The doctor who discovered shocking brain injuries in American football stars has predicted that people will stop playing contact sports within "one generation".
Doctor Bennet Omalu was the pioneering neuropathologist who first discovered chronic traumatic encephalopathy (CTE) in the brains of NFL stars.
In an interview with the Sydney Morning Herald, Omalu, who was played by Will Smith in the Hollywood film Concussion, said: "In the next generation or two, mankind won't be playing sports like rugby or football or ice hockey or mixed martial arts.
"It just doesn't make sense to be damaging the brain of a human being."
The Nigerian-born doctor also called for a ban on children playing contact sports: "It's almost like child abuse, to intentionally expose a child to injury," he told the SMH.
Omalu first began developing his theories on CTE when he conducted an autopsy on former NFL player Mike Webster in 2002.
Webster had once won four Super Bowls but died penniless, only able to sleep by tasering himself.
Omalu found large amounts of tau protein in Webster's brain. The protein affects the brain in a similar way to how beta-amyloid proteins contribute to Alzheimer's Disease.
Omalu published his findings in 2005, calling for further study of the disease: "We herein report the first documented case of long-term neurodegenerative changes in a retired professional NFL player consistent with chronic traumatic encephalopathy (CTE).
This case draws attention to a disease that remains inadequately studied in the cohort of professional football players, with unknown true prevalence rates."
The NFL tried to play down the findings and hired their own specialists to discredit Omalu's work.
He went on to study more NFL players and public awareness of his work increased, resulting in the NFL finally acknowledging a link between their sport and long-term neurological effects in 2009.
It took until 2016 for a senior NFL executive to testify before the US Congress that the organisation believed there was a link between gridiron and CTE.
A Herald investigation in 2016 found numerous cases of former rugby players who went on to develop dementia.
Speaking to Herald journalist Dylan Cleaver, clinical neuropsychologist Dr John Glass said of the link between rugby and dementia: "There's a pattern and it's sad."
A group of top US scientists told the Herald earlier this year that no child should be playing contact sport before the age of 12, saying that tackling might be too much for the brain development of young children.
Dr Bob Cantu, the "Godfather of Concussion" said a key factor in developing CTE was not the severity of the trauma but "the total amount of hits you took and when you started taking them".
Cantu said impacts received when young came at a greater price than those as an adult, regardless of force, and was adamant there should not be any tackle codes until high school.
"Your neck is weak and your brain isn't myelinated, and it's easier to disrupt brain fibres," he said.
Earlier this year, New Zealand Rugby head of medical Ian Murphy said there was still much to learn about the risk-reward of contact youth sport and said his organisation would continue to offer tackle rugby to children, with a continuing onus on technique.
"You're seeing an emerging discussion around non-contact forms of contact sports at younger ages. That's emerging slowly. It's arguably not a bad thing but I think there'll always be a group that likes to play the contact form of games," Murphy said.