (about 110 million years old) have yielded preserved thrips. These have pollen grains still attached. The theory is that these insects fed their larvae with pollen. The larvae would have lived in female ginkgos. The thrips would have transported pollen from male trees to the larvae, thus pollinating the trees as well. Another rare fossil find has yielded very old evidence of insect mimicry of gingko leafs (Ren, 2012). Both leaves and insects from Jurassic deposits of similar age show that the wings and abdomen of Juracimbrorophlebia ginkgfolia mimicked the ginkgo leaf.
The largest and oldest Ginkgo in the world may be the so-called ‘Grand Ginkgo King.’ (Xiang, 2009) This stands about 30 meters tall with a ground level diameter of 460 cm. The internal tissues with their growth rings of the oldest part of the multi-generational trunk are gone; but the age has been estimated as 4,000-4,500 years at a maximum. You can find it in the hamlet of Li Jiawan in China. Ginkgoes are now used as ornamental plants; in China and Japan the seed kernels are a foodstuff; and it has been claimed that the leaves have medicinal properties. It has been tested as a cure for diseases ranging from Alzheimer’s to MS but with inconclusive or controversial results. (There is a large literature of medical research. See for instance Posadzki, 2013.)
Like the ginkgo we are the last of a wider family. Neandertals and Homo erectus and ‘Denisovans’ and the hobbit-like fossil found in Java a few years ago are all extinct. We see the future only through a fog. We have no way of knowing, but it is at least conceivable that we will someday be extinct and the ginkgoes will survive us. This ‘living fossil’ may then give rise to other dynamic, evolving species. But then we would not be around to name them, in Kiaxana or any other language.
- Gomez, Africa Et al. (2013) “Multiple global radiations in tadpole shrimp challenge the concept of ‘living fossils’” PeerJ, 2013; 1. http://peerj.com/articles/62
- Koch, Marcus Et al. (2008) “Phylogeography of a living fossil” Molecular Phylogenetics and Evolution Vol.48, Issue 3, Sep. 2008, Pp.1094-1105.
- Mao, Kangshan and Jianquan Liu. (2012) “Current relicts may be more dynamic in history than previously thought” New Phytologist Vol.196, Issue 3, Pp.329-331. Oct., 2012.
- Mosely, Christopher (ed.) (2010) Atlas of the World’s Languages in Danger. 3rd ed., Paris, UNESCO Publishing. http://www.unesco.org/culture/en/endangeredlanguages/atlas
- Penalvar, E. Et al. (2012) “Thrips pollination of Mesozoic gymnosperms” PNAS. Early edition 14 May 2012
- Posadzki, Paul Et al. (2013) “Adverse effects of herbal medicines: an overview of systematic reviews” Clinical Medicine Feb.1, 2013, Vol.13, No.1, Pp.7-12
- Ren, Dong Et al. “Jurassic mimicry between a hangingfly and a ginkgo from China” PNAS Dec.11, 2012.Vol.109.No.50, Pp.20514-20519. http://www.pnas.org/content/109/50/20514.short
- Tang, Cindy Q. Et al. (2012) “Evidence for the persistence of wild Ginkgo biloba (Ginkgoaceae) populations in the Dalou Mountains southwest China” American Journal of Botany, Vol.99 No.8, Pp.1408-1414, Aug.2012. http://www.amjbot.org/content/99/8/1408.short
- Wu, Chang-Shien Et al. (2013) “Chloroplast phylogenomics indicates that Ginkgo biloba is sister to Cycads” Genome Biology and Evolution. 5 (1): 243-254. http://gbe.oxfordjournals.org/content/5/1/243.full
- Xiang, Zhu Et al. “The Li Jiawan Grand Ginkgo King” http://arnoldia.arboretum.harvard.edu/pdf/articles/2009-66-3-the-li-jiawan-grand-ginkgo-king.pdf