Marseille a million years ago: a Garden of Eden?

Marseilles, an oasis of life and food

A million years ago, a migratory wave of humans (Homo erectus) and large mammals from the east swept across the northern Mediterranean shore, aiming to conquer new territories. At the time, the ecosystems they sought to ensure their survival were wetlands, veritable oases of life and potential food in the midst of a generally arid Mediterranean environment. The Marseilles tuff, with its ecological diversity, its edible plants including proto-cereals, fruits and herbaceous plants, and its water resources, was a favourable site for hosting this migratory dynamic.

By reconstructing the Marseilles paleoenvironment at the beginning of the Pleistocene, paleomagnetic measurements have enabled us to identify the Jaramillo magnetic inversion and date Marseilles' tuff between 1.06 and 0.8 Ma. Sedimentological data show the existence of a varied depositional environment including natural dams formed by accumulations of plants stabilized by carbonate precipitation, favouring the development of upstream water bodies bordered by swamps. Carbon isotope ratios indicate that the Marseille tuffs are not travertines (carbonate formations associated with hydrothermal water resurgences) but are associated with cold-water springs and flows. Climatic reconstructions based on pollen data indicate a slightly cooler (especially in winter) and wetter climate than the present.

An environment rich in plant species that are now rare

Fossil pollen analyses indicate a semi-arborate, diverse, mosaic plant landscape, dominated by a Mediterranean forest of pine and oak with beech, fir and spruce, species that are now rare or no longer grow at low altitudes in Provence, mainly due to human occupation. The presence of chestnut is unexpected in a limestone environment, but this tree was able to grow on the Oligocene decarbonate clays that outcropped everywhere in the Marseille basin. Along the rivers, the riparian forest was diversified and included walnut and plane trees, as is the case today in the eastern Mediterranean, and trees such as alder, willow, hazel, and ash. The potential diet of the first hominins, which we have reconstructed from pollen and plant macroremains, was varied and included the fruits of chestnut, hazelnut and walnut trees, as well as arborescent Rosaceae such as various species of plum and apple. Grapevine remains have also been found, showing that grapes were already part of the diet of frugivores, including hominins. Among the many edible herbs identified are the Compositae, which include many salads, nettles and mallow, a plant particularly popular in North Africa.

Discovery of proto-cereal pollen

Hominin populations were potentially able to feed on sea resources, diversified at the time, and land resources, including large herbivores. The most surprising discovery was the presence of cereal pollen (proto-cereals because of their age), including rye, which was identified. These proto-cereals, which grew within the steppe herbaceous procession, were able to substantially enrich the diet of mammals (including hominins) that frequented the Marseille basin a million years ago with carbohydrates. The Marseilles Basin is the third site after those of Acigol and Kocabas (Andrieu-Ponel et al., 2021), in south-western Anatolia, to show the presence of proto-cereal pollen well before the start of the Neolithic period, 12,000 years ago. The identification of spores of coprophilous fungi shows the presence in situ of herds of large herbivores. It is possible that, as in Anatolia, the disruption of ecosystems by large herbivores was responsible for the genetic mutation of Poaceae and the appearance of cereals. These sites show that human populations were not responsible for the appearance of cereals, but rather that it was a natural process linked to biotic interactions between populations of large herbivores and steppe ecosystems.

In the Neolithic period, man, having become a farmer out of necessity due to the reduction in mammalian fauna, would have cultivated edible plants that pre-existed in herbaceous ecosystems. This discovery of proto-cereals calls for a new vision of the history of human nutrition, as previously suggested (Andrieu-Ponel et al., 2021).

This article is available through open access. It can be downloaded in its entierty.