Over the last two decades remarkable advances have been made in our knowledge of the archaic hominins presence in the Aegean Sea Islands (Kopaka and Matzanas, 2009; Runnels, 2014; Runnels et al., 2014; Carter et al., 2019) and the surrounding mainland [the Hellenic peninsula (Runnels, 2001; Harvati et al., 2009; Galanidou et al., 2016; Bartsiokas et al., 2017; Tourloukis and Harvati, 2018; Harvati et al., 2019; de Lumley et al., 2020), Anatolia (Kuhn et al., 1996; Runnels and Özdoğan, 2001; Dinçer, 2016; Baykara et al., 2016) and the Levant (Shea, 2008)] (Fig. 1 and Table 1). These advances in conjunction with the known palaeo-geographical configuration of the Aegean Sea (Lykousis, 2009; Sakellariou and Galanidou, 2016, 2017; Tsakanikou et al., 2020) suggest that archaic hominins, first visited the present-day Aegean islands as early as mid-Middle Pleistocene. The question is whether they reached there on foot or by sea. The present consensus is that archaic hominins were crossing the Aegean on foot during glacial sea-level low-stands when the Aegean was sub-aerially exposed and connected to the Hellenic Peninsula and Anatolia (Carter et al., 2019; Sakellariou and Galanidou, 2017; Tsakanikou et al., 2020). However, Runnels (2014); Runnels et al. (2014); Howitt-Marshall and Runnels (2016); Leppard and Runnels (2017), based on the presence of late Middle and Late Pleistocene endemic fauna in the islands, which is indicative of their insularity, argued that archaic hominins sea-crossings could have started earlier in the Aegean. Similarly, Ionian Sea studies have shown that Neanderthals crossed to the southern Ionian Islands from the Hellenic peninsula between 110 and 35 ka and pre-Neanderthals probably as early as 200 ka BP (Ferentinos et al., 2012).
This paper aims at shedding further light on whether archaic hominins crossed the Aegean on foot or by sea. To answer this question, the insularity of the Aegean Sea islands from the surrounding mainland during the mid-Middle and Late Pleistocene, is examined in association with the spatiotemporal pattern of the early and middle Palaeolithic lithic industries and hominin remains in the Aegean Sea and the surrounding mainland. This paper: (i) provides a detailed restoration of the palaeo-shoreline configuration of the Central Aegean Island Chain (CAIC) (Fig. 2), that offsets the tectonically driven subsidence prevailing in the area, (ii) points out the tectonic component effect on sea-level fluctuation and its importance to the paleogeography, (iii) discusses when archaic hominins started sea-crossing the Aegean, and the palaeo-shoreline configuration impact in motivating them to attempt sea-crossing and (iv) provides evidence that the archaic hominins in their “Out of Africa” to Europe dispersals, used terrestrial as well as marine routes.