Scientists, academics and medics gathered this week in a London hotel to discuss a topic that has been virtually unmentionable in academic circles for decades - did humans descend from aquatic apes that spent more time swimming than dragging their knuckles on the ground?
The last time this question was asked, at a conference in 1992, there was much scoffing and ridicule. Other academics sneered and Bernard Levin wrote a full-page article lampooning the idea in a national newspaper, the Independent reported.
This week's conference, Human Evolution Past, Present and Future - Anthropological, Medical and Nutritional Considerations, at the Grange St Paul's Hotel, has also already been the subject of much derision.
Followers of the conventional and overwhelmingly accepted belief that our ancestors were very much land-based are launching a parody campaign online to argue we evolved from space monkeys.
Most scientists will openly scoff at the idea of us deriving from water-bound primates.
But, perhaps emboldened by the presence of Sir David Attenborough - who was booked to attend the conference for one session but asked at the last minute if he could attend both days - the aquatic ape theorists are back.
The conference is chaired by Professor Rhys Evans, an ear, nose and throat surgeon at the Royal Marsden Hospital, who is candid about the scope of the conference.
"We are trying to discuss the pros and cons of the theory," he said.
"But many of the things which are unique to humans - such as a descended larynx, walking upright, fat beneath the skin, and most obviously an extremely large brain - it seems can best be accounted for as adaptations to extended periods in an aquatic environment," he added.
The original aquatic ape theory, developed by Sir Alister Hardy and made public in 1960, posited that a population of early humans, or hominoids, was isolated during tectonic upheaval in a flooded forest environment, similar to that of parts of the Amazon.
Our ancestors, it was argued, either adapted to water - and climbing in trees - or died out.
Over many generations, mutations that made swimming and diving easier reproduced in the population at the expense of the more traditional, water-averse ape genes.
Modern-day apes do not like water. In zoos all around the world, apes are contained by moats of water.
Even wadeable moats are sufficient: if you drop a baby orangutan into water, it sinks like a stone.
A human baby, however, will close its larynx and automatically paddle its arms and legs, giving you a few precious seconds to retrieve it.
The aquatic ape theory would explain this ability - unlike the traditional savannah theory of human evolution.
Widely accepted wisdom states that when humans came out of the woods and on to the savannah, walking upright gave them an increased field of vision and freed up hands to use tools.
Bipedalsim also exposed less of the human body to the harsh sun and humans shed hair and increased sweat production to cope with the heat.
But, the aquatic ape proponents point out, deer and antelope kept their fur and their quadrapedal ways on the savannah.
Our copious salty sweat production, and water consumption requirements, they argue, are far more indicative of life in the water.