Man could have descended from a predatory marine fish that lived some 500 million years ago.

This was concluded in a 25-year study which found that majority of vertebrates, approximately 65,000 of them, descended from a common ancestor that had a well developed electoreceptive system. Of the 65,000 living vertebrates, some 30,000 are species of land animals and this include humans.

In a report that came out in the October 11 issue of Nature Communications, the study found out that the ancestor was probably a predatory marine fish with good eyesight, jaws and teeth and a lateral line system for detecting water movements.

The study was conducted by Willy Bemis, Cornell professor of ecology and evolutionary biology; Glenn Northcutt, a world expert on vertebrate neuroanatomy based at the Scripps Institution of Oceanography and Claire Baker, also of the University of Cambridge. Melinda Modrell, a neuroscientist at the University of Cambridge, is the lead author.

According to Bemis, the study caps questions in development and evolutionary biology, popularly known as "evo-devo" that he has been researching on for 35 years.

The study claimed that a major split in the evolutionary tree of vertebrates happened hundreds of millions of years ago with one lineage leading to the ray-finned fishes or actinopterygians, and the other to lobe-finned fishes or sarcopterygians. The latter group gave rise to vertebrates.

The study found out that some land vertebrates including the salamander, have electroreception which is also present in some ray-finned fishes such as paddlefishes and sturgeons. Using the salamander and the paddlefish as models, the researchers found that electrosensors develop in almost the same pattern from the same embryonic tissue in the developing skin, confirming that this is an ancient sensory system.

Another compelling evidence that the two sensory systems share a common evolutionary heritage was the finding that the electrosensory organs develop immediately adjacent to the lateral line, the study said.

With this study, researchers can now build a picture of what the common ancestor of these two lineages looked like and better link the sensory worlds of living and fossil animals, Bemis said.