Marseille in France one million years ago: a garden of Eden?

1 Ma (million years ago), a migratory wave from the east consisting of men (Homo erectus) and animals (large mammals) swept over the northern Mediterranean shore with the objective of conquering new territories.


At that time, the ecosystems they sought to ensure their survival were wet habitats — true oases of life and potential food within an otherwise arid Mediterranean environment. The tufas of Marseille, with their ecological diversity, edible plants including proto-cereals, fruits, and herbs, and their water resources, provided a favorable site for this migratory dynamic.

A multidisciplinary study involving the CNRS Terre & Univers (see box), focusing on fluviatile calcareous tufa deposits, offers a reconstruction of the paleoenvironment of Marseille at the beginning of the Pleistocene, 1 Ma. Paleomagnetic measurements have identified the Jaramillo magnetic reversal, dating the tufas of Marseille between 1.06 and 0.8 million years.


Sedimentological data show the existence of a varied depositional environment, including natural dams formed by plant accumulations stabilized by carbonate precipitation, thus promoting the development of upstream bodies of water bordered by marshlands. Carbon isotope ratios indicate that the Marseille tufas are not travertine but are associated with cold water springs and flows. Climate reconstructions based on pollen data indicate a slightly cooler (especially in winter) and wetter climate than today.

Analyses of fossil pollen reveal a semi-wooded, diverse, mosaic landscape dominated by a Mediterranean forest of pines and oaks, with beech, fir, and spruce, species that are now rare or no longer grow at low altitudes in Provence due to human occupation. The presence of chestnut trees is unexpected in calcareous environments, but this tree could thrive on de-carbonated Oligocene clays that were exposed throughout the Marseille basin. Along watercourses, the riparian forest was diverse and included walnut and plane trees, much like what we see today in the eastern Mediterranean, along with alder, willow, hazel, and ash.

The potential diet of early hominins, reconstructed from pollen and plant macrofossils, was varied and included the fruits of chestnut, hazel, walnut, and tree Rosaceae like various species of plum or apple. Grape remains have also been found, showing that grapes were already part of the diet of frugivores, including hominins. Among the many edible herbs identified, notable were the Compositae family, which includes many salads, nettles, or mallow, a plant especially appreciated in North Africa.



The hominin populations could potentially have fed on resources from the sea, which were diverse at the time, as well as terrestrial resources, including large herbivores. The most surprising discovery is the presence of cereal pollen (proto-cereals due to their antiquity), including rye that has been identified.

These proto-cereals, which grew among the steppe herbaceous flora, could have substantially enriched the carbohydrate intake of the mammals (including hominins) that frequented the Marseille basin one million years ago. The Marseille basin is the third site, after Acigol and Kocabas in southwestern Anatolia (Andrieu-Ponel et al., 2021), to show the presence of proto-cereal pollen long before the advent of the Neolithic period 12,000 years ago.

The identification of coprophilous fungus spores indicates the in situ presence of large herbivore herds. It is possible that, as in Anatolia, ecosystem disturbances by large herbivores triggered the genetic mutation of grasses, leading to the emergence of cereals. These sites demonstrate that human populations were not responsible for the emergence of cereals but rather that this was a natural process linked to biotic interactions between large herbivores and steppe ecosystems.

During the Neolithic, humans, who had become farmers due to the reduction of mammal fauna, would have cultivated edible plants that pre-existed in herbaceous ecosystems. This new discovery of proto-cereals calls for a revised view of the history of human nutrition, as previously suggested (Andrieu-Ponel et al., 2021).


References:
Andrieu et al., Vegetation, climate and habitability in the Marseille basin (S.E. France) circa 1 Ma.
Geosciences 2024, 14(8), 211.