We may not have been able to see ghosts, but in our earlier, fish-like form, we did have a sixth sense, according to a study.
Scientists have discovered that we are descended from a predatory fish-like ancestor that roamed the oceans 500million years ago and had 'electrosensors' - the ability to detect electric fields in water.
It used this skill to detect prey, communicate and to find its way around.
Researchers at the University of Cambridge and Cornell University in New York believe that not just humans, but 65,000 living vertebrate species - that's any creature with a spine or backbone - are descended from the beast.
This includes 30,000 species of land animals - including humans - and a similar number of ray-finned fish, the scientists found.
Their conclusions, which appear in the latest edition of Nature Communications, mark the culmination of 25 years of work into the subject.
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| Older, but probably not wiser: The first 'fish' to walk out of the sea 375million years ago may have looked something like this |
'This study caps questions in developmental and evolutionary biology, popularly called "evo-devo" that I've been interested in for 35 years,' said Willy Bemis, Cornell professor of ecology and evolutionary biology and a senior author of the paper.
He explains that hundreds of millions of years ago, there was a major split in the evolutionary tree of vertebrates.
One lineage led to the ray-finned fishes, or actinopterygians, and the other to lobe-finned fishes, or sarcopterygians.
The latter gave rise to land vertebrates, some of which, such as the Mexican axolotl salamanders, retained electrosense ability.
Some ray-finned fish, including paddlefish and sturgeon, also retained these receptors.
Professor Bemis and his team found that the electrosensors of the ray-finned fish and the salamander developed in precisely the same pattern from the same embryonic tissue in the developing skin, confirming that this is an ancient sensory system.
'These two sensory systems share a common evolutionary heritage,' added Bemis.
However, over the years reptiles, birds and mammals lost their electrosense as it wasn't needed for life on terra firma.
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