Homo and Quercus were long standing partners during their shared history that has been extensively counted by artists, writers, scientists in their works. Their history tells about reciprocal benefits, shared wonder, mutual respect, but also competitions and fratricidal struggles. Since the first European Homo sapiens venerated Quercus robur as Axis mundi, the oaks have acknowledge humans by providing for all their vital, cultural and mystical needs. And since then this intimate relationship has grown stronger over the ages to our time. Almost everything has been said about their respective and shared pasts, but their future raises unexplored questions. At a time when men are concerned about the conservation of oaks, have we really wondered who among humans and oaks are facing the most challenging risks for their sustainability? What does biological evolution hold for Quercus and Homo? After all, they face the same evolutionary challenge, as any living species, of sustaining and surviving regardless of extreme events, climates, and the course of history. Starting from this equal footing, it is appropriate to question the strengths and strategies specific to Homo and Quercus which will enable them to face their sustainability challenge. The approach may seem inappropriate and would undoubtedly be strongly contested by the scientific community on the grounds of mixing and confusion of roles, but the comparison will have the merit of reconsidering the place of Homo in future evolution. It will undoubtedly be objected that the elements of context make any comparison scientifically illegitimate. Yet, that species may be able to evolve and adapt requires that they are equipped with basic properties, regardless of their ecological status. Evolutionary sustainability depends on demography, diversity, reproduction and gene flow.
No need to take a census on a global scale, a comparison on the level of the French territory is enough to show the demographic inequality between Homo and Quercus. A quick calculation based on statistics of french forest areas suggests that there are more than 5 billion sessile oak trees in France, and even more if we add pedunculate oak. There are therefore 150 times more trees (sessile oak and pedunculate oak combined) than human beings in France.
Homo sapiens is desperately lonely and no longer has a congeneric partner species (belonging to the same genus). On the other hand, oaks are always associated with other oak species with whom they share the same forests. The best known example in Europe is the Sessile - Pedunculate pair. But in many other places in the Northern Hemisphere multiple oak species cohabit.
Beyond specific diversity, genetic diversity within a species also deserves to be considered in relation to the future evolution of Homo and Quercus. Here again, the figures are irrefutable. The availability of reference genome sequences in both species allows us today to compare their diversity. Depending on the statistics used to assess genetic diversity, there is 5 to 10 times more diversity in oaks (Quercus robur or Quercus petraea) than in Homo sapiens. Not only are oaks more numerous, but they are also more diverse.
Is it really necessary to do a numerical calculation to illustrate the astonishing fertility of an oak tree? Hundreds of thousands of acorns are produced during the lifetime of an oak tree … offering many opportunities for natural selection to operate. Not only are oaks highly prolific, but they are also able to reproduce vegetatively. Even extreme disasters (storms, fires, etc.) that destroy all aerial parts of trees cannot eradicate them. Oaks have still the opportunity to regenerate by stump sprouting or suckering.
It is challenging to compete with Homo for genetic mixing, which has continually genetically shaped human populations. Of course oaks also disperse their genes, mainly through pollen clouds, but most likely at shorter distances.
But the difference is not in intra-species mixing. The essential difference lies in the mixing between species. Interspecific hybridization is the rule in Quercus, while Homo has now partner species any more. Hybridization was essential for oaks to survive and expand in the Northern Hemisphere. Evolutionary investigations have shown how one oak species has facilitated the dispersal of another, like hitchhiking. In other situations, hybridization has contributed to the adaptation of another species by sharing its genes and thus helped the partner species to get established on new sites.
In short, caricature has virtues when it shows evidence. This comparison suggests that it would perhaps be better for oaks to be concerned with the conservation of Homo sapiens than the other way round. In spite of its technology and its mastery of the physical world, it is not sure that Homo is as well equipped to maintain itself as Quercus. Such reminders should recall Homo for more humility and modesty on our planet, and cohabit in better intelligence with his neighbors living beings whether they are oaks or other organisms. It is time for Homo sapiens to sit near Quercus sapiens.