The South African scientist who shook the literary world by suggesting the Bard smoked dagga is not letting up. Professor Francis Thackeray's latest shock is that Homo naledi did not bury their dead. He arrived at his conclusion after analysing some of the 1550 bone fragments found in an isolated chamber 30m below ground in the Cradle of Humankind.Last year, Thackeray declared that Shakespeare was a "stoner" after chemical analysis of the playwright's pipes.When the new species Homo naledi was revealed last year by Professor Lee Berger of the University of the Witwatersrand and his international team, one of the most astounding details was that Homo naledi had deliberately deposited their dead.But Thackeray, of the Evolutionary Studies Unit at Wits, is having none of that. He says it can't be true because there is evidence of lichen on the bones, and it could not have grown without daylight."There could have been a second route into the caves," he told the Sunday Times this week. "Maybe the 15 individuals, a family, were actually in the Dinaledi chamber when there was a roof collapse. It could have been an emergency situation."story_article_left1Thackeray's research paper will be published next month in the South African Journal of Science, and it comes hot on the heels of a critique by Wits postdoctoral fellow Aurore Val, who argues that the assumption of dead bodies being deliberately deposited was made without enough evidence."The Dinaledi chamber ... would not have been accessible without the use of some kind of light source," she said, and since there was no date yet for Homo naledi's existence, a "meaningful investigation of the possibility of fire use" was impossible.It all adds up to the equivalent of a courteous game of Cluedo for palaeoanthropologists, who are quick to praise each other's expertise.This week, Berger was named one of Time magazine's 100 most influential people of 2016, and Thackeray said: "I have enormous respect for Lee and his amazing research. I am also grateful they gave me access to the bones."Berger, for his part, said he had "enormous respect for Thackeray". But he was sticking to his guns.When the new species was announced last year, the public was enthralled by its strange body - a patchwork of features previously thought not to go together.It was the biggest hominid fossil find on African soil, and the news that Homo naledi had deliberately deposited their dead also captured the popular imagination.The researchers said carnivore activity was ruled out, as was falling or flooding or any other catastrophic event, so they must have dragged their dead into the chamber through an elaborate cave system and a tiny entrance of 20cm.This made Homo naledi the only other species apart from Homo sapiens that had a ritual for "burying" bodies.But Thackeray said they could have made it into the chamber alive and died there."Even to this day in the Cradle, rocks are tumbling down where there are already chimney-like passages from the surface. They could have been trapped when that happened," he said.mini_story_image_hright1This would mean that the carrying of bodies through tiny dark passages and a 20cm opening was not the only possible explanation.Thackeray said black spots on the bones supported his theory. They are made of manganese dioxide, which is related to the growth of lichen."This would mean there was definitely some light penetrating the cave."Berger said that even if there was another entrance, "it wouldn't change our result and belief that dead bodies were deliberately deposited. It would still mean the chamber was restricted and we know that no predators or scavengers got in."Also, sediments in the chamber were different from those in the rest of the cave, which meant that nothing had entered from the outside: the chamber was isolated from the earth surface and other chambers in the cave."[The] current entry point was always the entry point into the chamber," said Berger."[Thackeray's] is a flimsy hypothesis. Even if we showed there was sunlight coming in, there is no evidence of a collapse or any other catastrophic event, so I am sticking with my theory."sub_head_start He's got the world talking sub_head_endProfessor Lee Berger, named this week among Time magazine's 100 most influential people of 2016, has spent two and a half decades studying millions of years of human evolution - and has got tongues wagging and arguing in the process.According to Time's citation, by Jeffrey Kluger, on why Berger was included, this is a sound measure of his influence."One way scientists know they've had an impact is if they've gotten their peers talking. A better way is getting them arguing. By that measure and others, Berger, a palaeoanthropologist at the University of the Witwatersrand in South Africa, has had a huge year."But Berger is the first to acknowledge the support around him that has made for a "huge year".Talking to the Sunday Times this week, while presenting a series of lectures at institutions in his native US, he said: "I was not expecting this at all and it is a pleasant surprise. I need to point out, however, that all the work I have done has been supported by an amazing team of other people."Berger brought light to the mysteries of our ancestry last year when he led the team that discovered, analysed and described Homo naledi - fossils of which were found underground at the Cradle of Humankind.Before that, he was celebrated for his work on the most complete fossils of our early human ancestor Australopithecus.While heated debate on his work is likely to continue, Time managing editor Nancy Gibbs pointed out the value in this: "As much as this exercise chronicles the achievements of the past year, we also focus on figures whose influence is likely to grow, so we can look around the corner to see what is coming."farbert@sundaytimes.co.za..