Scientific evidences point to human activity in ancient times on both sides of Ram Sethu (the narrow sea between India and Sri Lanka) as found by Dept. of Earth Sciences and ocean technologists of Bharatam.
     The Geological logging of the bore holes drilled in the inter tidal areas of Ram Sethu reveals very interesting details. In all the bore holes the top portion is seen to be occupied by recent marine sands. In almost of all the boreholes between 4.5 and 7.5m the borehole intersected hard formations, which have been found to be calcareous sand stones and corals. It is to be pointed out here that Corals are comparatively less dense, compact and somewhat easy to carry.
     The Corals normally grow atop compact to hard formations for the purpose of stability, and as the sea level rises, the Coral colony grows up vertically to maintain water depth of 1 to 2 m, which is essential for their survival. In the case of Ram Sethu area, we observe that the Coral formations hardly occur 1 to 2.5m in length and resting on loose marine sands. Most of these coral rock pieces are seem to be rounded pebbles of corals. These things appear to point these coral rock pieces and pebbles have been transported and placed in these areas. Since the calcareous sand stones and Corals are less dense than normal hard rock and quite compact, probably these were used by the ancients to form a connecting link to Sri Lanka, on the higher elevations of the Ram Sethu ridge and this is analogous to modern day causeway.
     In support of these observations there are many archaeological and geoarchaeological evidences on the south east coast of India around Rameswaram, Tuticorin and the western coast of Sri Lanka. There are raised Teri formations that supported a rich assemblage of mesolithic—microlithic tools indicating the presence of strong human habitation and activity in these areas as early as 6000 to 7000 years BCE and as recent as 2000 years BCE. On Sri Lanka side there are indications of human habitation extending to late Pleistocene (about 11,000 BCE) based on bone and fossils of human and animal form.  All these point to a flourishing human activity on both side of Adams Bridge and probably when the sea levels were just right the link between India and Sri Lanka could have been established.

Sources: Dept. of Earth Sciences, Government of India (March, 2007), Organiser (29 April 2007)